Jump to content

2006 KX450F Help

Recommended Posts

Hey all. 

About a month ago I bought a 2006 KX450F for $300. Cheap, right? Well, the reason it was $300 was because the bike was stripped to the frame, and the engine was basically in a box. He told me he had the bottom end rebuilt, never got around to putting it back together. He had a receipt to prove the work done. So, we got the engine reassembled. No start, low compression. Pulled the head back off and the head was scarred and the cams were scarred as well. So we ordered a brand new head and brand new cams. We reseated the valves, adjusted the bike a bit and gave it a few kicks. Compression was way better. It started eventually after having a hell of a time starting it. When we got the bike to run we noticed a side engine cover was leaking, put the new gasket on and tried to restart. Nothing. Giving it slow kicks we heard the bike jump time by almost 4 teeth. Compression went way down while this happened. Pulled it apart again and fixed the timing and gave it a few kicks just to see, did not jump time again but compression is still lower than it was when we put the new head on. Valves look good we checked that when we re-timed it again. Kicking the bike we get a lot of backfires. We are thinking our next step is to order a new cam chain and see if that helps. Valve clearances are in spec as well. 

Anybody have any suggestions on what to check? I'm all ears. We want to get this thing running without dumping a ton more into it. This is my first engine rebuild and of course I got in way over my head, but I'm learning every step of the way. Any suggestions on what to check that'll fix the backfire problem and the compression issue would be appreciated. 

Thanks!

Kyle 

IMG_0020.JPG

IMG_0356.JPG

Share this post


Link to post
Share on other sites

Those are not 06 Forks, might have a 07 more likely.  I would also have changed the timing chain and tensioner.  Check that the auto decompression mechanism is also working proper.

Share this post


Link to post
Share on other sites

Okay thanks. 

The forks may be different. Previous owner put a lot of money into bike when he had it. Title says 2006 unless he gave me the wrong title which is possible. 

Share this post


Link to post
Share on other sites

that may make sense then, you can check the VIN.  a simple google search, there are several sites that are free to verify.  Let use know how it all goes.

 

Share this post


Link to post
Share on other sites

check the cam timing again, but the lobes to the marks on sprocket, there is a hole in the sprocket and the top of lobe has to line up there, on the 06 models, quite a few sprockets rotated .

Share this post


Link to post
Share on other sites

Change the chain tensiner to a new or to a manual one.

Either way if it jumps gears its the tensiner that not working properly.

Could also be that you forgot or didnt put it back right and forgot to tension it again?

Edited by skorpan777

Share this post


Link to post
Share on other sites

looks like an 06 frame with the groove down the main spar...

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×