My DS has been running great all year until now. When I started it today it didn't fire right off then once it did it wouldn't stay running. Eventually I had to pull the choke to position 2 just to start and then it would only idle. ANY throttle and it would die. Finally it got to the point that it wouldn't even start.

Pulled the plugs. Both were black but not bad looking (about 30-40 hours on the bike, original plugs). Put in 2 new plugs and it fired right off. Revved fine at first, but then started running rough after only 2-3 minutes. Then whole cycle started again.

Any ideas why the plugs are fouling all of a sudden. The bike is stock. I've checked the air box (even tried starting without the cover, no luck) and it is clean. The only thing I can think of is right before we put it away after the last ride, my buddy turned the idle screw (left side, just below the choke) because it idled too low when cold.

Anyone have any ideas or seen this before? I was supposed to leave for a weeks vacation today, but this happend. We are still leaving in the morning, but I won't have a bike to ride. [img]i/expressions/face-icon-small-disgusted.gif[/img][img]i/expressions/face-icon-small-sad.gif[/img]

 

I agree with BajaX, although I don't have choke "positions" on my TM...make sure that the choke is full pushed in...And do you mean your friend moved the idle SPEED screw or the idle MIXTURE screw (Air screw)?

The Idle mixture screw I think when turned a ways off could be causing richness...but I don't think the idle speed could..

 

I can move the choke between no-choke, 1st position and second. With new, clean plugs I can start with no choke, but after 2-3 mins it runs rough then dies. after that I have to use the choke in position 2 then eventually position 3. now matter what it won't run for more than 2-3 mins.

 

I agree that it is fouling because it is running rich, but the only adjustment that was made was what I believe is the idle screw. whatever screw it is, it is on the left side of the bike just below the choke. the screw is connected via a cable to the carb.

 

Well I have the stock carb off my 2000 DS in my hand...and there is no screw on the left side of the carb.... The idle speed screw (connected to carb by a rubber cable, about 5-6 inches long with a brass end) is on the right of the carb, just below where the throttle cable goes into the carb...

Maybe they changed that or something over the years...but the IDLE MIXTURE screw is on the very bottom, in between two holes...

 

TyreSpinner,

I wasn't describing the screw very well, on my bike the adjuster is on the left of the bike but the rubber cable does take it to the right side of the carb. sorry for the confusion.

Any ideas about what would cause the mixture to suddenly get so rich.

 

an all of a sudden richness would most likely be caused from the needle valve in the bowl to be stuck open from junk or debris, causing the bowl to overfill which forces excess gas up the jets. also improper float level, but that's unlikely in your case because nothing was messed with. are you getting any gas outa the bowl overflow tube? if there is any gas at all dripping from the overflow this would confirm the needle valve sticking. if there is no gas dripping, there still could be an issue with the float/needle valve, so this is something I'd check for sure. remove carb, remove bowl, be delicate and gentle to not disturb the float adjustment, disassemble the float from the needle valve it operates, and hose it all out with carb cleaner. inspect the rubber tip on the needle valve, and inspect the seat it closes in.
you may need small vise grips to break the bowl screws loose, just clamp them with the tips of the visegrips and crack them loose, then use the screwdriver.

there's also the less likely possibility that its an ignition problem spark related, and it appears like a rich problem on the plug from gas not burning well, fouling the lug quickly, and then even further with choking attempts.

 

I agree 100% with hightower. Have you installed a fuel filter in the fuel line yet? This is very important and will keep all the crap out of your carb. The stock DS' don't come with one. It is about one dollar so it is worth every penny.[img]i/expressions/face-icon-small-wink.gif[/img][img]i/expressions/face-icon-small-smile.gif[/img]

 

Sounds like stale gas. If the gas stinks or looks like a urine sample, you got trouble.

On the good side, its easy to fix. Drain gas tank and carb. Then replace plugs.

jbt