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waterdog3

unplugged the "TPS"

14 posts in this topic

Bike Was Running Bad Like It Needed A Total Re-jet..."indy" Told Me To Try Unplugging The "tps", I Did And It Cured About 99.9% Of The Sputtering, And Misssing......what I Don't Understand Is, Exactly What Did I Do To The Bike??????and What Do I Need To Do To Make It Run Correctly With The "tps" Plugged Back In????

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During normal off road riding the feedback loop instability created by the TPS on the CDI is not an issue. If you really ride it as a dual sport disconnect the TPS and she will ride well for you at steady speeds. :naughty:

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"steady speeds"....

Hmm.... This is interesting. I am getting some popping when holding midrange throttle settings for more than a few minutes. Is this what you're talking about, and does it apply to the 250 as well?

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I ride hare scrambles, which has a lot of tech. stuff. I ordered a James Dean jetting kit today. If i install it correctly will i be able to reconnect the TPS, and have the best of both worlds???

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Sounds like the 3-D map in the CDI is on the fritz, I proved it could happen by installing a different carb, when the 1/4 throttle sputtering stayed after the change I unplugged the TPS and problem was gone. Bike runs great and might look into getting a Vortex CDI, 10 different maps in that unit.

Good luck

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During normal off road riding the feedback loop instability created by the TPS on the CDI is not an issue. If you really ride it as a dual sport disconnect the TPS and she will ride well for you at steady speeds. :naughty:

I'm getting major sputtering at 1/4 to 1/2 throttle. Where is the TPS connector so I can disconnect??!!

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Left side of the carb a plastic connector that goes to the carb sensor and is clamped against the frame with a black removable clip. :naughty:

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Left side of the carb a plastic connector that goes to the carb sensor and is clamped against the frame with a black removable clip. :naughty:

Thanks!

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What is the TPS and what exactly is it supposed to do? :naughty:

Throttle Position Sensor. It's a safety device IMO that can be worked around.

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TPS works with the crank position sensor to tell the timing how far to advance for a better power curve. With it unplugged (I have been told) the bike thinks the throttle is wide open. It must only make small adjustments because unplugged works fine. I also heard it will protect the over-rev issue.

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crank position sensor? safety device? slow down guys. there is no crank position sensor. the magnets in the flywheel generate that information. that's why when the flywheel keys used to shear the bike wouldn't run. it was trying to spark at the wrong time. safe from what? the bike will hit a rev limiter with or without the tps plugged in.

modern dirts bike use 3D mapping in the ignition. two stroke and four. in the old days your ignition would advance the spark as the rpm's would increase. that was it, no variables. now with 3D mapping the throttle opening is part of the information. the weak point is how the ignition is programed to react to the variables. it looks like one of the wr's weak points is going down the road at a steady throttle. the ignition seams to be "hunting". it's got rpm's but the throttle doesn't show that it's open very much. grab a hand full, it'll take off. it's got rpm's and the throttle is wide open. it knows what to do.

an interesting side note (to me at least). yesterday i did my warm weather jetting change. JD red needle and 68 starter jet. i thought i'd go ahead and unplug the TPS this weekend. the bike ran smooth around the neighbor hood. no surging. it did seem that the idle was hanging a little. the pilot fuel screw didn't do much to help. well, always go back to the last thing you did. i plugged the TPS back in. it idles fine now. it's always something.

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Thanks for the info., the sensor is actually a pickup coil, which is just a tachometer for the CDI. I had checked all the voltage\ resistance on my bike, but everything agreed with the manual. Well, will still need to look for a short in the wiring before buying another CDI, maybe get lucky on eaby?

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