engine issues

[Anonymous]

83 gs750es.

Tends to backfire out the exhaust (no flames though) when off the accellerator. Also at higher speeds I.E. 65+ in 5th gear engine seems to hessitate, pushes forward, slows down, pushes forward, slows down. Any ideas? Also, this happened twice in the last few days, going at race track speeds 90+ engine seems to get flooded? acts as if it ran out of gas. engine will basically die, pull off the road, wont start without choke fully closed, but if I wait like 5-10 min, starts up fine again... Weird things.. Anyone else have any ideas? Thanks!!

[lhanscom]

Sounds like she's running lean, have you done anything to the bike recently? Is this a new 'feature' or has it been happening for a while?

[SqDancerLynn1]

Check the gas cap, the vent may be plug with crud creating a vacuum not allowing fuel to flow

[Anonymous]

"Sounds like she's running lean, have you done anything to the bike recently? Is this a new 'feature' or has it been happening for a while?"

I just bought the bike. Person I bought it from said the carbs are brand new (about 6 months) and a new head gasket. motor has 20k miles on it. Only thing I have 'done' to it was adjust the idle control screw.. She wouldnt idle at all before I did that..

"Check the gas cap, the vent may be plug with crud creating a vacuum not allowing fuel to flow"

Gas cap looked ok... but I will do a further inspection on it later today.

[lhanscom]

Does the bike have an aftermarket exhaust or modified/removed airbox? Is the air filter in place? If it's stock, your carbs should have a 117.5 (I think) main, if it's had any mods it should be bigger (most likly).

[Anonymous]

Does the bike have an aftermarket exhaust or modified/removed airbox? Is the air filter in place? If it's stock, your carbs should have a 117.5 (I think) main, if it's had any mods it should be bigger (most likly).

Everything on the bike is stock from factory. The original owner hardly ever rode it, and he was an older guy who liked the bike the way it was.

[lhanscom]

I would check your jet size, as the 'new carbs' may not be setup properly. You may also want to check the condition of your air filter.

[oldschoolGS]

Make sure the cone shaped air box cover is installed and pointing forward. It was designed to draw air from the front of the seat. If this does not help I think your comment about the recent carb work could be the key. I would check to see who did the work and what was done. Ride On, Ed.

[Anonymous]

Any other ideas?

[earlfor]

I would LEAVE the carbs ALONE until all other possibilities have been eliminated! Considering your symptoms, the "light in my head" says
filter screen on the petcock is cruded over with sediment to the point that there is sufficient fuel flow at normal riding fuel consumption demands, but at higher speed requiring more fuel, the flow is insufficient to maintain rpm. the engine dies until fuel availabale catches up with demand. The first thing I would do is remove the petcock and make sure the screen is clean and there is no sediment in the bottom of the gas tank. Its also a possibility the gas cap vent is plugged, but you can test ride with the cap screwed on lightly to check this possibility.

Eark

Any other ideas?

[bybowtie]

what about exhaust gasket or torn intake tube(thats always a possibility when you mess with the carbs....

[Dave_A]

make sure you have a lid on your airbox...

My bike came sans-lid... Same problem... Bought the lid... No more problem...