Intermittent Fuel stutter?

[khshattuck]

Hi all, (love this site, BTW!)

I have a '79 GS1000EN. Had the bottom & top ends rebuilt, have Dyna Ignition & coils and new spark plugs & wires (NGK). Also bought the carbs rebuilt and have stock carbs with the air box.

My problem is that I have an intermittent "stutter" for lack of a better term. (It seems to happen more in warmer weather, but not exclusively). The stutter feels like fuel starvation, and, at it's worst, sounds & feels like I'm running on 1 cylinder of power. I can still accelerate, but very, very weakly.

Sometimes I can "reef" on the throttle and it'll "break out" of the stutter. Sometimes, not. The stutter happens on acceleration, steady throttle and (rarely) on deceleration - even sometimes on idle. (The engine doesn't die, though, even if it stutters on idle.)

One suggestion that I just received was that it is possibly some junk in the fuel filter that is randomly plugging my line.

Any thoughts?

Thanks so much!

LOVE this bike!

 

[Agemax]

strip out the fuel tap and clean it, including the filter. check in the tank to see if there is any rust or crud floating around inside. give it a good flush out if it is just crud or if it is rust you may have to get it treated.
thats a start anyway!

 

[BassCliff]

Hi,

Are you using and inline fuel filter? Is the fuel tank venting properly? If the fuel cap is not venting properly it can be disassembled and cleaned. Make sure the little breather hole in the fuel tank filler neck is clear. Have you tested, or better yet replaced the petcock? Check the vacuum line to the petcock.

Where did you get your carbs? It makes me a little suspicious when some unknown entity "rebuilt" the carbs. If aftermarket "carb kits" were used then it's possible not all passages were properly cleaned and not all O-rings were replaced. Aftermarket carb kits are notorious for incomplete and inferior parts. See the "how to" guides on my little website.

I suppose there's also a possibility that it's related to timing advance but since it happens at all engines speeds I guess that's a low probability. Still, make sure there are no worn wires under the fuel tank, or anywhere else in the harness, that could be shorting at odd times causing the miss.

Thank you for your indulgence,

BassCliff

 

[hampshirehog]

As above plus the float levels could be out. Try the other stuff first - it's easier.