EXPANSION CHAMBER BUILD PART 1: Design, Math, and Materials

In this video series premiere, we start the process of building a two-stroke expansion chamber from parts. This involves careful planning out of the design of the pipe. It will be welded in shop, and fit up to our 1974 Yamaha DT400 2 stroke rat bike project. If you're wondering how to build an expansion chamber, or pipe, at home with minimal tools and experience, this is the tutorial for you.
Pipe Spreadsheet:
docs.google.co...
Please subscribe for more videos! Thank you and enjoy.

[@kuladeeluxe]

I gotta say...that was one of the Best DIY videos I have seen. All that free info, zip tie degree wheel , then using video tools to measure. Great teacher skills.

[@FormulaJake]

Thank you so much! If you enjoyed this one, feel free to check out the rest in the series. A few parts later and we have a running motorcycle 🤙🏼

[@caleballen5592]

This was very helpful because I want to build a pipe for a engine that probably no one has built a pipe for.

[@FormulaJake]

Sweet! What engine?

[@tumeh7410]

@@FormulaJake well... Someone got left hanging

[@ferrononferro3941]

@@tumeh7410 he has a rotary logo though. 13b rew? who knows.

[@slobodanboban8717]

Rest both hands on table while your welding,so they do not shake much... Also, if you are welding thin tubing, scale down amperage setting and use pulse if you have it on machine,with combination of thinner wire (for Mig welding cutted to length and straighten). If you are welding from lets say right to left, you are adding wire from opposite (left) side... Nice video, good work!

[@fredymredy]

Thank you. you explained more than some yt videos that are 15min. long

[@johnakroyd115]

Thank you so much man I've been trying to do this for so long. your videos are much appreciated keep it up

[@FormulaJake]

Glad it's working out for you! We have parts 2 and 3 on KZbin, and a 4th part in the works!

[@johnakroyd115]

@@FormulaJake nice man I've been wating for part 4 and can't wait to hear how she runs on the bike

[@Tattmemore]

Cracking video, well done…and good use of the word “plethora”…reminded me of El Guapo from the film 3 amigos!!!

[@cobre7717]

This is cool! I'm going to try out this spreadsheet for my ts250 expansion chamber. Its like your dads rat bike i just saw that video. I got it for $350 many years ago. Mismatched wheels, no wiring harness. No lights. Tape everwhere holding stuff down. I do have a solid clutch wire and the cool 1972 gas tank. Ill try and make a video of repairs.

[@FormulaJake]

That sounds like a blast! One of these days I'll design one for his bike. I'm interested in seeing how yours goes 👍🏼

[@cobre7717]

@@FormulaJake i started it for first time in many years. the entire oil injection tank siphoned into the crankcase when it was sitting and man was it smokey. it still fired right up and dumped mouse nests out the pipe. it was spewing oil out between the pipe flange and exhaust port. the old owner broke off the exhaust stud and started to drill it out. the frame is also broken on the top tube under the gas tank. they tried to fix it with gasless flux core and it looks like big bird shit on it. i have 180 amp tig welder so it all needs to be cut out and fixed. its such a cool bike i rode it around the block even though it had a dirty cloged up mikuni, no presure in the super knobby tires and the only gas i had was some premix from my puch moped. some how all that oil still didnt foul the plug. just need to clean carb and rejet. then fab an expantion chamber and prob rejet it again. then get some street tires and a taller sprocket.

[@thailandmopedadventures611]

Great Info - highly appreciated!

[@Trycer]

Bro, you´re f...ing awesome.

[@liamsarsfield8292]

Great to see you tackling the unknown and doing such a great job. I'm building a custom pipe for a very early model Yamaha DT-1 by rolling cones from 20 gauge cold-rolled sheet, some 1-7/8 mandrel bends, 1-1/4" stinger from DOM pipe, and my handy-dandy TiG machine. Learned a lot from you - many thanks!

[@FormulaJake]

Best of luck! I hope the rest of the videos help as well. I'd love to see your progress!

[@J27M]

This is very interesting and your spreadsheet is very helpful. I’m going to build one for my 4 stroke car engine, I’m just wondering if there are any changes in the principles for 4t as opposed to 2t?

[@marcusmcclelland]

I should have said this earlier. Mate, dont go with a target of 10000rpm. This is a dt400 yes? The transfers aren't big enough/ have enough duration to supply mixture at this rpm. you want someting like 7800-8200. you just wont get what you want expecting the dt to rev like that. Even then the transfers are pretty small. The crank probably wont like it either. If you have a way of lifting them with a grinder lift them like 3mm too try to spin it that hard. if you have an mx400 you should be ok.

[@FormulaJake]

Thank you for the advice. My original plan was around 7500 or 8000 rpms. The program's default value is 10,000 rpms, and I didn't change that value in the video. Thanks again!

[@ryan-danodano]

If you can find the exhaust port duration online, chances are you can already find the expansion champer specs, or an already built tune-pipe

[@outfittersoutdoors]

Way cool video

[@098santi]

Thanks a lot for the video it´s very useful but I still have a question. When it says in the spreadsheet "inlet diameter" where could I measure it ? Thanks a lot once again :)

[@FormulaJake]

Inlet diameter refers to the inside diameter of the first piece of exhaust tubing. Match this up with either the inside diameter of the existing exhaust/flange, or measure the exhaust port itself. Those values should be the same or at least very close, and any one will work!

[@nctaurussho4664]

Pethora!!

[@sampappalardo949]

What's your opinion on an expansion chamber for a single cylinder motor with twin exhausts?

[@FormulaJake]

Is it a two stroke? If so, an expansion chamber could help it out a lot

[@sampappalardo949]

es it is a two stroke. t s a 1950 / 150CZ which I raced back in the 60s after fitting a reed valve out of a Danarm chainsaw. @@FormulaJake

[@rogerstafford-wakeinc.2088]

Thanks for sharing the information and the build. 🎚🇺🇸⚙️🚲⚙️👍🏼💯👊🏼

[@avalanche15301]

Thanks for the info man. 👍subbed your channel!

[@jimcatanzaro7808]

How about a customer 2 stroke exhaust on a outboard motor?

[@air-driveaquaponics204]

Who did this spreadsheet? The outlet calculation is WAY off!

[@Trycer]

Jake, I got a question... ¿The measures of the sheet are on inches or in real life units? #SeriousQuestion

[@FormulaJake]

The sheet is in inches

[@backyardrestorations]

When I go to the exhaust plot it’s just blank

[@rifleman7313]

Would this style of exhaust be applicable for use on a turbocharged LS V-8?

[@FormulaJake]

It wouldn't, as two-strokes operate on far different principals. The turbo also adds different factors to consider

[@shroomskunk]

Getting some crazy numbers when inputting 0.750” ex port diameter. It’s asking for a belly section 12” long!!! 😂😂😂

[@jkoeberlein1]

Jake I've been looking for cones for my motorized bike. We know how to calculate the shapes, but the cones we've found are the wrong size i.e. too big.

[@FormulaJake]

Hey John! Have you looked at Cone Engineering? They have all sorts of sizes at different angles. One of my cones is 3/4" on one end, and 4" on the other end. If it's too small on the small end, or too big on the big end, I'll just trim it with a band saw or cutoff wheel. As long as the angle is right, and the ends can be cut to the proper size, you're good!

[@jkoeberlein1]

Thanks, I have the dimensions but we'r don't have the rollers to make the cones. Sweet!

[@Rxmohan]

Bro calculatedbchamber port advantage?

[@ruudiutsenikov609]

you sound like brad but look like bearded Jack

[@jacksonschoep2640]

What's your opinion on putting an expansion chamber on a 4 stroke? I'm trying to make it as quiet as possible.

[@FormulaJake]

It seems as if most 250/450 4 stroke manufacturers nowadays use some sort of expanding header, or stepped header. It's commonly done to control the power characteristics of the engine, even on 4 strokes. As far as keeping the noise down, my best advice is to install a restrictive muffler, and ride in higher gears, lower RPMs, and lower throttle response.

[@akshyvp6599]

which app is used to calculations of cones

[@FormulaJake]

I use Google Sheets or Microsoft Word, and us the document in the description.

[@TellTheTruth1]

Where did you buy ur cones ?

[@FormulaJake]

Online, from Cone Engineering 👍🏼

[@garage_34]

where can i found the link for the software that you use?

[@FormulaJake]

I used Google sheets. If you go to drive.google.com and make and account, you can save this document as your own. Or you can use Microsoft Excel, or any other spreadsheet software.

[@garage_34]

@@FormulaJake link?

[@FormulaJake]

Spreadsheet: docs.google.com/spreadsheets/d/1nksxtd8M9KeJJ8l10ZHtq8yk8W6gZQZhXmFXj4fGZC4 Either open it right in Google Sheets or download it and use it elsewhere 👌🏼

[@johnakroyd115]

How do you edit the spreadsheet on an android phone? Thanks

[@FormulaJake]

With either Google Sheets or another Excel editing app. If using Sheets, make sure to click "Make a Copy" on the original document, that way it lets you edit the fields. Good luck!

[@YeeThirty]

Wheres pt.2 ?

[@FormulaJake]

In the works. I changed designs and ended up doing pie cuts on the cones, which requires more equipment than I normally have. I hope to have it done within a few weeks, but we will see!

[@galaxystar6370]

Next to part 1 and 3😁

[@bansku1137]

There are lightsabers in the background noise

[@johnakroyd115]

How do you use the spreadsheet? Cheers

[@FormulaJake]

Edit the top three values to match your bike, which are the exhaust port duration in degrees, the RPMs, and the exhaust inlet diameter, in inches. The rest of the values that come out of the spreadsheet are what you use to determine how long/wide each piece is. Let me know if that doesn't make sense!

[@johnakroyd115]

@@FormulaJakethanks for the info also how do I edit the spreadsheet on an android phone?

[@pkguy52]

Wheres pt 2?

[@FormulaJake]

It will be here soon. I'm doing a pie cut exhaust and it's taking longer than expected.

[@marcusmcclelland]

how the pipe going?

[@FormulaJake]

Coming along! We are gathering our last few materials and getting ready to fabricate the pipe.

[@MK_Weldings]

How i due the angles of the pipe?

[@FormulaJake]

The default angles on the program are 16° on the expanding pipe, and 8° on the contracting pipe. If you read deeper into two stroke theory and mathematics, you can find angles that work better for your machine. However, these angles will work as a good reference or starting point for any engine.

[@MK_Weldings]

Sorry, i tell about courves. How i due angles of 90°, 120°, 180°? I find the program "Cone Layout" but this program make cone each cone. Its Very dificult to due any pipe with 16 sections on 220mm of courve. Sorry for english. You can undestand ?

[@MK_Weldings]

I due exhaust for motobecane av10 engine. Its "easy" to makes on a paper. But, i have projects for dirt bikes and scooters, but the courves has killed me 😕

[@MK_Weldings]

Look the vídeo: kzbin.info/www/bejne/lZO8coGcjZhooZI

[@YeeThirty]

Pie cuts mate, or search up "cone templates", you can make most sewing templates work for metal as well ;) good luck!

[@peduruwahandichampa7550]

Im very happy with ur video .and thanks.but I cunt find the spread sheet that u had mensioned. I ve made my owen engine .I started it without a expansion chamber or cylancer.Can u design me a expansionchamber if I give u the three nombers

[@cliveswabs9365]

Couldnt understand any of this as im a thick imbicile bastard

[@royrenschop2148]

Really? 😂😂😂 😢

[@D.Technical.S]

euhm , what crap is this ? that excel sheet ... what crap is that ? it does not take in calculation the stroke , the bore , conrod length exhaust temperature etc etc if you fill in the excel sheet , with a timing of 196/197 degree exhaust timing , with a rated rpm of 15000 rpm , my pipe would be 1.3meters long , and the power band (D2) comes out negative numbers 😆 the only way is to lower RPM's to 10000 , but that's for street and tuning , not for racing applications . There is something seriously wrond with youre excel sheet , i would not recommend to anybody to use this sheet ... The codes light be wright , but there a lot variable that are missing , maybee link the

[@098santi]

Thanks a lot for the video it´s very useful but I still have a question. When it says in the spreadsheet "inlet diameter" where could I measure it ? Thanks a lot once again :)