Need help with my 1985 XR350R, It boggs off idle, looking for advice??

Just picked up a 1985 XR350R. road it over the weekend and had a great time. What a great trail bike... I only have one problem. The bike will die if I gun it. It will bogg or hesitate off idle. I have checked and changed the spark plug, cleaned and oiled the air cleaner, taken the snorkel out, raised the slide needle one step, tried different settings with the pilot screw but have seen little or no change.

The bike has a slip on supertrap and thats it. The rest is stock. I think the jets are stock #150 main, #50 slow. I can raise the slide needle up one more step but dont know if that will help? May be I should try diferent jets?

This is a realy cool bike, great low end power and its in great shape. Now I need to get it running right.

please help, Thanks Damon


I would say the bike is too lean. I hate to keep going to the pilot jet but have you checked to make sure it is not plugged? Also, did you move the clip up on the needle (lean) or did you move the clip down (rich)? The needle should not affect just off idle to the point where the engine stalls but I've seen wierder things in the past. It sounds to me like a plugged or too small pilot jet concern.

Have you cleaned the jets and set the float levels? Throttle cables properly adjusted? :cry:

Yes I moved the the needle clip down one setting. I checked and cleaned carb and jets. Main jet was a stock #150, the slow jet was a #52, stock is #50. float level looks good. Took the bike for a ride no change in performance. still boggs :cry:

If I try to change the main jet what size should I try? And should I change the slow jet as well??

What's the plug look like? Find somewhere that you can run the bike at a steady throttle position for 10-15 seconds. I prefer a slight uphill. Warm the bike up and then let it idle for a minute or two, check the plug. Then run the bike at a steady 1/4 throttle under load for 10-15 seconds minimum then kill the bike before letting off the throttle, check the plug. Do the same at 1/2, 3/4, and full throttle making sure to hit the kill switch before pulling in the clutch and stopping the bike. The plug should be tan to chocolate brown at each throttle position. If it's white, your lean. If it's black, your rich. On an air-cooled bike I prefer to have a rich reading (chocolate/dark brown). It doesn't lend itself to max power but does give the bike the ability to lug better and helps the bike to run cooler over-all. Your reply to this question will give a better idea of how to proceed.

If you're expecting the bike to respond well if you whack the throttle open right from idle then you're gonna be disappointed. It always will bog if you do that no matter what, short of swapping the stock carb for a pumper.

Ditto pumper carb

I've only ridden a few thumpers that did not bog off idle if you cracked it WOT instantly

my kids xr50 was one, not an agressivly tuned motor

Maybe you guys can help me with my 85 XR 350. It runs great but is very difficult to start. I thought it was the carb, but even after replacing the stock carb with a pumper it still takes 30 to 40 kicks and starter fluid, or a tow behind another bike to get it started. Once it starts it runs great. Could it be the electronics? Any ideas as to how I should go about troubleshooting it. I also changed out the spark plug, but that had no impact either.

Check the valve clearances & adjust if needed. I had the same trouble & this fixed it for me.

I also had to play around & try different things to find out what my pumper wanted for me to get the motor cranked in one or two kicks. With a cold engine in neutral, I slowly depress the kick starter untill I find solid resistance. Then pull in the manual decompression lever & push the kick lever down another inch or so. Release the decompression lever & let the kick starter return all the way up. Quickly twist the throttle wide open twice. Give a firm kick.

Same procedure for a warm engine except I don't need to twist the throttle unless I've taken a long break.

What pumper are you guys running on a 350?

What pumper are you guys running on a 350?

I ride a 250. But the procedure I outlined should be the same for a 350 afaik.

interested in the carbs used. This is the first I've seen of pumpers on 350's. XR's Only sells a pumper for the 400 but not for the 350. And there's so few of them out here that I've not heard anything about alternate carbs that fit. So wondering what you all (couple of you) are running. :thumbsup:

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