76 GS750 Bogsville at 2500 rpm

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Hey I am puzzled with this bike,I have read many posts and they point me in good directions but I dont think I am getting there.I had such good success with my GS1000L here that my friend had me work on his 750 that bogs out real bad.
I have torn down the carbs and soaked them in chemtool,then carb cleaner,then air blasted.all ports are clear.I changed out all the orings from cycleorings.com and the intake orings from the dealer.I put new points,condensers,plugs,and timed it. Compression tested 125psi give or take a few on all 4.
Still runs bad at about 2500 rpm and up.Its especially bad under a load like climbing a hill.If I snap the throttle it also bogs out and if I hold the throttle it will die.It does idle real nice and it dosent pop or backfire.I have checked the petcock and it flows very well.
The spark plugs are white,so I have the carbs off again and I am going to raise the needles to see if this helps.The needles are on the third notch I am going to try raising them all the way.
Any input you can give would be very helpful,

Thanks, Kirk

[RunForYourLife82]

last

Hey, My GS650E had the same problem when I got it running again, even after a carb cleaning. I ended up finding out I had leaky carb boots and the bike was gulping much more air than it should. I replaced the boots and the problem went nearly completely away. I was still running lean and I tried adjusting the carbs. No luck, what I ended up doing was taking a piece of air filter foam and stuffing it into the vent on the top of my airbox....no more bogging! Bike runs wonderfully. I suspect the seals on my airbox have decayed with time and the filter foam I stuck in the vent made up for it. It's worth a shot anyways.

[KEITH KRAUSE]

If the intake and exhaust are stock, including the air box lid being on, I wouldn't raise the jet needles from their factory position. It wouldn't be the needles fault.

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Ok. I wont mess with the needles,the bike idles way to smooth to have a vacum leak but I will check anyway.Yes it is stock.
There is one thing that makes me wonder if it is the air box,I hear the carbs,it is very noticable on acceleration.I dont know if this is normal with the stock air box on these early bikes or not.This air box has ends on it.
It looks like someone glued up the inside of the box at one point with rubber cement.I will look it over closer.
Do you get by with a visual exam of the carb boots? Mine looked ok,

Thanks for the direction,
Kirk

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Air box did help

I resealed the air box and it did make a difference I am not shure if there is supposed to be oil on the uni filter or not so I left it dry for now.It still acts like it needs more fuel .But it idles fine and moves out ok for now, I think I am going to give it back to my friend and say I did my best.It runs better than it did.
Kirk

[Guest]

Not oiling the air filter will make it run lean.

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Ok

I will oil the filter up and hope it helps more,thanks,Kirk

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Lightswitch Performance

Yep, it may sound funny but it is running badly in boggsville then it snaps out of it and screams.I have just about given up on this mystery bike.I have pulled alot of hair out over this one.

Kirk