400ex timing

[dxcody]

How can you tell which TDC is the compression TDC on the flywheel?

[CJM]

Easy, take your flywheel inspection cover off and the bolt access cover and turn the bolt counter blockwise to the "t" mark on the inspection area-theres a little tick mark you line it up with.

see here:http://www.atvriders.com/articles/valveadjustment400ex.html

You will know its truly at TDC comp stroke if you grab the rockers and they are loose. If you want to make sure its at TDC, take a small pen and stick it in the spark plug hole as your lining up the timing mark-pen should move upwards indicating at TDC.

The cam and cam gear must also be lined up in order to properly time the engine. The cam must have the lobes facing down and the gear has 2 lines that must line up with the top of the head.

[dxcody]

Originally posted by CJM
Easy, take your flywheel inspection cover off and the bolt access cover and turn the bolt counter blockwise to the "t" mark on the inspection area-theres a little tick mark you line it up with.

see here:http://www.atvriders.com/articles/valveadjustment400ex.html

You will know its truly at TDC comp stroke if you grab the rockers and they are loose. If you want to make sure its at TDC, take a small pen and stick it in the spark plug hole as your lining up the timing mark-pen should move upwards indicating at TDC.

The cam and cam gear must also be lined up in order to properly time the engine. The cam must have the lobes facing down and the gear has 2 lines that must line up with the top of the head.

Ok so its the l I looking mark and not the l l- ? Thanks for the reply!

[CJM]

You line up the | marking on the case with the T mark on the flywheel. You will see it.

[dxcody]

Originally posted by CJM
You line up the | marking on the case with the T mark on the flywheel. You will see it.

Ok thanks alot man. Oh and do you know where i can get a compression tester? my dad has one for a car but its too big i wasnt sure if they made an addapter or something. I know i am loving this single cam rather than a dual cam on a 450 haha

[CJM]

I got a nice one at harbor freight tools made by US general. Its the one that comes with 4 different hoses with different ends on them, has worked great for 25 bucks.

[dxcody]

Originally posted by CJM
I got a nice one at harbor freight tools made by US general. Its the one that comes with 4 different hoses with different ends on them, has worked great for 25 bucks.

Ok man, sorry to bug you, but the timing is dead on now, BUT i have a new problem. I am getting spark from my spark plug if i plug it in while the spark plug is out of the head. But when its in the head its not getting spark i guess because it floods out, its so bad that it pours out the exhuast if i pump the gas enough.. Could i need a new spark plug possibly? Or what do you think?

[CJM]

Carb problems or maybe the plugs fouled out. If the plugs no good it will be all black and nasty looking-tan on the electrode means its good.

Remove the plug and leave it on the wire, place plug in a spot you can see on the head and crank it-look for spark. If you have spark then your ok, no spark-check the coil.

Next step would be to check to make sure its getting gas and the jets arent clogged, the float isnt getting stuck and it has the proper jetting.

Last like I said-check compression, under 128psi you either have blown a head gasket or need rings. In either case you need to break down the top end to see for sure.

You should really PM a moderator and have them move this to the 400EX section where you will get more replies.