This is my second KLX This is a 2013 KLX 250S that I've only had for a few months. 7500 miles and I got it with the head off due to a bent valve. Got it back together, added an manual chain tensioner, and she's been great for about 150 miles. Engine is quiet and smooth and has great power with the jetted carb and FMF header and pipe.

I took it out yesterday and as I slowly got going in first gear I heard interment dull clicking coming from what I think is the lower end. It doesn't do it consistently (a few dull clicks every 15-10 sec or so) and it doesn't increase frequency with speed but it seems to be present in at least the first 5 gears. Not sure about 6th as the wind and tires are pretty loud and it's hard to hear it. If I pull in the clutch there is no noise and I've checked chain and everything else and it only does it under power. The engine is smooth and runs really strong so I'm doubting it's anything with the piston/rod or lower end. I'm wondering if it might be something in the clutch or trans. The clutch grabs strong but I don't know anything about the bikes previous 7500 miles.

It shifts smooth and I threw it up on my stand and actually ran it through the gears and didn't hear the sound so it must only be under load with a rider.

Any thoughts from the group here on where to start looking or other things to test to further diagnose the problem?

Thanks!

 

 

outrecording - thanks for the suggestion. I just cleaned and waxed the chain last week but I don't know the history of it and that's a good place to start looking. I'll investigate this evening and report back.

 

Low octane gas might be causing "pinging".....detonation. This would show up under load.

Ride on
Brewster

 

Brewster - thanks for the suggestion and you and I think alike. Upon hearing it I pulled in and filled up with 93 Octane. I was hoping it was that simple.

 

So I thing the chain may be where my issue lies. I threw the bike up on the stand and checked it and I've definitely got some stiff links. I tried to lubricate it just to see if that was definitely the issue.

After a few trips around the block it seemed a little bit better but I could still here a few faint clicks here and there and they definitely seemed to be coming from the lower left side near the front sprocket. I had my 2009 KLX SF for 2 years and always maintained the chain with no issues but I'm not sure what constitutes the need for replacement.

There are a number of links that don't seem to rotate easily. Can someone give me their opinion if I should be swapping this chain out? I removed the guard to lubricate and check the chain.

 

Look at your sprocket - it seems pretty hooked. Combined with stiff links = you're in the market for chain and sprockets. You can probably squeeze some more miles out of them if you're tight on budget, but don't put it off too much longer.
Also, your chain 'looks' tight to me, but cannot really tell from the photo. Definitely do not over-tighten the chain. A tad on the loose side is better IMO.

 

See that black plastic fender flap in front of the tire in your first picture? I've heard a noise under load and it turned out to be that piece vibrating against the swingarm.

 

Thanks for the feedback and suggestions guys. I think I'll get a new chain and sprocket set for the bike. The chain doesn't look that old but I'm not sure it was maintained properly.

Thanks for the tip on the chain tension. It may be the way it looks in the photo as it set it to about 1.6" of deflection (Manual says 1.4" - 1.8") but I'll make sure I go on the loose side when I get the new one one.

I'll report back to close the loop. Thanks again.

 

I think I'm running around 2"+ slack, looser is better than too tight. And yes the one image has the sprocket looking a bit hooked. When I get links like that and the sprocket is visibly hooked I go new front and back w/chain. No low buck special chains either. O-ring type DID, EK, RK, or the like.