Diagnose this engine noise

[milkmandan]

I was warming up my new motor build on my KLX110 for the first time when it started making this noise. Motor was running and idling great until this suddenly started. Motor has a fresh Wiseco piston and rings, ported head with an aftermarket cam. Didn't touch the bottom end as the motor was running great before.





Top end? Bottom end? Any tips on what to check?

[PlanetMinis.com]

[trvshonda]

What are your valve clearances set at?? Is it a big bore kit you put on or is it stock bore with a new piston and rings? You also sure that you have your timing dead on? Make sure your timing line on your fly wheel is lined up and then check the line on your cam chain sprocket and make sure it lines up with the cut out spot in the head.

[milkmandan]

Thanks for the reply, I set the valves at .05mm as per the shop manual. Just checked them again, and it looks like the intake valve has slipped to between .1 and .07mm - could that be enough to make a noise like that? I had the cylinder bored out 2mm to fit a 55mm piston - the machine shop took the piston and set the clearance of the bore to match. When I was checking the valves just now I noticed the pressure of the springs wanted to rotate the cam slightly forward or backward vs the timing mark - it took a delicate touch to get it to stay dead on the mark. Problem?

Thanks!

[trvshonda]

Are you sure you are checking the clearances at TDC on compression stroke? The way to make sure you are on compression stroke is to get both your flywheel line and cam lines lined up and see if you can wiggle your rockers against the valve. If you can wiggle it just alittle bit then you are on tdc compression stroke. If both of them are tight and dont move then your tdc but on exhaust stroke. Make sure you are on compression stroke and reset your valves to .003 both intake and exhaust and let me know if it sounds any better.

[snowisgr8]

Thanks for the reply, I set the valves at .05mm as per the shop manual. Just checked them again, and it looks like the intake valve has slipped to between .1 and .07mm - could that be enough to make a noise like that? I had the cylinder bored out 2mm to fit a 55mm piston - the machine shop took the piston and set the clearance of the bore to match. When I was checking the valves just now I noticed the pressure of the springs wanted to rotate the cam slightly forward or backward vs the timing mark - it took a delicate touch to get it to stay dead on the mark. Problem?

Thanks!

Just a guess, but it might be the timing chain tensioner or possibly one of the chain guides moved? It almost sounded to me like a loose chain noise I had on my klx. I have crappy sound on my laptop though. Can you hear the noise when you kick it over without the plug wire on? If you can, you might be able to track down something loose or damaged.

[milkmandan]

Did the rocker wiggle test and reset the valves to .038mm (smallest feeler gauge I have) and the sound is still there. I pulled the plug and made another video, you can hear it pretty clearly:

[trvshonda]

Are you using a stock head? If your using a different head with oversized valves then the valves could be lightly touching the piston. If its the stock head and valves i would look to make sure that your oversized piston has big enough valve reliefs so the valves arent touching the piston. Also .038mm (.0015) Is pretty tight. I would reset them back to .05mm (.002) and double check your timing marks. If you can take a couple pictures of your flywheel lined up where your checking your clearances and also a pic of your cam chain sprocket line where it lines up with the casting mark on the head. Also check your cam chain tensioner and make sure its not letting the chain flop or not catching on the metal chain holder behind the fly wheel. Also make sure you are using the line on the cam sprocket with the T next to it. If i remember right i think there are two lines there. If your not timed on the right line then it could be your problem letting the valves tap the piston. Take a couple pics so we can see what you got going on. Kinda sounds to me it might be a tooth or two off time but also check the timing chain and make sure its all good.

[jordon372]

I agree ^^^ sounds like the valves are hitting the piston. Check the timing as he said there are 2 marks on the cam chain sprocket and make sure you are lining it up to the T mark.

[milkmandan]

The head is a stock head.

Pulled the timing cover off this morning and took these pics:


Lined up mark on flywheel


And where the cam sprocket ends up

I took the tensioner off and tried to reset the chain on the sprocket, but it always seemed to be half a tooth off.

The click was still audible, and by turning the flywheel I was able to locate where in the cycle it was:

This is less than 180 degrees of rotation from having the flywheel and sprocket aligned, and it would click a 2nd time in another 90 degrees.

[trvshonda]

Timing is just a touch off. If you move it one tooth does the line line up about the same way but just past the timing casting mark? Also you said it makes the noise just less then 180 degrees of a rotation to tdc. Can you check and see where the piston is at during this area where its making the sound. Just pull your spark plug out and line your timing marks back up like you have them and put a long screw driver into the spark plug hole and verify the piston is for sure at tdc. Then while rotating the engine keep the screw driver pushed to the top of the piston and see where it makes its noise. I would like to see if its making the noise at tdc again or if the piston is towards the bottom of its stroke. Also i forgot to ask but this is a stock cam as well right? Im still thinking its something to do with the valves lightly touching the piston but once you find out where the piston is at in the cylinder when its making the noise then we should know alittle more. Cause if its making the noise and the piston is at BDC then we know its not the valves hitting the piston but maybe the piston skirt lightly hitting something. Never heard of that happening but i guess there is a chance.
If you find out what area its making the noise at you might make a video of it and move it around alittle bit so we can see and hear what your dealing with. Good luck man, I know this stuff can get frustrating but once you figure it out you will be that much more knowledgeable about it. lol

[trvshonda]

Also after thinking about it some more i would really like to know where this piston is at when you here the sound cause if its at BDC after the power stroke and your hearing it twice im wondering if the piston skirt is lightly hitting the the rod as it comes down from the powerstoke and then comes back around and touches again as its go back up for the exhaust stroke. Guess once you find out where the piston is at when it makes the noises i will know alittle bit more info. We'll get this figured out though. lol

[koby686]

If the piston is bigger then stock then it might be gritting the head an u need 2 head gaskets, just did this on a motor I built for a friend. Try it out.

[koby686]

Hitting**

[fatcaaat]

Don't use 2 head gaskets regardless...two base gaskets is what you want. Also, from my experience when I find that I can't get a direct line up with the timing notches and it is either just before of just after, I always have better success with the motor when it is just after the notch rather than just before it. I also suggest doing the following which is real easy...remove the cam chain tensioner completely on the cylinder, reset it, and put it back in. Better yet, rotate it without the tensioner in there and listen for the noise. Only take a 2 minutes to do that test.

[milkmandan]

Ok, now I feel like a real idiot...

So last night I took the cam sprocket and the tensioner off again and reset the timing, and magically the noise disappeared! Took the bike out this morning again to put its first heat cycle into it and change the oil, and after 5ish minutes the clicking came back. Pissed as hell, pulled the cam and stator covers and while turning the crankshaft, I noticed the cam sprocket bolts were shifting at the same time it was clicking. Turns out the loctite I used didn't take or something and the cam sprocket bolts were backing out, and letting the cam sprocket shift on its shaft and make the clicking noise. Tightened them back up and the noise is gone! I gotta thank all of you for your help with this, learned a lot about diagnosing a problem and how the top end of these engines work.

[klxadogg437]

Good Work man way to stick with it

[trvshonda]

Sweet! Glad to hear you got it figured out and it was something simply. Its always a relief to find the problem but then again 90% of the time we also feel like a dumb a$$ because its normally something over looked. Glad none came out fully when you had her running. That would tick you off big time.
Now its time to go rip things up.