Klx250sf cam chain too tight on "new" engine
 

About three years ago my engine locked up. It had about 10K miles on it.
After messing with it off and on, I bought a new engine and installed it recently. Got it started and it is making this terrible clanking sound. Searched online and read about the problem with the automatic tensioner. The sound seemed similar to others that had problems with their automatic tensioner.Bought the kreiger manual tensioner, installed it. This didn't help.

So, I got the cylinder head cover off and am just looking around in there.
I inspected the cam shaft chain. It is really tight, even with the tensioner removed, there is no slack.
Can the cam shaft chain guide get stuck on something?
Does anyone have any experience with this?
Thanks for any help.

From what I recall, the rear chain guide is locked in place with a bolt at the bottom, but the front chain guide is not locked in place. It can be pulled out.

Since you have the cover off, check cam timing and maybe also valve clearance.

Does removing the lower cam chain slider tensioner (non-adjustable) provide any slack in the cam chain?

Possibly the wrong chain length? If someone got inside there and used what they had laying around...

I just removed my cams about a week ago and had the same scenario. I removed my adjuster in preparation for the cam removal and noticed the chain was tight. My motor only has around 1,500 miles on it. I double checked everything and never could see a problem. Reinstalled my cams and have rode it about 200 miles and no issues. I think this is a normal condition. The noise your hearing isn't. My engine is quiet.

Video the noise and post it to youtube so we can have a listen.

The cam chain noise is rpm related, it starts above 4K and goes on from there, sounds worse than it really is but needs fixed, if yours sounds like a box of rocks at or around idle you have bigger problems.

I'm starting to wonder how tight is "tight".

If it is honest to gawd so tight there is no flex you have big problems. On the other hand, when new the chain probably will not be loose enough to move it up off of a sprocket, there won't be that much play in it. There will be play though. If you cannot rock the cams back and forth a bit when the tensioner is taken out, there is a problem.

Remember too, that there is the spring in the middle of the slider, I'm thinking it isn't overly strong, but could cause the sensation of a tight chain, I don't know.

When my adjust was completely removed it was tight in that you could not get the chain off the gears and you could get no movement between the cams.

There is a spring on the back guide? I thought the only spring that pushed on the guide was in the adjuster.

Small one mid way down.

I really think you need to get someone who might be a bit more familiar with the drive to to physically look at it to know if there is a problem. I wish I could help more.

How much force does that spring apply? When I did mine the slack side was tight with the slightest amount of movement. When I posted my concern someone posted their's was similar so I just went with it. No problems so far.

The valve springs may be acting on the cams to keep the chain taut across the top.

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