Valve problem? hanging idle

[spots25]

So, I took it to the shop, and they couldn't figure it out, but they said it was probably carbon build up on the valves. So, I spent $170 for nothing. It's a 01 GS500.

It wants to idle up like the choke is set too high, but it's off. It runs perfectly across the whole range, just doesn't like to idle down

[Nessism]

Idle mixture is lean. Commonly an air leak but could be a simple idle mixture adjustment. Rubber o-rings on the intake pipe boots (item 22 below) is a very common leak source on our old GS bikes. Carb sync could also cause it but not as likely as lean mixture.

[spots25]

Idle mixture is lean. Commonly an air leak but could be a simple idle mixture adjustment. Rubber o-rings on the intake pipe boots (item 22 below) is a very common leak source on our old GS bikes. Carb sync could also cause it but not as likely as lean mixture.

that's what I thought at first, but turning the idle mixture screws way out didn't help. I checked for an intake leak with the WD40 test to no avail. That's why I gave up and brought it to a shop. The head mechanic seemed to think it was a valve problem on one of the cylinders, it only made 80 while the other made like 120

[psyguy]

pour a spoon of engine oil in the cylinders and test the compression again
that should tell you if indeed the valves are at fault

[rustybronco]

it only made 80 while the other made like 120

has someone checked the valve clearance yet?

[spots25]

the guy at the shop said he adjusted the valves, but I might tear it down and have a look myself

[bikerfox]

as far as checking for leaking boots, WD40 is not very reliable. It is very thick and does not suck through the same holes air will very easily.

[spots25]

correct me if I'm wrong, but a intake leak of a size large enough to cause the bike to hang at 4k rpm would be big enough for wd40 to get through

anyways, I picked up a feeler gage and attempted to get my hands on a compression tester, but couldn't find anything to borrow for free that went in a 12mm hole. Update tomorrow on the valve clearances

[spots25]

wooo... the left cylinder exhaust valve was so tight that I couldn't even cram the smallest feeler gage in there. I got a vastly smaller ship and she runs like a champ. yay!!!

[Nessism]

wooo... the left cylinder exhaust valve was so tight that I couldn't even cram the smallest feeler gage in there. I got a vastly smaller ship and she runs like a champ. yay!!!

Good job. Amazing what a little maintenance does.

[Suzuki mad]

and they did what for $170.......

wooo... the left cylinder exhaust valve was so tight that I couldn't even cram the smallest feeler gage in there. I got a vastly smaller ship and she runs like a champ. yay!!!

but before.....

the guy at the shop said he adjusted the valves, but I might tear it down and have a look myself

Well you got ripped off $170 then. Hope that it wasn't a main Suzuki dealer. I wouldn't be going back an complaining.

So you now know how to do the valves. Work on the engine oil/filter and the air filter change so that you can cut the service people out.

Suzuki mad.

[spots25]

I did valves on my old GS400 before, and I thought about doing the valves but didn't think it would make that much of an impact. At the suzuki dealer I paid for a carb clean, and he 'did' the valves basically for free. I went in to the dealer to get the new shim, and he said that he put in 2 different shims in there. Anyways, he traded me shims so it didn't cost me a penny for a new one. They also put in some bolts that I was missing for free. I'm a little mad, but not that mad. I'm more mad that I didn't do the valves myself because that would have solved all my problems the first time. I guess I learned how important a good valve adjustment is.

The only complaint I have with that dealer there, is that they put my fuel lines on the wrong way. The GS500 has a really complicated fuel system (dual lines from tank to vacuum operated petcock) and now my motor only gets filtered fuel when it's on 'run'. I might take it back and have them redo the lines, I really don't want to have to pull the carbs for something stupid like that.