Funny you ask about TDC TNC ( hey it rhymes). I think in the pic the engine is not quite at TDC (TDC mark is in the notch in the inspection hole but not quite centered). TDC made the alignment a touch worse. I was moving the flywheel back and forth trying to figure out if my eyes were off from one side of the engine to the other. Sounds exactly like the problem you describe. Maybe it's time for a new cam chain. How many miles did you have when you replaced yours? How long are they supposed to last? Mines at ~5100 miles.
Dan

 

Dan, mine had 11,000 miles. I can't imagine that yours would be worn out in half that time without having made lots of noise all along since you've owned it. But...I know mine with a new chain has those cam alignment marks dead level with the head surface at TDC. When I see you say, "moving the flywheel back and forth"...I'm guessing you already know that TDC should be achieved by turning the flywheel counterclockwise only to check the cam timing marks...right?

 

UH...I kinda knew that. I did turn it counter clock when coming to TDC. After I got to TDC I didn't like the way the marks were off just a touch so I played with the flywheel TDC mark, back and forth, to see if the cams lined up any better. Sounds like I should have kept turning it CW another full cycle to see if I could get the marks to look more level.
I will round up some shims for the valves and take another look at it.
Great info to have. For future ref where did you get your cam chain, and roughly how much are they? Thanks Dan

 

I'm not a good source for prices on my purchases. The shop where I worked for many years still takes care of me. I got my chain from Kawasaki. They retail for about $85. There are other sources in the Tucker-Rocky catalog that retail for about $50-$65. I don't think the Kaw chain is the problem, though. Mark at Krieger tensioners is still working on a manual replacement and will notify me when the prototype is ready. I'm going to post on it as soon as I get it.

 

Did you check the clearance between the piston and the head? I had that noise on my over bored klx and I end up finding that the piston was hiting the head due to bad mechanic installation.

 

Wow!...that's interesting. Could you elaborate about what happened?...type of big bore kit, etc.

 

I can't add anything to this discussion, except that it isn't the octane causing the problem. If it was related to octane, it would get worse as it warmed up, not better.

I am very interested in this topic, as I'm going to get a Bill Blue kit of some sort, after I make sure my suspension upgrades make the bike handle well enough to keep. I'm actually leaning toward the 331 at the moment, due to the extreme heat I ride in 1/2 of the year.

 

i havn't had any heat problems and that is in 40 degrees +

 

Noted! Thanks!

 

I hope this helps and not be too long to read for you. (I apologize for my english mistakes)
I have a 1994 klx250R that I bought in 2000 almost not used. I used in stock condition for two years and then I start a step by step series of modifications so, I know the hard way what effect have each mod on this bike.

the case of the piston knocking noise was this: it was a LA sleeve with a 78mm wiseco piston. but,as far as I check on internet, it wasn't the part number regulary used.
the fact was that as the piston/head clearance was too small, at the first moment It had detonation at mid range revs and 3/4 to full trotle. This problem was solved with proper carb tunnig.(bigger main jet and needle from 4th to 3th clip)
after some miles on it the same noise that I heard on the video appears. It could be heard from idle to low revs with the engine was cold. after the engine was hot, the noise disapeared. Some miles later, it start to be present even with the engine was hot.
Then, we disassembled the top end and we found that the piston was knoking the head on one part of the circunference.
IMO, this happend because:
the lenght of the cilinder could had been reduced by the machinist that installed the sleeve
the piston skirt wears out and piston start to tilt over the pin and the knocking noise appears. (piston pin is not in the center)
when hot, the piston adjust the clearance to the sleeve and the piston does not tilt.
We found also that there were some wearing on the rod conection to the cranckshaft.

the solution was to replace the cranckshaft set (I choose to install a 300 cranckshaft) and to machine the top of the piston 0,5mm. And, I also change the mechanic.

we check the piston/head clearance and then finished the assembly.

it goes very good for an entire season even the piston was not new.

Then, it start to smoke and I bought a 351 kit from BB and I plan to install it this month (if I have time)

So, the mods are:
revalved inverted showa forks and stiffer springs.
race-tech shock spring and revalved shock damper.
CR brakes and front wheel
Guts 1" taller seat foam and guts racing seat cover (I strongly suggest this mod because ergonomics improve a lot form few US$ and a litle of work adjusting the foam)
wirtz handlebars and levers.
IMS wide foot pegs.
maier plastics
engine:
all free mods
head ported ( I do twice, the first one wrong, the second, I reduce the section of the intake ducts using epoxy an the thing goes excellent)
white brother all around camshaft (new)
351 BB kit (yes, I have to machine the cases) (new)
klx 300 cranckshaft
mikuni tm 33 pumper carb bored to 34.5mm
custom made oversized header pipe and muffler.
stroker mod on shift star
klx 300 2007 clutch disks.

I would like not to spent more money on this bike so please ...do not talk about FMF powerbomb header or a WER steering damper...

see you guys.
GABB