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Really need some help, driving me crazy

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Ok so just bought a non running 05 kx250f. Seemed to have low compression and wouldn't run. Found intake valves not sealing. Ok so got a head with a fresh valve and seat job and installed it. Making sure to check timing marks multiple times. Performed shimming process on the valve before putting head on the bike. Pretty sure I have all of them in spec, I'm an auto mechanic of 15 years and pretty savy with engines. Got it all back together and it def has more compression now as it seems pretty hard to kick, but still not running. Interesting thing is this, tried bump starting the bike and the wheel just locks up and drags. Before I tried doing this with the old head and it would at least sound like it would almost run. My question is, did I set something up too tight causing to much drag? Bike does have a brand new cyl. Works big bore 269 cylinder also. Also carb was nasty, but got it all cleaned up and working. I have spark. Just not getting why now I can't even try to bump start it. Try shooting a little gas/starting spray and still won't even try and run. Has popped out exhaust a couple of times. My leg it tiiiiiired! Please help

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As an update I think I might have identified my problem. The cams aren't spinning freely after the caps are torqued down, causing the tightness I'm feeling in the kickstart

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Ya my problem is the cam caps are from old head, new one didn't come with them so as soon as I torque the rear bolts on the caps cam is very hard to turn, I can polish, but do I polish the head or the caps or both so it will fit nicely?

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So what totally sucks about the setup is that the cam caps and head are line bored for the cams together as a unit so trying to mix and match them is a crap shoot and probably pretty tough to find cam caps from a different head that will fit another head. If you get it running the extra drag will just create excessive heat and probably cause your top end to seize eventually. When I got my KXF I got it for free because the cams melted the the cam journals and long story short, ruined the entire engine.

Your best bet would be to call a machine shop that specializes in MX engine heads to see what they can do for you. Those tolerances need to be spot on otherwise you may be costing yourself a lot more cash in the long run. Ive had good service from Fast Heads and a friend had good luck with a guy out of Florida after Millennium botched the job twice. 

Good luck

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Ok as an update, I have taken the cams back out and polished the caps and journals so they turn now when torqued properly, triple checked the clearances and timing marks. It kicks over much better now but still no start. Also odd thing is I can't get it to bump start. Tried 1st and 2nd gear and rear wheel just locks and drags. I'm ready to pull out what little hair I have left any other ideas? The bump start not working at all has me wondering what is causing this. With old head it would at least turn over and wheel would spin

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Hmm...I'm kind of at a loss as to why the rear wheel would be locked up when trying to bump start. I would check out the auto decompressor on the exhaust cam and make sure it is actually engaging when trying to start. If that wasn't operating correctly it would be really hard to turn the engine over. On a side note, there is a plug over an opening on the front right of the head that allows for an optional manual decompression lever just as a heads up if you want to just do it manually when you start the bike.

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Ya I'm at a loss too. I think I'm going to put the old head back on after I get the seats cut and new valves since the cam caps fit properly and spin easy.

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Ok one more thing to ask, I redid the carb and it already had an aftermarket adjustment screw for mixture, I thought its supposed to have a spring and washer and orings. It only has 1 oring on it and is really loose/wobbly

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are u trying the bump start in 1st or 3rd?  1st will not work well.  That being said, if you cannot kick it, something is wrong and bump starting it my cause more harm than help.

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Well did another leakdown with this different head and it coming out exhaust a good rate, ugh, so I'm taking my original head to a local machine shop that does all the machine work for the major motorcycle dealers around me. Once I get it back and put it on should finally have full compression

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