New to me 1982 GS750T

[Lloyd]

Hello everyone,
I recently purchased a 1982 GS750T which did not run. Well after several searched and endless hours of reading threads on here, I now have it running well at idle. The problem I am having now is that at lower RPM's I can rev the bike with almost no problem. But if I rev it to a higher RPM it will go but almost stall out if I rev it again to a high RPM.

So far I have clean and rebuilt the carbs about 4 times (thinking something was clogging something in there), new plugs, air filter, oil change and a new petcock. I have also synced the carbs with a meter.

When cleaning and rebuilding the carbs, the only thing I didn't do was set the float height. I am thinking that when I rev it to a high RPM it is starving for fuel. Am I on the right track? Any help would be greatly appreciated!!

Thanks,
Lloyd.

 

[Dave8338]

Could be a float height setting as you mention no problems in the pilot range. Also, are you sure that there are NO air leaks anywhere? I don't think the 750's have the intake o-rings but it is equally important to make sure that the intake rubbers are healthy and not brittle. Also and it may sound strange but, how is the charging system on the bike? Everything check out correctly? R/R working as it should?
With low battery level charge, as resistance builds in the coils, it can and will effect spark in the upper range of the tach. Food for thought.

Welcome to the fourm. A TRUELY GREAT place for GS preservation. Some even know what their talking about. :-$

Basscliff will stop by at some point and throw you a roll of carpet.

 

[Lloyd]

Do you know what the float height should be? Yes the 750 does not have the Intake O Ring's and the Intake Rubbers are in great condition. I do not believe that I have any leaks, I have sprayed water and WD-40 on them while the bike is running and the idle does not change at all.

 

[Dave8338]

Do you know what the float height should be? Yes the 750 does not have the Intake O Ring's and the Intake Rubbers are in great condition. I do not believe that I have any leaks, I have sprayed water and WD-40 on them while the bike is running and the idle does not change at all.

Not sure of the float height on the 750's. Someone here will have that info OR you could do a search and see what you can find.

Try some starting fluid instead of the WD40 and use the little straw that comes with the can. It helps to aim the fluid directly at a suspect area and IF there is a leak, the idle will jump up a bit, not down like the WD40.

 

[flyingace]

Make sure you have adequate fuel flow into your carbs. Check clogged fuel filters, petcocks, etc. Do you have full flow? Check by disconnecting the line to the carbs and turning the petcock to prime. It should run out at a good rate. If it dribbles, you may have found your problem.

 

[gearhead13]

Are you revving it out under load?

 

[Lloyd]

Not sure of the float height on the 750's. Someone here will have that info OR you could do a search and see what you can find.

Try some starting fluid instead of the WD40 and use the little straw that comes with the can. It helps to aim the fluid directly at a suspect area and IF there is a leak, the idle will jump up a bit, not down like the WD40.

Im about 99% sure that I don't have an air leak.

 

[Lloyd]

Make sure you have adequate fuel flow into your carbs. Check clogged fuel filters, petcocks, etc. Do you have full flow? Check by disconnecting the line to the carbs and turning the petcock to prime. It should run out at a good rate. If it dribbles, you may have found your problem.

Fuel filter and petcock are clean and flowing good.

 

[Lloyd]

Are you revving it out under load?

Right now no, it is on my lift. When revving it twice quickly it bogs down almost to and stalls unless I feather the throttle. After rebuilding everything and getting to run pretty good I took it for a ride. It has a little hesitation from a dead stop, and it is pretty good in mid range. But at full throttle it bogs and hesitates, but sometime it will pull real hard.

HELP!!!! I really want to ride!!!!

BTW my Tach does not work, so I don't know exactly at what RPM's all of this is occurring.

 

[81ZUKI75]

Did you pull the plugs on the enrichment screws and adjust those as part of the carb rebuild?

Float height is 22.4 +/-1 mm per service manual

GO here http://members.dslextreme.com/users/bikecliff/
and download the "GS750 (16-valve; LT, LX, EX) Service Manual (17MB)"

Thanks many time over Mr. BassCliff!

 

[tkent02]

What are you using for an intake and exhaust system?

 

[Lloyd]

Did you pull the plugs on the enrichment screws and adjust those as part of the carb rebuild?

Float height is 22.4 +/-1 mm per service manual

GO here http://members.dslextreme.com/users/bikecliff/
and download the "GS750 (16-valve; LT, LX, EX) Service Manual (17MB)"

Thanks many time over Mr. BassCliff!

No, I didn't pull the plugs for the enrichment screws... They were already pulled. Right now they are 2 1/2 turns out. Thanks for the float height, I will get that all set tomorrow. I'm sure that manual will come in handy!

 

[Lloyd]

What are you using for an intake and exhaust system?

Everything is all stock.

 

[flyingace]

Fuel filter and petcock are clean and flowing good.

Consider the possibility that the problem is not fuel related. It's the place to start for sure, but once you've eliminated all possible problems, it's time to look elsewhere.

I've seen threads where this kind of problem is related to the ignitor or coils. It may be the advance is malfunctioning. Do a search on these items and see if any are similar to your problem.

 

[Newbee]

Simular problem on my 82 750T

Simular problem on my 82 750T

It ended being coil leaks/wire leaks and shorting to the frame. Replaced coils and wires and problem solved.

 

[Lloyd]

Update

Update

Well the bike still bogs out to a stall if I'm not "revving the balls" out of it from a start. Mid and top end are pretty good. I set the float as close as I could, checked the coils and I believe they are both good. Any other suggestions?

 

[gearhead13]

Check voltage at the battery with the bike running. Compare voltage at the coils to battery voltage to see how voltage drop you have, maybe do the coil relay mod. Check plug cap resistance.
Fix your tach, maybe you just need a cable from a bike salvage yard.

 

[cloudbreakmd]

Welcome from another T owner.

 

[almarconi]

Float height should be checked but FUEL LEVEL is critical. I've found that even if all your floats measure the same height your fuel level could be off. It only takes a tiny amount of adjustment on the float tab to make your level too low (lean) or too high (rich). The fuel level effects all the jetting positions in the carbs.

 

[Lloyd]

Check voltage at the battery with the bike running. Compare voltage at the coils to battery voltage to see how voltage drop you have, maybe do the coil relay mod. Check plug cap resistance.
Fix your tach, maybe you just need a cable from a bike salvage yard.

Yes the tach cable is broken at the engine. I want to get it running properly before I dump anymore money into it.

Tomorrow I will check the voltage. How do I check the plug cap resistance, the plug wires do not come off the coil packs. Also what is the accepted voltage loss at the coils?

Thanks.