Aermacchi engine tear down // Paul Brodie's Shop

[@krabatparakan8929]

Nice to see you in youtube, very clear explaination... Like a teacher in classroom... Hope to be your student❤❤

[@paulbrodie]

Thank you Krabat. Yes, I did use to teach Framebuilding 101 at a local University for almost 10 years, and I really did enjoy that....

[@kennethbowry1521]

For Gods sake the Engine Stand is a work of Art.

[@paulbrodie]

Thank you for thinking so... 🤒

[@feltwashers]

This is my kind of entertainment! It would be interesting to see a shot of all the custom tools that you made/use for this process in one view. Thanks for sharing Paul and Mitch

[@paulbrodie]

Thank you. Never even thought about one shot of all the tools. We'll do that for assembly...

[@andyZ3500s]

I wish I made your comment. That would be a good one.

[@jeffkeen6943]

Paul straddles the divide between a race bike builder and a mad scientist...don't you love it!!! 🙂

[@wilsonlaidlaw]

Very nostalgic for me. I used to have a 1964 Ala D'Oro 350 with the motor originally built by Sid Lawton of Southampton, UK and then rebuilt by Dave Lintott (who built the one off 500 and 700 Aermacchi Twins) of Cranleigh UK. I regret selling it in 1981 but at the time, needed the money.

[@paulbrodie]

We will be building that motor soon. The frame awaits!

[@dannysunwantedopinions]

God bless you for not ruining these timeless videos with annoying and unnecessary music overlays. ❤

[@paulbrodie]

Danny, thanks for watching!

[@colinmartin2921]

I love these old Italian bikes. Thank you Paul.

[@paulbrodie]

You and me both! Thanks for watching :)

[@glenpiro313]

Another exceptional episode! I very much enjoyed the explanations in regards to the stock VS modified parts. Removing two pounds of rotational mass from the internals? That must make a massive difference!!!!!! I have split approximately 6.23 million engine cases (that may be embellished....) since I was 13, and learned very early on that screwdrivers were a No No!!!!!! I will tell you right now, I jumped three times in this video, first when the wrench slipped , then when the kabooms happened with the puller....... I thought for sure you had broken the cases!!!!!! Thankfully I was wrong, but good god that was tight!!!!!! Great stuff!!!!!!!

[@paulbrodie]

Thanks Glen. Yes, I have already polished a few tenths off the shafts. Way too tight!

[@otillahickmon1067]

My 350 sprint has been in my garage the last four years, thank you for this video

[@paulbrodie]

Thanks Otilla :)

[@prostwest]

The 14 seconds at 5:11 is literally the best unboxing video the internet has ever seen.

[@tomthompson7400]

We love Mitch , and of course Pauls great too ,,, now its coffee and a sit down to watch the new content. All I need to finish the thing off is a suggestive biscuit and a signed T Shirt with a picture of Mighty Mitch on. Messing aside , its amazing how having the right tool for the job just speeds things along , the investment in time to make such tools must have yielded dividends many times over. Very interesting to see all the details and where changes have been made.

[@paulbrodie]

Thanks Tom. I'm sure Mitch feels the same way about you.

[@Timoteo53575]

Had no idea how well built these motors were. Now it's "clear as a bell"...

[@CNCMachinistEducationNetwork]

Great series of videos. I teach machining last 10 years. I also build and race Kawasaki Dragbikes and used to work at a motorcycle machine shop. Plus I did 30+ years ago as a CNC machinist for many companies. I can appreciate all that you do and the practical way you approach it. And how methodical you are. I will continue to watch and share with the class - I think to see the use of what an engine assembly is and its relationship to machining. It starts to make more sense the difference between clearance holes and press fit holes. etc. thks again paul

[@paulbrodie]

Thank you! You certainly have a lot of experience too. I appreciate you sharing with your class :)

[@Paddington60]

Hi Paul, I was once on a boat with two V8 Cat engines. One overhaul the lock tabs were not bent up to stop a small end coming adrift. So, the small end came free and then it beat its way out through the side of the engine, the lack of oil pressure stopping the engine. I think it was US $68,000.00 for a short engine. Jolly useful chaps lock tabs!

[@paulbrodie]

Good story! Thanks.

[@garygable2312]

I saw your 1972 race engine tear down, my question is will the race gears fit my 1973 engine, love your show, Thanks

[@paulbrodie]

Thanks Gary. To the best of my knowledge, the race gears should fit your '73 motor...

[@garygable2312]

@@paulbrodie my last question is we’re can I buy them,Thanks again

[@paulbrodie]

@@garygable2312 I bought mine years ago from Rudolf Jungjohann in Germany, but he is retiring so I'm not sure if he has any left...

[@garygable2312]

@@paulbrodie Thanks for your help

[@thebones]

I loved that, it was really interesting to dee what an expert tuner does to a stock motor, thanks Paul.

[@paulbrodie]

Thank you.

[@davidprocter3578]

Over the years I have had two bicycles two motor cycles two cars and a van stolen, careless of me I know. It is a real pain in more ways than one, particularly when you have time and money invested in them and they have attained a place in your heart. The only one I did not really care too much about was the van. All the rest had history and great stories leaving me with definite holes in my life but some wonderful memories.

[@paulbrodie]

Yes, having a hand made race bike stolen really left a big hole in my life. I know what you are talking about.

[@ruko6286]

Great video, thanks. One additional info: as far as I know only the standard bikes had this press-fit between shaft and bearing. The original racers had a slide fit and their cases are easier to split

[@paulbrodie]

Thank you. That would make sense that the original racers had a "slide fit" for their bearings..

[@tomfortson5147]

Hi Paul & Mitch, --Mitch, God's gonna get you for laughing at Paul!!! (Yes, it WAS funny!) Paul, I really enjoy your ability to create these special tools. WOW! I can see how they make the job possible. Without them, a person would be helpless! Great episode!

[@paulbrodie]

Thanks Tom. I can't not say something when Mitch has a huge grin on his face...

[@squidcat2024]

Every second is worth watching while learning at the same time...another awesome video, thanks, Paul (& Mitch) 😃👍!

[@paulbrodie]

Thank you Eric.

[@ralphnorris-vk8ff]

I had a 1969 350ERS and it was the fastest 350 I ever rode! I was 16 when I bought it new and I'm 71 now and still wish I had it back!

[@paulbrodie]

I hope you are able to find another 350.. It will be worth the Chase :)

[@bryanwhitton1784]

The special tools needed is what makes me hesitant to tear down my Sprint. I have the parts I know of to convert my 1972 Sprint into a 1973 W/O the heavy electric start and alternator. 5 speed transmission, head, studs etc. But trying to find/build those tools would be a major issue.

[@paulbrodie]

Yes, I made all of my special tools, and I have a lot of them... Trying to find factory tools would be very difficult. You say you have all the parts, but there are a lot of of small stuff like locking tabs, o-rings, shims and gaskets, so I really doubt you have "everything". When Moto Italia sold and vanished, they really did leave a big hole in the Aermacchi parts trade...

[@bryanwhitton1784]

@@paulbrodie You are correct on that. I know I don't have those parts but I never figured that Moto Italia would go away so quickly. I was talking to him about my old 71 Sprint that he purchased many years ago. He said he still had it. I said I might be interested in getting it back. Tom Sifton built the motor and it ran like a scalded cat. I can't tell you how many generator armatures I replaced. I could rev that motor way high. he put in a custom cam and push rods and ported the head. I don't know what else he may have done. My uncle was Sam Arena and owned the Harley Dealership in San Jose. He purchased my Sprint then gave it to Tom to "fix". My uncle decided he didn't want it after all and sold it to me. I flat tracked an 1969 ERS for a couple of years before replacing it with a Kawasaki Bighorn. The ERS had a BSA .040 piston in it. The piston land height was taller than a Sprint so it had what looked like a stroker plat below the cylinder. We had to clay the piston and grind judiciously to get it to spin over. Lots of compression. Built a manifold and mounted a 32 mm Mikuni on it and got the jetting from Mert Lawwill. It ran REAL well after that.

[@roybartran6756]

thats a great little engine after you work your magic on it......love it

[@paulbrodie]

Thanks Roy.

[@paulgaudio3266]

Hey Paul B… will we see you and your Aermacchi at the AHRMA race at the Ridge!? I’m prepping mine!!

[@paulbrodie]

Hi Paul! Long time no see. I broke my leg badly 3 years ago so I am not a racer anymore. Everything changes. Hope you are well.

[@millarfarewell5343]

Well guys, a very interesting show. I see many similarities between this engine and the 125 cc Rapido Silver Wing engine I raced back in the 70's at Westwood. The tapers on the primary drive gear and the racing clutch details are similar. The special tools you made really help get the engine apart without damage.

[@paulbrodie]

I was at Westwood in the 70's :)

[@andrewwasson6153]

Really neat stuff again Paul. I’ve got several mid-80’s GSXR’s but I’ve always had a penchant for cafe race bikes with spoked rims, long fuel tanks and Rickman fairings. I’m not sure I’ve got room in my shed for one so I’ll just live vicariously through your KZbin channel.

[@mikeydizme1]

Great info. Thanks. Beautiful old machine.

[@paulbrodie]

Thanks Mike!

[@rickfazzini22]

I just tore down a 2 stroke KX250 they also require a case separator to split them. Thanks for sharing guy's as always very entertaining!

[@paulbrodie]

Thanks Rick.

[@tiffinthyme5822]

Hello Paul, this was a very entertaining episode. (Flinch included!) I was fascinated watching you split the cases, bearing in mind the engine hasn’t run, I could only imagine what splitting a used motor would be like. My mind was going ahead of time imagining you having to press the cases back together, a nervous time. I hope you ease the connections to help? Good luck! Thank you again Kevin.

[@paulbrodie]

Thanks Kevin. That engine had run. I raced it either one or two seasons. Can't remember. I polished the shafts so it will be easier to get back together.

[@tiffinthyme5822]

@@paulbrodie I’ve worked on a few 1970’s (and older)engines and getting them apart after so many years is half the challenge, without making mistakes. I do enjoy your methods and the gadgets to achieve it. But the pressure you had to apply was setting my teeth on edge! Thanks again Kevin.

[@lynxg4641]

Paul's favourite tool, "The Persuader" ;-)

[@ОлександрФедосєєв-ц3х]

Thanks guys, for another one nice series. P.S. nice hat, next to "Sartorius'' ;-)

[@randyroy4074]

Watched again. Enjoyed it as much as the first time. Thanks. I've a 125 Stornello I've split so this is instructional.

[@Manandmachine772]

Very informative and enjoyable video. Please do some more videos on the aermacchi.

[@paulbrodie]

Thanks Carl. More Aermacchi videos are in the works.

[@Manandmachine772]

Woohoo!!!

[@twowheels90]

Love all the special tools you made for the engine

[@paulbrodie]

Yes, I have a few. We will have an aerial shot of them all in an upcoming episode.

[@VashSpiegel]

This is great, always wanted to buy one just to check out the engines.

[@fairthorpefanatik1700]

Paul, ARP makes 12 point cylinder head nuts in a variety of sizes. They would be lighter and they typically could use a smaller diameter wrench. Loving your channel and learning a lot from you . Thanks to you and Mitch!

[@paulbrodie]

My Excelsiors use ARP studs for the barrel and heads. They make some very nice stuff. Thanks.

[@donsipes]

Thanks Paul. Good episode

[@paulbrodie]

Thanks Don.

[@matthewsmith6486]

Somewhere I've got a Hot Rod magazine that tests a 250 Aermacchi/Harley Davidson scrambler. Early 60's I believe. Bob Green was the editor of the magazine and also a big motorcycle guy. Anyway Harley dyno'd every scrambler engine. There were 2 states of tune. Flat track and scramble. Each 250 had to make a certain number before they would release it. Something like 28 horsepower. I'm not sure most people know nowadays how fast and popular Aermacchi's were. Anyway I love what you're doing and how you're doing it. A very enjoyable video in a great series! I can't wait to see the bike all done.

[@paulbrodie]

Thanks Matthew! You're probably talking about the 250 2 stroke, correct?

[@matthewsmith6486]

@@paulbrodie No, laid down cylinder 4 stroke. I'll see if I can find it. It's a great article!

[@ralphnorris-vk8ff]

They did make a 250 sprint 4stroke in the early 60s. The 250 race bike was called a CRS and the 350 was a ERS.

[@diegobordon6364]

The real Máster of Special Tools!!! 😂 Fantástico episode!! 🏆🏆🏆🏆

[@paulbrodie]

Thanks Diego.

[@derekgee8504]

Great video Paul , thank you

[@paulbrodie]

Thanks Derek.

[@moabd4234]

Much respect! Thanks for sharing.

[@paulbrodie]

Thank you!

[@gordonhenagar6652]

You have put a lot of mods in that engine, really cool.

[@broxy55]

Case splitters make me nervous! Usually they only have three studs, and only 6mm at that! Splitting a modern dirt bike case takes a bit of force as well.

[@williambarry8015]

Is that a Peacock yacking @7:00?

[@paulbrodie]

Not sure... did Mitch sneak a peacock into the video and not say a word?

[@williambarry8015]

@@paulbrodie sorry I'm not a regular viewer but I am a bird nerd.

[@paulbrodie]

I did have peacocks until about a year ago, when I got sick and ended up in hospital. At that time I only had one male peacock, so I gave him back to the woman where he came from. I had peacocks for about 15 years, and the most I owned was eight. Beautiful birds, and fairly low maintenance.

[@leighharron]

As always, extremely interesting. And now with added jump inducing noises!

[@paulbrodie]

Yes, I jumped!

[@roberthoffmann6603]

Like a Symphonie. Thanks

[@paulbrodie]

Thank you Robert.

[@SandyBoneTube]

Hey Paul, Just enjoying yet another wonderful episode of mechanical delight by yourself and Mitch. At one point, when removing the clutch plates, you made a small tool from welding rod to pull out the plates. They immediately minded me of one of my favourite tools: for years I collected the wires or tangs which fell of street cleaner brushes, you know, the big circulating brushes that were mounted on street cleaner trucks. They are flat and just over and 1/8' wide made of fairly soft steel. They can easily be shaped and sharpened and bent to desire. I have a collection of them in my car, house and tool boxes and all for the price of looking down occasionally when walking city streets. Anyhow, I was wondering, for removing the clutch pates could you not just use a small magnet? You did ask. Just a thought. Thanks to you both for this wonderful programming and your creative genius in all things mechnical. I love what you do. Cheers.

[@paulbrodie]

Thanks Sandy. Yes, someone else has suggested small magnets for removing clutch plates. That could be a good idea!

[@andyguy1981]

Paul. While checking the crank make sure you pull the big end plugs out and clear the inside of the pin. The Macchi's a filthy engine and due to the oil feed hole going to the inside of the wheel all the debris gets stuck in there. Its best to do this a few times a season. You'll be amazed how much crud is in there in a short period. A little secret is to alternate the clutch plates, ie, two fibre plates together and same steel. You get the same frictional grip but helps control the slip on starts. Sounds like Tony Foale's trying to get his new bike out for June. Is that what you are aiming for?

[@paulbrodie]

Yes, I do know about the crankpin being used as a sludge trap. Will do. Never heard of bunching clutch plates like that. With the dished steel plate, starts are no problem. I am aiming to make more videos. I am retired from racing, unfortunately.

[@franciscomelendez3894]

Love those excelente Videos. My favorito engine, second to the Ducati Desmo (w/tower shaft), which is the one I desided to buy in mid '60.

[@franciscomelendez3894]

Did you know the LINTO?

[@paulbrodie]

Thank you Francisco.

[@paulbrodie]

@@franciscomelendez3894 I have read about the Linto. Known for being fast and fragile, I think.

[@UAVresearcher]

Did you make a video of putting the two cases together?

[@paulbrodie]

Yes, we did. It is lurking there somewhere in the Archives... I'm sure you can find it!!

[@TheOldaz1]

Seems to be well made, I've never seen one of these in the flesh. Thanks Paul.

[@paulbrodie]

Thanks for watching.

[@mohanrao8664]

Thanks for sharing . Lots of love from india !

[@paulbrodie]

Greetings to India! Thanks for watching.

[@lotus7even]

Great video love the way you work Paul great to see the detail. Is it worry that the cases could crack putting them back together

[@paulbrodie]

They were tight coming apart, so I sanded the shaft down a few tenths of a thou to make assembly easier. There is no good reason to have such a big interference fit.

[@lotus7even]

@@paulbrodie I hope your beginning to feel better Paul

[@paulbrodie]

@@lotus7even It's a long process with a lot of good and bad days. Today the pain is under control, so I would call it a good day.

[@itsverygreen532]

Very similar to my bevel Ducati inside ... with the obvious addition of an extra cylinder, but the construction is very similar!

[@thediddly]

Paul, please look for a ducati cylinder head spanner. This is what we use to torque heads down. It is basically a half moon ring spanner, with an allowance for a square drive. The torque setting don't need to be compensated as the ring side and drive side are in the same plane

[@maxwamsley6671]

Do you make the tools for tearing down Sprint engines?

[@paulbrodie]

Yes I did make all my own tools for working on Aermacchi motors...

[@maxwamsley6671]

@@paulbrodie do you make them for other people?

[@johnpublic168]

Shot blast and rms the gears less friction less heat more reliable. Like your mods great approach to racing. Enjoyed your Portland antecedent. A owner has to switch off when racing that leads to a few repairs.

[@malibu188]

Helical primary gear sets were also used by other Italian makers of that era . The early 500 cc V twin Ducati desmo 1982 also used a helical gear primary and clutch hub. The crankshaft bearings used were these massive angle contact spindle bearings, shims were needed to preload the bearings on assembly. I’m guessing this was to stop the crank being driven sideways off the helical spline and knocking each time the engine fired. Straight cut gears and normal bearings with no pre-load issues sounds like a great race modification to the engine.

[@paulbrodie]

Thanks for watching and commenting.

[@georgeboduch6015]

Great Videos,I Did find a 1971 350cc been in the rain and snow 30 yrs,Probly unsavable,I did get two 250cc sprints in bad shape going Yes parts are harder to find.Thank you

[@paulbrodie]

Thank you George.

[@RogierYou]

Are you still going to finish the Tiger Cub?

[@paulbrodie]

Of course. Parts are out for anodizing and nickel plating..

[@roundtuitracingaz132]

25:14 That's a fugly casting. Do you clean the flash off to prevent stress cracks or have you not had a problem with cracking cases? And I reviewed the oil line episode. Now I know why he hides behind the camera. (just teasing!)🖖

[@paulbrodie]

I have not had a problem with Aermacchi cases cracking.

[@alanmony1582]

Always good to see you and not see Mitch! I'd suggest replacing those *%?/#$ snap rings with Spiral Locks, much easier and just as secure.

[@MegaTubescreamer]

hi again Paul and Mitch, brill teardown exhibition, and most edifying. the raw materials for the motor though,, are a damned sight older than 50 years lmao ! 😂

[@paulbrodie]

Thanks William.

[@Tanshanomi]

I have been a longtime fan of Aermacchis, but I’ve never owned one because I was under the impression that maintaining them is a black art. This video has mostly confirmed my suspicions.

[@paulbrodie]

Black Art, eh?

[@paolofalini]

molto interessante...domanda:ma tra testa e cilindro non c è guarnizione? mi interessa SAPERLO..GRAZIE

[@paulbrodie]

Paolo, thanks for watching!

[@paolofalini]

@@paulbrodie l'd like to know it there is gasket betwen cylinder and header.... aermacchi 250 cc thank you Paoul

[@paulbrodie]

@@paolofalini Yes, there is an exhaust gasket between the cylinder head and the exhaust pipe. A parts list will show you that. To work on these bikes you need a parts list and a workshop manual...

[@paolofalini9065]

@@paulbrodie molto gentile grazie......i suoi video sono bellissimi

[@jessierubio5038]

thanks brodie for this! I just don't know how I=I'm going to find tools that'll work like the special tools you created wish I had you nearby to coach me

[@paulbrodie]

Yes, having the special tools really does make the job easier. I hope you find a way to make it happen. Thanks for watching! 😉

[@jessierubio5038]

@@paulbrodie any idea why my fork frame serial number doesn't match with serial number on engine?? 😁 once again thank you for what you do

[@paulbrodie]

@@jessierubio5038 Probably because someone has swapped out the motor. Frame and motor numbers match from the factory... 😉

[@jessierubio5038]

@@paulbrodie makes sense, if I ever have questions is there any way we could have a line of communication I have high aspirations to restore what I have

[@paulbrodie]

@@jessierubio5038 I do have an email address that can be found... 🙃

[@hordboy]

Head and cylinder reminds me somewhat of a Ducati. They have a neat U-shaped tool for doing the cylinder head nuts. Although I do have a modified 15mm similar to yours. 😀

[@starcarrier1874]

Hello Paul, does shortening the stroke offer more rpm’s? I always assumed the longer rod stroke provided more power, but maybe rpm’s are better? Now I know why Harley chose this manufacturer for their small bike. Interesting stuff!

[@paulbrodie]

Starcarrier, Yes, shortening the stroke can mean more rpms. But, I didn't shorten the stroke. I used a shorter rod. You might be confusing the two....

[@Seekelot]

I wonder if heat would help to get these crankcase halfs apart. Like on vintage BMW's where everything is an interference fit too, and heat is being used in almost every assembly/disassembly step. The aluminium expands a lot more then the steel, so that helps a lot.

[@paulbrodie]

I was removing the shaft from the bearing, so steel on steel. Using heat to expand the aluminum does not work here, but thanks.

[@thediddly]

Pulling the clutch pack out, 2 magnets do the trick to pull out the entire pack one by one. If Strong enough, it can bypass the friction plate. The higher the N number, the stronger the magnet.

[@stevevasquez7754]

I would be interested in pumping up my 1969 Sprint 350 as a tracker. Not so much eraser but one to go out have some fun and that's it and put it back in the garage.

[@paulbrodie]

Did spellcheck add "eraser" to your comment? I'm not exactly sure what you mean! Sprints are good project bikes for sure..

[@stevevasquez7754]

@@paulbrodie racer

[@paulbrodie]

@@stevevasquez7754 OK, I get it now.

[@johnbewick6357]

On the Benelli egg motors which are very similar to this we have to fit a wedge between the crankshaft webs when pulling the crankcases apart to prevent likely damage to the crankpin. I was very suprised you didn't use something similar.

[@paulbrodie]

The puller pulls the case off of the pinion shaft. I don't see how that is applying force to the crankpin?

[@johnbewick6357]

@@paulbrodie Yes I agree with you that it pulls the case off the pinion shaft, but the shock loading on the crankpin when it suddenly starts to move the bearing ought to be avoided. This is what Benelli recomends when dismantling and definately when reassembling.

[@Vikingman2024]

Nice video! Did you manage to cross the finish line when the engine blew? The engine cases seem overly big for the internals, although the manufacturing looks to be very good. Is the 5 speed racing gear upgrade also German made? Thanks!!

[@paulbrodie]

Thanks William! I was a DNF in that race. The cases look big because they also serve as the oil tank. Wet sump. The transmission is 73/74 Aermacchi with German gears for the final ratio. A higher ratio which also serves to make it into a close ratio transmission.

[@geraldfitzgibbon7428]

Hi paul an mitch. Back in the early 80s a lot of the 350 racers were areamaci.thos wer fast and low machines.on the irish road race scean

[@paulbrodie]

Yes, the Aermacchi was a good choice for the Privateer.

[@northcountyautorestoration5385]

Hello from just south of you in Washington! We enjoy the videos, very inspiring for our own aermacchi build the my son and I are doing. Is there any one that could build a good street version of this 400 big bore? Or would you be interested in being commissioned to build one? Thanks!

[@paulbrodie]

Thank you. Ron Lancaster (Lancaster Sprints) in Illinois has done a lot of work on Sprint motors.This KZbin channel is my full time job, and there is no extra time for projects like yours, sorry.

[@northcountyautorestoration5385]

@@paulbrodie no worries! I appreciate the reply! Keep up the great work. And if you're ever down south in the everett area, we would love to buy you guys coffee ☕️

[@paulbrodie]

@@northcountyautorestoration5385 Thanks for the offer. I used to cross into the US many times a year, for racing, holidays, and shows. I have not been across since August 2019.

[@deitydhskater]

Omg yes. I have one that has a bent shifting fork and been wanting to see how to tear them down

[@paulbrodie]

Now you know!

[@jwoodyr1]

Thanks for sharing another great video! Can you achieve the same engine-to-wheel speed with the countershaft and rear wheel sprockets without changing the primary ratio?

[@paulbrodie]

I don't think so. Stock countershaft sprocket is 14T, and I have gone to 15T. I didn't mention it in the video, but I also have changed the final drive gears (5th..) for a higher ratio, which also serves to make the 5 speed a close ratio. The rear hub, whatever you use, will only let you use a certain size of sprocket; I use a 36T, which, with all the other changes, will give me a top speed of 125 MPH. Thanks for watching!

[@paulb2506]

Changing the primary ratio will also reduce the torque applied to the clutch and gears, giving them a longer life. But the final gears have to be changed to get the desired top speed for the track you are on. Love your work Paul and Mitch.

[@paulbrodie]

@@paulb2506 Thanks Paul. Yes, the final gears were changed..

[@twowheels90]

My colleague and his dad have been racing these aermacchi's extensively in the past. They build small series racers from the ground up. I was amazed by the effort and work they had put in. Cast magnesium forks, custom made carbs. Apparently they own the brand name too. To bad they don't really post stuff on the internet but it's called aermacchi racing Holland. Owned by Jan kampen. Maybe you know them, you both seem to love these bikes.

[@paulbrodie]

I have heard of Jan Kampen. I was buying my racing parts from Rudolf in Germany... Thanks for watching.

[@colinmartin2921]

They also make road bikes to order, which I really like!

[@cpdevon]

If you reduce the base circle on a good stock or aftermarket cam(s), you get more lift. You can also reprofile the lobe a little. It's an old trick. My drag bike has Andrew's n4 grind cams with a slightly reduced base circle.

[@lorimcquinn3966]

Doesn't this typically suggest the cam is a performance regrind if the base is smaller?

[@cpdevon]

Sorta. Smaller base circle will most likely require other parts that are not stock, like lifters and adjustable pushrods. Most if not all perf. cams that are drop in, will have a base circle equal toa stock base circle.

[@paulbrodie]

I haven't checked enough cams to know how often the base circle has been ground smaller. Thanks.

[@steveyoung5520]

Paul, just curious; what's the advantage of a 10mm shorter rod?

[@paulbrodie]

I can move the engine farther forward for better weight distribution.

[@neillambton4065]

Hi Paul, here in the UK, back in the mid 70s, Harley Davidson had a 250cc 2 stroke single in their model line up. We had a magazine called "Motorcycle Mechanics" (now called "Classic Motorcycle Mechanics"), and in the mid 70s, they did a multi bike 250 test, with all the 250cc motorcycles available in the UK on test. The braking on the Harley Davidson was described as "a brown trouser affair". I believe, but not sure, these Harley 250 2 stroke singles were also made by Aermacchi and badged as Harley Davidson, do you know anything about them?.

[@paulbrodie]

Yes, Harley had a 250 2 stroke made by Aermacchi. I was never fond of them.

[@stratowing]

I had one back in the mid 70s, paid less than $20 for it. Pretty sure it was stolen. It was also missing the back wheel, an whatever linkage was required for the shifter... I was a desperate kid with few resources, I had a back wheel from something that I managed to fit. Got it running, no clutch, don't remember why, just push start and go. I'd reach down and yank on the shifter arm and worked it up to top gear. Pretty fast I thought. One day the cops stopped me, of course I'm like 15 at the time, bike is completely illegal. When I went to court, my mother asked the judge to refuse me a drivers license until I turned 18! He did! Happy Mother's Day mom. 🤣 Still love motorcycles!

[@paulbrodie]

@@stratowing Wow! Good story. Thanks.

[@Henrik.Yngvesson]

I use a heat gun to help with press fit bearings.

[@paulbrodie]

Someone else commented about that. It works on aluminum to get the bearing out of the case, but in this teardown we are taking the shaft out of the bearing, so heating isn't going to help. But thanks.

[@Henrik.Yngvesson]

@@paulbrodie I do it on bearings that fit tight on the crank as well. When mounting it becomes a slip fit when the bearing is hot and crank is cold. Don't know exact temp but might be around 100-150°C.

[@johnnyburgess211]

Glad to see you don't have to strip and split the engine to change the sprocket! The English like to make things hard work.... don't mention Brexit!

[@paulbrodie]

Yes, I like working on the Aermacchi motor.

[@johnnyburgess211]

@@paulbrodie Thanks Paul. I have to ask what are your plans for the Superhawk/Firestorm/VTR1000? You will probably say 'just to ride it' ! Cheers.

[@paulbrodie]

@@johnnyburgess211 The VTR brakes are fixed so yes, it is time to ride!

[@chuckp8705]

In the beginning of the video, I had to wonder how the factory would get the nut on the engine if I thinned down wrench was needed to get it off. What type of tool would they use, especially on a production line. Nice video though.

[@paulbrodie]

I have modified my motor from stock. The barrel is shorter so I had to modify the head studs, by using 73/74 studs and cutting off most of the thread. Then I had to make thicker washers to compensate. The stock 350 Knucklehead motor is easier to get the head nuts torqued.

[@chuckp8705]

@@paulbrodie Okay, gotcha. Thanks for the explanation.

[@Engineertedutube]

Another great video! Most of your viewers might not know that a stock 72’ did not come with the bolt style head or the 5 speed. Did you do the 5speed conversion? Plus I don’t see the advantage of the shorter Rod? Most of the time increasing the rod length and decreasing the piston compression height is more desirable.

[@paulbrodie]

Thank you. Yes, the stock North American 350 Sprint had the Ashtray head and a 4 speed. I took the 5 speed out of a 73/74 motor, and also added the close ratio conversion, which means changing the (2) final output gears for a taller ratio. The shorter rod is lighter, and allows me to move the motor forward in the frame to get better weight distribution; more weight on the front wheel.

[@africadreamin]

Whenever I have something that tight, be it in an engine or something in the press I nearly always use a soft flame, especially where you have aluminum and steel, as the aluminum will heat up quicker, what I don't want is for the steel to damage the bore and lose the interference fit.

[@paulbrodie]

I'm not pulling the bearing out of the case, I am separating the shaft from the bearing.

[@stratowing]

Are Aermacchi parts hard to come by? I've recently seen a few raggedy sprints for sale, kinda wondering what kind of an adventure it would be to take one of the these on. Not looking to race, just like old singles. Are parts expensive, good investment potential? Once sorted are they fairly reliable? Is a stock sprint a fun bike to ride, suspension, braking?

[@paulbrodie]

Aermacchi parts are becoming harder to find, especially since Moto Italia in California got sold.. Parts are no more expensive than other brands, definitely less than Ducati. To make them reliable you would probably want a Mukini carb and electronic ignition. With a good set of modern tires, they will handle very well. Shifting on the right side..

[@davisworth5114]

I have been riding and restoring Sprints for about forty years and most of them, especially the 350s, have very low miles. I have never had a 350 with a bad bottom end, pistons are easy to find as are points, gasket sets, carb kits, and kicker gears are available, weak spark is a problem sometimes, you have to renew wiring, check generator field coils, but once running they are fairly bulletproof. They are so much fun to ride on fire roads or country backroads, the low center of gravity allows footpeg scraping without worry, they are very nice bikes and well worth having. And you don't need any special tools or an engine stand for regular maintenance, my old wheelbarrow and some scrap 2x4s do the job, but I'm no Paul Brodie.

[@paulbrodie]

@@davisworth5114 Thanks for commenting!

[@TheVisidor]

I couldn't find Mitch in a hubcap, so still a mystery man to me.

[@paulbrodie]

That hubcap was 4-5 episodes ago. You would have to search..

[@JR-bj3uf]

Here in the US you can find all kinds of incomplete Harley Sprint 250 and 350s. In other words you can find a number of incomplete Aermacchi 250 and 350 machines. I always wanted to take one of these rollers and make a Aermacchi race bike.

[@paulbrodie]

Yes, years ago I used to buy complete Sprints for $200 each. Ended up with quite a few. The price has gone up! That's how I started on building Aermacchi race bikes.

[@gerry343]

That was very interesting! What is the little domed cover forward of the clutch? Don't a lot of Japanese bike engines split horizontally?

[@SB-vb8ch]

Bigger stuff tends to be horizontally split but there are some exceptions, especially with the earlier Yamaha 2 stroke smaller twins. From memory some of the smaller Honda 4 stroke twins were vertically split too.

[@randombuilds8336]

It's mix and match, a lot of the honda XRs are vertical, CBs and XSs are horizontal. Lots of bikes out there I've never touched, but I can see advantages with both ways.

[@SB-vb8ch]

End of the cam so could have been for points/contact breakers or maybe just timing?

[@paulbrodie]

The little domed cover is to hide the points, which are no longer there..

[@tinymotogarage]

Nice tearodnw. Could you not get a crowsfoot into those head nuts on a 90 degree for torque?

[@paulbrodie]

Thanks. I don't think there's room for a crowfoot.

[@FrankDiTommaso-o3f]

Are the race gears out of Germany still available? I have 2.52 ratio gears in my ‘67 CR and I’d like to convert to the 2.09’s which were found in the CRTT’s. I enjoy your videos. Hope all is well.

[@paulbrodie]

I don't believe they are. Rudolf Jungjohann sold them for many years, but I believe he has retired. Thanks for liking our videos. You can email me if you want to try his email...

[@FrankDiTommaso-o3f]

@@paulbrodie thank you Paul. I looked him up and sent an email. Fingers crossed. I see a custom carb manifold on your Aermacchi and was wondering if you did a video on making it.

[@paulbrodie]

Yes we did a video on that. It's called Aermacchi Intake System...

[@Fidel_]

Очень приятно смотреть ваши творения! Вижу на заднем плане наш флаг, спасибо за поддержку!

[@AndySlade1]

Is the modern day Linton the same or a similar engine Paul?

[@paulbrodie]

The Linto was a couple of 250s side by side.

[@braddobson2060]

Very good video, I wonder how many of those motors were destroyed by people trying to get the case apart

[@paulbrodie]

Thanks Brad, I really have no idea!

[@davisworth5114]

Probably not many because most Sprints have very low miles.

[@ccbproductsmulti-bendaustr3200]

👍👌look forward to your videos every Monday and Thursday here,acceleration should be very brisk with the loss of all that rotating mass Cheers Chris

[@paulbrodie]

That little Aermacchi really was a fun bike to ride fast around a race track! Thanks Chris.

[@SpringVinMoto]

How hard would it be to fit an Aermacchi engine into a Honda Minitrail?

[@paulbrodie]

I think the front of the cylinder head would hit the tire.

[@markfoggy9933]

I'd look at Electronik Sasche, might have something you don't know about and highly recommended.

[@paulbrodie]

If you are talking ignition, I've ordered an upgraded Lucas Rita from the UK. That's what my other race bike had.

[@whalesong999]

Yum, what an engine! For the most part, the Italian singles available in the U.S. were by far the best in the era: Aermacchi (Harley-Davidson), Parilla, Ducati, and Motobi (Benelli). Best materials but there were some short comings with all as well, kickstarter mechanisms among them. Is this 350 based motor the same stroke as the 250? The German NSU was also well done but it was bulkier for racing compared to the Italian marques.

[@paulbrodie]

Yes, a bit over the top.

[@paulbrodie]

The 250 had a 72mm stroke, and the 350 had a stroke of 80mm. And then there was the short stroke 250...

[@pashakdescilly7517]

@@paulbrodie That means the Aermacchi 350 bore must be around 74mm - the same as a Velocette KTT or KSS. I seem to remember a UK importer of Aermacchi had an ex-works 350 short stroke motor which was slightly oversquare, maybe 76 or 77 bore

[@paulbrodie]

@@pashakdescilly7517 The Aermacchi bore is 74mm stock. I think the UK importer was Sid Lawson. ?

[@pashakdescilly7517]

@@paulbrodie I think that was the name. I vaguely remember a Classic Racer magazine article, possibly in the '80s, of a test of the short-stroke ex-works bike by Alan Cathcart. The engine had been carefully gone over by Lawton(?), and the chassis lightened and lowered so the rider could get well tucked in. BTW I found the old videos of you holding 'first start' celebrations for Excelsiors two and three. How many did you build?

[@toronto6752]

Greetings from Squamish. Working on my 1973 Ducati I am finding that some of the bearings are not typically found at the bearing supply store , the ones I need are 16mm width and it seems 12mm are more common . Just wondering is that an issue with your race bike ? Thanks Bert

[@paulbrodie]

Greetings. Yes, it is not always easy to find bearings. Standard sizes have changed a bit in 50 years.