HELP! She's a stallin and a poppin and rockin all over!

[Anonymous]

Well, my 78 750 did it again... completely baffled me. I haven't even begun to troubleshoot, but maybe you guys can tell me where to start. She doeesn't like to idle, even after warmed up. Also, she's always popped alittle while warming, with no throttle, or while engine braking, but now she does it at all degrees of warm, and all rev bands, even while throttling up. A hesitation is coinsided with it, seems like a miss. when she does it at idle (which never lasts longer than a min, and is always decreasing in RPM) a slight knock accompanies the miss. The only things that have changed since the last time she ran beautifully are : my brother borrowed the battery and killed it trying to start his bike, then recharged it by riding my bike with it in for about 45 min, and the gasket for the left side of the airbox cover pretty much completely deteriorated and had to be removed. The bike ran fine for about 30 miles after these changes, but now... not so much. Sometimes at a stoplight shell be idling fine, and I'll start to release the clutch and throttle, and it will just die. also occasionally, while starting, everything just turns off... I wiggle the positive cable (which is tight to the post) and it all comes back. Thanks for any help. ~Ben Reilly

[Anonymous]

Just a couple of thoughts you might check the connections on the ground cable on the engine and check all battery connections and check your condition of the battery, it sounds like a poor connection.

[Anonymous]

I'm going through a very similar situation myself. When I change my plugs to a new set all the problems seem to dissapear, only for a short while though. My problems were compounded by changing carbs and throwing the original air box. If your air box is deteriorated to the point of being opon to the atmosphere it will surely have a bad effect on running. Maybe try to patch it up temporarily and see if it improves it at all.

[Anonymous]

To start with, I would definately replace the airbox cover gasket. You can make your own out of some cork sheet, available in any hobby shop. If everything dies (including your dummy lights) then you have a power problem. Check all the connections, and especially check your fuse box. I only have 1 main fuse on my 78 GS750, check the connections havn't corroded. Also, batteries can be funny and tempremental things when they start to misbehave. You may want to consider just buying a new one if you are in doubt. The sudden popping and missing sounds electrical too, rather than carb related. Make sure your plugs are firing when in the engine, not just by holding them to the case and looking at the sparc. I use an inductive strobe light for this. With the pickup attached to the HT lead, the XEON light illuminates (flashes very fast). You can see wether you have got a high misfire rate. If so, don't muck around cleaning plugs, just replace them. I hope this helps

[Anonymous]

New Info

Well, I noticed a few more things, first, my brother is an idiot, and failed to do any more than finger-tighten the posts, they just seemed tight because of the way the wires connect ot them, so the disappearing power trip is fixed, but she still likes to pop and stall.
Also, upon checking my oil, I found it over-filled, despite a decent sized oil leak, ofcourse it was FUEL filling the crankcase, not all oil. I suspect, as I have read in these forums oh so many times, stuck needles and a broken petcock are the culprits. now the question is:Would stuck needles overfill the combustion chambers causing it to flood, bogging it down and possibly stalling it? If so, anyone in the St. Paul, MN area wanna help with carb rebuilds?
As for the airbox gasket, as soon as I have cash, the box is gone and I'm going with Uni Pods. (K&Ns are too spendy) and rejetting with the rebuild.
Thanks for all the help, ~Ben Reilly 78 GS 750EC

[Jay B]

Re: New Info

Well, I noticed a few more things, first, my brother is an idiot, and failed to do any more than finger-tighten the posts, they just seemed tight because of the way the wires connect ot them, so the disappearing power trip is fixed, but she still likes to pop and stall.
Also, upon checking my oil, I found it over-filled, despite a decent sized oil leak, ofcourse it was FUEL filling the crankcase, not all oil. I suspect, as I have read in these forums oh so many times, stuck needles and a broken petcock are the culprits. now the question is:Would stuck needles overfill the combustion chambers causing it to flood, bogging it down and possibly stalling it? If so, anyone in the St. Paul, MN area wanna help with carb rebuilds?
As for the airbox gasket, as soon as I have cash, the box is gone and I'm going with Uni Pods. (K&Ns are too spendy) and rejetting with the rebuild.
Thanks for all the help, ~Ben Reilly 78 GS 750EC

OK Scarlet first things first...Go slap your brother and tell him to stay very very far away from your GS.

Someone mentioned checking all your connections. Do that first. No the overfilling into the combustion chamber would not cause that HOWEVER the gas getting into the crankcase will cause you a lot of problems. Dont run the bike until you get that gas out of there. Drain your oil, flush the crankcase with some cheap stuff to get all the gas out and then refill with good oil. Then go to the GARAGE section of this forum and follow the instruction in the Carb Cleaning Guide. Between that guide and YOUR shop manual you should be able to clean them yourself with out any help. If you have any questions post them here and someone will be able to help you out. Attilla the Bunny is fast becoming the Carb expert so check with her.