TECHNICAL > ALL MOTOR TALK

strokers and rods

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THEMOTORHEAD:
which length rods are you using with what results?

longer is better but with tts runnin very low rod ratios is anyone having any problems?

dragzooks@indy:
i spoke to richard and he is running a really long rod in the 1900cc
contrary to what people on some boards have been saying, that engine uses the +10.5mm crank
not a 19mm like i have read

he said he has added enough length to the rod to get the rod ratio back to stock which is around 1.89 : 1

when i built a stroker 5mm we werent sure about getting the cam chain to have enough slack and getting the motor mounts in the head to line up with the frame if we used regular length carillos and a spacer plate so we used .100" shorter carillos (neither did we have the time to have special stroker pistons made to solve the height difference that way)

it lasted well enough in my opinion for a race bike that got beat up on the street
bout 2000 miles and bunches of passes and dyno pulls

it finally started eating up the rod bearings
upon disassembly i found the pistons were "kissing" the head just a little
squeezed it a hair too tight p/h wise and he banged it off the rev limiter repeatedly
i think it would have lived alot longer if not still be alive if not for those two things
banging up against the head definitely pounds the shit out of rod bearings
 
richard claims his 1900 looks great after disassembly and we are in the process of trying one of those out with longer ti rods to get the rod ratio back to stock and reduce the reciprocating weight/load on the bearings

everyone argues that the oiling is not the problem and its things like the compression being too high or the babbit being too soft and the oil film shearing it,... but i just cant make sense of how the exact same bearing lives in an oil cooled in more extreme situations (high comp and NOS shootout levels)
compare an oil cooled and busa oil pump and you'll see a big difference
also the oil cooled rod ratio stock is 1.98
more favorable for less bearing load/cylinder thrust loading
????????????????????

dragzooks@indy:
above is refernece to tts' personal 1900cc engine
i dont know what he is selling in kit form or what rods people are using that just buy the crank alone

and i know some people are gonna plug 73.5mm stroke into b*b*s*.7854*4 and wonder how in the hell is he getting 1900cc

reverse out the math and solve for the b (bore)
and then wonder how the hell you get that much offset  

AssAbuser:
How on earth could you expect someone to answer all of those questions....

Well here goes

yes
no
no
yes
maybe

hope this helps

LOL  

dragzooks@indy:
nick,
lmao

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