Polini corsa compression readings after 2 years.

[Speedtrip]

My scoot randomly started feeling slightly sluggish last weekend. I wrote it off to the muggy weather or a sagging contra spring. I pulled it apart and swapped my other koso spring in (known good) and the sliders looked good. Slapped it back together and had same results..... Now ive been tuning and riding for a long time and my setup is fairly unchanged over the years. Corsa, pg long, oko24, zx trans, 9.1's. So its common it needs new rollers/sliders or a belt or general maintenance. So on a whim i pulled the plug out (perfect chocolate color) and did a compression test. I get like 122psi. The kits probly got about 3k on it over 2+ years. I dont remember what it was new but i thought it was 140ish before. Anyone recall what theirs was when new??? I though i wrote it on the shroud but its not there. Its idling slightly lower too so i was thinking it could be showing its age finally. Let me kno if you have tested yours fresh or recently. Thanks guys.

[maddog]

I got an easy 40k from my bore, when I lost power it was bad ramp guides.

[1man8scoots]

I got an easy 40k from my bore, when I lost power it was bad ramp guides.

And then you woke up. Liar.

[Speedtrip]

Yea i checked it again when it was cooled off some and i kicked it up to 135psi so i really dont think it's anything top end related. It feels trans related but ive swapped a bunch of stuff and lightened up the weights a little and it still down on rpm and power especially when you need it to downshift and get back on it. Im gonna try swapping my S rear pulley back on and see if it's somthing related to that. I still kno my complete trans setup i had in it with the s trans that always felt awesome but lacked a little take off. So im gonna try that.

[curtis966]

Dude quit with your rambling nonsense and cluttering up the board it's getting old and really annoying. You and maddog can get a room and talk your dumb s*** together.

[1man8scoots]

why dont we just see for ourselves what the problem ends up being.

That's what I'm saying. I doubt the vario will clear up a lower idle. But just because it's never ever cleared up a lower idle doesn't mean it's not possible. Codename is a master tuner didn't you know?

[1man8scoots]

I have 145 on one corsa and 139 on another. The one with 139 has a mhr base gasket.

[Xxbeejay45xx]

I have 2 corsa both reading differently, 141 psi and 136 psi

[S4Patrick]

140psi on a Corsa seems to been the trend here. I've measured 182+ psi on a couple Corsa builds.....using the Polini-supplied gaskets.

What gasket(s) are you guys using the lower your compression to the 140ish compression number?

The Polini-supplied deli-thin base gasket & green o-ring only? Or are you substituting the O-ring with a metal head gasket?

[1man8scoots]

Hi patrick, elevation plays a role in compression also. I use the polini supplied base and o ring. The difference of compression can be linked to deck height of the block or variances in machining. Around .5mm of gaskets either way can net 40 psi in change.

[S4Patrick]

1man! Thanks for the feedback/ information...

You're just using the Polini-supplied gaskets & seeing the 140ish PSI? Or are you using an additional gasket in conjunction with the Polini-supplied gaskets?

[1man8scoots]

Stock polini metal and o ring. Vast majority have been around 140-160. Contessa 140ish always, malossi iron 140ish, mhr 150-175, tai bores 120-180, and stroker mini or full you set to your desire. I've yet to have a corsa over low 160, or mhr below 150.
I've heard of high compression randomly from people on a bunch of different cylinders and only conclusion is altitude, deck height of case, or abnormal casted cylinder or head. There are some differences in con rod length also and is a reason for having a minimum of .7 squish is super important. Rods do stretch under high tension and are definitely not all the same length. Some may be .1mm longer than spec and I've heard some have been .2 on stock yamaha jog rods.