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Jeff Policky
Jeff Policky, Motorcycle Mechanic
Category: Motorcycle
Satisfied Customers: 2425
Experience:  Yamaha Gold, Suzuki Gold, Honda Bronze, Polaris Bronze, BRP
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I have a ktm 300sx 1998 model starts fine, but will not warm

Customer Question

I have a ktm 300sx 1998 model starts fine, but will not warm up or even get into power band .carb has been cleaned, air filter is clean. Any thoughts on possible cause?
JA: When was the last time the filter was replaced? How has your mileage been lately?
Customer: Haven't ridden because icant figure out why it won't open up.
JA: What is the model of your '98 motorcycle?
Customer: 300sx
JA: Are you fixing your bike yourself? What have you tried so far?
Customer: Rejetting, moved needle position, new plug,
JA: Anything else you want the mechanic to know before I connect you?
Customer: I bought bike a couple months ago thinking it was just a dirty carburetor, but that isn't it. I've got a hunch that its got something to do with power valve but don't really understand how it works or what it should be doing
Submitted: 7 months ago.
Category: Motorcycle
Expert:  RSRBOB replied 7 months ago.

Hi and thank you for your question.

It is certainly possible we could have some issues with the power valves. They are not impervious to having various problems. However, to make sure we are not overlooking the obvious, I suggest starting the diagnostic process with a compression test. The symptoms for power valve related issues and compression related issues are very similar. A compression test is an easy test to perform. Remove the spark plug, install the compression tester, put the spark plug back in the spark plug cap and lay it on the cylinder head, hold the throttle wide open and give it a half dozen or so really swift kicks of the kick starter. You can watch the needle on the compression tester and when it stops making significant jumps in readings, you have achieved your goal.

Let me know what you get and we can take it from there.



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