Compression problem

[Capinure]

OKay so my knowledge with motorbikes are very low.

Anyways my 89 Gixxer 250 has a low compression problem.

So i took it to the shops and i find out.

Dry tested it and all cylinders come out in the 50's and wet test only brought it up 10ish Psi's.
Valve clearances are good.
Spark Plugs are fouled with carbon.

I think we need to do a leak test to see which parts are causing it but right now i really think its the piston rings.

What do you guys at KB think?

[tri boy]

Sounds like rings/bore wear. Whats the Km's?

[Capinure]

Only 27,000 :pinch:

[jonbuoy]

If a wet test only gave you an extra 10PSI wouldn't it be more likely valves/gasket?

[Warr]

Can you believe those k's if it's your "89 Suzuki Gsxr250"
For all 4 cylinders to be down in the 50's the rings could all be tired.
Has the engine been overheated ?
But before I started pulling things apart I'd price out a replacement engine..

[Capinure]

I only had the bike for about a month now.

They said the valves were good so i just left it at that.

Overheated you say? um i've never seen the tempurature gauge go over half way but saying that i did check the coolant and the guy who sold it to me left this shity looking green water goo (looks like that shit from a outdoor pool in winter) so i got that changed.

[Hoon]

Valve clearances good does not mean valves are good.

Could be rings, gaskets or valve seats. All
fixable. Pull the head off and take a look.

[Katman]

It's not uncommon on those motors for the inlet valves to start recessing themselves into the seats.

[MSTRS]

... i did check the coolant and the guy who sold it to me left this shity looking green water goo (looks like that shit from a outdoor pool in winter) so i got that changed.

Anti-freeze? Gotta have that stuff.

[Suddy]

I too have just had the same thing happen to my 88' GSX-R 250 just got word from the mechanic today that 3 cylinders tested 50psi and the 4th was 25psi strange considering the bike was running so great and then after a long highway ride when i stopped for lunch and went to restart it it just wouldnt spark up thought i was just carbon build up on the plugs but it would appear otherwise...what octane fuel have you been running? i recently switched from normal unleaded to 98 octane. The machanic told me its unlikely this was a contributing factor but still makes me wonder...My little gixxer only has 18,000ks on the clock also, 16,000 when i purchased it 2 months ago..

[Capinure]

dude! wow its good to sure problems with someone! ( not that its good we have a problem in the first place)
I've always run 95 in it the bikes running great atm even if the mechanics are telling me that it has low compression.But i no that i have an carbon buildup problem i thought it might be that the piston rings are worn out but another mechanic has told me that my bikes running too rich and he had another gsxr with the same problem.
my had 26,000 when i brought it its hit 28,000 just the other day.

[munterk6]

after a comp. test the next test is a leak-down test which will show where the comp. is leaking from( inlet valves...hissing out the inlet ports, exhaust...out the ex ports, rings???...hissing out the crankcase breather).
I have a old sparkplug I have gutted and silver-soldered an air fitting onto the top. Screw it in to cyl head, set piston at firing TDC, and apply tank pressure(100ish psi) You will soon hear where the compression is leaking from.

IMHO, I reckon those odometer readings are a bum-steer on the age/condition of the engine, could be double the shown kms, in which case the rings to cyl will be fairly slogged. Taking the head off and measuring the cylinders ovality will say it all.
Also, the valves will be fairly worn, hey, wouldnt you be worn out if you were doing 10 to 15 thousand RPM most of the time???
I have used a product called "Subaru upper engine cleaner" at work with great success. Ya spray it (aerosol can) into the intake ports and leave it to do its work. It actually melts hard crusty carbon....dinkum!!! then start the engine after 5-10 mins. HUGE cloud of blue smoke, and a nice clean top end!
Cool eh. It actually improves power. Try it, if ya want some, PM me.