ToomeySheeLE Posted June 9, 2008 Report Posted June 9, 2008 Hey Guys. Hoping I can get some info so I dont end up buying a bunch of parts I dont need.. I have a ported 4mill (35pwks,Cpi's,150psi)that doesn't run any stronger than a bolt on bike(t5's and coolhead), and therefore I'm thinking something is up.. I've got jetting nearly spot on. Done both a compression test and leakdown test and there's no flaws there, reeds look good.. Swapped my CDI box out with a friends and it ran the same... My local yamaha mechanic sold me new plugs and caps(without resistors) and the bike seems to idle stronger with the new caps, but thats about all that $45 got me.. Is there any one component in the electrical system that will just cause a lack of power everywhere and no other noticable engine running issues? Thanks for info Brad Quote
locogato11283 Posted June 10, 2008 Report Posted June 10, 2008 compression seems kind of low. why are you only running 150? what head and domes do you have? the advantage to running a 4mm stroker is that you can pull higher gearing, taller tires and be able to leave stock bikes and 450's in the dust.. i think part of your problem is with your compression. bump that up to 170 or 175 so that youll gain more on the bottom. that in turn will let you run a taller gear and pull off the line harder. what exactly is your jetting at?? Quote
ToomeySheeLE Posted June 10, 2008 Author Report Posted June 10, 2008 compression seems kind of low. why are you only running 150? what head and domes do you have? the advantage to running a 4mm stroker is that you can pull higher gearing, taller tires and be able to leave stock bikes and 450's in the dust.. i think part of your problem is with your compression. bump that up to 170 or 175 so that youll gain more on the bottom. that in turn will let you run a taller gear and pull off the line harder. what exactly is your jetting at?? I'm running 20cc domes cut for the 4mm, and I'm about 500feet above sea level.. Jetting is 158mains, dgk needles middle clip, and 50 pilots..I've had all kinds of different jetting to try to make it run better and it seems it likes this as well as any other combinations.. Even with 150psi its not leaving my buddies stock stroke/port 150psi banshee behind.. I have a timing plate and cranked the timing to +7 instead of +4.. didn't make much difference, all other electrical components are stock.. Quote
KEVSWS6 Posted June 10, 2008 Report Posted June 10, 2008 Are you sure its ported to the 4 mil crank? Are you sure its ported at all? Quote
blowit Posted June 10, 2008 Report Posted June 10, 2008 I'm running 20cc domes cut for the 4mm, and I'm about 500feet above sea level..Jetting is 158mains, dgk needles middle clip, and 50 pilots..I've had all kinds of different jetting to try to make it run better and it seems it likes this as well as any other combinations.. Even with 150psi its not leaving my buddies stock stroke/port 150psi banshee behind.. I have a timing plate and cranked the timing to +7 instead of +4.. didn't make much difference, all other electrical components are stock.. Sounds like you have done enough homework and problem may lie in the porting, pipe combo. Give more specifics on the engine. Does not sound like you have electrics issues. B Quote
ToomeySheeLE Posted June 10, 2008 Author Report Posted June 10, 2008 Yes, its ported by a well known builder for the 4mm stroke and my pipes.., I'm running cpi inframes, was told i should expect around the 75hp mark with my setup.. Quote
KEVSWS6 Posted June 10, 2008 Report Posted June 10, 2008 Yes, its ported by a well known builder for the 4mm stroke and my pipes.., I'm running cpi inframes, was told i should expect around the 75hp mark with my setup.. Does it seem to run well but is just not fast? Does it miss or fall off at certain RPM's? Does it feel like it never gets on the pipe? Quote
ToomeySheeLE Posted June 10, 2008 Author Report Posted June 10, 2008 Does it seem to run well but is just not fast? Does it miss or fall off at certain RPM's? Does it feel like it never gets on the pipe? It seems to run well, just not fast... I have a brand new wiseco basket and new hd barnett fibers/streetbike fibers... so i dont think it can be a clutch issue... Quote
blowit Posted June 10, 2008 Report Posted June 10, 2008 It seems to run well, just not fast... I have a brand new wiseco basket and new hd barnett fibers/streetbike fibers... so i dont think it can be a clutch issue... I would say it is time to pull the head and do some measuring if nothing else can be decided. Also, sometimes a lean motor will run well but not strong if that makes sense. Brandon Quote
KEVSWS6 Posted June 10, 2008 Report Posted June 10, 2008 I would say it is time to pull the head and do some measuring if nothing else can be decided. Brandon I would agree on that. Quote
ToomeySheeLE Posted June 10, 2008 Author Report Posted June 10, 2008 I would agree on that. Damn... just had the head off to look things over, to the eye it seems like everythings fine.. where would i begin to start with the measuring? Quote
blowit Posted June 10, 2008 Report Posted June 10, 2008 (edited) Damn... just had the head off to look things over, to the eye it seems like everythings fine.. where would i begin to start with the measuring? Top of port to top of deck on all ports and discover if xfers and exhaust fully open at BDC. may also want to take a few pics to see if we can spot anything troublesome. The pistons are in the right direction, right? Windows in the intake side? That will make for a turd in a punch bowl if not. Brandon Edited June 10, 2008 by blowit Quote
ToomeySheeLE Posted June 10, 2008 Author Report Posted June 10, 2008 Top of port to top of deck on all ports and discover if xfers and exhaust fully open at BDC. may also want to take a few pics to see if we can spot anything troublesome. The pistons are in the right direction, right? Windows in the intake side? That will make for a turd in a punch bowl if not. Brandon I'll be tearing back into it tomorrow then.. The pistons are definitly in the right way, it looks to the eye that all ports are opening fully, i'll check it over and take a couple pics.. Quote
locogato11283 Posted June 11, 2008 Report Posted June 11, 2008 pilot seems a little too big, but i doubt thats much of your problem..i think a drop to 48 or maybe even 45 will help it some.. blowit knows his shit, and i think he may be on the right track with checking everything.. your setupi should run hard and leave that stock stroke shit in the dust.. ohh, i have another question.. what tire/swingarm/sprocket combo are you running?? how much do you weigh? Quote
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