[bobthebiker]

does anyone know why I'd be getting around 100-120 miles per tank of fuel? I dont ride it at much over 6k rpm, carbs have been cleaned about 4 times now, and it still gets crappy milage.

this problem began quite suddenly after I replaced the rear tire, going from a 90 to the proper 70 profile size tire, which i think had SOMETHING to do with it. before this, it ran perfectly, not too lean or rich, and then suddenly one morning I went to ride, and it just wouldnt start until I tuned the carbs again so that they werent just dumping so much fuel into the cylinders. its something that just developed literally overnight.

anyone know WTF is wrong here? I sure as hell aint got an idea. all I can say is its carbs, not in the motor.

 

[fog]

Most likely a partially stuck float valve. Thats passing more fuel than the engine needs but not enough to cause bad running.
Does it stumble or hunt at steady throttle at say 40 MPH.
FOG

 

[bobthebiker]

no, it doesnt hunt or stumble at all, but it does leave a coating of black soot thats rather obvious on the exhaust pipes from just riding 30 miles.

 

[fog]

Still most likely a float problem. Check the levels. Fuel should be just level with the float bown split line check with a transperant tube connectd to the drain on each carb with the engine running and the bike on the center stand hold the tube up above the top of the carb and observe the fuel level.

Or set the floats at 17mm above the spit line whenjust lightly resting on the valve springs.
Back flush the line back to the tank to clear any debries that may be preventing the valvs from seating.
Finally check to see that the Float valves are actually stopping the flow of fuel.

FOG

 

[bobthebiker]

I dont totally understand how to do all of that. a pic would possibly help a lot.

 

[fog]

You said "I tuned the carbs" I took that to me you understood them.
OK whats hard about hooking a clear tygon tube to the drain nipple on each carb? All you need is about a foot of 1/4" tube, On the bottom of each Carb there is a drain nipple with a screw along side , open that screw and see the gas come out. Close screw start engine. (bikes on the center stand) attach tube to nipple, rout tube upward open drain screw observe the level of the fuel in tube. Match it to the side of the carbs . Fuel level should be even with the float bowl split line.

OK got it.
If it's not you got to pull the carbs .

FOG

 

[bobthebiker]

ok, it was just how you wrote it the first time that I didnt understand, probably due to being tired.

now I understand. I'll try this and see how it goes.

 

[bobthebiker]

fuel level is above the float bowl, so I guess I'm pulling carbs off and doing some more internal carb stuff. AGAIN.

 

[fog]

Well if you did it right the first t......

Read my reply to Audreez in the general catagory

FOG

 

[bobthebiker]

Thanks FOG. I got em workin a lot better now that I took some time to clean everything right. god I'm tired of things that dont work right. specially them things that need to run well.

 

[bobthebiker]

ok, I'm an idiot, once again and I show it. the bike works fine on the centerstand, but when its on the ground it doesnt run well at all.

so how do I go about setting the floats? I know diaphragm carbs, but these float carbs are just totally different.

 

[fog]

Ok,
With the cabs off the bike and the float bowls off .

Hold the carb bodies upside down so the floats are resting on the valve springs lightly. Then measure from the same bowl split line to the top of the floats. This should be 17mm.

To change it bend the little tab the touches the valve and re check the 17mm.

Remember the word Lightly

While you have the carbs off, back flush the line back to the tank. This will clear any junk that may be in there messing up the valve.

You have pulled and checked the pilot jets of course Right?

FOG

 

[bobthebiker]

yes, I've checked everything short of the flux capacitor, which seems to transport me to the year 2099.

thanks for the info FOG. I'll get that adjusted proper and make it run right.

 

[bobthebiker]

Thanks FOG. you were DEAD ON. floats were set at somewhere around 15mm, not 17. probably had to do with the old tire profile because it was taller, which I'm betting messed with the factory settings, so the owner changed it a little to fix that.