My mechanic is trying his best. I asked for a complete once over to have my bike ready for the season. He doesn't work on many offroad bikes. Anyway, he sent me this video asking if the engine sounded OK... I said I'd check with you guys because I don't know 😂

He said he adjusted the valve intake clearance from 0.19 to 0.14 (intake1) and 0.15 (intake2). The timing chain appeared good.

Bike is a 2018 klx250 with just over 11,000 kms and 1k oil changes 👍

 

Is all that noise coming from the right side? The side with the cam chain tensioner? If it is, either the automatic tensioner has completely failed, or if it is a manual tensioner it is likely out of adjustment being too loose.

I've got a fair amount of experience having had a couple tensioners fail in my 1995 KLX650 within 14,000 miles in 2000. I had to replace the tensioner in my Zephyr 550, sounding like a hornets nest under the tank, at 12,000 miles. The tensioner in my 09 KLX250 was junk when I got the bike and my manual unit was put in shortly after buying the bike. I've also been in touch with numerous owners about the noise like that in the bike. I have no idea why some mechanics ignore that issue. Seems they just say "they're all noisy." At least your mechanic is asking the question, clearly he thinks the noise may be an issue. I can tell you they don't have to be, if it is cam drive noise. A manual tensioner allows adjustment to take out cam drive chain slack by the mechanic and is relatively easy to do. Plus when the automatic tensioner quits locking in properly the cam drive will eventually allow enough play that the cam chain can skip a tooth at the crank, possibly break the chain, and damage the top end.

I sat down with the two mechanic/friends who rebuilt the top end of my bike, when it made noise like that. They were kind of shrugging their shoulders at first, then one, who was a drag racer, said, "Drag racers put in manual tensioners.." Then the other, who raced flat track, said, "my XT500 flat tracker had a manual tensioner to start with." So I made the manual tensioner for the KLX650. Several years later when I got the 550 it would buzz like crazy off and on. Doing a manual tensioner for it was what put me in business. It quieted the noise down immediately after adjustment. From there I've had hundreds of riders contact me about getting manual tensioners and I point out it is about the least expensive first step to making the cam drive work right and quiet down. In at least 99% of the cases the cam drive was adjusted for near zero play and the noise gone, cam timing right.

Listen closely to your engine, if that noise is loudest on the right side or if you get a mechanic's stethoscope and find the noise is coming from the area of the cam chain tensioner, it is bad and needs replaced. Don't try to jam in tight or loosen it to get it to click and lock, that will put tension on the cam drive and possibly pull on the cams hard enough to cause metal to metal contact with the cam and cam journals. I think there should be enough riders here to tell you the fix is to do the manual tensioner. I happen to make and sell them, but if that noise wasn't there I wouldn't tell you to listen closer and to consider doing the manual unit. It's about keeping the bike running right, has been since I made the first one. No noise no problem, but if that rattle is on the right side around the tensioner fix it.

Feel free to message me if you have questions or find you should need the manual tensioner.

 

One should always adj the valves on a DOC engine to the loose side of the clearances, to do otherwise doesn't make sense. The valves will never loosen up unless there is a major failure in something. Normal wear will always tighten them up.

 

I can get him to test with a stethoscope. I'll send him this thread also. He has my friends klx there with 45k+ kms and said that bikes engine sounded smoother than mine, hence his concern.

Will PM you about the manual CCT.

 

As I have little to no mechanical knowledge, can you explain to me if that is what he has done with the above notes?

 

He measured the clearance, then changed the size of the shim's to get the valves tighter. Probably cause he thought the noise was from them being 'loose'. The intakes max is .0039 in, min is .0012.
If he takes it apart again, I would have him loosen them back up to at least where they were which is in the middle of the service range.
DOHC engines: Valves get tighter with wear, so making them tight is just shortening the time till you will have to pull it all apart again.

 

Thankyou

 

Update: my mechanic readjusted the valves as recommended above and now believes the cam chain needs replacing, so we've ordered one of those plus the Krieger manual cam chain tensioner 🙏

 

Measure the chain before replacing. Though personally I wouldn't bother. Those HyVo design chains are used for two reasons -

1. They run quieter than a roller chain
2. They are extremely durable and should last the life of the engine. Especially considering it is running in an oil bath..

I seriously doubt the chain is worn out. Mine had 12,000 miles when I went to the manual tensioner, my Zephyr had 12,000 miles too. It is purely the tensioner, don't spend the money on the chain. They do not wear much at all. The big risk is if the chain should jump time. Yours hasn't.

With proper adjustment on bikes with the original chain, the manual tensioner will hold the adjustment and very likely run more than 10,000 miles without need of any adjustment. I had one rider put a tensioner in his Concours and after the first adjustment he hadn't needed to adjust it in over 20,000 miles of riding. The adjustment is only done if it is determined there is clicking coming from the tensioner area indicating some play. Even then the adjustment is only maybe .010" Right now that clicking you have indicates the tensioner is being pushed in more like about .250" then snapping back with that and chain slap making that noise.

 

Does the stock tensioner self adjust? If not, how long do they usually run? I've never put a tensioner in any bike I've owned since the 1980s!