Starting project to install a KLX300R cylinder in my 2007 KLX250S. Got the 300 (292) cylinder for $100 last year and finally decided to see what it'll do...

------------------------------------------------------------------

I've removed the four large cylinder bolts and the two smaller 8mm bolts by the cam chain. Put a few good knocks on either side with a rubber mallet but no dice.

Does this center allen bolt need to also come out?

 

Remove the engine mount, lower photo, right.

(I did the same thing first time through...)

 

*hangs head in shame*

off to the shop.

 

Man, now that's funny.......LOL


Yeah, we all do stuff like that....... Laughing with you...

 

 

why did you take the cams out?
Maybe it is necessary, but I don't remember that.

 

I'm swapping in a KLX300R cylinder.

 

and? I don't think cam removal is required for cylinders, but as I said, I don't remember exactly.

 

Sure it is. The cam chain goes around the crank and both camshafts. The head will not come off without moving the cam chain off of the camshafts. I mean you could technically just remove the cam sprockets, but honestly, you should be setting your valve lash any time you work on the cylinder as I am here. So the cams would need to come off then anyway, to get to the buckets.

This is pretty basic information, search youtube for several videos showing engine disassembly and valve adjustment on a KLX250S.

 

When doing something like a full top end disassembly for a big bore or other modification, I don't want to leave anything to chance on the condition of the other components while I'm this deep into the engine. Cam bearing surfaces, etc., I want to know if there is anything that looks amiss before I get everything up and running again. It's comforting to know you didn't miss a wear indicator or eminent failure just to save 30 minutes to an hour of your own free labor.

A similar comparison would be swapping in higher performance heads on a something like a small block Chevy. There's no need to pull the cam or lifters. However, it's not uncommon to find the beginnings of a bad lifter/cam lobe interface in the making every once in awhile. I'm in the camp of "better safe than sorry". It's very little work to insure that other components are good-to-go before proceeding with other major repairs or upgrades.

Obviously I'm not recommending pulling your crank or tranny at this point to insure integrity, but some of the components that are easily checked at this point can be worth it and take little time to do so. I'd consider the cam bearing surfaces at this point of an engine modification to be one of those worth doing at the time.