couple timming questions "400ex"

[honduh440]

when you are setting the timming about an inch at the most to the left of the "T" on the flywheel is an "F" im curious to what that means.


also another question i have when your setting the timming and you have the marks on the cam sprocket that are level with the head after you put the timming chain tensioner on it moves the cam a hair and the lines will be off parallel of the head about a 1/4 of an inch is that ok?

[honduh440]

anyone?

[Colby@C&DRacing]

That is the fire mark. That is when the spark plug fires. Which happen while the piston is still traveling upward. This has to happen so that the fuel charge can have time to fully ignite before the piston is going back down.

[BLEEDRED]

I did notice that last year my timing chain had a bit of slack in it. When I lined up the marks and then put the tention on the chain it was off a bit. I ended up moving it one tooth and it lined it up good. Timing was spot on.

This year I threw in the CRF450R timing chain and it was pretty tight. There was no question on how to line it up. If you moved it a tooth it was way off. I think the stock timing chain stretched a little and that is why it was off.

Just make sure that once the tension is on the chain and you turn the engine over by hand a couple of times the marks are pretty darn close to lined up.

Goog luck.

[wilkin250r]

I ran into a little problem a week ago with a 250X. There are a few degrees of difference when the "T" mark is at the top of the window, or the bottom. It would seem to make sense that TDC should be when the "T" is in the exact center of the window, but it wasn't in my case.

Try to find TDC by some other method than the timing mark. When I did that, I found the "T" near the bottom of the window, and it caused me to shift my cam sprocket one tooth, and now the timing marks line up exactly.

Now, that's not to say that YOUR timing mark should be at the bottom of the window, it just means that mine was. Like I said, try to find TDC by some method OTHER than the timing mark on the flywheel.

[cals400ex]

on the 250x is there a T mark only or is there a line with a T next to it? on the 400ex, there is a line next to the T.

[wilkin250r]

I can't remember. I didn't look at the flywheel all that much. I took the head cover off, and used the cam for TDC. Once the cam was out, I used the piston for TDC, both disassembly and reassembly. I didn't look at the flywheel until I was re-installing the camshaft. I THINK there was a mark, but I'm not sure.

[cals400ex]

yeah, not that it really matters i guess. i think you can get a little more precise with the line. however, who is to say that is dead on. my buddies rancher just has a T and no line and i felt it was a little more difficult but maybe that is because i know my bike much better than his.