gs750 running lean

[Guest]

i have a 1980 gs 750E. I recently changed the head gasket and valve cover gasket, they were leaking pretty bad. Adjusted valve clearances. I cleaned and synced carbs. I have brand new spark plugs. The bike rides great in town but when i get out and really gun on it. it won't quite rap out all the way. it will only rev to about 6-7 grand. I went back and pulled the plugs while they were still hot, they were very very WHITE. My pilot screw r 2 turns out, is that the source of this lean problem? Does turning them in add more fuel or add more air? the bike has great low and midrange power, but falls on its face at high rpm. I am using the stock airbox and filter, and a 4 into 1 exhaust.

[trevor]

i have a 1980 gs 750E. I recently changed the head gasket and valve cover gasket, they were leaking pretty bad. Adjusted valve clearances. I cleaned and synced carbs. I have brand new spark plugs. The bike rides great in town but when i get out and really gun on it. it won't quite rap out all the way. it will only rev to about 6-7 grand. I went back and pulled the plugs while they were still hot, they were very very WHITE. My pilot screw r 2 turns out, is that the source of this lean problem? Does turning them in add more fuel or add more air? the bike has great low and midrange power, but falls on its face at high rpm. I am using the stock airbox and filter, and a 4 into 1 exhaust.

Did you put in a stage 1 jet kit when the 4into1 went on? If not you will have too. I did the same thing and have the same bike.
Pa any pics?

[p_trice]

I bought the bike with the exhaust already on it. The jets r stock to my knowledge. So if i put the stage 1 kit on, it won't run as lean? does it need to be an authentic dynojet kit or does it matter?

[p_trice]

tore my carbs apart today and looked at the main jets. they say 142 on them. r these the original?

[BassCliff]

Greetings and Salutations!!

Hi Mr. p_trice,

You'll find a chart with all the stock jetting on my little website. Look on the "Carb Specs" page.

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Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

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Thank you for your indulgence,

BassCliff

[p_trice]

ok, so if my main jets are already bigger than stock, why won't the bike rap out like it should? doesn't make sense

[hampshirehog]

If it won't rev out it's running rich. 142 mains are massively over size for a pipe alone. Stock is 112.5. I would run those with a 4-1. Or 115s maybe, just to play a little safe.

Set your tickover using the highest revs method. You're probably a bit lean on the mixture screw hence the white plugs.

[p_trice]

so do u think a stage 1 jet kit will cure my problems? it come with a 116 and a 120 main jet.

[hampshirehog]

so do u think a stage 1 jet kit will cure my problems? it come with a 116 and a 120 main jet.

Probably but 4 main jets are a lot cheaper than a Dynojet kit.