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Still runs like crap....83 GS750es

  • Thread starter Thread starter rvnkvn
  • Start date Start date
R

rvnkvn

Guest
Well, Here we go again....After I removed the engine mounts to install a Factory Air box AND put the stock needles back in the carbs AND installed 120 mains,40 pilots AND made sure the float level was at 23mm, It still will not Idle.

I pulled all the plugs,all black, dont have a compression gauge to fit the head, but the finger over the plug hole has alot of compression. I retorqued the cylinder head,and will tripple check the valve adjustment as soon as it cools.
It has great vaccum at the #2 carb going to the petcock, and I think I hear A LEAK but I cannot seem to locate it. It HAS to be a vac leak...all the boots are in good shape, o rings new,the boots to the stock air box are sealed....I tried to cover the inlet up with a rag to block off the air, but it made no difference. Isn't this suppose to be like a vaccum , to where the box is sealed?

I'm loosing my mind with this bike. I thought I had checked about everything, but it still runs terrible. I really don't want to take the stock air box back out, but the change back to stock from the Uni Pods made NO difference in how the bike runs...and thats still bad....

Please tell me what I am doing wrong..Thanks!!!
 
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Did you get an air filter for that airbox? It will not work properly without one
 
I have a Uni filter coming for the factory box.... It is going to make that much of a difference??? Is this bike that tempermental? Wow!!
 
Yea...needs the resistance of the filter to create enough vacuum to operate the petcock and get fuel. Try a folded rag over the airbox intake, see if it makes any difference. How many turns out are your pilot jets?
 
I'm now at 2 1/2. BTW, i was using a remote tank to fire this and to check everything with the petcock vac line blocked up with a golf tee. I don't know if THAT makes any difference or not. I am getting a strong vac signal at that hose from #2 carb. Still will not idle, choke works great, but as soon as you shut off the choke, dies.
 
While your waiting for your air filter. Go to a foam store and get a piece of 5 eighth`s inch foam. Rap it around with rubber bands, or glue it together at the seams, if you`re really ambitious. That`s what I did on my 83 750E while I was waiting for my air filter to be shipped. It ran just as good with the foam as it did with the new air filter. But it ran like crap, with nothing in there. Foam store charged me 2 bucks for the foam.
 
black plugs means rich or inefficient combustion due to ????many possible thing.
at this point an air filter does not matter(plugs would be white due to being lean).
FYI
the petcock vacuum comes from the engine....has nothing to do with no air box or air filter ect...
 
I have vacuum to the petcock, did not use it with a remote Motion pro tank.

Terry I'm checking everything twice/ 3 times, cannot seem to find out why this is happening. It actually ran better with the 3 DJ needles and the 1 stock needle in the carb's before I installed the Factory Air box, whether it had a filter in it or not.At least it would idle

If I could find 1 Dyno Jet needle ,to go along with the other 3 I removed, I would go back through the process and remove the stock box, rejet the carb's again and use the Uni-filters that I had better luck with. Sure is alot easier to work on!!!!
 
Try 3 or 3.5 turns out, this simple change was the difference between being able to idle and not. 2.5 was NOT enough, although I do have pods and a difference exhaust.
 
It is almost always the carbs, did you remove the pilot screws? are the jet plugs in? you say it runs like crap what is it actually doing?
 
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Vacuum problems suck?

Vacuum problems suck?

Just jumping in with the magic answer is, not likely. :-s

Ask yourself:
Have you done a compression check? Valve issue?
Did you bench sync the carbs before you installed them?

Could be a lot of things, you'll have to patiently zero-in on the leak. :-k

At this point I would try to isolate which carb, cylinder or valve is the problem.

Try putting a vacuum gage on each carb at the little test port provided on each intake pipe. Look for the lowest vacuum readings.

Could also be a worn carb diaphragm leaking air, or valve out of adjustment or a few other guesses.

Bill

PS this guy's site is a BIG help: http://www.dansmc.com/mc_repaircourse.htm
 
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I did remove the pilot air screws, replaced the o rings and washers,reset them 2 1/2 turns out. I replaced the main jets to 120's and the pilots to 40's. It starts fine on choke, takes fuel, great hi idle,but as soon as you shut the choke off, wont idle, will run smooth with the throttle opened up to about 1800 rpm. Soon as you let off...DIES. Only thing I did different is install a fact. air box. i see no visible connections where it may be leaking, but I am certain it is a vac leak.

I rechecked the valves, and retorqued the head gskt... but i'm out to go to work. Chime in if I need to do something else...PLEASE and thanks!!
 
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I would bet the problem is in the carbs somewhere...what about the rubber plugs over the pilots? how do they look?
 
Did you do a bench sync and how close did you get the plates? I'd be willing to bet Dynojet would send you the one needle if they still have them. When I bought my first kit from them I felt I needed mains richer than were in the kit and they sent me them at no charge. Give them a call.

Just realized you are trying to get it to run with no filter in the airbox. The DJ needles helped correct for that. No way it will run right with stock needles and no filter.
 
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The plugs in the rebuild kitdid not seem to seal as well as the stockers did. I replaced the factory ones back on and seemed to fit a LOT better.
 
Hi Billy,
I did do a bench sync, got the factory manual out and set them all to the small hole in the carb per the instructions... I'll call DJ after work, and see if I can get the missing parts to put the pods back on. I don't mind moving the engine to get the box back out if it fixes the problem AND makes things easier to work on...K
 
I called DynoJet today, I can send back my 3 aluminum needles and they will replace them with the new titanium ones for $50.00. I may do this. I also have a Uni filter ordered for the airbox. Should be here anytime.

Valves were right on .005 across the valves.

Should the box be sealed completely to make the engine die with the intake hose blocked off? i tried this without a filter while it was running, and it did not seem to even have any vacuum on top of the airbox.
 
I had a similar issue until a couple of days ago. It sounds like you have been very thorough, but double check your throttle cable tension and your idle knob position. Even a bit out of whack, as mine was, made a substantial difference.
This is an easy thing to adjust just to rule it out.

Good luck.
 
Would a bad fuel petcock problem show up after the bike gets up to normal temp, and shuts off the fuel supply? I have NO problem with the bike with the aux gas tank(motion pro) but as soon as it put the gas tank back on the bike, hook up all the lines, it quits running on a few cylinders, and dies shortly after.?
 
Do you have the idle adjustment knob out at all? Are the butterflies open with the throttle released?
 
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