Did I Screw Up?

[400exrider720]

I am doing a rebuild and am done tearing the top end apart. I was reading on here that I should have set the motor to TDC. I didnt. Now what do I do when putting it back together? Please help.

[Robbob91]

Just set it to TDC when you put it back together


Rob

[400exrider720]

Where do I put the cam at? I dont know where the cam would be rotated.

[250X_project]

When the engine is at TDC put the cam lobes both facing down, with the lines on the cam gear flush with the head. ;)

[400exrider720]

Thanks for the help!! I was worried I screwed up.:D

[jeremy_283]

make sure the engine Is at the actual TDC because u will see the TDC mark two differnt times when u rotate the flywheel and one places the piston and the bottom of the cylinder and one places it at the top

[lpmaster]

the t shows up once per flywheel rotation, everytime you see the t the piston is at tdc, when you install the cam with lobes down and sprocket lines flush you just determined the piston to be at tdc on the compression stroke. while the cam is out and head is off there really isnt more than one tdc

[wilkin250r]

And don't worry about the ignition. Many people worry that their ignition and cam timing are opposite, and their spark is firing on the exhaust stroke instead of the compression stroke.

In reality, the 400EX sparks EVERY revolution, so it will automatically adjust. It's very common in motorcycle and ATV ignitions.

[250X_project]

No worries. Glad to help. lpmaster is right the easiest way to determine TDC is when you can see the piston at the top of the cylinder when the head is off. Good luck!