I am trying to restall the stock cam after replacing the head gasket. The piston is at tdc, the T mark is aligned with the index line, the cam sprocket is installed so the lines are aligned with the top of the head.

The question is should the cam lobes be pointing up when installing the first bolt in the cam sprocket? Seems to be that I can align the bolts with the cam lobes either pointing up or down. I don't want to mess it up. I've read the manual over and over and can't figure it out.

If someone responds, others please respond too that they agree or disagree.

Thanks,

Jon

 

When on TDC the lobes should be DOWN so that the valves are closed.

 

Moto is correct, lobes DOWN, make sure the engine is on the compression stroke though. Hope this helps

 

I am on the compression stroke if the piston is at TDC and the "T" is aligned, right?

 

no, u may be on the exhaust stroke, on either one the crank mark will be a TDC.

 

There is no compression stroke until you install the cam, or, how you install the cam will determine compression stroke. You can install it either way, noturaptor. But when you install the head cover, the cam lobes should face down, that will be compression stroke. Otherwise you are fighting your valves trying to open when you torque the head cover. Time it lobes down and put your first sprocket bolt in and just bottem it so you can still wiggle the sprocket. Turn it so the you can install and torque the other, then go around again to finish torque the first one, lobes down at this point and you're ready to install the head cover.

 

if you get it on the wrong stroke ignition will fire on top of exhaust stroke

 

One side note...when you install the cam chain tensioner, your timing will back up a tooth and the machine will not run if set correct before install of the tensioner.

 

This shouldn't be a problem. The 400ex has a crankshaft mounted pulse generator, it fires on every stroke of the crank. The spark at the exhaust stroke (piston at TDC but not on compression stroke) is just wasted.

 

Thanks for all the help. Hopefully I get around to getting it back together this weekend.

Garyc660R, your signature line is wrong. All the 400exs are faster than my Raptor most of the time. It isn't hard to beat a sitting duck. [img]i/expressions/face-icon-small-smile.gif[/img]

/Jon