1982 gs650g will not pull past 6k

[Guest]

so iv read around seen a few things on this fourm just can not get this issue to go away
the bike was a barn bike since 95 it has 3600 mi on it and is in really good shape the carbs were replaced with a set off an 81, got it running and the base gasket leaked replaced all the top end gaskets and went thru the carbs again.
Got it on the road with cheap pod filters and the new gaskets , it would break up and fall on its face around 5500, read these fourms and decided to reinstall the air box and get a filter for it, thought the pods were my problem, unfortunatly not quite. bike runs better with the box but cuts out cold at 6k

At this point the carbs have been cleaned througly 4 times the factory air box and exhaust are on it with a new uni foam filter.
everything looked great in the motor and im at a complete lose
i set the float height, cleaned all jets and passages again rebuilt the petcock put an inline filter on put 120miles on it and it just will not exceed 6k, did a plug chop this morning waiting for it to cool to take a look.
i cant imagine it needs jetting with just a uni filter but maybe im wrong it pulls like a frieght train up to about 5500, no matter if rolled onto or wot, will rev to 6 but not a tick further doesnt spit and carry on like its lean or way to rich. any help would be greatly apreciated. thank you in advance


also downloaded the factory service manual and have been on basscliffs site all the jet sizes are stock floats were set with calipers,

[steve murdoch]

Welcome to the site, jfs.
Sounds like you have eliminated carbs as the culprit so i would look at the timing advance.
Busted spring? Not advancing should occur before 6000 rpm but something else to check. got a timing light?
btw, excellent details on your first post.

[MechMessiah]

So the bike won't go past 6,000 RPM's in any gear?

I'm having a very similar issue with the same bike but only in 5th gear. And I'm pretty sure mine is a jetting issue. If you're interested here's my rebuild thread. I had to do a lot of the same work as you. The bike had a bad petcock leaking fuel, the top end gaskets all had to be replaced, carbs were stripped down and rebuilt.

Also here's a link to a CV Carb tuning guide that' been useful for me. http://www.factorypro.com/tech/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

[tom203]

I'd also be suspicious of the mechanical advancer.. it should reach about 40 degrees btdc by 4k rpm,maybe it's rusted or sticking in place ,although it's hard to believe it could be consistently maxing out at 6k. P

[jfsfabrication]

Man you guys got me excited with the timing advance went out pulled the cover off seems to be free as a bird very smooth and both springs are intact.
After checking the plugs this morning the outer two look a touch on the fat side (rich) inner two look a little glazed maybe a touch lean, the plug chop was kinda halfbaked tho, not gunna say its 100% accurate to the top end, didnt wanna shred the alley out front of the shop to hard.
The only things im hanging up on are maybe the carb slide diaphragms, witch are in good shape no rips or holes but alittle wrinkly when seated, and i did not check valve clearance yet... thanks for the quick reply's. Im really in love with the way this bike looks, rides and its condition. That said this problem says me yanking at my hair

[jfsfabrication]

0602171946a.jpg

this critter looks good

[gustovh]

Count the pins between your cams, 20 pins not 21. The notches in the end of the cams should either be point right at or directly away from each other and parallel to the head as I am sure that you know, but is an easy one to screw up. Don't ask how I know. My 850 quit spinning up after 7000

V

[MechMessiah]

Count the pins between your cams, 20 pins not 21.

19 pins if it's chain driven.