82 GS450S Carb Help-High Idle

[Guest]

I purchased the bike about a year and a half ago as my first bike. Its been a great bike to learn on while riding around town and on some country roads. The bike is completely stock besides what I am guessing is a Ebay exhaust (put on by a previous owner). Bike has a few little problems that I am currently working out to make the bike more reliable. The one problem that I need some help with is carb and jet settings. So when the bike gets to operating temperature, if you blip the throttle the engine will hang at 3-4000 RPM until you blip it again and then it will go back down to idle, sometimes. Also if I turn the bike off with the engine stuck on 3-4000 RPM it will let out a very loud backfire. I have checked for air leeks around all the intake boots and have found nothing. My research and train of thought has lead me to believe that the pilot jet is to small. If anyone has any information or advice it would be greatly appreciated.

Thanks SteelIDan
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[roeme]

I was just about to begin a thread on this. You seem to have exactly the same problem as me. Does this seem familiar?

I'm also slowly reaching the point where I begin to question an air leak.

[sam000lee]

Have you checked for air leaks? The boots between the cylinder head will dry out after a number of years as will the O-rings that seal between and in this case they should be replaced.
It look like you have a Mac 2 into 1 exhaust or something similar, it could change the jetting but not as drastically as POD filters. I would ensure that the air intake was tight before messing with jetting. You could try turning the mixture screw on the sides out a half a turn.

When were the valve clearances last checked? That could also be adding to your problem if they're out of spec.

[steelidan]

Roeme=Yea mine will hang like that but it will not drop as easily as yours does

Sam000lee= I did check for air leeks but i was thinking of replacing those O rings just as a precaution. The mix screw, are you thinking 1 1/2 to 2 turns out? I have not checked valve clearance but that is something I have thought about doing. Is that a hard job to do on these bikes?

Thanks SteelIDan

[sam000lee]

In order to sort out carb problems, a full teardown and cleaning is needed. Many people here use cycleorings.com (they have a GS450) O-ring kit to replace the old O-rings and the owner is a member here. You should at least check the O-rings if you don't know what their condition is. If I remember correctly the full O-ring kit for the GS450 including the intake boot rings is $15 or something. I believe that that the stock air screw setting is 2 turns out so maybe try it at 2 1/2.

Checking the valve clearances is not hard, but depends on your comfort level. It NEEDS to be done every 3,000 miles or so because the clearances decrease with time and can lead to more serious problems. My guess is that a shop will charge you $200 or $300 to do the job.
There is a lot of information on this on BassCliff's site including GS450 carb rebuild tutorials and valve clearance checking/adjusting tutorials

http://members.dslextreme.com/users/bikecliff/

[steelidan]

sam000lee= Thank you so much for the information. I will start with a carb clean and rebuild. I think I could handle a valve clearance job just need to source the correct tools. Ill post any results that I get this upcoming week. Thank you again for the help.

SteelIDan

[Nessism]

Please check the newbie mistakes thread linked in my signature. It will help you...

[steelidan]

Ed thanks for that. I now have some hope that this problem can be fixed.

SteelIDan