03 yz450f help! Think I just messed up with timing adjustment

Ok, I'm new to this forum. First post and all. But I think I just royally messed up my bike. What was going to be a quick fix I think just turned into a major issue. So here's the breakdown of events.

I bought this bike a month back, knowing the previous, previous owner did a top end rebuild on it.

It was a pain to get started if it wasn't warm, and stalled out constantly when i would ride it. Whether it be my lack of experience on a 450 or not. I've been riding 250s for a Long time now and they've never been an issue, but having a 4 speed, I think is what made the stalling an issue for me.

Regardless, I opened the valve cover to see if the timing was off, and it was. So lil ole me decided to adjust it. I went through the book and adjusted everything to how it was supposed to be, put it all back together, and THEN decided to turn the crank to see if TDC was correct. So I rotated it.

It stopped and wouldn't rotate anymore after maybe a half a turn. That got me pretty irritated as it was just fine before I messed with it.

So I took off the valve cover again, and pulled the cams out.

And that's my problem. I now have both cams out, and it's not at Top Dead Center. I have No idea where the cams where before, and I think the crank wouldn't rotate due to me not knowing that there were (piston like) rings in the cam, and one fell out jamming it up.

I also noticed a little bit of metal shavings when I pulled out the (intake?) cam. Not sure what that cams called. The other one from exhaust cam.

I'm in dire need of help as to where to go from here. I have both cams out and everything covered. But what do I do?? I'd appreciate any response. I'm about to just take it too a shop and have them fix it up. Thanks!

Oh and by the way, I found my spark plug was completely fouled when I pulled it out for the first time after I got the bike. It looked to have fuel or oil on it and was pretty dark. Im assuming it was running way too rich. Thanks again. ImageUploadedByThumper Talk1442871176.335973.jpgImageUploadedByThumper Talk1442871332.330476.jpgImageUploadedByThumper Talk1442871395.505786.jpg

I really need some help with this if someone can spare the time!

I'd pull the spark plug out and put a screw driver down the spark plug hole to give a very rough estimate of finding tdc. Hold the cam chain in your hand as you turn the motor over, let the chain roll through your hand till you hit tdc and put it all back together and ride.

If the cam journals are not scored you should be okay. Wash everything down with brake cleaner (not carb cleaner) and put it back together. Make sure those little half moon things that look like rings are in place and the cams are seated properly. Sometimes they will sit a forward and the cam caps won't go on correctly. If you have to force it then things are not in the right place. Get some assembly lube for the journals and buckets.


Always double, triple check your three timing marks and use your finger in the tensioner hole to put a little tension on the timing chain while you are checking. Without a little pressure on the chain the marks can look aligned and still be a tooth or two off. Use a torque wrench and follow the sequence in the book to tighten the cam caps down. Once you have it all tight and the tensioner reinstalled turn it over with by hand using the crankshaft, not the kick starter, and make sure it is not hanging up on anything and I would even double check your timing marks just to be sure. 


Assuming all that is good, drain and refill the oil since it is probably fouled with brake cleaner and who knows what else. After you get it started I would change the oil and filter one more time before you take it on a ride to just be sure you get as much crap out of the engine as possible.

Thanks man. I appreciate the response. I just thought I messed up pretty bad when I pulled the cams and it wasn't at tdc. I didn't see any scoring or marring in the journals at all which is kind of odd, considering there was a decent amount of metal shavings that fell on my hand. Maybe enough to cover half the tip of my pinky.

Can you tell me anything about the oil and crap on the spark plug?

Thanks again. You've helped me a lot!

There is always a chance you banged a valve, but I wouldn't too excited about it yet. If you have the stuff you can pressurize the cylinder to check for a bent valve. It could be that the cam gears ground the side of the valve cover a bit it you didn't have the cams in the right spot.


The dirty plug could be a variety of things, if it is black and oily that indicates burning oil. If that's the case, it's most likely worn rings but you could also have a bad valve stem seal or even a over-oiled filter. Black and sooty would indicate it's running too rich, again filter could be culprit or the jetting is off. I would clean the filter with either a commercial filter cleaning product or gas and then hot soapy water (Dawn dish soap works well). Put in a new plug and ride it. If you can have someone follow you for a while and pay attention to the exhaust. Blue smoke=burning oil, black= fuel (too rich) and go from there. If it is just little bit of blue smoke I wouldn't worry too much and start saving your pennies for a top end (just remember to check your oil before each ride). If it's lots of smoke you should do something sooner rather than later.


Allot of this stuff comes down to maintenance, keeping your filter clean and oiled and frequent oil changes are your two best friends. I put a new plug in once a year weather it needs it or not; and checking/adjust your valves at least once a year. If you are putting a fair amount of time on it a new timing chain is a good idea (they are only about $20). If you can, don't run ethanol gas and use a little Sea Foam a couple times a year to keep the carb clean.

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