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Discussion Starter #1
first off, i'm john from salem indiana. i ride an 04 kfx 400 with full yoshimura exhaust, jet kit, hot cams, and a g-force axle. my problem is i took my quad to a friends house, and while i was riding his honda cr450r dirt bike he was on the kfx. all the sudden he just stopped, we got it back to the garage and upon further investigation we found the timing chain had jumped 3 or 4 teeth on the intake cam. i got it back in time and tried to start it, and it fired and ran for a few seconds but, then shut off. my questions are, are these engines valve benders, second how involved is removing the head to have the valves replaced, and third what all can i expect to replace other than timing chain, tensioner, cams, and valves? any help would be a great help.
 

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wow, that stumps me
 

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removing the head is not to bad but getting everything in time can be a little difficult. i am not 100% sure about the bending valve issue. but i do know that some of these had valve problems along with timing chain and tensioner issues. i rebuilt my sons quad last year and replaced all the stock valves and upgraded the valve springs with the drz springs along with a full port and polish. i also installed a better chain and tensioner. when running the hotcams it is a good idea to run the better chain. here is a link to a guy that carries all the parts you need to fix your quad. he has the best prices from what i have found. good luck Advantage Cycle LC - Indianola, Iowa
 

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Your engine is an interferance motor the valves could have hit the piston maybe not you better get your self read up on top end tear down i have seen this happen i work at a drr dealer in ankeny ia as far as the repair parts you got if covered just add a gasket kit unless valves are bent then the valve guides may be cracked email me at [email protected] i can price the parts once you tear it down
 

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Discussion Starter #5
i assumed it was an interferance engine, and from working on that type of engines in cars, i know when a chain or belt breaks, it's time to pull the head and start replacing valves. so it looks like i'm gonna have to rip it apart and take a look.:pissed:
 

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timing inspection help

:Dthe timing marks are on the left side of the engine there are two circle plugs with allen heads 8mm the other is 10 one is where you line up the timing mark the other is where you use a 17 mm to turn the crank counterclockwise to line the marks up at top dead center. the cams should be pointing away from the sparkplug to see this you have to remove the front plastic the fuel tank also the vent box on the right hand side also the cam cover 6mm allens once you do this it also makes removing the timing chain tensioner easier once you line up the T mark 8mm allen plug
 

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the kfx has a ratcheting type tensioner inspect it with the center bolt removed and with the tensioner removed from the engine release the lock on the tensioner the plunger should staw fully retracted if not toss it probably the cause of the timing jumping 98 out of 100 times this is the case
 

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Discussion Starter #10
one of the guys at the shop brought up a good idea. we got the leak down tester out of the race trailer and tested the cylinder. it had an 8% leak down at 100 psi, so no bent valves!!!! so now i'm in the middle of a chain and tensioner replacement.
 
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