Apologies about posting topics and not contributing much knowledge but nothing of the sort pops up on the search, and I have to get my darn GS to start. I would really love some help because I'm stuck...

Bike turns over and chugs a bit but never gets going. There is definitely fuel going into the bowls, and I'm pretty sure that the float needles are fine. Completely cleaned the carb out and still nothing. New spark plugs. When i squirt a little fuel straight into the carb throats the bike will run fine for a few seconds. Most of the shims are good except one which is a little thin - don't know if that would cause it to not start up though. Compression is above service limit but not ideal yet. I also have 127.5/40 jets in there, with a K&N filter (in air box) and V&H exhaust system. Have a brand new stator and regulator and the battery was being charged the whole time.

I'm throwing money away driving my dying truck to school so any input would be hugely appreciated. I was considering going with a new carb altogether because the one I have has been giving me issues ever since I got it. If i did, what years would be compatible with my 90? I want to say 89-02 but don't want to assume anything.

Is this a new bike?  Did it run recently?  Have you made any changes since it last ran?  Also, this may be a dumb question, but are you using the choke?

Quote
When i squirt a little fuel straight into the carb throats the bike will run fine for a few seconds.

I think there is still a clogged orifice in your carbs.

Quote from: greaseman on November 20, 2010, 04:16:02 PM
When i squirt a little fuel straight into the carb throats the bike will run fine for a few seconds.

So its not getting fuel.
Start at the tank, check there is fuel coming out of the tap. Check its getting to the carbs. Open carb drains and make sure there is good flow through. If that all checks out,there's something wrong with the carbs.
Tell us how the problem started, might help the diagnosis.

Alright some more background information to help address the issue:

I got this bike about 4 months ago. Replaced the stator and regular off the bat, and figured out the guy had a K&N filter and V&H exhaust in there with stock jets causing fuel starvation issues, so I talked to srinath to get the appropriate sizing. Ever since I got the bike I've just done preventative maintenance (i.e. chain tightening, timing check, cables, etc) but haven't done anything major.

The bike was running fine for a few weeks but everyday it got harder and harder to start. Finally one day it started, ran for a few minutes smoking like crazy (whitish smoke) so I killed the engine, waited a bit and started it again. Ran fine without smoke for a few minutes then abruptly died on me and hasn't been running since.

I haven't been connecting the tank because I've had to test the carb so many times so I just take a syringe of fuel straight into the fuel line. Fuel is definitely getting to the bowls, I check both of them after I turn the bike over a few times. And yes, i've been playing with different settings of choke and throttle but no luck.

I might need to do another carb clean and maybe just soak the whole thing in carb cleaner, but I took out the jets, rubber diaphragms, floats, needle valves and seats, etc. Checked all gaskets, sprayed carb cleaner into every passageway and let it sit for a while, blew out with compressed air, let everything dry and put it back together. One thing i'm curious about is that small rod with the tiny hole that the floats seat themselves on. Are they easily removable because maybe i'm missing something but I couldn't get them out.


Really appreciate the input guys, keep it comin.  

Have you done a compression test since the white smoke episode?

Yes I did, it was at about 140. The clymer manual says that's service limit but I'm not sure what I can do to get it back up to par. I was using my friends diesel engine compression tester which runs from 0-1000 psi so might not have been too accurate.

Good news, I went through the carbs again and cleaned out the float passageways and the float seat hole with some more compressed air...threw the carb back on and after some babying the gs came back to life for the first time in 2 months  . Was blowing smoke for 10 minutes and slowly it died down. I had a hard time telling whether it was white or blueish...seemed a little of both. I'm guessing that my cylinder walls/piston rings are worn so some oil slips into the cylinder until the rings get a chance to heat up and expand.

So the passageways in the floats are responsible for getting fuel to the pilots, correct? I should take it apart and spend more time figuring out exactly how it works but that would definitely explain why I wasn't getting fuel.

The floats and their needles and seats maintain the fuel level in the carbs at the right height. No fuel passes through the floats. For instance, the motor would run fine without the floats in the carbs, as long as you could pour fuel in to the carbs at just the right rate to maintain the level!