YTM 200 backfiring in carb

[Bucksmith02]

What would be causing this? It stumbles when holding the throttle steady and it appears to be backfiring in the carb. Any ideas? Looking to possibly just purchase a new one and was wondering which was best, upgrade or stock? Sorry for all of the questions, im learning lol

[webbch]

There's only 1 thing I'm aware of that can allow backfiring to occur - intake valve is open or poorly sealed, allowing the combustion gases an additional escape path. So check the timing first I'd think, then maybe the valve adjustment - they may be too tight. As a last resort, may need a valve job if the intake valve isn't sealing.

[muthey]

are you positive that it is backfiring, or might it be flooding out, also what type of fuel are you running? Have you checked the main needle in the throttle body for any wear or warpage? There are a lot of different things that can give symptoms of backfiring, I do recommend checking the valves and timing, but am giving you some other options as well.

[emmie357]

I had a lawn tractor that did this. Timing was off. In my case the flywheel key has sheared and the flywheel slipped out of place.

If it's not the timing then likely an intake valve not closing fully.

[Bucksmith02]

Ok well I can see the carb "kicking back" some when it does it and like a puff of air when it stalls. Will I have to pull the motor out to check the timing and intake valve or can it be done with it in the trike still? Ive worked on trucks a bit but am new to ATVs. Could I run some sea foam or something similar to maybe get it to unstick the valve?

[barnett468]

Ok well I can see the carb "kicking back" some when it does it and like a puff of air when it stalls. Will I have to pull the motor out to check the timing and intake valve or can it be done with it in the trike still?

yes, do a compression test twice then adjust the valves and do 2 more compression tests.

Could I run some sea foam or something similar to maybe get it to unstick the valve?

if the valve is sticking you midst remove head to repair it.


heres a manual. it takes up to 5 minutes to download.

http://www.oscarmayer.net/atc/manual...vicemanual.pdf
.

[Bucksmith02]

Ok thanks, man you are awesome. I needed that.

[Bucksmith02]

Funny thing is it will idle smooth for a couple of seconds and then it will start acting up and shut off unless I give it throttle input. Really wishing it was something simple but in my case it hardly ever is.

[barnett468]

check the spark

start it up

wait until it dies

check spark again, if it is noticeably weaker it is electrical.

if spark looks good check float level. too high it is flooding, too low it is lean.

[barnett468]

drain float bowl into clear glass look for debris. if gas is old like a yesasr or more it will not burn well. if gas color is apple juice color or darker it is either old or discolored from rust in tank.

[Bucksmith02]

It fires right up almost every time. So just do a visual check before starting, then once it dies, do it again? Ok will do

[Bucksmith02]

Ok I still haven't fixed this issue yet(time) but I did take it out and ride it for a good while the other day. I noticed I had some fuel dripping from the air box. What does this mean?

[muthey]

and muthey might be the winner!!!! you are flooding out, which more than likely is causing your backfire issue. time to open the carb and check your float, float needle, and float needle valve, along with the o-ring that goes on the float needle valve.

[Bucksmith02]

Good I hope that is it. Much easier than tearing into the engine. Thanks guys for your help so far

[MtDew]

Are there Carb rebuild kits available for the Yamaha 3 wheelers? I have a 225 DRS and would like to clean and rebuild the carb.