08 yz 450 timing...

There is too much tension with the tensioner off to move the cams...I guess my only other option is to unbolt them?

There is too much tension with the tensioner off to move the cams...I guess my only other option is to unbolt them?

Try unbolting just the back one (IE Intake). Then put the Flywheel TDC and pull all the chain slack up onto the Exhaust cam and line it up then slid the Intake cam back in and line it up and bolt it up. Put the tensioner back in and set it so it applies tension then move the engine forwards and backwards and see if the timing stays right. If it does torque everything down to specs and go ride!!

PS: also to the tensioner test as explained in the manual so you can make sure that it isn't faulty>.

What do you mean by move the engine back and forth?

What do you mean by move the engine back and forth?

put a wrench on the flywheel and "turn" :thumbsup: the engine over forwards and backwards then back to TDC and see if it's still all lined up.

I thought thats what you meant..I didn't know the engine could turn over backwards, is why I asked, knew it went forward to get it to TDC but not backwards..but thanks!

Looks like the cam chain was off a little, I fixed that which explained why the cam chain was so tight. Don't laugh if my questions seem elementary but...when turning the motor over (both ways haha) at a certain point it would just rotate on its own..is this normal? I'm going to check the starter gear to see if maybe that might be stripped out...any other ideas?

at a certain point it would just rotate on its own..is this normal?

Yes..

The certain point is where you get over onto the back side of the intake lobes and the valve springs drive the cams forward, turning the entire engine. Normal.

I'm going to check the starter gear to see if maybe that might be stripped out...any other ideas?

I have none other than checking the drive gear on the crank. You should be able to look behind the flywheel and see if the chain is on the gear. Also like someone else mentioned check the black plastic slides and make sure that they are in place properly.

I have a question or two.

After you figured out that the chain was a little off did you correct that and then try timing it?

If so did it stay timed after turning the engine over?

If yes to the last one then I say ride it... :thumbsup: Cause yaur problems be fixed.... but if no... I'm not sure where to go.

Did you check to make sure that the tensioner is working properly?

If not do that. Like Gray said earlier don't move the engine with the tensioner out. You'll end up having to redo the timing again.

Like Gray said earlier don't move the engine with the tensioner out. You'll end up having to redo the timing again.

You can move it, just do so prudently, and don't rotate it in either direction past the point where the cams begin to open the valves.

I did not move the motor until I had the tensioner on and followed all of everyone's instructions. It took a few turns of a wrench and the timing would line up, should just one rotation of the flywheel be one full turn of the cams? or does it take more than that due to the smaller size differents of the gear behind the flywheel? The cam chain went into place once I reinstalled the intake cam, so i'm assuming I had the cam chain sitting on top of the lower gear after the rebuild, which is why the cam chain was so tight to begin with?

Just to make sure I did everything correctly...I just took everything apart again and made sure everything was perfect. It is, just waiting for my oil filter (stainless) to dry and I'm going to fire it up! Pray for me! haha

well i just watched oil come out of where the header meets the cylinder...what the heck is wrong with this thing? Also its extremely hard to start...but that sounds like the least of my worries...i'm soo frustrated...

well i just watched oil come out of where the header meets the cylinder...what the heck is wrong with this thing? Also its extremely hard to start...but that sounds like the least of my worries...I'm soo frustrated...

hmmm your sure that the timing was correct?? There are two dots on the cams on the exhaust it's supposed to be lined up on the forward part of the case and sticking straight up. Intake: backwards part of the case and straight up again. Um oil?? Not too sure on that.

Was the oil squirting or just seeping? Grayracer might have to put some knowledge in on this...

hmmm, you said you rebuilt it.

Were the rings lined up according to the manual?

You said you bought a new head?

Did you have the cylinder checked out to make sure it was good?

How about torque spec's on cylinder bolts, and head bolts did you follow a manual's instructions on that?

A exhaust gasket did your rebuild kit come with one and did you install it?

Where did you buy a head from?

Did you just have work done on the head or a completely new one??

How about valve seals?

Oil coming out the exhaust could be from the valve seals leaking and letting oil drizzle down into the exhaust.

Starting hard Get a compression gauge and check the compression. Check your spark. And and check to make sure that it is getting fuel and air.

But if oil is coming out of the exhaust you could have oil going in on top of the piston too causing the start process to be hard. Did the bike smoke alot when running?

These are my only thoughts but they all shouldn't cause issues like you stated...

You didn't notice oil coming out on the first 3 hrs of riding the bike??

Above all get gray to put his input in.

Also you might be well off to ask your local yamy mechanic to look at it.

Things like this cause major frustration, but go through everything and see what you have and you might find the problem. :thumbsup:

Everything is brand new on the top end and all oem parts including : cylinder head, valves, seals, springs, piston, rings, pin...you name it its brand new. I had a friend whose been working on 4 strokes since they've came out help me put it back together. Everything was done per the owners manual. It does sound like it could be a a seal...when we but the cams in the dots were lined up per the manual but the tension on the chain was rediculously tight, which I found out yesterday after retiming the cams it was not on proper track..I'm going to disassemble it again tonight, but don't have a tool to compress the valve springs..any suggestions?

no smoking while running, i was just looking at the motor while the bike was running and i saw a little oil seep from where the header meets the cylinder. bought everything from babbits yamaha because they had the best prices. oil has to be getting to the spark plug because it comes out black, which I assume is the cause of the difficulty in starting.

Everything is brand new on the top end and all oem parts including : cylinder head, valves, seals, springs, piston, rings, pin...you name it its brand new. I had a friend whose been working on 4 strokes since they've came out help me put it back together. Everything was done per the owners manual. It does sound like it could be a a seal...when we but the cams in the dots were lined up per the manual but the tension on the chain was rediculously tight, which I found out yesterday after retiming the cams it was not on proper track..I'm going to disassemble it again tonight, but don't have a tool to compress the valve springs..any suggestions?

You did the cylinder head, or the cylinder and head? How did you put the valves in originally if you don't have a compression tool?

Ya if oil is getting on top of the piston that would cause havoc starting.... I'd say if it's a seep if could be valve seals... again see what gray has to say.

the cylinder was fine, looked brand new..but the head needed to be replaced due to cracking which was causing oil to leak onto the piston which was causing it to burn oil..the piston i pulled out had about 1/16" of carbon build up on it. my friend has all the tools, unfortunately he lives about 2.5 hours away...and my truck doesn't get the best fuel economy....

the cylinder was fine, looked brand new..but the head needed to be replaced due to cracking which was causing oil to leak onto the piston which was causing it to burn oil..the piston i pulled out had about 1/16" of carbon build up on it. my friend has all the tools, unfortunately he lives about 2.5 hours away...and my truck doesn't get the best fuel economy....

ok well one possiblity is that the cylinder even though it looked good was warped too and those issues are showing up now. But I'd def look at my valve seals first and make sure they are seating properly. Hopefully that is it!! Again luck to you!!

***edit*** I think that if the cylinder was warped it would show up somewhere else other than the exhaust port.

I appreciate all of everyone's input and information! I'm takin this thing to the dealer, tired of fooling with it. Its time to let the "expert mechanics" take a look at it. Its been up for sale but thank God nobody has been that interested because I couldn't possibly sell it in the shape its in.

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