PassionRE

I forgot to add that on ANY hi-perf 2 stroke...if you cant calculate the proper compression ratio to match your pipe/porting combo, youll never hit the really nasty violent sweet spot....Jim

Numbers are concieving unless you know what to look for. For instance...last year my 421 alky was pumping out 110hp on a relentlessly stingy dyno...thought I had really done something. That motor was a complete turd compared to my current set-up. Havnt had a chance to dyno it since the latest eureka thoughts.... and Ive been working on new pipes etc...will let you know when the time comes. PIPES or having your porting matched to your pipes in relation to compression ratio, flame speed,and burn duration is where its at...trust me...theres more than one way to do it. Correct intake resonance alterations help alot as well...It makes the difference between fast, and simply just stupid fast....Jim

Exactly! Thats why you see well built Cubs smoking big Cheetah's & Twisters

Did it blow the piston top out on the intake side or exhaust side?

I thank all of you ,and all the HQr's Ive done business with over the years. Without your support, the data research I do wouldn't be possible...thanks again...Jim

Not sure if the Sea Foam can be used in diesels...but BG has killer diesel cleaners and additives..not trying to push BG, but no joke, BG is the real deal...Jim

Send me a Pm with ALL info ..... rider weight. all mods, carbs, pipes ,elevation, desired octane, type of terrain and desired power style and I will give you the specs your looking for...Jim

Would have to agree with Loco on this one. Had a set of big bore Banshee WSM's let loose on the dyno and lost the cases out of the deal. Intake bridges on both sides broke out and trashed the cases bigtime. Both bridges busted out on the same pass...what are the chances of that?....Jim

Just be glad your not tearing off teeth on the countershaft after 2hrs!...gets old

33PWK Keihins work well on that combo...Jim

Mark, your exhaust ports are set for peak efficiency of 12325 RPM....a little high in the banshee world, although the PV will help some. If your trying to match exhaust ports for peak HP you will need a tuned length of approx 875mm depending on your compression ratio. Closest bet will be a shearer...but it will need to be modded to clear the jugs...good luck....Jim

Pretty good stuff but if you want the real deal, try BG 44K...it will actually clean the Cat as well as everything else........look it up at www.bgfindashop.com ...Jim

With an upgrade on carbs you can expect 70RWHP on a good duner port...Jim

Ultimately your carb itself is going to mandate intake velocity at a given RPM. Pulse strength over 6500 RPM will equalize itself throughtout the entire intake tract and the buck stops with carb bore diameter. Pulse strength at higher RPM levels is so intense it has the ability to actually make its way into the air filters, so loss in velocity in the reed area is not an issue at mid to high RPM levels. Power losses caused by intake velocity deficiency's will generally only show up at lower rpm levels in the form of gasping gutless power delivery. Loss of velocity at high RPM is typically of no concern where power output is concerned, LOSS OF VOLUME IS OF MAJOR CONCERN. On a 421cc engine at 9500RPM rated near 100HP the difference in power output between 35mm carbs and 39mm carbs is nearly 7HP, meanwhile the changing of carb sizes drops the intake velocity 19.5% at 9500RPM...food for thought....Jim

I cant imagine it being any harder to hybrid than the 600 engines that seem so popular to wedge in, plus the power to weight ratio of a well built H2 will be light years ahead of any modern day 600cc or 1000+cc for that matter. I had a 920cc H2 back in 78'.....sick SOB is an understatement... stupid fast is probably more accurate...Jim

Unless your on a budget, just go with the VF3's. Unmodified they are good to 120hp on gas..Jim

You can make plenty of power with it...big numbers are easy on that engine with a good builder. The downfall........ the H2 engine is very heavy, and you'll also find the gear ratio's of the transmission are not very well suited for sand , makes a killer 1/4 miler though :biggrin: ...Jim

If your traction issues are good, TT or a Hot MX port with broad usable power will work best. Drag ports are too explosive for hook off the turn, duners make power too late for effective acceleration off tractable turns, and you usually dont have long enough straights to need mega top end unless your running 1/2 miles.. Broad tractable power makes the best short track engine by far. You can pull more gear, shift less. and have better lap times....Jim

I just found it odd that my bike will just blow off 14 paddle extremes like they were drag slicks...really suprised me and Im looking for other options on tires...really hate to shorten the bike up..I like the front end on the ground. Just wondered really if your motor would pull as much gear as Brads bike I guess..Not really a sand bike, but he's got enough motor to take care of just about anything that comes along...within reason ofcourse

I was just trying to get a feel for what your 10 mill will actually pull... I run 17/39 on 14 paddle extremes and its not near enough tire...just burns them off on a 12 over arm at LS

Dave, what would you consider max gearing on your motor in deep sand? without the bottle...just curious... my 4 mill would just bury itself on a 14 arm and a 14 paddle extremes ....Jim .......... any video?

Results will vary, my personal heavily ported 421 made .4HP more on OOF's on the dyno but the OOF's were un-silenced. Dyno runs were made within 30 minutes of each other...Jim

Long rod, stock stroke, low hours, trued and welded $175.00 shipped....Jim 918-232-3950

Im not quite out of the Shearer market,yet :biggrin: . If you need Shearers, give me a call, Ill make it worth your while...Jim