So I recently posted because I thought my carbs were dirty. Turns out they aren't.
Bike wouldn't idle, loss of power at low RPM? While a possible indication of dirty carbs and sticky float needles, turned out to be a whole lot worse for me.
After cleaning the carbs, fuel lines, and tank it was still performing poorly. I had a an old motorcycle hand I recently met (who worked for Suzuki 20 years) help me with the whole process and when cleaning it out didn't fix the problem he suggested we check the cylinders. We started with the spark plugs, that's when we noticed the right plug looked like it had been working twice as hard (lots more buildup). So, cleaned both plugs and they fired straight and blue. So we decided to check compression.
Sure enough, the right cylinder has about 20lbs of compression out of a desireable 140lbs or however much.
Looks like a bad seal.
Which means I'm suddenly in the market for a new engine....or a new bike.
Any suggestions about the next course of action? What would you do?
Did you check the valve clearances? A tight valve could cause that compression loss and be fixed with a new shim.
We debated if it was possible to reshim that valve but with only 25-30 psi compression the chances seem very very poor and really not worth a try. If we had 75-80 psi then MAYBE worth a try. Plus, re-shimming valves is getting beyond my technical abilities, so I'd have to pay. I could hire my new friend, but even at his extremely fair prices I'd be risking money I can't afford.
Also possible piston / rings are damaged / seized, burnt valve is most likely suspect, but if piston/ ring damaged... then the re-shim is a waste of time and money, since I'd need to hire my friend to help me. The other concern is if this valve is so lacking in maintenance that it burned, how is the rest of the engine maintenance wise? What if we open the engine up and the cylinder head is damaged (valve seat melted through) or left side is about to fail? The $ add up fast when you are buying and installing new parts everywhere.
So that's why he recommended trying to find a parts/wrecked bike for a good engine.
If I could re-shim myself then it certainly wouldn't hurt to try, but I'm still pretty new at this stuff. Cleaning the carbs is as technical as I've gotten at this point.
So, new engine or new bike. My Suzuki guy says he'll help me put a new engine in if I can find one.
I'd just hate to have to buy a new bike because my current one won't sell for much and I'm not sure I can afford to take a hit for a decent used bike at the moment. (I'm a transportation rider.)
Quote from: AWRobinson on May 17, 2007, 10:07:48 PM
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Any suggestions about the next course of action? What would you do?
Pull the head and look at the valve seats. Probably have some carbon build up or a seat that could be lapped to be good again.
yea, tear it down and see what you've got. I did it on my bike and found a bent exhaust valve. About $100 in parts (valve, guide, new rings) and a little time and work and it's good as new. The only special tool you need is a valve spring compressor but your mechanic buddy might have one you could borrow. Engines don't come much simpler than the GS.
The first thing to do is check the valve clearances. It really isn't hard and there's even a video floating arround here that thakes you by the hand and walks you through it.
That'll probally fix it.
If it dosn't, pour a tablespoon of oil into the cylinder and take another reading. If the compression goes up considerably, it's probally the rings that are shot, if it dosn't it's a valve problem.
Even, doing a top end on these things is easier, cheaper, and faster than swapping an engine. You don't even need to remove the engine from the frame.
Saying that you'd rather buy a new motor than check the valves makes no sense to me whatsoever. It's scheduled maintenance and is supposed to be done ever 4k or so.
I have a motor ... with ahem ... no numbers. Been ground off. Shipping will be a beeatch ... but can try it. $250 and shipping.
Cool.
Srinath.