Other Tripple compression

[Vumad]

Why do I keep reading that stock twins have 150 PSI and stock tripples have 120 PSI? Why do the tripples have lower compression?

 

[tor*p*do]

becasue that is how they build them . . .

 

[Shonuff]

Only one p in triple, btw.

And if you look on ADA's website, they recommend race gas for anything over 150psi.

odd . . .

 

[Freakrider]

what is it a heat issue in triples combined with potential crank torsioning timing problems ? anyone know the answer on this ?

 

[Crab]

Compression probably has to due with higher port timings.

 

[WFO Speedracer]

The standard compression is 110 to 120 lbs, crankshaft torsioning is a problem with triples due to the crankshaft length, it actually throws the timing on the rear cylinder out by a couple of degrees at max rpm's. Yamaha actually varies the compression on the rear cylinder of their triples to compensate for this. Compression over 150lbs lets the engine rev higher, these higher RPM's and compression create heat which makes the use of race gas mandatory on engines running over 150lbs of compression and or turning over 7000 RPM's.

 

[tor*p*do]

In order to be an immaculate member of a flock of sheep, one must above all be a sheep oneself.
Albert Einstein

are you still on the search for the immaculate sheep?
you baaaa-d boy!

 

[WFO Speedracer]

are you still on the search for the immaculate sheep?
you baaaa-d boy!

:sneaky:

 

[scottie mac]

ADA's recommendations on compression are VERY conservative. Especially on Kawis. You can run 170lbs of compression on a triple Kawi without problem in anything other than a runabout. If you put that motor in a blaster or stand up, they less weight decreases the amount of load on the motor, which decreases heat and detonation. We run a triple superstock 1100 at 7800 rpms with 5 degrees of timing in a carbon blaster on 93 octane without issue. Put that same motor in a 7-800 lbs runabout and it would be dicey on whether or not race gas would be needed.

SM

 

[WFO Speedracer]

ADA's recommendations on compression are VERY conservative. Especially on Kawis. You can run 170lbs of compression on a triple Kawi without problem in anything other than a runabout. If you put that motor in a blaster or stand up, they less weight decreases the amount of load on the motor, which decreases heat and detonation. We run a triple superstock 1100 at 7800 rpms with 5 degrees of timing in a carbon blaster on 93 octane without issue. Put that same motor in a 7-800 lbs runabout and it would be dicey on whether or not race gas would be needed.

SM

That is probably correct, all I have to go on is my experience, which with that engine or any other triple would only be in runabouts.