1978 GS750 Cold exhaust pipe

[ZakDanger]

So the other day I noticed fuel dumping out of my pod on the #1 carb when I give it gas. Checked my pipes after running for a bit and sure enough #1 is cold in comparison to the other three. Checked spark, she's bright and blue. Checked my float needle, she springs back no problem. Even checked to see if my floats were still floaty. In the middle of checking the carbs I notice a screw plugging up the overflow drain tube. Great. So apparently this was an issue before, and this is how the guy fixed it.

The slide works, which would let gas in... so... huh? Anyone have this issue? Whats goin on??

[Big T]

Take out your jets and clean them (BTW, you did clean your carbs?)

The gas is running out the carb because it's not going into the cylinder

[Dave8338]

If you didn't pull the float needleandseat, May I suggest doing so.

[btbarb]

So the other day I noticed fuel dumping out of my pod on the #1 carb when I give it gas. Checked my pipes after running for a bit and sure enough #1 is cold in comparison to the other three. Checked spark, she's bright and blue. Checked my float needle, she springs back no problem. Even checked to see if my floats were still floaty. In the middle of checking the carbs I notice a screw plugging up the overflow drain tube. Great. So apparently this was an issue before, and this is how the guy fixed it.

The slide works, which would let gas in... so... huh? Anyone have this issue? Whats goin on??

Not sure on your root problem, but if the pipe is still cold a few minutes after riding, the pilot jet could be clogged, that jet and the choke tube get crud in them easy.

Not sure of whether there could be other reasons on your overflow, but if the float needle valve seat, float needle valve, and petcock aren't all working together the way they're supposed to, that will cause overflow.

Carb dip and rebuild with new o-rings is usually recommended, probably not so much because everything needs to be fixed, but because you have to get a good baseline and cross a lot of little gremlins off the list, unless you do it, it's hard to know for sure.


(pic is from the VM rebuild pdf)

[ZakDanger]

Is there any way for me to just get the o-rings and gaskets so I don't have to buy a full $ 25 rebuild kit for each one? About 125 to rebuild my carbs? Ick.

[tkent02]

Usually all you need are o rings, unless some PO glued the gaskets down.
Robert Barr has what you need.
Search him on this forum.

[ZakDanger]

Wow. This guy is a friggin saint. Thanks alot man, you and he saved me some serious coin.

[ZakDanger]

Ok. Pulled the carbs apart, dipped each one individually, carb spray and compressed air through the jets, replaced the float needles (actually found some K&L for $5 each), replaced the gaskets, replaced the o-rings, including the ones connecting the carb boots to the engine... These things could NOT get any cleaner. Lookin, workin, feelin GOOD.

Started her up after kicking the hell out of her and some ether, keep her at a choppy idle (needs a sync), pipes 2,3,4, nice and hot. #1. Still cold. Pull the plug, no change in idle. Unscrew the plug, she fires with a gorgeous but disheartening purple spark. Pulling the 3 & 4, get a blue spark, pull #2, get a mostly blue, somewhat purple spark.

I think I might buy an ignition module, but I wanna ask the experts first. Whatchoo think?

[MisterCinders]

When you pulled the No. 1 plug, was it wet or dry?

[ZakDanger]

Looked dry to me, but then again I wasn't really checking for that. Also clean. Way too clean. Didn't think to check how wet it was tho... good call...

[Big T]

Dry means its not getting any fuel

Wet means the plugs not firing

You don't have an ignition module, you have points or an aftermarket electronic ignition

[allojohn]

Did you remove the jets and and soak them with each carb? It's possible #1 is still blocked.

[chuck hahn]

Take the screw out of the overflow tube so it stops holding the float up..If the floats are adjusted properly then theres no need for the overflow to be blocked. Id be interested to see if the screw head is hitting on the float hinge somewheres. Look at the brass area for any tell tell witness marks from the screw head rubbing.

[ZakDanger]

I actually have all new main and pilot jets, doing pods. Dipped every part on the carb that wasn't made of plastic or rubber. The overflow tube doesn't need/have a screw in it anymore, took care of that when I rebuilt the carbs. So its not getting fuel huh... Checking compression on it tonight. 8.7 to 1. I will check out the plug again, is it possible that I am getting a weak spark, enough to burn the gas but not enough to fire ignition?

[chuck hahn]

Got the 1 and 2 carbs transposed?? Someone just went thru that mistake as well. Note that you should have the air screws pointing to the left on 1 and 2 and to the right on 3 and 4..If they are all going the right way then look to see that carb 1 DOES NOT have a brass nipple on it...should look like this...