Hi, all.

I have some engine noises that I'd like for you guys to try to decipher for me.

Bike is an 09 klx250s with about 2600 miles on it. I picked it up with 2300 on it. Pretty much entirely stock minus the !snorkle mod.

I had a slight bit of clatter from 5-6k rpm, just enough to be annoying. After doing a little bit of searching, I found it to be the Cam Adjuster. Other low RPM buzzes, whirs, and noises I've narrowed down to radiator covers, plastics, and the gas tank lid.

I did the loosen the 2, 8mm bolt method to manually adjust the cam adjuster. The first time I did this I loosened up the far bolt and then the near bolt slowly. I probably only went about a turn, turn and a half. I thought I heard a click and tightened everything back up, but the noise was still there.

The second time I did the manual adjustment. I backed out the farthest bolt a good bit, and then slowly worked the near bolt. Between the adjuster body itself and the engine block there was probably about 2.5mm-3mms of a gap. I didn't want to take it any further, and I didn't hear a click, so I tightened everything back up. Started fine, idles smooth and quiet, and the slight clatter was gone from 5-6k rpms.

But since the fix, I've been exploring more of the top end, and here is my main concern. Above 7k rpm there seems to be a clatter as I go up near redline. It isn't too terrible, but loud enough to make me wonder if something else is wrong. I honestly can't tell if it is something that is loose rattling around, or something in the motor itself, but I'm leaning towards a motor issue. Is it possible that I over did forcing the cam adjuster?

 

If you read most of those cam chain posts, you also probably saw the manual adjuster that Krieger Tensioners has for the KLX. It works and ends all that putzing with the autotensioner. Some don't have any problems with their OEM tensioner, but if you do, the manual tensioner is the fix. Mark's tensioner is very reasonably priced.

 

the chain rattles at 5000 rpm.. its just how the engine sounds.. Ive got 5000 miles on mine, chatter and all.. it runs like a champ.. practically indestructable.. just enjoy the bike, change the oil, and ride

 

In the last 2 thousands miles or so mine has started this also, it comes on at 5k rpms and sounds like the top end is full of loose change. I may go with the manual adjuster or another brand bike I'm not sure at this point.

 

Hmmm...if I did the math correctly, the Krieger manual tensioner seems to win out every time from a cost-standpoint.

 

If your rattle is the cam chain...and it probably is...and you continue to let it run that way, you'll be replacing your cam chain well before 10,000 miles like I had to. If you're lucky, that's all you'll have to replace.

 

Yep the one click method worked for me perfectly! All quiet now.

 

How about top end noise? starting around 7k and it is intermittent. Normal thumper top end, slight rocks in a tin can, noise?

It doesn't sound like valves to me. Could I be experiencing some knock?

 

Yep, now your cam chain is too tight.

I got a lot of experience on this one. I had two "automatic" ones go bad on the KLX. It has to do with the dynamic wear of the chains (650 has two) versus the indexing of the ratchet tensioner as well as tolerance stacking.

I will also tell you that you may be preloading your cam chain by up to .125-.250" by doing the "one click" method. Now picture having a preloaded cam rubbing against the plain bearing surface of your head. I hope your oil is incredibly good at lubricating two surfaces being forced together like that.

I've found that the difference between a clicking manual tensioner due to chain seating to that after it is adjusted is about 1/8-1/4 turn of the M8-1.25mm bolt - or about .012-.025". Compare that to what you just did and you may have an idea of why some knowledgeable riders would prefer the manual tensioner. It's not about being quiet, it's about being properly adjusted.

On that point, the term cam chain tensioner is a total misnomer. The proper term would be cam chain adjuster, because ideally the perfect adjustment is no tension at all, but no slack in the drive. This perfect adjustment is easily approached with a manual tensioner, because as I said, 1/8 turn is only .012" and I guarantee you can hear and feel the difference between 1/8 turn when it's right on the edge. There is a light tapping on the adjuster bolt and a light ticking that will go away with a miniscule turn of the adjuster bolt.

So the question is do you want to overstress your cam drive by any of the override maneuvers with the stock unit or do you want to do the job properly? In my case on both bikes I chose the latter, because I knew another OEM would fail and heads are costly if the timing jumps or the cams sieze. It got me into this whole cam chain tensioner thing to the point where it is today. It also got me into doing a whole lot of looking and thinking on the whole tensioner issue too.

I can also tell you once your cam drive is seated in the adjustments become long and far between. I have done 4 adjustments on the KLX650 in 11 years and 30,000 miles, the first few were early on since the cam chains were new courtesy of the first set being trashed by the two OEM units going south. The last two were pretty far apart and I don't remember when I did the last one. I think it was about two years and several thousand miles ago.

I'm just telling you what I know and have seen, it's your choice.

 

If you want to know for sure where the noise is coming from get either a mechanic's stethoscope or a long handle screwdriver, handle against your ear, and put the tip in various areas, like the valve cover to see if valves are making noise, the cam chain tensioner to see if it is rattling there, or on the cylinder to see if you can hear the noise from the piston. That will get you closer to what the problem may be. My KLX has a bit of clicking from piston rocking, but no big deal.

Do the testing and see what you find.