OuiBJammin Posted July 10, 2015 Report Share Posted July 10, 2015 Looking to build a 600cc twin for a hybrid bike.I would rather use a CP cylinder and Mattoon cases. I have looked and saw that Sphynx cylinders are available 72x72 but I assumed it would take a wider bore center to fit them as well as different stud pattern. I am limited by pipe diameter to 300cc ish to get them under the case and clear the swingarm. My background is building and racing 2 stroke bikes(dirt and track) since 1975 and working on turbine engines in the Navy.I am familiar with a lot of bikes but always like my RDs and RZs best. Thanks for any help and suggestions. Quote Link to comment Share on other sites More sharing options...
OuiBJammin Posted July 10, 2015 Author Report Share Posted July 10, 2015 Thanks, Square motors make more power per CC.Even in cases with transfers flattened out by narrow bore centers. It is my understanding Servals/Cubs/Wampus are intake limited HP wise. Yes 72x72 = 2 x 293cc=586cc Street legal trackday bike with modern frame and suspension. I'd seen a 72mm DM cylinder but it was 4mil on the CP site but I had heard there were other options not on there. I'd considered an RZ500 motor but it would need a lot of work and would weigh quite a bit more,even than the billet cased Banshee based motors. Looking for 120+rwhp on pumpgas or 110 with a decently wide spread. Quote Link to comment Share on other sites More sharing options...
OuiBJammin Posted July 10, 2015 Author Report Share Posted July 10, 2015 Cool,I'd seem most of that lurking for years. I am stuck with gas as the bike will be 1.Street ridden occasionally 2.Alky needs almost double the volume,cutting track range I am stuck with lower CC to get an exhaust to clear,10.4 inches of clearance with no pipe and simulated load currently.No way a bigger motor will be happy on pipes too skinny to breath. I had looked at the Super series Cub/Servals but it looks as if 120 is out of reach on gas and that the intake chokes them too.If a 14 to 18mil Super Cub/Serval was available and could work that would be cool as it would save a few $ and pounds. Quote Link to comment Share on other sites More sharing options...
sprinklerman Posted July 10, 2015 Report Share Posted July 10, 2015 Cool,I'd seem most of that lurking for years. I am stuck with gas as the bike will be 1.Street ridden occasionally 2.Alky needs almost double the volume,cutting track range I am stuck with lower CC to get an exhaust to clear,10.4 inches of clearance with no pipe and simulated load currently.No way a bigger motor will be happy on pipes too skinny to breath. I had looked at the Super series Cub/Servals but it looks as if 120 is out of reach on gas and that the intake chokes them too.If a 14 to 18mil Super Cub/Serval was available and could work that would be cool as it would save a few $ and pounds. A PROPERLY built SCub can meet your goals,, mine did 138-ish on alky. Knock about 8% off of that for race gas. But it needs a few custom mods to get there. Call Redline. He's got the super cubs dialed in. Sent from my SM-G900R4 using Tapatalk Quote Link to comment Share on other sites More sharing options...
OuiBJammin Posted July 10, 2015 Author Report Share Posted July 10, 2015 Awesome,thanks. I may still want the billet cases just for durability but those are in the ballpark. Quote Link to comment Share on other sites More sharing options...
bluebanshee98 Posted July 10, 2015 Report Share Posted July 10, 2015 The 10dm is mine on that graph and I'm running stock cases. Can't go wrong with billet though! But the engine is gonna weigh more with the billet cases. Pick your poison.... Had that engine for 2 years now and I love it. Quote Link to comment Share on other sites More sharing options...
n2otoofast4u Posted July 11, 2015 Report Share Posted July 11, 2015 Thanks, Square motors make more power per CC.Even in cases with transfers flattened out by narrow bore centers. It is my understanding Servals/Cubs/Wampus are intake limited HP wise. Yes 72x72 = 2 x 293cc=586cc Street legal trackday bike with modern frame and suspension. I'd seen a 72mm DM cylinder but it was 4mil on the CP site but I had heard there were other options not on there. I'd considered an RZ500 motor but it would need a lot of work and would weigh quite a bit more,even than the billet cased Banshee based motors. Looking for 120+rwhp on pumpgas or 110 with a decently wide spread. You can plug all the numbers you want into your computer dyno, but I have yet to see a square motor run worth a fuck at the track. Don't know why (I have my ideas but no way to prove) but the ones I've been around just never ran like I thought they should have. Quote Link to comment Share on other sites More sharing options...
OuiBJammin Posted July 11, 2015 Author Report Share Posted July 11, 2015 The kart and roadrace guys who raced anything but square lost mostly.They get 90+ out of 250 twins(how big does a cub need to be on gas to get that?).65+ out of a CR250 based single.FPE and BRC motors may make even more. The 500 4 cylinders made 180+ when they stopped racing them 15 years ago.On racegas not alky.Granted they had frequent maintenance cycles If I could find one those 500cc GP motors for less than what my truck cost I wouldn't be dicking around on an old ATV motor based on an old street motor that I had nearly a dozen of in the 70's and 80s. I'd looked at RZ500 and even RG500 street motors but they would cost nearly as much as the GP motors to get going that well and barely weigh less than the H@nd@ 600 motor on my current racebike.The banshee stuff seems the best compromise of reliability,availability and cost and I am a big Yamaha fan. I think the cramped transfers from narrow bore centers or just crappy transfer design period may be the culprit in your experience seeing them perform poorly.There may be more to it because i looked at the Sphynx and Puma HP#s and they don't really seem impressive either even square.The other big cylinders(Athena,ESR,ProX etc) look even worse. I just don't see a reason the country who made the Space Shuttle and Ohio class subs can't get the performance out of motors that Aprilia,KTM and Japanese did already 10 to 15 years ago knowing exactly what they did to get it.Then again,we(2 strokes) are a small market. I really do appreciate all y'alls help ,the bike sites and at least one other ATV site really discouraged any out of the box ideas. Quote Link to comment Share on other sites More sharing options...
registered user Posted July 11, 2015 Report Share Posted July 11, 2015 not to bust your balls but im not sure why you made the thread to begin with. 35yrs experience you should know what your up against. ancient tech. sure you can incorporate some modern ideas to these old dinosaurs but at the end of the day your still building onto a ancient foundation. you should know this already i would hope ????? since your willing to dump a mountain of cash on billet cases, why not do something better and design some cases in CAD and send the drawings over to matoon and have it made. use the 70hp cr250 cylinders and youll be a leg up on all of us if your not happy with engines available to you, make something better. thats what a good tuner would do Quote Link to comment Share on other sites More sharing options...
OuiBJammin Posted July 12, 2015 Author Report Share Posted July 12, 2015 ru,bust my balls all you want it's how ideas get fleshed out.I have a thick skin after being an engineer in the USN. I was in hopes of hearing something I hadn't heard or thought of.I did learn that you can get 120+ on stock cases on gas. I will probly end up taking base gaskets from various modern 250 to 300cc bikes or snomos(like the old crankensteins) that do have better transfers/geometry and overlaying them on stock,dm and the wider Mattoon gaskets to see what may work.The main issues so far are mechanically driven PVs in the cylinder,rotary valves or case reeds. As far as a good tuner,not me.I am just a garage hack who likes smoky bikes better than sewing machines. Quote Link to comment Share on other sites More sharing options...
sprinklerman Posted July 12, 2015 Report Share Posted July 12, 2015 Gotta love engineers. Sent from my SM-G900R4 using Tapatalk Quote Link to comment Share on other sites More sharing options...
dozer Posted July 12, 2015 Report Share Posted July 12, 2015 (edited) i agree with n20 on the topic of square motors. ive been spending more and more time around track racing and for whatever reason the square ones dont run near as impressive as they should. several different theories from volume of air moved in relation to bore size vs stroke, crank case volume or transfer design/size/shape, they dont seem to work well. you can talk on for days about about moto gp did this and that, when your done we will simply tell you they didnt do it with a banshee engine. dont get me wrong, sometimes traditional wisdom is more tradition than wisdom but guys far smarter than us are still trying to get them to work. tim bond is still playing with toroid domes so its not like guys have just given up on making more power with banshees. for the money spent, if i was starting out fresh i would build a super between 10 and 14 stroke. wouldnt worry one bit about the intake choking it. currie motorsports set the 426-525cc limited record with a super and now is opening the bore up to go after the 526-650 limted class. that means they are making power and have a perfect setup. can you even use 130+ hp? Edited July 12, 2015 by dozer Quote Link to comment Share on other sites More sharing options...
OuiBJammin Posted July 12, 2015 Author Report Share Posted July 12, 2015 Dozer,thanks I will look a the supers again.And thanks for not being a dick. I got 120 now and the motor can get up to 140.But I don't like red bikes or 4 strokes,this bike was nearly a gift pricewise. so I run it. Quote Link to comment Share on other sites More sharing options...
n2otoofast4u Posted July 12, 2015 Report Share Posted July 12, 2015 You will also want to call CP and talk to Chris. When Calvin was alive he would onesy twosy of odd ball shit. The new owner as o understand has basically said fuck that unless it's big $. I don't believe they are still casting quite a few of the cylds that they used to. 1 Quote Link to comment Share on other sites More sharing options...
dozer Posted July 13, 2015 Report Share Posted July 13, 2015 chris told me in kansas they were going to make another run of cheetah cylinders when he seen that was what i was using. he didnt say anything about any other cylinder though so like n20 said your best bet would be a call to him. i wanted to talk with him more but garret moore of gt chassis was trying to get his turbo bike to make some good passes so i was busy checking that thing out. Quote Link to comment Share on other sites More sharing options...
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