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Old 07-01-2011, 10:05 AM   #13
askmrjesus
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Join Date: Nov 2008
Location: Everywhere, all the time.
Moto: '0000 Custom Turbo Cross (with jet kit).
Posts: 6,481
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Quote:
Originally Posted by Porkchop View Post
We don't even know what is wrong yet. He was just guessing. That is why I'm going in tomorrow to talk to them in person and look through stuff.

Though, I already have a guy wanting to take the engine and cosmetics, another guy to take the rolling chassis and title, and another to take the carbs.
It's the "just guessing" part that bothers me.

I ran my own shop for several years, and I can't tell you how many guys would show up with a bike that was pronounced D.O.A by a dealership, only to find out that I could have it running in two days.

The thing is, a lot of shops don't want to fuck with old bikes. Partly, because they don't think you're going to want (or be able to) spend what it will take to fix the thing at a shop rate of $45.00 an hour or more. The other reason? They're lazy, and it's a hell of a lot easier to do brake jobs and oil changes, than it is to actually fix something. Profit, of course, also figures into this equation.

So, back to your bike- Lack of compression is caused one or two reasons (or a combination of one and two) bad rings or bad valves.

The first thing I would ask, would be the results of the compression test. What's the spec compression supposed to be, vs. was the reading was? If it's within 25% of where it's supposed to be, that's usually just normal wear.

Bad rings, as previously noted, is not too big of a deal, unless the cylinders are so far gone that they need to be re-bored. Unfortunately, there's no way to know that without tearing it down, inspecting for pits, and mic-ing the bore to see if it falls within spec. You probably don't have a micrometer that will do that, but a local machine shop could do the measuring for you, for not much dough.

Checking the valves is actually relatively simple. Pull the heads off, and yank the camshafts. All the valves are now, or should be, in the closed position. Place the head on a bench and level it with the combustion chambers upward. Fill the chambers with alcohol. Go to bed. Wake up, and see if the alcohol is still there. Yes? Good. No? Bad. 50% of the valve issues I've dealt with, were caused by carbon build up (caused by putting around at low RPM's). Simply cleaning up the valves and the seats will cure this. If the valves still leak after cleaning, you have bigger issues.

So, all that said, it's easy for some of us to just say "Hey man just, blah, blah,blah" because it's easy for us. It may not be easy for you, I don't know where your skill/comfort level lies, so that's something you obviously have to judge for yourself.

For what it's worth, the symptoms you descried sound more like carb issues (i.e, clogged pilot jets or out of sync) than compression issues, but without knowing the numbers, I can't say either way.

Out of curiosity, how many miles are on this thing?

JC
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