HELP ktm bottom end issues

so, i picked up a 2000 ktm 65 for my kid, i got it cheap because it needed top end, the bike also came with a box of extra parts including another bottom end that appears to be good.

so anyways i got a new top end for the bike and while rebuilding i checked the existing bottom end and it seemed ok...i proceded to rebuild top end, put the bike back together, fresh fluid, all set to fire her up.

Sooo, i kicked her a few times nothing......trouble its a spark issue...easy that i have spark i start kicking again, she starts up...than instantly seizes....grrrr

sooo i pull the bike apart once end is fine...bottom end wont move.

so my only choice now is to swap it out with the spare bottom end that came with the bike.

  as i start breaking down original bottom frees up, ass it turn it it has resistance in the same spot of the question is what could have caused this? what could it be? and how can i prevent this from happening when i put other bottom end in.

thanks for the input

Hello there. 


You will have to replace the selas, Big end bearing and the main bearings. The big end bearing will need the crank split to do this or buy another new crank. It is a must and the only way to be sure. 


Good luck. hoping ill be ok with the other bottom end i have...............also anyone know an easy way to remove magneto??

You will need a puller. Either a fylwheel puller or sometimes it can be done with a steering wheel puller and change out the bolts to make them fit. Steering wheel puller can be purchased from any auto store.

yeah thats what i still in the learning process, so any tips are appreciated....once i put the motor back together, are there any tests, or important details i should be aware of to avoid disaster?? so far for the tear down, iv kept every thing labeled and organized, so i know what goes where, i got the top end off, piston removed, bottom end off frame, and both side covers off...thats how i left it...until time permits me to ill want to transfer clutch (wich is new btw), and magneto over to other bottom end, replace gaskets and put side covers back on...then cont to again any tips or important DOs and DONTS would be helpfull

To be honest with you there are a few and the best thing to do would be to get a Clymer manual for that make and model. 


Like you say........strip and label everyting and clean it. 

Put new seals in and make sure they are lubed and home square to the case. 

Your crank needs a new bigend bearing. It will need to be lubed with a few squits of 2 stroke oil when installing. 

If you are going to rebuild the crank get a good engine builder to do it or buy a new one. 

Clean all the old gaskets or threebond from the surfaces and lap the cases so they are flat. 

Use threebond to assemble where there are no gaskets.

You will need new main bearings and the best way to fit is thermally but they can be pressed in. Lube them with 2 stroke oil. Buy original or get aftermaket as long as they are C3 bearings.

Make sure you check your piston to cylinder clearances. Piston - cylinder clearances should be (rule of thimb) 1 thou for each inch of bore size.

Replace the little end bearing. Oil it with 2 stroke oil.

When installing the piston c clips install them directly up or down.

Get the correct ring end gap and install with marking at the top.

If you can lap the barrel and the head.

Good idea to check squish at this stage.

I like to pressure test my engines before installation.


There is lot more and your manual will cover all the tolerances.


If you have face book here is a link to our engine rebuilding page and there may be some things here you will find helpful.

Also check out our youtube.  


awesome i really appreciate your for mentioned, im a newbie at all this tech stuff...iv been around bikes most of my life, riding em, doing the "easy" maintenance tasks, but lately iv been diving deeper into the mechanics of the 2 Stroke, and am finding it quite enjoyable, almost as fun as riding them....its nice to have the resources that are available here on the again thank you...perhaps as i move along with this project, ill post some pics...thanks sure ill be seeking your input/advice again

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