GS1000 engine bucks at low engine speed

[mharrington]

Fixed up a 1979 GS1000N for my brother. The bike was purchased un rideable due to collision damage (bent forks) and neglected maintainence. The bike runs fantastic. Starts easy and has tons of power. He rides it aggressively and takes it to redline often and past 100mph often. When we are cruising thru the local beach park the speed limit is under 10mph or less. His GS engine will buck vigorously in 1st gear at this very low speed. Pulling in the clutch the engine resumes a smooth buck free mode. City speeds of 25mpg-35mph it does not buck. Just at this really slow speed it does it. The carbs are synced and spot on- valves adjusted and in spec- carbs clean with all RUBBER NEW- even genuine Mikuni needle and seat assemblies at $33 each!. New Barnett clutch springs and the steels and friction discs well within spec. Points and condensers new. Again- this bike runs like a brand new bike and is fast- its just the low low speed engine buck. Any ideas? Thanks!-Mike

[1980GS1000E]

The bike wasn't really designed to have any engine load at idle speed. If it idles smoothly and revs cleanly to 2000 rpm, then my guess is that at such a low speed applying power requires very precise throttle use. This is assuming that the bike is in proper tune.

[bellucci]

Gearing different than stock?
Curt

[chuck hahn]

What 1000E said. Its not geared low enough to run well at idle RPMS...which is about what youll be close to at only 10 MPH. Youll have to go at about 1200 to 1300 RPMs or there about to be smooth in first gear.

[mharrington]

Ahhh I have learned something today!! Thanks guys! When we are idling thru this park the speeds we are moving get slow enough we have to but are feet down. The gearing I believe is stock. Brand new chain and sprockets from Dennis Kirk and the owner specified stock ratios when he placed the phone order. The bike is such a blast to ride! So now I know- Thanks again !!!!!

[chuck hahn]

Sounds right by my experience with all my bikes..feet ready and feathering the cluth . Its not good on the clutch plates and fiber though.

[Gonzo]

Gorgeous bike!

Try dragging the rear brake to load the engine and smooth it some. Think of those low speed maneuvers in MSF classes where you drag brakes. I imagine as long as you don't drag it too long it won't get overly hot.

[eil]

Ditto on practicing low-speed MSF stuff often. Throtle, clutch, brake. Sometimes you need to modulate all three at the same time in order to be smooth at very low speeds. Slipping a wet clutch at low speeds will not hurt it any, that's what they're made for.

[mharrington]

Thank you gentlemen!

[Steve]

It will sound a bit counter-intuitive, but ... shift to second gear.

Yep, the the ultra-low ratio of first gear, any throttle transition is greatly magnified at the wheel.

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[tkent02]

Which method did you use to adjust the fuel pilot screws?
Might be juuuuuust a tad lean.

[mharrington]

The idle mixture screws are adjusted to factory spec- which I do not recall. The bike does have an aftermarket ABC brand 4 into 2 turnout exhaust. Plugs look good at all spectrums but we can check again. The owner is 55 years old (my oldest brother) and is very nostalgic about the big 70s GS suzukis- they were the hot ticket when he was a young man in the 70s. His other bike is a 2004 Ninja 900. He says the Suzuki still provides a rush even though he is used to the power of the crotch rocket. Also says the GS is more fun to ride- sounds better and gets much more attention!

The red bike in the foreground is my 1979 XS1100. Its cool to see people who recognize and appreciate old 70s musclebikes!

[Steve]

The idle mixture screws are adjusted to factory spec- which I do not recall. The bike does have an aftermarket ABC brand 4 into 2 turnout exhaust.

Considering that "factory specs" were a bit lean, and you probably leaned it out a bit more with the aftermarket exhaust, I would concur with tkent, it's a bit lean.

The red bike in the foreground is my 1979 XS1100. Its cool to see people who recognize and appreciate old 70s musclebikes!

Somebody must have flipped your picture.

In the picture that we got to see, the red bike is in the background.



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[mharrington]

Im gonna hang up my auxillary tank and do a idle mixture adjustment on the GS again. Yes I meant to type my XS1100 is in the BACKGROUND!