1984 YTM225DX spits and spudders during warmup.

[12wheels]

Bought this trike about 15 years ago, vary good condition. At startup with choke on trike starts right up and runs fine, after a few minutes when choke is off it will spit and spudder for another 10 minutes. After that it will run fine. I have cleaned carb several times, new plug, air filter. The trike has always done this from day one. Any ideas ?

Thanks

[350for350]

My last one would do that when the engine was cold. When it was warm, it would run fine. The guy I sold it to said that the valves needed to be adjusted. I know that it's different than what yours is doing, but it wouldn't hurt to check.

[ATC King]

Has it always been like that?

It sounds like a typical lean condition, or, cold blooded engine if you prefer.

An intake leak after the carb can cause it. A bad O-ring on the intake manifold or cracks in the rubber. If that model has an enricher valve instead of a choke, it could have leaks that let extra air in. The bottom of the enricher valve may have a rubber seal. If that's leaking it may be sucking air through the cable or enricher nut.

[12wheels]

My last one would do that when the engine was cold. When it was warm, it would run fine. The guy I sold it to said that the valves needed to be adjusted. I know that it's different than what yours is doing, but it wouldn't hurt to check.

I was going to mention that it sounded like the valves were making noise during warmup. I never adjusted the valves on this trike because it ran great after warmup and never made any top-end noise after warmup. Will check adjustment thanks.

[12wheels]

Has it always been like that?

It sounds like a typical lean condition, or, cold blooded engine if you prefer.

An intake leak after the carb can cause it. A bad O-ring on the intake manifold or cracks in the rubber. If that model has an enricher valve instead of a choke, it could have leaks that let extra air in. The bottom of the enricher valve may have a rubber seal. If that's leaking it may be sucking air through the cable or enricher nut.

Yes, from the first day I bought it. I'm sure my intake and o rings are good. It runs flawless after it warms up. Going to check the valve clearance today. Thanks

[12wheels]

Oh well not the valve adjustment.

[ATC King]

I'm sure my intake and o rings are good.

Since a valve adjustment didn't correct the issue, it's probably a good idea to go ahead to pull the carb again and the intake, replacing the O-rings on the carb and engine side. Also check the intake really well for cracks.

Beyond that, the carb may just need a skosh larger pilot jet. You can check OEM parts websites like Partzilla and see if the '85 used a size larger pilot. That potentially means Yamaha figured out the previous year was a bit lean for some markets/locations and increase the size the following year model.

Absolutely never buy generic jets. Get the same brand as the carb and from a reputable seller to maker certain they're not counterfeit. It may just require one size up to fix your issue.

[12wheels]

Since a valve adjustment didn't correct the issue, it's probably a good idea to go ahead to pull the carb again and the intake, replacing the O-rings on the carb and engine side. Also check the intake really well for cracks.

Beyond that, the carb may just need a skosh larger pilot jet. You can check OEM parts websites like Partzilla and see if the '85 used a size larger pilot. That potentially means Yamaha figured out the previous year was a bit lean for some markets/locations and increase the size the following year model.

Absolutely never buy generic jets. Get the same brand as the carb and from a reputable seller to maker certain they're not counterfeit. It may just require one size up to fix your issue.

Well took carb off again, this time I checked the choke adjustment at the carb and found that it needed adjustment, was not retracting all the way in. Runs great now thanks.