Setting up the cams after piston change.

[mrBird]

Hi.

I have just put everything together after changing the piston in my wr450.

I got the two dots on the cams to lineup perfectly with the cylinder head.

However, I couldn't get the to line up perfectly and at the same time get PISTON in t.d.c

The crank had to be a little bit past (clockwise) the I in HI.

(The thing to the right of the right line is not the actual I, or it might be, but looking directly into the hole, the I will be perhaps 5mm to the left of the marking in cover).

Should I be worried about this? I haven't actually started the bike yet, but no strange sound when turning the engine over.

[zibbit u2]

there can be a few contributing factors that could lead to something like this.

1. check that the fwd (LH) chain guide is seated properly in the upper and lower locations. If it's not seated near the crank shaft, it could affect the spacing between the crank and exhaust camshaft. Which would throw out the angle between the crank and camshafts.

2. check that the slack in the chain is actually at the rear (RH) chain guide on the cam chain tensioner side.. The chain should be as tight as possible between crank to exhaust cam, then from exhaust cam to intake cam, with the leftovers going to tensioner.

3. if step 1 & 2 are good, then you might have a stretched cam chain. Which would mean it's replacement time.

Did you install the chain with the tensioner completely removed? Try rotating the engine in a CCW direction one full turn until the lower timing mark comes into position with the tensioner in place. All those marks should line up perfectly, if not something is wrong. Don't rotate the engine CW at all.

Myself personally I wouldn't run it until I see those marks all aligning perfectly. It's a lot more expensive changing a head/valves/piston because of a missed timing mark than it is changing another HG to check what is going on.

[mrBird]

I opened it up again. Rotating the crank one turn didn't do anything, and I can't see that it should. The cams are off about half a tooth.

Couldn't see anything wrong, but i suppose I need to remove the cylinder head again, to make sure the forward chain guide is set correctly. I know the center part of the guide is seated properly, but I am unsure about the lower (since it was a pain trying to get it to place with the engine still on the bike).

How often do you need to change the timing chain? Every time you change the piston, every other time? xx hours? Is there any kind of general rule? The chain-tensioner seem to have about 5-7mm left to tension the chain. Is this normal or a sign of excessive chain wear?

[barbwire44]

Bird that is close enough, most often you cannot get the cam marks in a perfect line with the top of the cylinder, sometimes when you add the chain tensioner they will line up more closely, I was pretty much told if you cannot get perfect alignment of the marks try and move one tooth, or link, in both directions and if it gets worse leave it in the closest spot, too many variables in the alignment of the dots, worn chain is gonna change it, worn cam sprockets, worn cam, etc..etc...

[05-WR450F]

What about the numbers of pins between the top dots as a final check?