Need help setting timing on my1985 250 big red

[Scary Gary]

hi. i just put a set of rings in my 250 big red but do not know how to set the timing to put it back together.

[MonroeMike]

Welcome aboard.

Check out chapter 6 of the manual.

http://72.52.143.80/~trikes/Manuals/ATC%20manuals/atc250es-85-87servicemanual.pdf

[MudBug]

I have a question about timing too. When lining up the cap sprocket marks, should you have the chain tensioner taken out, and put it back in after? Or should you leave it in and do the timing that way.

[Honda_Dude]

When I did my SX, I had the tensioner out. I put it back in AFTER it was timed & tightened back up.

[MudBug]

When I did my SX, I had the tensioner out. I put it back in AFTER it was timed & tightened back up.

and your bike worked good after right? :lol:

[Scary Gary]

i currently dont have a manuel 4 it. would like to know how the timing marks line up, so i could put it together today thx

[MonroeMike]

Again, the manual is here, download it.

http://72.52.143.80/~trikes/Manuals/ATC%20manuals/atc250es-85-87servicemanual.pdf

[Dirtcrasher]

Well Scary Gary, you scare me without a manual.... :lol:

TDC on the compression stroke with the flywheel at T, the lobes are 180 degrees AWAY from the rockers and it's FIRING at this point. The cam sprocket "O" goes either up or down ( I forget) and that doesn't matter, it is not pinned to the cam. Its all in how well you know your 4 stroke motors and where the cam lobes are in relation to the rockers.

ANY 4 stroke motor can be timed without a book if you understand how it operates.

Many guys do this and end up "180 out" or in other words, it's firing at the completion of an exhaust stroke and NOT at TDC on a compression stroke.

180 out won't bend valves but 175 or 185 "out" might. Some of you get what I'm saying and some don't. The best suggestion I always make is put manuals and other tech books next to your crapper and you'll be surprised to learn what you didn't know :beer:

Please read the free manuals that Monroe Mike provides EVERYONE links to. That explains anything else I didn't cover and helps you double check yourself.

I either remove or loosen the cam chain tensioner when setting timing, then double check it when you ready to tighten it all down. EVERY one of these motors need new timing chains (the gears are usually just fine) and the guide and tensioner guide should be replaced. Dennis Kirk has a tensioner guide and guide kit for cheap money and a DID chain for it too.

It's your motor, do what you want..............

Wouldn't it be nice to know your torque values and torque the bolts too?? :D

GOOD LUCK!

DC

[MudBug]

thanks for that DC! I still need a new coil for mine and I havent worked on finishing up the motor