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2001 400 SX Getting harder to Kick Start

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I have a 2001 400 SX. Bought it used in 2002. Do the usual maintenance - Oil - check/adjust valves But have never done anything major. I have always been able to kick start bike without using decompression lever (original owner took it off!). Just kick and it almost always starts. It has been just great. This last weekend the kick became significantly harder. The bike still starts well and runs well but I'm wondering if it is time to do the top end. Is a tougher kick a sign of trouble? To me it would imply compression is going up not down. What signs should I look for to know the Top end is needing work? The bike is getting up in hours but want to avoid the work as long as possible.

Any advice would be great.

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Thanks for the info. I did do a valve adjustment just a couple of rides before the Kick starting got more difficult. I will go back in and check them again. Is there a way to know if you need top end work? The bike does not smoke nor burn oil. It has not lost any performance. I just don't want to wait too long. Typically how many hours do you get out of the 400 SX before having to be concerned?

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your kick starter hasnt been off and has been put back on the wrong spling giving the impression it it harder to kick wen infact it just your leg finding it harder???

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I do a top end and valves one time a year, about 180 to 200 hours. The valves are probably not seating any more, due to wear or carbon build up. I would do piston, pin, rings, valve guides and at least check the valves, clean them, then reinstall them, if they are cupping throw some new ones in. Check the valve seats, if they are smooth get the seats cut at an auto machine shop. One other item that you might want to change on an older bike is the cam chain. It sounds like a lot, but that is just a typical thumper freshin up.

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That is a fair assesment, typically on KTM's SX excluded the intake valves are junk, the exhausts a little ugly and guides are premo and chain just fine.

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The kick starter has not been moved. So that is not the cause. I'm planning on checking the exhaust valves per Dave's suggestion. Its the easiest and seems to make sense. I will check the compression as well. Do any of you know what compression value I should get - more importantly what is the low end number where I should start worrying about the top end. This has been the first thread I have used this web sight. It is really helpful. Thanks to everyone.

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A 400 in good shape with the autodecompressor working normal has 115 lbs compresion at kicking speed. If you want to get more sofisticated you can lossten the adjusters on the exhaust 1 turn from their normal setting, then you should have around 170 lbs

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