Topend Compression

[02yamahablaster]

What good and whats not? I have 125PSI even in both cylinders and my buddies Shee he just got has 170PSI. I checked them with the same gauge.

[ASRBanshee]

damn I am like at 120 psi.

[quadracer87]

tighten ur bolts on the head / cylinders might help


run it til its under 120 ish and rebuild or rering/gasket

[Wacko Jacko]

a stock banshee at sea level has around 130-135psi
i hope your friend with 170 runs race fuel
i wouldnt start tightening down bolts, if they were torqued right that doesnt have anything to do with anything, 120 pounds is fine, ride it
most people say when they get around 100 psi its time for rebuild

[ASRBanshee]

I was at 104 and 107 on each cylinder and needed a rebuild so somewhere around is the time. Where can I get a compression gauge

[Wacko Jacko]

sears, autoparts store

[02yamahablaster]

Originally Posted by wacko jacko

a stock banshee at sea level has around 130-135psi
i hope your friend with 170 runs race fuel
i wouldnt start tightening down bolts, if they were torqued right that doesnt have anything to do with anything, 120 pounds is fine, ride it
most people say when they get around 100 psi its time for rebuild

No he's running 91 octane.

[dajogejr]

Ok guys, let me give you a few facts.

Stock compression at or near sea level is 125 to 130.
If your buddies quad is truly at 170, even with no timing advance, I'd say he need at least a mix of race/pump gas.

What is done to your bike to get 125PSI, what is done to his? If they're both stock heads, get a new compression gauge. That's physically impossible. to get those readings. Sears/Craftsman make a nice motorcycle compression tester kit for 59 bucks. Has all the adapters you'll ever need.

If you're at or near sea level for your buddy to get those readings, he's got a TON shaved off his head, or has 18 or 19cc domes.

[ky 2stroker]

my brothers banshee had 85psi in the left cylinder and 115 in the right. it would run, but it was a bitch to start and acted pretty stubborn.

[dajogejr]

Once you start getting below 110 PSI...or, 10% or more variance in cylinder pressures, it's time to do something about it. Once a motor is worn, it only gets more expensive if you don't do something about it.

My old stocker motor had about 105 in each, was a bitch to start cold, but ran like a raped ape once started. 1 kick to start it when warm...it was due...LOL.