Still need a little help ATC200

[Savage99]

I am still having some problems getting my ATC 200 running properly. Actually the problem is when it's cold...when its warm it runs and idles like a top. When I first start it the darn thing won't idle, even with the choke on...I have to sit there with the gas on manually and it takes for ever to warm up. If I rev it quite a bit then it 'pops' out of the exhaust. I checked the timing as was suggested and it is all lined up properly now I am thinking maybe valve adjustment? But if the vavles are out then it wouldn't run so well when its warm would it? I have played and played with the carb and the only thing different on the bike is the 95 jet instead of a 105 but it is my understanding that the main jet does not come into play when it's idleing. If I adjust the idle so it idles high then it stays running when cold but then when it warms up the idles are way too high. Any help would be appriciated and the help given so far has also been appriciated.

Mark.

[TravEX]

mine does the same thing, just cold natured is what i think,,,however, my 200S will idle sooner than my 400EX in cold weather, actually starts better too in cold weather,,,later

[MTS]

my 200 is like that 2, i start it with the choke on and have to keep on the throttel for a few mins, then i drive it around burn a cuple dohnuts with the choke at half, then turn it off and go...adjust the throttel settings when its warm.....

[mx600]

I am still having some problems getting my ATC 200 running properly. Actually the problem is when it's cold...when its warm it runs and idles like a top. When I first start it the darn thing won't idle, even with the choke on...I have to sit there with the gas on manually and it takes for ever to warm up. If I rev it quite a bit then it 'pops' out of the exhaust. I checked the timing as was suggested and it is all lined up properly now I am thinking maybe valve adjustment? But if the vavles are out then it wouldn't run so well when its warm would it? I have played and played with the carb and the only thing different on the bike is the 95 jet instead of a 105 but it is my understanding that the main jet does not come into play when it's idleing. If I adjust the idle so it idles high then it stays running when cold but then when it warms up the idles are way too high. Any help would be appriciated and the help given so far has also been appriciated.

Mark.


My CRF450 did that when my intake valves lost their clearance. It would be a bear to start when cold and wouldn't idle. It'd pop and backfire a bit (from a too lean condition). Once warm it was fine. Just sharing my experience with a valve problem, maybe it'll help with your 200?

[Savage99]

Would it run lean enough to cause your engine any problems? How did you fix it? Thanks for the info.

Mark.

[mx600]

Would it run lean enough to cause your engine any problems? How did you fix it? Thanks for the info.

Mark.

On my 450 I had to replace the valves because they wore so much that they couldn't be adjusted anymore. But on your 200 (assuming it is a valve issue), I'd be surprised if you had to replace the valve. Probably just require an adjustment. If you don't have a service manual, get one. Adjusting them is pretty easy. The best part about it is the adjustment on a 200 is with a screw and nut, whereas on my 450 I had to remove the valve cover, remove cam assembly and replace shims. The 200 has ports in the valve cover to get to the adjuster screws, so you only need to remove the gas tank and you should be ready to check/adjust them. I've never done it on a 200 (just got my 200 about a month ago and only spent 1 day on it so far), but it looks to be like a 30 minute or less job, even if you're a complete novice at it. Go slow the first time to make sure you know what you're doing and every time after that will be so much easier.

Even if your problem isn't a valve issue, I'd still check them once a year or so. I've talked to a Honda mechanic that said one of the biggest problems on 4wheelers that he services (didn't mention 3 wheelers) is a valve job, and the problem all starts at a dirty air filter. If the filter isn't clean, then dirt can enter the intake, and it acts like a sandblaster on your head. That's a bad thing.