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07 TE 250 'pulsing & surging' sensation on street

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I'm noticing an increasing problem with my TE250 that only gets occasional riding around town, sometimes commuting... it is a 'pulsing' sensation that I originally thought might be an overtight chain, but I've mostly ruled that out. It is somewhere in the drive chain, not the engine, which rules very smoothly. It feels like a on/off surging that you can feel mostly when cruising or deaccelerating, esp at 20-35mph, which of course is a common speed I'm mostly at when running around town on back streets. My nearest dealer is 75miles away, so I'm going to try to figure it out before resorting to loading it up in the pickup. Any ideas anyone?

Thanks

Ivor

Portland OR

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Are you sure you don't have a vacuum leak??? The intake manifolds on certain Huskers have been known to crack. It's easy to check. after the bike is fully warmed up and idling normal, spray some carb cleaner or other 'flammable' liquid all around the intake manifold. If RPM's increase, you've got a leak -that would certainly cause surging. Since it's doing it on decel, also points to a intake leak.

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Sounds like typical EPA lean factory jetting.

Put it on a stand & spin the rear wheel, any odd dragging, compress the rear caliper & check again. Is the chain beat, tight spots, check adjustment in several spots to be sure.

I'm betting stock jetting, right?

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Don't think it's the jetting... I bought the bike pretty tricked out and I'm quite sure it was jetted, and I don't recall this happening at all when I first had it, and it runs really good, no backfires, stuttering, nothing! This problem has been very gradual to the point where it's really buggin' me now. Those are good ideas about checking the chain for tight spots and the vac leak trick.

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The jetting could be just slightly lean, like one clip or a pilot size, even a fuel screw turn might do it. Variables like temp, altitude and even fuel blend at the pump can/will affect it. If it is JD jetted, is it time to go to the winter needle? My tweaking would start with an air leak or jetting for sure. I doubt you would feel a chain "surge" without seeing it was super beat. Let us know what you find.

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I'm noticing an increasing problem with my TE250 that only gets occasional riding around town, sometimes commuting... it is a 'pulsing' sensation that I originally thought might be an overtight chain, but I've mostly ruled that out. It is somewhere in the drive chain, not the engine, which rules very smoothly. It feels like a on/off surging that you can feel mostly when cruising or deaccelerating, esp at 20-35mph, which of course is a common speed I'm mostly at when running around town on back streets. My nearest dealer is 75miles away, so I'm going to try to figure it out before resorting to loading it up in the pickup. Any ideas anyone?

Thanks

Ivor

Portland OR

Tight chain links will definately cause a "boxcar" sensation.....but that should be obvious....tight links will be evident visually... as they are the ones that wont straighten out as they come off the sprocket....

Aside from that...surging from a lean condition....could be it...check the three bolts holding the intake air boot(commonly come loose) to the head....and make sure the carb boot clamps are not too tight or misaligned

If thats all ok... it time to rejet....and or re adjust the fuel screw

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Narrow it down before you start changing stuff. Take it for a ride. When it is acting up, pull the clutch in and coast. If it is still there it is not engine related so start looking close at chain / brakes / wheels. If it goes away when you disengage the clutch, change gears and see if it is RPM related. Mixture trouble may be more prevalent at different throttle openings & RPM ranges.

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if it occurs at constant speed (slight throttle opening), my money would be on LEAN mixture.

My WRF has the same feeling, only when coasting/cruising. As i understand it, this is in-built to pass noise testing procedures.

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My 07 450 started doing the same thing. JD jet kit and all "stuff" removed. I thought it was a fuel delivery problem. I guess you can say it was......1/4 turn richer on the mixture screw.....no more surge.:thumbsup:

BTW, I could only notice when holding a constant speed riding fairly easy.....if I was riding it "hard" never noticed anything

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