atc200 timing Question

[Jeckel]

I recently rebuilt my honda atc200 and it ran great till I set it up for a few months. I like to tinker so I tore the head down to look at the Jug,cam,valves also cleaned the carb/tank and the normal maintenance tune up. Well when I put it all back together I set the timing adjusted the valves and attempted to crank and all it does it hit and pops through the carb/muffler mostly carb. I figured it was the timing so I have been working on this thing for the past 2weeks trying to set this up but just doesnt seem to want to run. Ive set the carbs needles, new spark plug, good spark, plug is wet. It takes a long time to finally hit and when it does it backfires and dies like the timing is off but ive set it the best I can. Flywheel T mark lined up with notch and cam mark doesnt line up 100% with the notch, but its about a 1/8" on the right of the head arrow can that effect it enough to not crank? And if so how do I line the cam mark up perfect the chain wont let it. Ive rotated the chain many times to try and get a better fit. Im in dire straights bout to go out of my mind can anyone give me a few tips pls!

[cybrman]

My tried and true non scientific method....
Take a screwdriver and put it down the hole where the spark plug goes to determine TDC (top dead center). Gently rotate the engine until your screwdriver is at its highest point - that is TDC
With the piston at TDC then all you need to do is line up the camshaft sprocket with the marks on the side of the head, making sure the lobes on the shaft are down (valves closed).
You may be off by 180 meaning the valves are opening when they should be closing.
(There are plenty of other recent threads talking about timing...do a search to see other tips/tricks)

[Erics350x]

also make sure the pin in the cam didn't fall out

[oscarmayer]

check to make sure the rotator on the cdi set is not backwards, if the line on it is not pointing to the pickup (black box under cdi cover) then it's backwards and it would cause this issue.

[Jeckel]

I figured out what the problem was my cam was TDC on the exaust stroke so i fixxed the timing 180 off now its just havin trouble starting it sputters for a sec but no run yet. I think just a little patience and trial and error on troubleshooting will fix this problem.

[oscarmayer]

hold the throttle open a little to ensure it's gettin fuel and air. check to be certain the rotating peice is not 180 out like i said.

[MonkOFox]

I recently changed all the gaskets on my 200s, and had to put the timing crap all back on...

I just used a srew driver as said earlier to get the piston tdc, then I just put the cam back in with the lobes down, put the gear and chain on, lined up the 'o' mark on the gear with the knotch on the valve cover. put the cdi back on and it cranked right up!

and when i said lobes down, one will be at like 225 degrees, and the other at -45 degrees( or 315 degrees) give or take some....

you'll know because the front part of the cam that the gear bolts onto will be straight vertical, and one way will be lobes up and the other will be opposite ( what you need).

And also, be sure you use all the correct torque specs for the bolts and stuff.

I think that is it....

Justin