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Discussion Starter · #1 ·
I have an '82 XT200 that runs great at lower RPM but after a high speed pavement pounding between trails will stall as soon as you let off the throttle and pull the clutch. It's hard to get it started again, takes a bunch of kicks but eventually starts and works great until the next high speed stretch.


It seems like it's a fuel flow issue, starving for gas. The tank is coated and has some very fine grit in it which wiped off where I can reach, but does not wash off. I first though this may be plugging things up so I drained the tank to clean it as best I could. I drained nearly two gallons through the petcock and it never slowed down. Using a paint filter there was virtually no junk coming out. I removed and cleaned the petcock. This type has a sock filter on reserve, and a straight pipe for normal, no restrictions or filter in the petcock for ON position. It doesn't seem to be the petcock or junk in the tank causing the issue.


I then thought about venting. At a glance I didn't understand how the cap was vented, so I disassembled it. The cap was full of tank liner restricting the venting. I cleaned this out and ensured I can spray carb cleaner and blow through the vent. Thinking surely this was it, I went for a high speed test ride and it again stalled and took a few kicks to start, but started more easily.


I then pulled the carb and rebuilt it. I had not been in the carb previously, but it was pretty clean. Regardless, I cleaned everything up, ultrasonic for the body and brass. There was a little junk, but nothing real bad and nothing in the fuel feed passage or needle and seat area. Needle and seat looked good, so I reused them. Float height was within 26mm. Adjusted to 25mm spec, with spec is +/-1mm so it was within spec, and it seems like a flow issue not a float height issue. Test ride and no change.


I then pulled the cap apart and removed the brass vent piece with cotton or cloth in it and the check ball. Test ride after that and it will still stall just the same after a bit of WOT, but starts right up letting the clutch out or after a kick or two. It seems to pull a bit harder up top too. Previously about 55 MPH was a stretch and slow acceleration after 50 MPH. This time it pulled pretty hard (for a 200) up to 55 MPH and slowly up to 60 MPH. Venting is obviously a problem. I'm unsure exactly how to modify the cap to retain the check valve, enlarge venting passages, and prevent fuel sloshing out when full, but I can probably figure something out. It won't completely resolve the problem though.


The fuel line is not kinked or pinched, though I might be able to make it slightly shorter.


I'm wondering if the needle and seat could be too restrictive. Maybe aftermarket, but the seat is stamped "20", the same as replacements are pictured as. $45 and might ship within two months, according to Partzilla. I wonder if I can modify this needle and seat for higher flow if otherwise in good condition and seals? Any thoughts?
 

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Well written thread starter.
Float level low?
 

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If it only happens after running harder for a while could you have a tight valve allthow you might have already checked them. If it has additions like different exshost or air cleaner the jetting could be off a little.
 

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It sure sounds like you have done everything possible to rule out a gas cap venting issue but I recommend doing a test run with the gas cap opened slightly or removed.

As a side note, I know some folks have had good results with tank liners but there are plenty of bad results as well, especially if any critical steps have been unsuccessful (proper cleaning for example).

Please continue to report your results and good luck getting this issue resolved.

SportsterDoc’s float level check is a great idea.
 

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Discussion Starter · #6 ·
If it only happens after running harder for a while could you have a tight valve allthow you might have already checked them. If it has additions like different exshost or air cleaner the jetting could be off a little.
I adjusted valved when I first got the biek, though I will check again in case there are wear or other issues, given this engine had a ridiculous amount or metal in the oil and filter. There is a bit of tapping when up to temp, not alarming for an old bike bit noticeable.

Exhaust is factory. Air box is in place but filter was missing when I got it, installed a new OEM filter oiled with motor oil. Jetting is factory. 122 main jet IIRC. It pulls hard at WOT in lower gears and in 5th, but tapers off after a bit as if staring for fuel.
 

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Discussion Starter · #7 ·
It sure sounds like you have done everything possible to rule out a gas cap venting issue but I recommend doing a test run with the gas cap opened slightly or removed.

As a side note, I know some folks have had good results with tank liners but there are plenty of bad results as well, especially if any critical steps have been unsuccessful (proper cleaning for example).

Please continue to report your results and good luck getting this issue resolved.

SportsterDoc’s float level check is a great idea.
Good idea. I need to drain some fuel to do that. I tried leaving the cap loose after it stalled one time but gas was sloshing out even though it's not entirely full, so tightened it before I could test. I'll keep everyone posted.
 

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Float level was at 26mm. Spec is 25mm +/- 1mm, adjusted to 25mm (slightly higher) and no change.
Obviously I missed that in your first post.
 

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I then thought about venting. At a glance I didn't understand how the cap was vented, so I disassembled it. The cap was full of tank liner restricting the venting. I cleaned this out and ensured I can spray carb cleaner and blow through the vent. Thinking surely this was it, I went for a high speed test ride and it again stalled and took a few kicks to start, but started more easily.
Was cap rechecked after that run?
 
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