lil3incher
Member
The chassis is in rough shape but the the engine and all parts are in very good condition, I performed a compression test on the engine, Left to Right the PSI was, 125, 130, 125, Is this a good number because I also have a 1998 VMax SX 700 and it has 147 PSI across all 3 cylinders, wondering what they shoulld have new and should I worry about engine trouble???
Gregsyamaha
New member
As long as they're close to even and above 100 you're good. If one cylinder has a big difference, then your into trouble!
roudyroy1
Active member
that v max must have shaved heads or the gasket mod
lil3incher
Member
Yeah roudyroy1 you may be right, She do fell more powerful then she should, and also I shouldn't worry about 5 PSI difference?
justin1620
New member
Your compression is good on all 3. Nothing to worry about.
Devilin AblueDress!
New member
Yeah roudyroy1 you may be right, She do fell more powerful then she should, and also I shouldn't worry about 5 PSI difference?
Most say within 10% of each other.
lil3incher
Member
Thanks alot guys, This is my first power valved triple, Very excited about it
roudyroy1
Active member
that 5 psi difference is on the pto side, thats because it has a different size head. its supposed to be like that idk why the other one is but its not a big deal
Devilin AblueDress!
New member
that 5 psi difference is on the pto side, thats because it has a different size head. its supposed to be like that idk why the other one is but its not a big deal
Never heard of this on a SRX........Enlighten us? Maybe you were thinking of the Viper?
roudyroy1
Active member
on an srx and viper, the pto cylinder head has a larger volume to reduce compression in that cylinder. the idea is that since that cylinder has to deal with heat from the clutch and all the stress from the other 2 cylinders putting energy through the crank it gets hotter. the reduced compression causes that cylinder to not make as much power thus producing less heat. on red head engine all head volumes are the same, so instead they run staggered jetting, the pto cylinder is richer than the other 2.
Devilin AblueDress!
New member
on an srx and viper, the pto cylinder head has a larger volume to reduce compression in that cylinder. the idea is that since that cylinder has to deal with heat from the clutch and all the stress from the other 2 cylinders putting energy through the crank it gets hotter. the reduced compression causes that cylinder to not make as much power thus producing less heat. on red head engine all head volumes are the same, so instead they run staggered jetting, the pto cylinder is richer than the other 2.
Sorry but NOT SRX, SRX heads (all 3) are the EXACT SAME AS THE OTHER 2. Pretty sure all Yamaha come from the factory with staggered jetting.
roudyroy1
Active member
i stand corrected then.
Devilin AblueDress!
New member
As far as SRX goes the 98-99 (8DN00) are the same and 00-02 (8DN10) are the same. Should not mix the two different heads on same motor.