top end refresh and jetting question

[jompy]

Nice one buddy

[Fladdem]

Hi, sorry mate, but could you run another compression test on it now she's new? I think mines a bit down, I got about 82psi, I'm aware two strokes run lower compression than a four stroke anyway, but my TTR 265 is pushing out about 135-140PSI, and the revs are hanging a bit when I rev it up in neutral and let it settle, the plug says it's jetted fine but my heart says something's up.

I might just put a new piston in her anyway.

[gregorious77]

Hi, sorry mate, but could you run another compression test on it now she's new? I think mines a bit down, I got about 82psi, I'm aware two strokes run lower compression than a four stroke anyway, but my TTR 265 is pushing out about 135-140PSI, and the revs are hanging a bit when I rev it up in neutral and let it settle, the plug says it's jetted fine but my heart says something's up.

I might just put a new piston in her anyway.

82psi is way low! Book for the AR says 177psi so you could be down 50% mine read 125psi before rebuild. not tested since but big difference in power.
viewtopic.php?f=6&t=9848

[chris1971]

Hi, sorry mate, but could you run another compression test on it now she's new? I think mines a bit down, I got about 82psi, I'm aware two strokes run lower compression than a four stroke anyway, but my TTR 265 is pushing out about 135-140PSI, and the revs are hanging a bit when I rev it up in neutral and let it settle, the plug says it's jetted fine but my heart says something's up.

I might just put a new piston in her anyway.

82 Psi is frightingly low mate . tested the compresion last night andTBH my old tester is not at its best . 4 different readings but all above 180 psi . seems high to me but the new piston size is far bigger now . kicking my mk2 crm is near enuf the same kind of compresion i get from my 89 cr 250 . not quite as strong but not far away . only way to tell with your bike is to nip the barrel off and get the bore wear measured mate . i got away with a quick hone and a new set of rings with mine after i first bought her . the rings that came out were worn so badly you could actually see a thick and thin part to them . good thing is if you have a mk2 the cylinder liner is cast and can usually outlast a set of rings for wearing down

[Bultacobob]

Hi Mk MK3 with 4000 miles was about 175 psi, Just been checking my dr350 and it was about 40 psi checked it again with a decent gauge and it read about 35 psi better. The first tester was from E bay enough said the, second a Gunson form Halfords. Your Bike should be about 160 -180 in great condition but would be OK in the 150 range.