gs650e carb problem

[dominionarms]

Got a used 1983 gs650e. Rebuilt the carbs and got it idling/ running smoothly. (the only thing not replaced were idle screws because slots were stripped-but it idles fine- I'm resisting "easy-outing" unless all else fails) Problem is that it won't rev over 5000rpm without bogging out. With quick throttle up can get about 6000 then bogs out-slow increase in rpms ok up to 4000rpm and will hold if not increased any further. Thought it might be starving for fuel but float levels good and nothing in the carbs are plugged.

No vacuum leaks detected and replaced with new intake flanges and gaskets.
Tried with vacuum line plugged and hooked up to petcock-no difference.
Diaphrams not torn. At steady 4000rpms sliders not particularly lifted much but all pulse about the same. Tried placing tape over intakes and there is a vast improvement in throttle response and full throttle- idle also increases significantly.
Anyone had similar problem or has ideas?

[Steve]

Believe it or not, EVERYONE has had this problem.

At least until they put the airbox back on.

These carbs need to have at least some restriction ahead of them to be able to lift the slides. If you want to do a quick test that is good enough to ride around the block, take a shop rag, fold it in half. Clamp it to the intakes of the outer carbs with hose clamps or zip-ties. Now it should do a LOT better. NOTE: while this is good for a quick check, it is NOT good enough to do jetting checks.

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[Larry D]

Welcome !!

Are you doing all this without the airbox and filter installed ? These bikes will not run properly without the correct mixture of air and fuel.

[dominionarms]

gs650 carb problem

Tried it with airbox with slight impovement-but because its such a pain taking on and off while experimenting-I'm currently using 4 KN filters well oiled- with only moderate improvement.

[Larry D]

First, I would highly recommend getting the idle air screws loose and removed. There is a rubber o-rings in there that should be replaced. Try soaking them with your favorite solvent for a few days. The tips of these little buggers tend to break off in the carb body from someone cranking them down to hard. I understand about stripping them, but, be careful, soak them and get a well fitting screwdriver.

Second, if you're going run pods the carbs must be re-jetted to account for the increased airflow. Or, again I recommend, getting it running properly with the airbox. I had a difficult time getting my airbox in and out at first. Then, one day, while I was jacking with it, it just kinda fell into place. It's an easy task now. There's a way it goes in and out, you just have to figure out what it is.

[Steve]

I'm currently using 4 KN filters well oiled- with only moderate improvement.

There is a BIG difference between "well oiled" and "PROPERLY oiled".

If you have too much oil on the filters (and it's easy to do), you are choking it to the point of not being able to breathe.

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[dominionarms]

gs650 carb problems

properly- as recommended with the kn filter oil per kn instructions.

Also I think you said you finally found a easy method of taking air box/carbs on and off. Always takes me more time than rebuilding the carbs! One of the manuals maybe Clymer book says to remove and install attached to the carburetor --thats plain nuts-I've been tilting the carbs between airbox and intake manifolds-but it always winds up being an ordeal to get the inboard airbox gaskets around carbs properly---any suggestions-thx much

[chef1366]

You need to rejet with the pods. You will run dangerously lean and could hurt the motor.

[duaneage]

I didn't see if you had checked the o rings on the rubber intake boots screwed to the head. Under the flange there are o rings and they might be flattened out or broken.

The carbs are vacuum sensitive and need tight connections on the Intake rubber boots, the airbox boots, and everything in between. the slides won't lift properly (if at all) if a leak develops.

If only one set of boots out of the 4 is problematic it upsets everything. Also, just one carb being out of adjustment (meaning not synchronized properly) can make the bike run horrible. I demonstrated this to a friend as I synced their bike. One carb far enough out and the bike would not rev above 5 grand. without trouble.

Check the boots at the head with wd-40 spray while idling. An increase or change in idle speed/quality shows the boots or o rings are leaking.