2 Stroke Squish Area Ratio Test - Plus Bonus PIPE test

[@thedarkknight1971]

05:52 - That rear tyre looks wayyyy to close to the deck, and could very well be offsetting/reducing your Dyno performance figures... Is there a way to place/mount a short section of 2x4 on the front wheel mount to push the bake back a coupla inches? 🤔🤔🤔 😎🇬🇧

[@AutoBeta2T]

I noticed that too when editing... I need to modify the Dyno to be able to bolt a separate wheel chock to it. I have bought a front wheel chock... Just need to get it done before more testing. Next time I'm at the Dyno I was going to check for any witness rubber marks on the top deck of the Dyno. I do think you could be correct. Good spot - I was wondering if anyone would notice 🧐😀

[@AutoBeta2T]

Just had a closer look at the footage on the big TV and it does appear to be catching... Certainly it's close 😬

[@thedarkknight1971]

@@AutoBeta2T Haha, I think I remember you saying something in an older video about the distance between front wheel chock and the rear wheel roller being a little long. And, well, it can't be good for trying to nail down higher power gains/figures if the tyre if being 'Gripped' by the bench.. You might find a healthy 10 BHP boost is revealed once this issue is corrected! 🤔😉🤪 Hahahaha

[@AutoBeta2T]

Yes - I noticed the first time but it still seemed to work okay so I didn't sort it. I've had the wheel chock for a few months 🫣 Looking at some more footage I have it's hard to tell for sure but it looks very likely. If it is there may be a bonus HP in it and a lesson to myself 😊

[@2strokepipes471]

The never ending quest for more. We all dive head first into that rabbit hole!

[@AutoBeta2T]

Yes... It never ends 😊

[@simonblackwell4273]

Big kudos to you. Keep on teaching us

[@AutoBeta2T]

Cheers Simon 😊

[@Grooty79]

Such good content and thanks for sharing your machining tricks

[@AutoBeta2T]

Danno - no problem, and thanks for watching 😊

[@jimdicko1483]

Another couple of hp required! This’ll be the longest series on KZbin at this rate 😆 keep up the great work 👌🏼

[@AutoBeta2T]

Cheers Jim 😊 I need to milk it out till the summer so the air is less dense... Less power but less aerodynamic resistance too 😉

[@jimdicko1483]

Who’s riding it for the record? I’m 70 kgs. Just sayin 😛

[@AutoBeta2T]

@@jimdicko1483 hmmm... You fancy it then?

[@jimdicko1483]

@@AutoBeta2T absolutely. Joe might weigh less though.

[@AutoBeta2T]

True... Maybe a good test. Joe, whose a bit lighter v Dicko? I'd be interested to see the difference, plus I could slip into to my leathers for the fat-lad test.

[@PeggyParrow]

More octane needed ? More timing ?

[@Ni9kye]

Just a thought, I noticed a rather large spacer where the reed block mounts to the barrel, it may be an idea to reduce the space as much as possible and pack out any unwanted volume in this area. Also consider using a thinner gear oil and use less of it, and make sure the chain isn’t dry

[@AutoBeta2T]

Yes - it has increased the volume/distance. I think I can close this up a bit... Also see Chris' slender intake. Thanks for the input 🙂

[@AutoBeta2T]

I need to get the WD40 out on the Chain.

[@davidwickboldt712]

You know how most things work on a two stroke. They are either good for the top end power or the bottom and you have to find the balance that works. High compression may be the wrong direction. Put a shim under it to see what it does.

[@AutoBeta2T]

Yep - they are fickle things :) It certainly doesn't like too much compression but it preferred a wider squish band. I'll look to recut the original head for less compression. Reading back through the magazine articles today the original challenge bike had 15:1 geometric comp... But a much higher exhaust port duration (203 deg) so the trapped compression would be lower.

[@davidwickboldt712]

@@AutoBeta2T have you looked at the toroidal chamber design? It seems to be what the aftermarket is using for some time now.

[@AutoBeta2T]

Hi David, I have years ago. Definitely something to put on the to test list. It would make an interesting test. 🙂

[@Errol.C-nz]

​​@@AutoBeta2Ttrapped/corrected is the measure.. geometric has no bearing.. you didnt say anything about retarding ign timing as comp's increased.. the graphs don't suggest it but you could have been getting close to preignition.. had you considered making a radial finned head.. or welding the top two barrel fins to form a water jacket & radiator.. same for head & an exh port jacket & an electric water pump.. if your rules allow it

[@tke7mu0u]

Interesting results from the testing. Sorry it didn't pay off as expected. The shorty pipe was clearly too short. Cant wait to see what comes next

[@AutoBeta2T]

Hi Shannon, yes, a bit disappointing but that's two strokes 😃 Hopefully more blowdown will cure the power shortage 🤞

[@tke7mu0u]

I do think the pipe needs to be a bit shorter say 10cm. I think that other pipe is just too short. Either that or raise the exhaust port so the pulses time slightly better for higher rpm but the bike will most likely become too peaky. Keep up the great work

[@AutoBeta2T]

Shannon, so probably somewhere in the middle at about 820-850mm. And thanks again 😊

[@Rustyy4]

Nice tests, great job! You could wrap the longer pipe with heatwraps rendering the pipe hotter and effectively makeing it shorter for a little more revs. Could be a nice and easy way to gain some hp

[@AutoBeta2T]

Hi Rusty, I've never tried heat wrap. It is something I'd like to test. I have been told it can lead to detonation if in the header. Still - something I'd like to test myself.

[@Rustyy4]

@@AutoBeta2T i dont think you need to wrap the first few cm of the header but the header and diffuser wrapped seems to be the go. It could be causing problems given you have an aircooled cyl with no water cooling the exhaust duct. The fresh charge that is scavenged and pushed back into the cyl will not travel very far from the port. Maybe about 1.5-2x the bore in lenght, so that part needs to stay as cool as possible to not heat up the scavenged charge before being pushed back in.

[@AutoBeta2T]

Good point - noted :)

[@AuMechanic]

Just wondering what the squish velocity was of both heads.

[@AutoBeta2T]

Hi, at 9000 rpm 50% is 34.19 m/s 39% is 24.1 m/s

[@AuMechanic]

@@AutoBeta2T Thanks 39% looks right but 24 but 34 seems high on the 50% Optimal being 22 to 25 range

[@AutoBeta2T]

Hmmm. It preferred the 50% SAR on the Dyno... However, I need to get my tyre catching issue sorted and re-run the test.

[@AuMechanic]

@@AutoBeta2T Yes 50% did yield a better HP result which is interesting but has me wondering, what if you increased the clearance slightly to have a lower velocity similar to the 38% SAR what the result would be. By that I mean to test the effect of SAR by essentially isolating it as the only variable and all other things like SV and CR being equal.

[@AutoBeta2T]

@@AuMechanic I'll try that at some point. Will be an interesting test. In hindsight I should have kept the original head as was and did one change on the other.

[@skyhawk409]

Is the intake spacer for a bigger reed cage? If you have more volume crank pressure will suffer if there's no stuffer.try 15 to 1.

[@AutoBeta2T]

Hi Skyhawk - yes the spacer was so I could fit a bigger reed cage. See here: kzbin.info/www/bejne/bnKXkniMdryInZosi=eHInf-DxiJuqgEew And yes - I did worry about crankcase compression... And I still do. Something for the new year I think. Cheers and thanks for watching.

[@janeali1174]

Sir i have two stroke cylinder i want to increase its rpm power please help me how i can increase the speed from its ports. Please help me tell me sir

[@daviddjerassi]

Love your work keep on its all about small increments but your skills are top class have a look at Van veen Kreidler 20 hp in the 1960s

[@AutoBeta2T]

Cheers David. Thanks and hopefully I'll get some more done over Christmas :)

[@billshiff2060]

Your back tire is rubbing on the floor of the dyno under load. That would just crush the figures.

[@AutoBeta2T]

Good spot - cheers. I had a look at this in this video: kzbin.info/www/bejne/bprIZWuKoMeYick It definitely was rubbing!

[@Cobra427Veight]

I've got an old bsa b33 , it's been bored and stroked to 597cc , I found the intake cam retarded 10 degrees , it had two spacers under the barrel, piston down about 2mm , I've removed the 1.5 spacer and found the piston just nipped off the plastersene off , it was easy to mod the edge of th chamber and I now have about .035" squish but only about 5mm wide tapering bigger toward the centre , piston is a harley shovelhead with a dome the bsa is a hemi dome , I've reset my timing and will correct any piston to valve issues , I hope this squish helps the old girl . Cheers

[@AutoBeta2T]

Hi, sorry for the late reply. Did the squish help the old girl?

[@Cobra427Veight]

@AutoBeta2T thanks for your reply , I would have tried it , but my magneto died , it's been rewound now , I reassembled it and gave it a cold comp test and got 190psi ,wow , but I still had very little compression if I kicked at a medium speed , I did a recalculate on the compression ratio, and realised I hadn't quite got the Calc right , i:e where barrel spigots in , new Calc came out at 11.3 to 1 so I took the barrel off and found the top ring groove had pinched down on the second ring and it was jammed , so now after much research I'm changing from a shovelhead piston to a evolution piston which is flat top and +2mm in pin height I will sort that and weld on two eyebrows for the squish band and reclearance for .040 , and hope that sorts it out , I found other issues as well, like one valve spring 13mm short ! It's Been hot at some point , but was from inlet side , New springs and seat pressure adjusted . Cheers

[@Op1zilla]

The search is real, ggz-👽👍

[@AutoBeta2T]

Cheers 🙂

[@Fumacenta2tempos]

How can i calculate the sar? I never understood the method

[@AutoBeta2T]

Hi please see below: Worked example of Squish, Cylinder Dia = 54mm Squish Band width = 8mm Area of a circle = A=πr^2 Cylinder area = 3.14 x (54/2)2 = 3.14 x (27 X27) = 2289.06 mm2 Cylinder area without squish band = 54mm - 16 mm = 38 mm Area = 3.14 x (38/2)2 = 3.14 x (19 x 19) = 1133.54 mm2 Squish area = Cylinder area - Cylinder area without squish band = 2289.06 - 1133.54 = 1155.52 mm2 Squish Area Ratio = 1155.52 ÷ 2289.06 = 0.505 or 50.5 % I hope this helps

[@EinarLerschen]

Is it a five speed and if so, are there any kawa 6speed transmissions that can be fit into that block? How about a trial run with tthat power to see how much it lacks? Im guessing it will do around 70mph. This is the point where the game actually begins! :)

[@AutoBeta2T]

Einar, I have the 6th gear from the AR80 but a closer ratio box could help. I have a KX60 box but it looks like the output shaft is bigger than the AR's. I've been told that there is an option of closer ratio gears from KX's but I'm still looking. I think you are right about 70 mph. I'd go out and try but it's bloody horrible here at the minute. Still 30mph increase from 70 mph is a big increase in Power 😊

[@kraftzion]

I didn't here you mention ignition timing. If it was correct with the old setup it would be to advanced with an increase in squish area plus a decrease in squish distance.

[@AutoBeta2T]

Hi, to be honest I can't remember if I did? I'm planning on doing some more head tests in the future, and I'll definitely be altering the ignition on each test. Cheers.

[@pierrefpv]

I think you needed to adjust your ignition timing with the increased compression to see the benefit.

[@AutoBeta2T]

Hi, yes agreed. I have since played with the ignition to get a bit more power.

[@pierrefpv]

@@AutoBeta2T cool, thanks for confirming 🙂

[@brianferreira6041]

get the exhaust port about 80 percent of bore wide

[@AutoBeta2T]

Hi Brian, I'm not too sure the rings would survive?

[@peterlubjak]

Are you using 95 or 100 octane (EU - RON number)?

[@AutoBeta2T]

Hi, it's Gulf E5, 99 RON from memory but I'll double check next time I go past the petrol garage.

[@spacebrowni6761]

Where can i find that spreadsheet mate

[@AutoBeta2T]

Hi mate, it's here: www.kiwibiker.co.nz/forums/showthread.php/187285-2-stroke-excel-for-ports-heads-and-pipes/page4

[@spacebrowni6761]

I dont know if its because im on my phone but i can’t insert my info

[@AutoBeta2T]

Hi, I've not tried it on my phone, just on my laptop. The spreadsheet does need the Macros enabled so I'm guessing that could be the reason?

[@postulator890]

So much to unpack here. First of all, with more compression, you need to back the timing down at higher rpms as the heat generated from higher compression will work against you. Also, mixture turbulence causes a faster burn. So an ignition with a retard function will help. Check to see what your ignition is doing with a high quality timing light after marking flywheel with additional timing marks. Compression is great for bottom end torque but not so good at high end. Have you looked into ceramic coating the crown of the piston? Ceramic will even out the temperature of the crown so hot spots don't develop possibly causing inaudible detonation at higher compression ratios. Are you seeing any detonation clues on the plugs? Also, ceramic will insulate the crown so the piston transfers less heat to the crankcase. When the piston transfers heat, the crankcase pressure goes up and you won't get a full intake charge as the pressure differential between the crankcase and top of piston when ports open won't be as great so scavenging will be hampered. You can see this after the engine has run for a bit by examining the bottom of the crown inside the piston for what is happening to the oil mix as it contacts the piston. Shiny aluminum means you need more compression, charred means too much. Shiny black means your near the limit.

[@AutoBeta2T]

Hi Dale, thanks for your comment. My ignition is fully programmable and I have had the timing light on it but I do need to try different settings as I've changed quite a bit. I have read that lowering the compression can give more energy to the pipe and if it's well designed it increase HP. I'm seeing no signs of detonation but if i'm honest my runs aren't long enough. I need to change the gearing to what it will be for 100 mph and test in 6th gear. Even then i'm sure i will have to jet up and retard ign for the real world. I'm also intersted in the effect on actual airflow over the engine and particularly the pipe and it experiences a higher or lower temperature than the dyno - could be a key parameter to ensure the pipe is tuned for 100 mph airflow. Any ideas on ceramic coaters in the UK? I have heard of this. I have also heard the polishing the combustion chamber and the piston crown can have a similar effect by reflecting heat out into the pipe. I'm not sure how effective this is but I see it as a test i'd like to conduct. Noted about the heat transmission into the crankcase - I'd never thought of this. Thanks. So in summary the only place you want heat in a two stroke is in the pipe?

[@postulator890]

@@AutoBeta2T Look for shop that offers spray coating, aerospace if possible. Many years ago, Tony Nicasia would race the Kaw triples at Fremont Raceways. After each run he would use a garden sprayer to cool everything down. When I began racing, Roland Cushway was one of my friends when he was working for Hunt Racing Products. He prepped TZ250 for AMA competition. One of the things I noticed was the ceramic coating on the crown. I looked into this and that was when I started observing the under side of piston for what I called the heat health of the engine which I described in the first post. Long story short, before we began closing up the squish band and coating the piston, we found that at a track like Sears Point ( I have no idea what they call it now) the bike would run out of turn 10 in 6th in the opening stages of the race, but as the race progressed, the bike would drop back to 5th and finally 4th gear as the engine lost power to crankcase heating which is what Tony was battling in triples. After the engine was developed, the bike would consistently drive out of 10 in top gear. In the end stages of the race, my bike had the benefit of a 15 mph greater drive out of the corner. Ceramic coating works. I spoke with a gentleman that worked at United Airlines at SFO as a flame sprayer reconditioning internal jet engine parts. He informed me that a proper ceramic coating has three levels of applied material. All three have different expansion coefficients. The first layer was more like a primer and allowed for a greater amount of expansion. The second and third were the coatings that did the actual work. But the coatings together would allow the piston crown to grow without cracking the brittle ceramic coating. This is something the Roland had observed, but at the time wasn't aware of the cause as they were using their Plasma Products vendor, the same ones that coated the Hunt aluminum brake rotors with the friction material. The downside is that the coating has a thickness that will need to be adjusted for with the squish clearance. Another word about ignition timing and dynos. There is a condition known as flash readings which is what some tuners used to claim their max HP reading. You have already alluded to this. In a nut shell, a cold engine will tolerate more timing and yield higher HP readings...for a moment. But as heat develops in engine, the timing will need to be retarded and along with it, the HP from max. If you wanted to do serious investigation into timing curves, I might suggest that WOT at various RPM's, for extended periods of time allowing heat to maximize. After several runs you may come up with a more realistic timing curve. Of course the curve will be dependent of the vehicle use i.e. a drag motor will tolerate more timing than a vehicle used for road racing, or in your case extended WOT for a speed record. All the best, and REALLY enjoying the work you are doing. Your inquisitive nature and patience is adding greatly to the knowledge that many can use.

[@madmaxsdog8040]

Surprised at the overall increase, I thought there would be about 1.5 hp, retarding the ignition may help, as well as tthe suggestions from N19ke, I had been thinking of the spacers as well but more from a tuned length point of view than overall volume

[@AutoBeta2T]

Yes, I was thinking 1 minimum... But that's how it goes. Ignition retard and advance just lost power.

[@madmaxsdog8040]

@@AutoBeta2T it seems like neither of those pipes is suitable, I didn't catch what engine the templates were for but why not just do one in your software?

[@AutoBeta2T]

Agreed, I think the BDK is a bit long for what I need and the other is definitely too short. The templates were originally for an AM6 pipe that didn't work too well (peaked too low). It did work very well on the original PS mag AR and was used in their attempt. I'm really interested to test it against the BDK pipe which appears to be pretty good. I'm sure I'll end up trying another sim derived pipe in the future.

[@markaddy53]

keep at it lad ul get there have u tried upping mainjet could need more fuel

[@AutoBeta2T]

Cheers Mark and no. I'm still waiting for the jets I ordered from Allen's last week... Hopefully not lost in the post. I will try that when I get them.

[@markthoughtswithukrainemas2072]

IM getting a little bit worried !!!!!! on why your work is falling short on power !!!! If a standard Ar80 which is what I had did 68 mph with a Stan stevens tune think it was 2 mill off head and port i was getting 78 mph would gone past 80mph with higher gearing as I was 1 though in red may be 1 1/4 .... so if standard bike had 10.2 bhp im guessing the tune gave me 4 more bhp !!!!! everything else was standard exhaust reeds timing everything --

[@AutoBeta2T]

Haha - me too a little... 😰 But I'm hoping the exhaust blowdown is limiting it and when that's addressed a few more ponies will be released. 🙏

[@2strokecarbtuningportingin187]

Surprised you didn't try adjusting your timing with the higher compression head.

[@AutoBeta2T]

I did but it made no difference... Probably should have mentioned it. 😬

[@AutoBeta2T]

Didn't try fueling mind. The new jets came today

[@2strokecarbtuningportingin187]

@@AutoBeta2T ahh thanks

[@2strokecarbtuningportingin187]

@@AutoBeta2T when tunning most modern sport bikes got the latest bosh o2 sensor on the dyno at the shop. People get caught up on the afr ratio. For Me it's just a reference # yes I want to see a non spiked even curve. But what ultimately I keep adding fuel to the map till point I start loosing power. And then add little more. Simply because most sport bikes have ram air sorta speak. So typically when off the dyno in moving air it's about best it can be. I rarely mess with anything any longer. With the exception of about 4 nhra prostock motors a year. This year I'm hoping to not fool with anymore motors or motorcycle. At 58 yrs old I just want to add gas and ride. Anything I ride nowadays is 100% stock. Guess I lost all intrest. Other than watching guys on KZbin

[@AutoBeta2T]

I have AFR on my Dyno to... tend to have it sniffing but as you say for reference. I haven't used it enough to build up a feel for what it is saying. From what I've read it's easy to be misled with in on a 2T. Sounds like a plan to enjoy putting gas in and just using them. Enjoy 😊

[@shakdidagalimal]

Very interesting.

[@AutoBeta2T]

Cheers. I suspect my ignition isn't as strong as I thought. Maybe if I can get a better spark the higher compression head may perform better?!

[@shakdidagalimal]

@@AutoBeta2T Yes I hear with that high compression spark plug gap should go down some. Like if it was 35 thou it should go down to 30

[@AutoBeta2T]

@@shakdidagalimal yes, I need to try that. I have a better coil to try too and I need to re-route some of the wiring to try and prevent interference. Should be interesting.

[@jw7201]

i had AR93 years ago 😁 had 6 speed gearbox and 35 mm carb 1987 got 75 mph down hill lol

[@AutoBeta2T]

Happy days 😃

[@2strokecarbtuningportingin187]

Tested head volumes on the junk bicycle engines from a 5 cc to 8 cc when running long distances and seeking mph the 8 cc was the better set up the 5 cc head made more torque but ran hotter I belive if I had a programmable ignition and ran a better fuel with smaller combustion chamber say like alcohol the results would be little different. But not worth the trouble for 30% to 40% more fuel and fixed timing. Never been into funny fuels on none race application. As far as alcohol motors go. Unless it was a forced induction motor never seen more than roughly 7% power gains. In my mind most of the 7% came from more timing

[@AutoBeta2T]

Cheers Brian, for the info, so I think I'll be having to use lower compression when road testing to keep the heat down then. I'm going to start monitoring CHT too. Cheers

[@2strokecarbtuningportingin187]

@@AutoBeta2T look closely for signs of pre ignition and detonation if you choose to run high compression. Seen a comment on your intake volume. I see zero issue with your intake. Simple rule applies to 2 strokes and 4 strokes longer intake runner length equals more torque and less rpm. More things I tested stuffing reeds stuffing cranks case flow porting my butt dyno said and speedo and tachometer said all was waste of time. Stick to the basics most power gains is in port timings cyl design. Ignition timing. And carb tuning and pipe design. Not sure what your rules are for hitting 100 mph. But if it was me I would be looking for a cyl that makes good power and retro fitting it to your lower unit. Basically like I did with the hybrid motors example the junk crap I use to tinker with. I installed a cyl from mxs that's capable of producing 18 ish hp compared to the stock 2.5 hp. Possibly look at a cr80 cyl. Or anything that was air-cooled in the past rm yz cr that produced more power out of the box I 100% get improving and learning. But there comes a point when our expectations are not realistic oo yea keep up the good work

[@AutoBeta2T]

Rules wise I guess there aren't any but I'd like to do it on pump fuel and a AR derived cylinder. However, maybe a time will come where I need to look at other options. I'm enjoying the journey and loving the input from yourself and others following this quest. Options are there but I'll keep going with what I have until the brick wall presents itself... All good stuff and appreciate the input. Cheers 😊

[@2strokecarbtuningportingin187]

@@AutoBeta2T I'm with you on using funny fuels. I don't and never did. I wanted to find out how much power I could make on low grade pump gas only. I tested all heads all pipes all reeds stuffed un stuffed basically I worked in reverse. Meaning I started at the most extreme custom stuff found the limit of how fast things could be. Meaning the best of everything zero gratification never happy. Then went back to stock and applied what worked only. Lots of gimmics I eliminated all gimmics did they make less power yes but the gratification came from my hands and knowledge. Basically I knew how the most expensive custom stuff ran. So I knew what my expectations and reality was. I left very few stones un tured

[@2strokecarbtuningportingin187]

@@AutoBeta2T kzbin.infovIYCgUJjCIE?feature=share. My buddys always were confused as to why I messed with the motorized bicycle engines

[@janeali1174]

Please help me sir I needed your help sir

[@janeali1174]

Hello sir

[@markthoughtswithukrainemas2072]

You should be at 19 bhp at least now with your work !!!! surely

[@AutoBeta2T]

Depends on the Dyno. Mine reads 14% lower than the two local Dynojet dynos who ran my BMW R9T... So 15.2 hp X 1.14 = 17.3 hp Dynojet.