Wierd Compression numbers

[professorman]

I did a compression test on a Katana I am looking on recently, and it has wired compression numbers. The first cylinder has 220 psi, the second one had 150. This alarmed me, but the others turned out to be 148 and 152. With 3 cylinders all in the same range, those seem to be the correct reading, but the cylinder with 220psi is odd.

What would cause this? This bike runs with the choke on, and idles at 3k-4k RPM, but as soon as you turn the choke completely off, it dies. I started it with the choke and got it going, and rode off, then released the choke and just continued riding, and it rides good, but as soon as I pull the clutch in the stop anywhere, they bike dies. I am thinking that this has some carb issues.

What do you guys think?

[md86]

Weren't you putting in another engine or something ?

[arsenic]

I have no idea what would cause compression too be HIGHER then it's supposed too. One of two things will correct that. 1) contact SuzukiRay and see what he says. 2) stop doing it wrong.

[Kfreak]

I have no idea what would cause compression too be HIGHER then it's supposed too. One of two things will correct that. 1) contact SuzukiRay and see what he says. 2) stop doing it wrong.

Are you checking thee compression on a hot motor?

[steves]

It sounds like the carbs are dirty.

[suzukiray]

The carbs definitely need gone through & if the needle & seat are leaking & letting gas into that cylinder it would cause the higher spike on the compression. Oil in that cylinder from a bad seal or guide will cause it also. Ray.

[professorman]

Well, maybe its the carb then, because it runs, but not very well. I know the carbs are not in the best of shape. I would get someone to go through them if I buy this bike.

[The CyberPoet]

Float flooding the cylinder with fuel, or something else flooding it with oil. The extra fluid is causing the air to compress to a much higher than normal level because the fluid is basically uncompressible...

Crap, just say that suzukiray already said all that.

So, +1 to suzukiray.

IMHO: unless the price is really low & reflects the state of the engine & carbs, walk away. That flooding could have been going on for a long time (while being ridden) and done damages to the rings/bores. Too many cheap Kats available to take one with major issues.

Cheers
=-= The CyberPoet

[Phil the Thrill]

Old Honda CBX's had bad float valves and needles. The bike would hydro-lock when put on the sidestand and started...voila bent rods. We had explicit instructions to NEVER put a CBX on the sidestand. Anyway, just like everybody said, either fuel or oil in that cylinder. I'd stay away from buying this one. If it's a fuel leak, then that fuel washes the cylinders and you loose ring seating, contaminate the clutch, and put too much strain on crank bearings. If it's excessive oil in the cylinder, then valve seals are probably toast.