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Posted (edited)

i just built motor , new top end , 60 over ,stock , wiesco pistons , slight porting , + 4 timing , stock carbs v force reeds , k+n no lid , i rode it 1 time , did a compression test and had 138 psi in each cylinder ,

 

is this too high ( only stock head ) do i need race fuel

Edited by woodro77
Posted

138 PSI with a stock head and slight porting? Good for you...if that compression gauge is accurate, you've got a nice tight bore and tight motor.

 

The highest I've seen on a bone stock motor, near sea level, is around 125 to 130....

 

You'll be more than fine with pump gas and a timing advance...

Posted (edited)
138 PSI with a stock head and slight porting? Good for you...if that compression gauge is accurate, you've got a nice tight bore and tight motor.

 

The highest I've seen on a bone stock motor, near sea level, is around 125 to 130....

 

You'll be more than fine with pump gas and a timing advance...

 

 

just cant get it to run perfect , runs fine , but when im riding it for a while it bogs and stalls some times then starts back up and runs fine , i am running vitos jet kit , 300 main , clip in middle , ,,,, not overheating , just runs a little shitty after 30 -40 minutes , if it was jetting wouldnt it happen all the time ?

Edited by woodro77
Posted

do a plug check or change to new plugs than run it. check the plugs color. sounds to me the mains are a bit big. a plug chop will let you know if that is the problem. what mix ratio are you running? you may be running rich on the oil.have you done a pressure test on the motor after the rebuild? that will tell you if you have any leaks. just brain storming.

Posted (edited)
do a plug check or change to new plugs than run it. check the plugs color. sounds to me the mains are a bit big. a plug chop will let you know if that is the problem. what mix ratio are you running? you may be running rich on the oil.have you done a pressure test on the motor after the rebuild? that will tell you if you have any leaks. just brain storming.

 

 

32-1 mix

 

leak down test is good

 

when i pulled the plugs out they were a red brown color

 

i am going to do a plug chop

Edited by woodro77
Posted
just cant get it to run perfect , runs fine , but when im riding it for a while it bogs and stalls some times then starts back up and runs fine , i am running vitos jet kit , 300 main , clip in middle , ,,,, not overheating , just runs a little shitty after 30 -40 minutes , if it was jetting wouldnt it happen all the time ?

 

 

Sounds to me like you are actually seizing it. What was the piston to cylinder wall clearance set at? If you didn't have any headwork done, I don't think you should have that kind of compression. I'm thinking, your clearances may be too tight. In my experience Wiseco pistons require a pretty strict break in period if you bore it on the tight side. Short heating and cooling cycles are how I do it. I have seized a few pistons during break in, by really getting on them too early.

Posted

im almost certain he didnt check his tolerances.., but im also willing to bet his is fine... 138 isnt normal on a stock motor for sure but its not impossible by any means... as long as your ring gap is good you shouldnt have any problems

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