cv carb cough . . .

Just checking with youse guys on this. Last several hundred miles carb has started to cough sometimes when I first blip the throttle at idle. Does not cough at any other time. This happens when bike is warming up and also after it has been ridden for a while.

First inclination is to turn the mix screw out at 1/4 turn increments till it stops. If I remember, this coughing is an indication of carb running LEAN (slight gold color on pipes, but not blue). I tried turning the screw in a 1/4 turn and coughing got worse . . . I turned it out a half turn and it still coughs sometimes . . . should I keep turning it open? At present carb mix screw is turned out (opened) to about 2 1/2 turns from the closed position.

what int. jet you have in it? go up one size

Bike was running fine before. Have put 7700 miles on her in the last year & a half with no problems with the carb. I'll check for leaks. Thanks, guys.

Its a shovel not the nicest intake to keep from leaking .dam cast to aluminum. Set up cv conversion correct

is the tempeture cooling down?as it gets cooler outside,it will need more fuel.a jetted carb for 90 degree weather will be lean in 65-70 degree weather

Hadn't thought of temperature changes. Instead of changing jets, which have worked well from January thru October with no coughing until lately, perhaps I can tweak the mixture screw for a more rich mix? But first things first; I am going out to the shop right now and check for vacuum leaks . . .

Yeah, shovels like to leak .

After finding no leaks anywhere around the intake area, I turned the mixture screw out an additional 1/4 turn (for a total of 2 3/4 turns out). So far, no coughs at idle or while on a 30 mile ride this morning. Will take her out again this afternoon for a longer ride . . .

I think it has. There has been no more cough/hesitation when blipping the throttle. Thankfully, it's sometimes the little adjustments that make the big difference.

Don't rule out something as simple as a gas additive like Sea Foam and/or Startron. That 10% ethanol is a biotch. Not sure how Shovel motors are responding to the ethanol if at all?

Hard to say. The coughing started soon after I switched from Seafoam to MMO. Must be a coincidence. The temps have dropped and that may account for some of the carb cough, according to Prodrag. I did get one cough yesterday, as opposed to several a day before I started fiddling with the adjustment screw, so I'll try easing the mix screw out yet another 1/4 turn. That will make a total of about 3 turns out . . .

Today I'll take the bottom off the carb and remove the jets and give them a good inspection & cleaning. I'm running 48 & 180 jets.

try a 52,I use them in a lot of EVO CV carb applications

That's a stock 74 ci. I have a 50 slow jet around here somewhere. If all else fails, maybe I'll try that. I have read that many shovel owners use 50s.
But the jets I have now have been fine since last year. I have run them through cold weather with no problem. How could jet size be causing this all of a sudden?

not really,if its ran that way in colder weather,look VERY carefully for a leak (depending on your ignition,check your advance weights too)

I agree, I had my timing advanced a bit much and even on the hottest days fully warmed I could get a darn sneeze. I retarded my timing and the sneeze was gone.

I checked for leaks twice. There are none. No cough today. I do have advance weights and will check them. As far as timing, I always static time the ignition at full advance and have never had issues before.

I suppose the problem could be in the ignition somewhere. But right now I think I may have gotten rid of the cough.

At the beginning of each new riding season (late winter/early spring), I always recheck timing and change points/condensor & plugs.

HRK, I check nuts, bolts & screws about once a month .