750 issues

[NLAvenger]

I recently picked up a 78 GS750C in a need of repair. The pervious owner hadn't ridden it in years and at some point attempted to fix it and put many things together incorrectly. With a lot of time into it now I finally have it running. So far I have cleaned the carbs, fixed the petcock, replced the air filter, new battery and other misc. non engine related items.

The bike sounds great in neutral and doesn't seem to have any issues there, but when I put it into gear and ease out the clutch the bike almost dies, and sometimes does, unless I keep it at 4000-5000 rpms. Once the bike is going I can't seem to get it over 30mph, and with the exception of 1st gear the rpms don't top 4000. Anytime I'm going over 10 mph and pull the clutch in the bike tries, and normally does, die and it takes a few minutes of waiting before it will start back up. I'm thinking the issue is somewhere in the carbs but I'm not sure where to start if that is the issue. All help is appreciated. Thanks.

 

[Nessism]

What did you do when you "cleaned the carbs"? Quick spritz out with carb spray or full tear down and soaking of the carb bodies in carb dip? Also, is the bike stock or are there mods?

 

[NLAvenger]

I stripped the carbs all the way down and dipped them and hand cleaned the rest with spray. As far as I can tell everything is stock on the bike.

 

[Nessism]

Where did you set the fuel and air screws? Common starting point is 7/8 turn for the fuel screw and 1.5 for the air screw. Also, the pilot jets need to be varified as open by holding it up to the light to make sure the orifice is open. And as with all GS bikes, it won't run for crap without the airbox and air filter installed. Since you say your bike is stock that should be good to go.

 

[NLAvenger]

I did hold the jets up to the light, they're open. I'm pretty sure that I set the screws right, but I'll go back and check. Would be nice if it were something simple like that that I've overlooked. Thanks.

 

[Guest]

You also may have an intake air leak.

 

[81ZUKI75]

How about the brakes?

How about the brakes?

The brake release fully, right?

 

[Steve]

What did you do when you "cleaned the carbs"?

I stripped the carbs all the way down and dipped them and hand cleaned the rest with spray.

Next question: how long did you dip them? :-k

You said it hadn't been ridden for years, so it would be best if each carb body and its jets was dipped overnight. Yep, that's a full 23 hours or so for each one. It takes about an hour to rinse off the carb and the jets, then re-load the basket with the next carb, so plan on it taking several days for a complete "dip" job.

.

 

[NLAvenger]

You also may have an intake air leak.

How do I check?

The brake release fully, right?

Pretty sure. The brakes are released in neutral and unless they stick during use and I haven't noticed they're releasing.

Next question: how long did you dip them? :-k

I dipped them each for about 10-12 hours each. One while at work and then switch and leave the next overnight. They looked clean when i pulled them out, but I'm no expert.

 

[tkent02]

Did you pull out the needle jet and clean the bore that it goes into?

Are all the little passages open?

 

[NLAvenger]

I pulled out everything I could. And I checked all the passages by light and could see through them, unless I missed something I'm pretty sure I got them all.

 

[bigbadbusa916]

750

750

Its a great bike , with lots of potential. As well as many other Gs parts will interchange, I had one in the past loved it and served me well with no problems at all

 

[Guest]

Sounds like it may not be firing on all cylinders. My bike does this when a plug or two are fouled - in neutral you can still rev it highish, but it sounds really rough.