Here's the deal, my buddy pretty much screwed his crank up in a motor so we found a guy who sells everything you could ever want for a 200s/185s so we took a drive up there today and bought a whole motor from him. After doing the swap it starts up after a few pulls, so far so good. Runs good except its missing and backfiring, not at idle speeds, but at higher rpm's or like when climbing a hill it misses alot. The carb is an aftermarket that worked great on the other motor, ran it up to like a week ago then we did the swap today. That kinda rules out the carb in my opinion. What else could be causing the miss, the timing is dead on, even moved it a tooth each direction to try it out. Switched out the CDI, still notihng, gets spark no problem. Any idea's, could a valve not opening be the problem, I'm clueless as is he, help if you can, its greatly needed!!!

 

Sounds like there's a airleak, did you replace the o ring on the intake?

 

my guess would be an air leak...

 

Check for conditions that will cause a lean condition. Air leaks, float level low, blocked fuel line or petcock, plugged jets. Could also be valves out of adjustment, or a bad spark plug.

 

You don't find many of these engines today that have good intakes. They dryrot and cause an airleak like the other guys here are saying.

The problem is that the intake has been discontinued from Honda. Used is the only way to go.

You can still purchase a new intake that is designed for the 2002 XR200R. It works great, but you have to make an airboot from the carb to the airfilterbox with this intake because it positions the carb at more of an angle than the ATC intake.

To eliminate this as being your problem. Crank the engine up and spray a small ammount of carb cleaner at the intake. If it's leaking, the enigne will rev up.

Don't assume, that because I mentioned the problem with age causing cracks, that this is indeed the problem. It could be the O-ring like someone elses said or even loose bolts at the engine or carb.

Hope you get it figured out either way.