Compression Test

[icerigger]

Anyone know if it makes a difference if you test the compression with the carbs removed?

Just did mine without the carbs and I got 150, 80, 120 & 120 dry. The 80 came up to 100 wet.

I can't see them coming up any higher if I put the carbs back on, so it looks like I'm doing the valves this winter, at least.

[TOOLS1]

If anything it would be lower with the carbs on. You must have unrestricted air flow when doing a compression check. That is why, you are supposed to open the throttle when doing the test. From your numbers it looks like you might have a valve out of adjustment on one cylinder.
TOOLS

[icerigger]

Thanks Tools, looks like I'm going to become more intimate with this beast than I wanted to.

oh well.

[icerigger]

Whoa. I thought your message said sticky ring!

Adjusted the valves before I took the test. All valves were within spec at the time of the test. Ran it twice before the battery went flat, going to try wet tests tomorrow after charging.

[TOOLS1]

One of us needs more sleep. I had originally thought those were dry numbers, and then thought they were wet numbers, and now I am thoroughly confused.
TOOLS  

[shinyribs]

It's hard to imagine that one cylinder would be that much lower than the rest. If anything i would suspect it id valve related,too. Honestly,if it were mine,and it still runs fine( no smoking or massive oil consumption) I'd rock it.  

I fit is a cylinder ring issue in just that one cylinder the spark plug may have oil residue on it. That may be a way to determine if it is ring related vs valve related.Just a thought

[TOOLS1]

Stuck ring was my first thought, but then I got to thinking that his numbers were from a wet test.
TOOLS

[robs750]

A leakdown test will pin point the leak.

[icerigger]

Confused doesn't begin to describe where I'm at.

Ran dry/wet tests this morning and these are the results.

Cyl 1 - 150/180
Cyl 2 - 110/210
Cyl 3 - 125/230
Cyl 4 - 130/200

I have no -ing idea what these numbers mean!

[Hoosier Daddy]

Pardon my ignorance but being the "New Guy" to the party...
 Is this a bike that you've been riding, one you rebuilt, or one you are bringing back from a long lay-over?
If it is an engine that has been sitting for some time, with those numbers, I'd say carry on and ride it! Then retest after at least a hundred miles. Give everything a chance to loosen up and reseat.
 That 80 is already improved to 110 then up to 210 from the oil you put in it for the wet portion of your test.
If it's your rider, as stated, a leak-down test will tell you ahead of time if it is rings, intake, or an exhaust valve issue.
Hope that helps.

[TOOLS1]

WOW Your engine healed it's self overnight. With those new numbers I would not worry about it. There not too bad.
TOOLS

[LukeM]

In my humble opinion, those numbers don't look bad.  Depending on the viscosity of the oil used (thicker oil = better seal rings to cylinder), that's not a bad jump from dry to wet.

I would assume this engine has some miles on it.  If you see blue smoke from the exhaust when accelerating hard, it's possible some oil is leaking past the rings. It's also possible there's some oil sneaking past the valve guides. Do you notice a drop in oil level, and if so, how often do you add more oil: every 200 miles?  every 1000?  You can also check the spark plugs, and get a good read of what's going on in the combustion process.

If it were me, I'd just keep riding it, and when the oil consumption got really bad, tear it down for a proper rebuild (bearings, rings, gaskets, etc).  The top end doesn't sound like it's doing too bad.

Luke M

[shinyribs]

230?!  Wow. Isn't that more than a new one had.  Ride it bro. You're good on that.

[icerigger]

Yeah, the wet side blew my mind. I didn't think it could go that high. The tester is brand new & the oil is just some 10W30.
The plugs, new with about 1,000km, aren't telling me much except that it's been running lean.
So, based on the sage advice I'm hearing here, I'll just clean it up and put it away for the winter.

Thanks Guys.