Stretched timing chain?

After taking out my chain tensioner and putting it back in, my bike wont start, it cranks (thump... thump... thump... thump), but wont run. The fist time the chain skipped a tooth on the exhaust cam, i guess because the chain tensioner didnt have time to engage, but when i adjusted the timing i noticed with the tensioner engaged that the TDC mark on the generator rotor advanced a degree or so counter clockwise. (sorry they're rotated)

https://i.servimg.com/u/f36/18/30/17/83/20130710.jpg

https://i.servimg.com/u/f36/18/30/17/83/20130711.jpg

This is as close as i can get it, if i move the chain a tooth over on the cams its even further off of the mark in the other direction.
I put the bike back together and it still wont start. Doing the same thump...thump...thump.
Is this little timing thing responsible? The bike was running fine before i took the tensioner out, (just a persistent click), and I dont know how the chain could've stretched in that time enough to mess up the timing.

I checked and the spark plug was not wet with fuel and is working fine. The fuel pump is also working but something i noticed is that it primes every time i flick the switch, whereas in the past it wouldnt.

The first time i adjusted the timing, i took the throttle body out. is it a possibility that i did something to it to cause this? all the hoses are connected.

anyway i hope you guys (and gals) can help. im really trying to get this fixed myself as i have no maney to take it to the shop.

It's hard to tell by the pictures that you put up.

When you reinstall the tensioner and start rotating the crankshaft to release the tensioner, are you keeping a hand on top of the cam sprockets to keep the chain from jumping a tooth?

Getting the cam timing right is a PITA, especially if you have to keep removing and resetting the tensioner, but it is easier if you hold the timing chain down on the sprockets while turning the crankshaft.

Its not jumping any teeth on the cams. the tensioner keeps the chain very tight. I did a compression test and i get absolutely nothing. i cant blow air through but i don't get anything on the gauge (yes i remover the oneway valve before before blowing in). my fear is that i fubar'd the exhaust valves when it skipped A tooth on the exhaust cam because the tensioner didn't extend fast enough and i didn't know to manually do it beforehand  


I dont know why the TDC marks dont exactly line up but using a long screwdriver through the sparkplug hole i can see that the piston is at its highest point when the cams are at their appropriate 10 and 2 positions so the timing should be fine

Rut-roh. Doesn't sound good. I have a spare head if you find that yours is too messed up.

Some general things I learned from this nerve wracking step in the valve adjustment process:

1) Make sure all of the slack is taken out of the exhaust cam side, leaving everything for the tensioner side.
2) On turning the crank (to have the tensioner unwind itself), put your left hand on the exhaust cam side first as to not skip any teeth when the exhaust lobes make first contact with the lifters.
3) Once everything is settled on the exhaust side in clearing the lobes across those lifters, then move your left hand to the intake side ensuring no teeth are skipped. Any slack that develops to the left of the exhaust cam will straighten itself out and tug the cam without skipping.
4) Once the 'pop' comes from the tensioner, check all 3 lines, both cams and through the peephole. Ensure that you are in fact reading the correct line, as there are two of them. The once you're looking for is a simple dash mark. I don't immediately recall the look of the other one.

I learned that the cam marks weren't 100% in line with one another and just ever so slightly off, causing me to redo this process thinking that I skipped a tooth. In redoing everything with one tooth over, I found that they were even further off this time around. The cam chain was perfectly taught with barely enough room to move the cams into position when using all the slack possible. After 3,000mi, the motor still runs like a dream without issue.

If you are having issues after taking all of these factors into account, look elsewhere, such as grounds or the starter itself, or the spark plug, fuel pump fully plugged in, etc. Hope this helps.

Carbomb wrote:

If you are having issues after taking all of these factors into account, look elsewhere, such as grounds or the starter itself, or the spark plug, fuel pump fully plugged in, etc. Hope this helps.

I'm guessing a bent valve here since there is no compression. I hope I'm wrong.

If you have a leakdown tester, you can listen for the leakage at the exhaust and airbox to check the valves. (provided the cam timing is correct)

Did the bike work before you took it apart?

Thanks guys for the replies. Yes the bike worked before i took it apart. All there was was a little ticking noise that was rmp dependant (not wheel rotation). i took the tensioner out to fiddle with it as i heard it was likely the cause and when i put it back in i didnt engage it. The bike wouldnt run so i checked the timing and indeed the exhaust cam was a single tooth off. i put it back in time but still nothing.

I have no compression now but if i take the hose itself and blow into the cylinder i cant blow through it at TDC. i forgot to check other positions to determine if the valves are stuck closed but i will tomorrow.

How would i check the valves? do i remove the cylinder head and look from underneath?

Thanks again guys im really stuck trying to figure this thing out

Leakdown test reports 90% leakage  

looks like ill be needing some new valves. hopefully just the exhaust ones

Alright so i took the cylinder head off and it looks like bent valves are not the problem.
Flakes of carbon nasties are keeping the valves from closing all the way.





ill clean everything and resurface the valves and hopefully thatll fix it.


This bike only has 21000 miles and for that amount of carbon i suspect the fmf programmer is causing the mixture to bee too rich so ill check my settings and adjust. Guess the guy who owned the bike before me is to blame.

Wow. That is nasty! Glad that it's not catastrophic. Definitely running way too rich!

Holy gunk Batman!  

All better  





Despite being a royal pain to figure out and do, I'm glad it happened so I'm not riding around with all that crap in there. Great way to get to know the bike a bit more too!


Next step is to take a look at the fuel programmer settings and see how much it was squirting in there

Good job!  

How does that kind of buildup in the cylinder happen??????   


That can't be just a symptom of running rich can it?
Not in the conventional concept of just being one or two numbers off on your fuel programmer.

What mods have you done to your bike?
What's not stock anymore?

Any clue as to how things got that bad?

Ive had the bike for 3 months, one of which has been spent trying to find and fixing this current problem. Two owners before me, a college guy who had it for about 4,000 miles and i dont know about the original owner. It has an fmf exhaust (not the q4, the loud one) but the stock header, fmf fuel programmer, partial airbox mod (hole drilled out of door and some holes in the fairing but the flapper is still intact) and thats it as far as i know.

It has been very easy for me to get flames out the exhaust so ive suspected it running rich but i havnt got a chance to check the programmer settings yet. Ive been considering getting it dyno'd and checking the mixture after its all back together but im still waiting for the new gaskets to come in.

Ok well I put it all back together nice and clean but it still wont start. Its got to be a timing issue because i still dont have any compression. I cannot get the timing marks to line up perfect. the best i can to is the cams being a little less than half a tooth late. Id imagine this would be the result of a stretched timing chain but my mechanic (whom i trust) says its just not normal or likely for them to stretch.

i cant figure out what else might be causing the timing to be that little bit off. When i try to start the bike i get a kind of suctiony pop on the exhaust stroke but in my mind that would mean exhaust valve opening too soon, not late like the timing would suggest.

If anyone has any input please let me know. i have just over a week until i move up to college and the bike has to be running by then..

Did you check that the valves were sealing while you had the head off? Run another leakdown test and listen for the escaping air. Compression leaks are not mysterious problems that can't be found. You are doing so much extra work. It would be helpful if you had somebody that actually knew what they were doing working on that thing.

I'm still going with bent valves from the skipped timing. Troubleshooting over the internet is not worth a darn thing though.

I'm not trying to be a d*ck, it just comes naturally. Sorry.

The valves are not bent and are seated properly because I lapped them (and yes I checked and there was absolutely no leakage, I squirted cleaning fluid in there while I had the head off). I am doing the work at a shop under the supervision of the owner, he just doesnt have much time to spare to help. I dont have the money to pay to get it done.
I will do a leakdown test again tomorrow to try and confirm the whether it is the timing or something else.

Thanks for the reply

When the leakdown tester is hooked up, you might try rotating the engine slowly by hand a couple of revolutions and watch to see if the compression comes up or it gets hard to turn. Unless there is overlap in the cam timing, you might find a place where there is compression. I have not ever done this before, just throwing it out there.

Hey man, just make sure that when you go and put the auto-tensioner back in, you have the valve cover off and your hand is pushing down hard on the timing chain(with the exhaust side of the chain tight with no slack in it) and start turning the motor counterclockwise. If you're not pushing hard enough when the tensioner snaps into place, there is a chance that it makes the chain jump a tooth..

Good luck brother

Alright, I finally got the bike running. The problem is that the fmf programmer isnt working right. The bike will run fine on the stock computer but sputters on the fmf. Anybody know how to check the fmf settings without it running the bike? id like to reset it to default and see if itll run but the only way i know how is to do it while the bike is running... (im not too familiar with it as the bike came with it when i bought it). Thanks for any replies and thank you those who have replied in the past.

Congrats on getting it running! What was the compression issue?

The issue was that i didnt know about the decompression mechanism on the exhaust cam... Doh