Carb lousy above idle

[newc4]

I’m working on getting my 79FS back on the road. Bike has been sitting for about 4-5 years before I began work. Ran great prior to that for the PO.

As with a lot of folks here, I’m working the carb issues. Cleaned them twice, removing the main, pilot, and air jets and the mixture screws, cleaning them and blowing through the various passages. Can see light though all the jets and the orifice appear clear. Checked the float seals by blowing air through the fuel lines while upside down, good seal. Floats float. Didn’t check the float height but I don’t think that is my problem.

The following performance is with the airbox off. Choke works fine at full, half and while in, mostly. Bike run well above half throttle and at idle. Proper colors with colortune at idle and I’ve synched the carbs with mercury sticks. Have the problem with idle running upto 3-4k by itself and backfiring and spitting above idle. Could the problem be that the airbox is off allowing a lean condition above idle? I doubt that that should make that much difference.

If not, what are the successful methods for cleaning all the pilot circuits? Which circuit is the one that affects above idle settings? Haven’t done the carb soak yet nor have I run carb cleaner through the passages and let it sit. (I know about keeping carb cleaner off the throttle seals). I’ve tried using a pipe cleaner but I can’t snake it all the way through to the other end of the various passages. I'm thinking about trying some fishing line.

Darrell

[mro]

Didn’t check the float height but I don’t think that is my problem.

Float height affects ALL carburetion circuit mixtures
Air box/filter does make a difference too.
Are the two carb vent hoses clear?

Way it's running sounds like both a lean condiction and outa sync.
Would check/set float height first.
Where are the pilot screws set?

While carbs off check condiction of carb boots/hoses/boot caps.
When back on and running check throttle shaft seals for a vac leak.


mro

[newc4]

mro

When I pull the carbs again, I'll check the float heights. But I think the problem lies in the pilot circuit. The pilot screws give a blue color with the colortune and the carbs are synched. Carb vent hose are clear (When updside down fuel gushes out of them)

Reading other posts I'll try the starter fluid check around the rubber mounts and caps.

[newc4]

3rd time is the charm

We don't call it a carb triple clean for nothing. I pulled them off again and broke down the carbs on the rack. I left the pilot screws in then shot carb cleaner through the pilot jet circuits. Saw that it was coming out of the three pinholes in the pilot circuit so I figured it was clear. The air passageways seemed clear and since the choke was working I knew the emulsion tube and fuel bowl orifice to be open.

Made sure the pilot jets themselves were clean and polished up the outsides.

Put it all back together and I runs fine. However I need to replace the fuel lines. The PO used the reinforced neoprene and safety wired the hoses. After three times they're leaking so I'm just going replace them all with lines ordered from MikesXS.

Darrell