XR200R Runs Only at Half Choke

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XR200R Runs Only at Half Choke

Post by 4Strokes » Mon Jun 06, 2016 8:26 am

Topic: 2000 XR200 runs great with Choke at half
Author: traneengineer
Posted: 01/09/2013 9:27:58 PM

I bought this nice 2000 XR200R recently, and it is like new. Very little wear. Changed the plug and oil, put in new gas, and it starts right up. Two kicks and it takes off. BUT, it doesn't like to run at open throttle unless the choke is half closed. It has great power with the choke 1/2, but sputters and won't run at open throttle if the choke is open. Runs well at low throttle. Here's what I have done:

Disassembled carb, and cleaned with carb cleaner. Twice. It wasn't dirty at all. Added a fuel line filter. Replaced the jets; stock are 110/38, and the ones in the bike were 102/35. Put in 108/38 (Honda shop didn't have a 110). No change.

Checked the float adjustment, and it's perfect, 1/2". Checked the fuel level with a clear tube connected to drain. When I open the drain the fuel rises to the level of the top of the fuel bowl. I believe that is perfect. I checked the manifold-engine and manifold to carb gaskets, and they're perfect. I opened the drain, and opened the fuel tank valve, and the fuel runs fine, without slowing. Continuously. Still no change.

The plastic jet holder is a little warped; but goes in just fine. Checked the vent tube--it's clean. (Is it supposed to connect to something?) Tried raising the needle one notch. None of these things have helped.

What have I missed? Is there a passage that leads to or from the main jet that may be hidden, and plugged? Please help!

Reply by GlennF on 01/10/2013 07:30:07 AM
The bike's behavior would indicate a lean condition at full throttle or fuel starvation. The "choke" or enrichener is adding fuel when half open. Is the condition a continuous bog or just temporary?

Reply by traneengineer on 01/10/2013 07:49:21 AM
Thanks for the answer, Glenn. The condition does not improve. If I keep the choke at half staff, it will continue to run well at open throttle. If I return the choke to open, it will only run at part throttle. It doesn't change after running for any amount of time. Lean it is, but where is the restriction? Could the valve adjustment be a problem. I haven't checked it. It runs very strong.

Reply by GlennF on 01/10/2013 10:11:26 AM
The "choke" is a mini circuit of fuel which is adding to your overall mix. I am wondering about the "plastic jet holder" you mention. I had both an XR600R and a XR400R and they both had a plastic upside down cup held in by the main jet. This was called a "splash guard" that isolated the fuel right under the main jet so that the fuel would't slosh away from the main jet during high G maneuvers. You say it is warped? It may be blocking fuel flow to your main jet.

Reply by traneengineer on 01/10/2013 10:59:44 AM
If that's possible, but it is only a tiny bit warped. And the problem has nothing to do with high accelerations. I'll examine it carefully. It is called the jet holder in the Honda diagram: Honda Motorcycle Parts 2001 XR200R A CARBURETOR Diagram

What about this choke circuit? Does it have a separate fuel source, or separate means, for fuel to mix in without the main jet? I'm thinking the problem has to be in the main jet circuit, and there is a clogged orifice or channel in the circuit. Maybe the needle jet. I don't think it has ever come out; maybe it's clogged. But I am really interested in the needle jet holder, as it has holes all over. They are clean (but I'll check again), but where does the fuel go after it leaves those holes? I will disassemble again tonight.

Reply by GlennF on 01/10/2013 11:20:14 AM
A faulty needle or needle jet would be indicated by a flat spot or hesitation when transitioning from 1/4 to full throttle. The starter enrichener (choke) is a mini fuel circuit independent of the rest of the system. If I remember, its fuel stream is injected between the slide and the intake. You are also running a smaller main jet than stock. I wouldn't think it would make that much difference.

Reply by traneengineer on 01/10/2013 1:12:46 PM
It turns out that stock on the California bike is 102. 110 is the rest of the world. I don't think that is the issue. It has to be something plugged, or something I've missed. The carb comes apart tonight, and it gets more thoroughly inspected.

Reply by traneengineer on 01/10/2013 8:53:59 PM
So tonight I tried again:
  • Removed carb.
  • Carefully removed every jet, and every removable part. This time I removed the needle jet.
  • Cleaned every orifice. Sprayed through every hole and tube.
  • Checked all lines. Checked fuel supply. Checked the float operation. Checked needle valve operation.
  • Checked throttle/needle valve assembly for perfect operation. Checked throttle cable and cap that cover throttle.
  • Checked all gaskets (they were fine.)
  • Everything was fine.
  • Reassembled carefully, leaving off the slightly warped jet holder.
  • Adjusted the idle valve.
  • Mounted the carburetor, tank and seat.
  • Checked choke valve operation: up is off, down is... WAIT! UP IS ON!!! DOWN IS OFF!!!
So it runs perfect! Starts on first kick with choke on. Warms up great with choke at half. Runs and idles (after adjusting idle speed screw) perfectly when warmed up. Runs perfectly at full throttle with choke off after warm-up. Stops perfectly. Starts again on one kick... are we getting the picture?

The guy I bought the bike from told me that "the carb needs adjustment", and I think he said "up was off" on the choke. I was looking for a carb problem, and it may have had a plugged jet or line. I'm not sure I had the choke positions wrong, as my mind and memory isn't what it was when I was younger. I could have been sure about the choke position if I had read the user's manual, but now I'll never know. I have the cleanest XR200 carburetor in North America! It's been fun! Next, I install a headlight. :)

Reply by GlennF on 01/11/2013 07:15:58 AM
Glad its running well! Sometimes the simplest thing is the cause of the problem. When you thought you were turning the choke off, you were turning it on full. No wonder it didn't run! Enjoy your bike.

Reply by traneengineer on 01/11/2013 12:02:00 PM
The lesson is: Read the instructions, and don't think the worst possible explanation is the real problem.

I am enjoying the bike this morning, when it was 21 degrees in the barn, I fired up and drove to my neighbor to help her with her propane. Way more fun than the golf car, or a truck!

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