17 replies to this topic

[trialbikematt]

hi, i started up my sherco 125 today and it starts and idle`s fine with the choke on, but as soon as i turn off the choke the revs drop and the bike cuts out. ive tried turning the air mixture screw on the carb, but if i turn it so it idles well, each rev lasts for about 10 seconds. i did put a little to much oil in with the fuel when i filled it up could this be the problem?

cheers matt.

[tony27]

trialbikematt, on 23 January 2012 - 03:17 PM, said:

hi, i started up my sherco 125 today and it starts and idle`s fine with the choke on, but as soon as i turn off the choke the revs drop and the bike cuts out. ive tried turning the air mixture screw on the carb, but if i turn it so it idles well, each rev lasts for about 10 seconds. i did put a little to much oil in with the fuel when i filled it up could this be the problem?

cheers matt.

Strip the carb & clean the jets, sounds like your pilot jet is blocked
It runs with the choke on because it's a seperate circuit to the other jets

[trialbikematt]

tony27, on 23 January 2012 - 06:34 PM, said:

Strip the carb & clean the jets, sounds like your pilot jet is blocked
It runs with the choke on because it's a seperate circuit to the other jets

ok thanks for the quick reply. ill check it tomorrow and give it all a good clean out.

[trialbikematt]

tony27, on 23 January 2012 - 06:34 PM, said:

Strip the carb & clean the jets, sounds like your pilot jet is blocked
It runs with the choke on because it's a seperate circuit to the other jets

cleaned it all out and cleared all the jets with a compressor, seems to be running perfect now. thanks for the advice.

[TNTrials]

Mine started doing this while riding, started to wheeze like it was running out of gas and then died. Wouldn't start unless choke was on nor would it keep running even if I gave it throttle. It did this warm, after riding for about 20 minutes. I suppose some gunk coulda gotten loose and clogged the jets, can't think of anything else that would cause this problem.

[copemech]

TNTrials, on 27 March 2012 - 12:05 AM, said:

Mine started doing this while riding, started to wheeze like it was running out of gas and then died. Wouldn't start unless choke was on nor would it keep running even if I gave it throttle. It did this warm, after riding for about 20 minutes. I suppose some gunk coulda gotten loose and clogged the jets, can't think of anything else that would cause this problem.

Water in the carb bowl will cause this type thing as well, whether induced from the fuel or coming in the bowl vents when washing and such. A good regular cleaning is your best bet!

[bputt]

+1 on what Cope said... I clean out my son's carb after just about every heavy wash with the pressure washer. And when I don't take the 15 minutes to do it, I'm generally rewarded with a bike that begins running poorly and requires the effort when I least want to do it! It doesn't take much water and/or grit to get into the carb before you suffer performance issues. On the newer ('10 and up) bikes, my experience is that removing, cleaning and re-installing the carb is 15 - 20 minutes in effort at most... well worth the time.

[TNTrials]

The carb turned out to be pretty clean, however one of the float rods was bent slightly and the left side float didn't move up and down easily. I bent it back a little bit so it would slide. Bike starts and runs like it did.

Is the tank supposed to fit so tightly and has to be pushed down when tightening the screws? They sure did put alotta stuff in a small space.

[copemech]

Tanks fit tight, arrangement is key, yet expansion due to alcohol laced fuel makes things worse as the tanks expand a bit. My tank has shrunk 7-8mm or so in length getting off the alcohol, at least for now.

I also run SHORT deflector tubes on the Dellorto with good success in the past. About 1.5 inches long to keep crap out. Long tubes are not good or required. (in my opinion)

[TNTrials]

What in tarnation is a deflector tube? I'll definitely get an inline fuel filter. I did notice that the emulsion tube sticks up into the throat of the carburetor more than I've seen in any other brand, Mikuni, Keihin etc. Works well, very light throttle spring, not what I'm used to, very touchy.

I just got two gallons of 93 octane pure gas, no alcohol. I hope this helps, 'bout time I quit.

Edited by TNTrials, 29 March 2012 - 12:18 PM.

[chuckmorris]

My 2001 290 now does this. A mate of mine kindly cleaned my carb for me but now it starts ok and runs with the choke on but dies when it's off.

He suggested turning the air mixture screw but I'm not sure which one it is.

Anyone got a pic of where I can find it? or if I post a pic, point me in the right direction?

[TNTrials]

I wouldn't mess with the idle mixture air screw yet, it ran before the way it was set, right? Sounds like you have a clogged jet or something else, you need to look in the float bowl.

[TNTrials]

copemech, on 29 March 2012 - 03:17 AM, said:

I also run SHORT deflector tubes on the Dellorto with good success in the past. About 1.5 inches long to keep crap out. Long tubes are not good or required. (in my opinion)

What exactly are deflector tubes? Are they like filters?

[chuckmorris]

TNTrials, on 03 April 2012 - 06:14 PM, said:

I wouldn't mess with the idle mixture air screw yet, it ran before the way it was set, right? Sounds like you have a clogged jet or something else, you need to look in the float bowl.

Yes it ran fine before my mate cleaned the carb.

I should learn how to maintain it myself but I don't have enough spare time.

[copemech]

chuckmorris, on 03 April 2012 - 08:16 AM, said:

My 2001 290 now does this. A mate of mine kindly cleaned my carb for me but now it starts ok and runs with the choke on but dies when it's off.

He suggested turning the air mixture screw but I'm not sure which one it is.

Anyone got a pic of where I can find it? or if I post a pic, point me in the right direction?

If it will only idle on choke, likely the pilot jet is still restricted with a bit o grit. Blow out may not remove this, as you need to unscrew the jet and possibly pass a fine wire through it to dislodge crap. You may never even see it, can be soo small.

The fuel screw is the small one on thengine side, should be 3 or so turns out from full in, depending. Must be set per bike.

Start over!