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/manuals/Yamaha/ytm200_yamaha_servicemanual.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.

[czac]

word to the wise... if you buy a new replacement carb, be sure its jetted the same as the one you have now. I just went through this with my 225DX the previous owner put a brand new Mikuni carb, a VM22 which is what it had stock. the new carb had different jets and it would idle but not run when I tried to ride it, then it would stall and not start. I replaced the jets with the ones from the old carb and it starts and runs great now. So be sure to find out what the specs are on your stock carb and match them to a new one... not just the part number. I think just a good cleaning, needle valve and re setting the floats will go along way. im willing to bet your jets are good, maybe just clogged up a lot.

[MtDew]

The owner said the bike was sitting for about a year. We did get it to run but as a precaution, I would like to remove the carb and give it a good cleaning. I figured while I was in there I could replace any old parts. I downloaded the manual so I will have to start digging thru it. Where is the best place to purchase carb parts?

[barnett468]

one option is moose carb kits possibly from rocky mountain atv.

[Bucksmith02]

I saw one this one on ebay "Jet Kit" from Sigman. http://www.ebay.com/itm/Yamaha-YTM-200-cc-Tri-Moto-ATC-6-Sigma-Custom-Carburetor-Carb-Stage-1-3-Jet-Kit-/331064162471?pt=Motorcycles_Parts_Accessories&hash=item4d14f638a7&vxp=mtr

[dougspcs]

Timing, valves, compression issue..yeah sure they could all be the cause.

Does not everyone trikes/outboards/snowmobiles kinda back-fart a bit when when they are cold and you try to shut off the choke and drive before it's warmed up? Mine do!

This is a common lean running condition issue...

Remove and clean the carb really well, drain and replace the old fuel in the tank, I'll buy you a beer if I'm wrong but I'll say your problem is sure to be gone!

Remember KISS guys??!! Never mind all the engine tests and exploratory until you've covered the basics.

[sanchez]

Both mine always did this. I just learned to pin it

[Bucksmith02]

Pin it? As in the throttle or what?

[brd812]

I'll bet the beer, the carb is flooding out as mentioned. I wouldn't buy a kit until before a real good cleaning. If it was me I would only buy Yamaha parts if needed. I used a moose kit on a alt of mine cuz that's all I could get and she doesn't run the same, not bad just not the same. Oem is still there, ie timberwolf minus the jets. I cooked a air filter on my dx , cuz the air screw had worn and settled at rich setting. It would not stay at the proper setting and vibrate back. Bought a new air screw and whalla all good. Start with the simple stuff like muthy and Doug said. Hope it helped

[El Camexican]

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.
http://www.jetsrus.com/carburetor/carb_mikuni_VM_series.html

Call these guys. Tell them what you need. They should be able to set you up for way less than a Yamaha dealer.

[Bucksmith02]

Ok so I finally got this all figured out with help from the local shop. I just replaced the carb on my 83 YTM 200(k?)(non electric) with a VM24 carb and it runs awesome!. Got rid of the factory airbox and just run an air filter off the carb. The boot between the carb and motor was caput and they didn't make the carb for my model anymore. The choke is now on the carb but isn't hard to get to.

[barnett468]

Got rid of the factory airbox and just run an air filter off the carb. The boot between the carb and motor was caput and they didn't make the carb for my model anymore.
Brand new original carb to air box boot. 20.00

http://www.ebay.com/itm/Yamaha-Genuine-Air-Cleaner-Joint-24W-14453-00-/230921679530#ht_232wt_930

1983 YTM200EK AIR CLEANER
1983 YTM200K AIR FILTER YTM200K
1984 TRI-MOTO - YTM200L AIR FILTER YTM200L
1984 YAMAHAHAULER - YTM200EL AIR CLEANER
1985 TRI-MOTO - YTM200ERN AIR FILTER
1985 TRI-MOTO - YTM200N AIR FILTER

[eBoyDog]

I had similar issue with my YTM200Ek along with other issues but my backfiring, flooding and stumbling was due to bad oring in the carb to intake manifold. Sounds like though you are set after replacing the carb but for before one gets too carried away with valve adjustment and such, spray a little carb cleaner around the carb while it's running and see if it smooths out or picks up rpms. If so then you carb air leaks which are fairly easy to fix.

[Bucksmith02]

It was pouring fuel into the air box and also leaking around the carb. The shop said they wouldn't waste money trying to rebuild this carb. It cost me $79 for the new carb, boot, air filter and a few other things it needed to work. They still make the Mikuni VM24 carb and still will for a good while.

[tundra111]

you said that you have installed a carburator vm24 on your ytm 200k did it worked good all the time , and if it did that vm24 was on what machine before
? thanks

[Bubba10]

Ok so I finally got this all figured out with help from the local shop. I just replaced the carb on my 83 YTM 200(k?)(non electric) with a VM24 carb and it runs awesome!. Got rid of the factory airbox and just run an air filter off the carb. The boot between the carb and motor was caput and they didn't make the carb for my model anymore. The choke is now on the carb but isn't hard to get to.

How did you run the tube off the crank case that ran to the block underneath air box.