Help with carb setup

[Anonymous]

I have a 1978 GS1000 with yoshimura 4-1 and individual pod filters. I am running 115 main jets, 1.5 turns on air screw and 1.5 turns on fuel screws.
I have tried various combinations in the last few days with little success. Is anyone running a similar setup? Any advice would be appreciated.

Thad in Indy

 

[WifeofDink]

What's the problem that you are having that is making you look at the Carb setup ?

 

[saaz]

Hi Thad
Whats the problem exactly? I run a warmed up GS1000 1978 with K&N filters (the more unusual oval ones with one filetr for two carbs), 4-1 and 28mm Kaw 900 carbs (yea, should have gotten 29mm smoothbores years ago!). Have run this setup for 15 years or so, so probably would have come across whatever you problem is. To get it running reasonably well I had to change the pilot jets as well. I can let you know the exact setup depending on the problem.

 

[Anonymous]

The bike runs like crap! The bike idles well, but upon acceleration it pops and misses. The plugs show carbon fouling. I have tried different main jets and settings of the fuel screws with little success. The pilot jets have never been changed so I assume they are stock. I am trying to get a good starting point. Any advice would be appreciated.

Thad in Indy

 

[argonsagas]

carb setup

carb setup

Thad.

Sounds just like my bike.


I have stock carbs, so the comparison is not exact, but when I pulled the carbs apart I found the pilot jets clogged on 2 and 3. After cleaning the carbs, I put them back on and it ran well briefly, then went back to your problem.

Second pull of the carbs and found the pilot jets clogged again.

This time before I put the tank back on I cut the fuel hose and added an in-line filter. That took care of it. Seems I got a bad batch of gas and those tiny bits that came with the gas were plugging the jets.

For cleaning the pilot jets there is a good hint on this site....clip off a single bristle from a wire brush and stick one end in a pencil eraser or something like that to hold it securely. (I used a wine cork) and gently clear the orifice. The junk will probably drop inside the jet and stick there, so be sure you then blow the entire jet completely clear before re-assembly or it will come back up and clog it again.

Good luck.
Ron Martin 82 GS1100G

 

[Don Lobacz]

If the idle is OK and the mains are pretty close (which they seem to be), then it sounds like the problem is in the midrange, which is controlled mainly by needle height. What are your needles set at? They should probably be at the 4th notch from the top. If you check and/or change them you need to synchronize your carbs. Also, check the needles for any visible crud on them - the clearances are very critical!

 

[Anonymous]

I rebuilt the carbs about a month ago and installed in-line fuel filter. My carbs are stock Mikuni 26mm. I do not recall the needles having different grooves for adjustment. I read on another post that washers could be used for adjusting the needles. Approximately how many washers would get me to the same spot as the "fourth groove from the top"? I suppose a little more trial and error is in store. Thanks for all the advice.