KX65 Engine Problem

8 replies to this topic

Posted January 16, 2008 - 02:18 PM


I used to motocross and now have 2 sons starting to ride. It's been 30+ years so bikes have changed a lot. I just bought a used 2004 KX65 and it starting frying before he made one lap on a little track. He over-reved and it locked up just like he was standing on the break. It started back up with a mild vibration when idling down. I let him ride again and it did the same thing. This time with a heavy vibration when idling down. We loaded up and went home..... I'm I looking at top end rebuild or crank. Any idea's and any pointers on how to do as cheaply as possible. I've got 2 of these things to keep up.

Thanks for any input.

  • Jeekinz

Posted January 16, 2008 - 02:20 PM


Search KX65 crank here, I think I recall a problem with the cranks on those.

(upper right hand corner for "search this forum")

  • frankiewhipit

Posted January 16, 2008 - 06:59 PM


If it seized up, then restarted I would think the top end is toast. If the top end is bad, check jetting, premix ratio & timing.

  • getndirty

Posted January 16, 2008 - 07:35 PM


Pull the jug and look for discoloration on the crank assembly where the rod connects...if it's discolored (looks like it overheated) that bearing probably went south - just went through the same thing. That bearing took out the whole top end on our kx65.

Repair bill to have J&M racing in Houston do it was about $900 - split the cases, new crank assembly, re-plate the jug, fix the squish band in the head, new piston and rings and gaskets all around. The guy I talked to at J&M said that bearing is a regular weak point on the kx65's.

If not, you may get off for a lot cheaper than I did...good luck and let us know what you find.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • no1clyde

Posted January 16, 2008 - 07:47 PM


I'm betting it's the lower rod bearing. This fall 2 friends kids 65's each lost lower rod bearings. Used hotrod cranks to fix them. I think there is a ebay store that sell the crank, main bearings and piston for a good proce. Good luck. Ed


Posted January 17, 2008 - 08:09 AM


I plan to work on this weekend. I'll post my findings.


Posted January 23, 2008 - 09:34 AM


No1Clyde... you're correct, It's the lower rod baring. Got it torn down and parts on order.

  • MattFisher

Posted January 24, 2008 - 04:10 PM


As I understand it the lower con rod normally goes out due to insufficient oiling. Big K didn't leave enough room in the oiling slot. Evidently the hot rods setup has that issue fixed. The other issue common to the KX65 can be porus cases around the main bearing area; causes air leaks, sometimes intermittent.

  • no1clyde

Posted January 24, 2008 - 05:42 PM


DIRTBIKEDADX2 I'm glad you can handle the problem. I also think running 20-1 oil is a good idea and jet for it, I know a lot of people say that is too much oil but in that motor I like it. Good luck with it. Ed

Related Content


what bike? KTM,RM,YZ,KX,or CR 125 by Numsa Hul

Dirt Bike   General Dirt Bike Forums   What bike should I buy?
  • * * * * *
  • 8 replies

01/02 KX250 Build - 1st 2 stroke by CD2T

Dirt Bike   Make / Model Specific   Kawasaki   Kawasaki 2-Stroke
  • Hot  36 replies

Help ! It refuses to idle...no matter what.. by UglyCasanova

Dirt Bike   Make / Model Specific   Kawasaki   Kawasaki 2-Stroke
  • Hot  36 replies

Best trail bike by Ripley

Dirt Bike   General Dirt Bike Forums   What bike should I buy?
  • * - - - -
  • Hot  103 replies

options on swaping a 07 crf450r for a 2003 kx250 by 92rmx250

Dirt Bike   Make / Model Specific   Kawasaki   Kawasaki 2-Stroke
  • Hot  40 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.