Compression on a Tri-Z????

[J.D.]

Ok I need to know how much compression a Tri-Z is SUPPOSED to have. I live at an elevation of 2,500 feet, and these are my readings with the throttle fully open.

1st kick: 95 PSI
2nd kick: 120 PSI
3rd kick: 130 PSI
4th kick: 135 PSI

pretty much stuck at 135 after 4th kick. Are these readings good?

[wanta250r]

Did you put the choke fully up. It says to do that in my manual. My 200x has 150psi or so

[J.D.]

You mean turn the choke on, like it's cold out?

[MR ATC]

i'm not positive on the exact numbers some of the TRI-Z guys can tell you that, but for a 250cc l.c. 2 stroke you should be around 180-200psi. new and serviced at around 155-165psi.

[J.D.]

well it still runs fine, starts up first or second kick, even in the cold(except for choke) starts up just fine...so I think I'll just keep running her till she dies.

[wanta250r]

I mean when you do the compression test put the choke up idea

[Billy Golightly]

Ubelievably the YAMAHA manual doesn't state what the compression for the Tri-Z is. It also makes mention several times to the "Powervalve" and how its a "Tri-moto 250". Real champs, them yamaha guys are.

[200xer]

If it starts right up the compression is good

[TimSr]

i'm not positive on the exact numbers some of the TRI-Z guys can tell you that, but for a 250cc l.c. 2 stroke you should be around 180-200psi. new and serviced at around 155-165psi.

Yep, if memory serves me right 180-200 is right. I dont remember about when they recommend service, but 135 means its time. If you change your rings in a timely manner, your cylinder will last a lot longer between bore jobs.