Peculiar starting problems on my 80 gs750

[80GS750]

Hi everyone this is my first post here on the forum and I was hoping someone would have some good advice for me.
Ill keep it to the point.
Ive had the bike for a month, when I bought from the previous owner the bike ran wonderfully started right up and I rode home for about 30 minutes with no issues aside from a small dead spot between 25-3k rpms that I thought was peculiar. The PO also told me it "has a weird problem when you havent started it in a week or so where it takes a while to get started (said he usually used starting fluid), and also gave me a new petcock for it.
Took it out two days after getting it for another 15-20 min, little hiccup at starting but no problem.
The bike has pod filters (yuck, PO not me) and a vance and hines exhaust by the way
Couple weeks of rain/no riding went out to start it, really tough, holding the choke open up (it doesnt stay) got it to sputter and sputter, turned the petcock vertical that got it to run, it ran for about a 1/4 mile down the road (rough) then sputtered out after 1 big rise in rpm's.
I replaced the petcock this morning since that was the quickest and I was limited on time, but it didnt seem to make a difference. Killed the battery so now I am charging it and also picking up some new plugs just in case (I havent pulled the #2 plug, but have read that its a bit notorious).
Any suggestions on the best plan of attack carrying forward or any other things you would suggest?
Thanks ahead of time, this seems like a good forum for info on these bikes.

 

[Steve]

Welcome to the forum, get ready to get bombarded with suggestions to do all the maintenance.

That maintenance would include adjusting the valves and cleaning the carbs AND checking/cleaning all the electrical connections.

Changing the petcock might not have been necessary, but certainly was not wasted, they do need to be changed every 25-30 years.

While you are cleaning the carbs would be a good time to verify that they have been re-jetted for the pods and pipe.
By the way, if you don't feel comfortable cleaning your carbs yourself (it's much more than just dropping the bowls and spritzing around some spray), there are a few of us here that do offer that service for a modest fee.

The only "problem" with the #2 plug is that it is the #2 carb that supplies vacuum to the petcock to turn it on. If the petcock diaphragm is leaking, you will see #2 plug darker than the rest, due to the extra fuel that is dribbling down the vacuum line.

.

 

[jsandidge]

After sitting for a week or so, some of the gas will have evaporated from the float bowls. Turn the petcock to prime for about 30 seconds, then back to on. It should start easier.

 

[dantodd]

Welcome aboard.

Here are some of the links that Steve alluded to.


The GSR welcome:
http://members.dslextreme.com/users/bikecliff/images/GSR_Greeting.html


A great webpage that collects all things GS (with a special emphasis on 850G's) he has tons of links to tutorials and guides as well as most manuals.:
http://members.dslextreme.com/users/bikecliff/


I believe that you have CV carbs on that bike, if so this is a great tutuorial on the cleaning/rebuild process:
http://zeus.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf


Here is the link to where most folks get the o-rings that need to be replaced to properly clean the carbs. Don't buy a cheap rebuild kit from eBay, try to salvage all the parts and just use these o-rings. :
http://www.cycleorings.com/

 

[tom203]

While you're are reading about maintenance stuff, make sure you understand how petcock works, especially if this is the 80's leverless model. You don't want to leave the petcock in the "PR" spot very long.