Try checking to see if your cam chain tensioner is working correctly? Maybe your chain is stretched and slapping the chain guides? And as for the bogging..it bogs when you get on the gas or just idle or ??

 

it bogs out when idleing and running

 

Clean carb. Even if you did it already. Your gas may have been sitting in your tank for a little while? Put fresh gas? Double check vacuum lines too. I got stumped once when I had mixed up where the tubes went.

 

U running high octane fuel?? U need to with high comp piston or u will get spark knock....as for the bog is it when u stab it ....ease into it...

 

ok thanks guys !!!

 

Is the bike smoking?
And
Is it more of a "tick" sound or a "ping" sound?

You should check the compression.
The bogging out could be losing compression if your rings are shot.

 

ya its smokeing had to put a quart of oil in it last night its more of a tick sound

 

I wouldn't wait anymore.

Tear it down.

Rings are most likely out and or valve seals and timing chain.

Once you get into the motor, you can see exactly what is wrong.

Let us know
Oh400ex

 

the motor was just rebuilt bottom up like 2 week ago

 

doesnt matter motors could last 30 years or 2 days

 

If its smoking something isnt right either in the head ..maybee some bad valve seals or some worn out valves even or maybee piston bore specs may be off

 

ok i drained the old gas and put 93 octain in it started it up now it "knocking"

 

Sounds like something went wrong with the rebuild.

It is really disheartening when you have to tear down a motor again shortly after being into it, but it happens to the best of us.'

You should tear it down again and see whats going on.

When you say it was rebuilt recently,
Was it you that rebuilt it or was it took to a shop?

If it was you,
Let us know as many details as you can, the more you share the more we can help.

Oh400ex

 

it was a family friend thats rebuilt many atv/utv motors he took 2 motors and made one good one

..so im goin to take the head off and take it to a shop and get new valve seals and see if my valve r good or bad

 

That is the best decision.

Check out the how to guide for rebuilding top end on 400ex

HERE

Yours will be very similar.

Let us know what you see when you get it apart.
Oh400ex

 

well i figured out the problem the high dome piston i put in was hittin the head causing the knock so i put 2 gaskets on it and it went away and its runnin good

 

This dosen't make any sense but any way glad it's running better now

 

I was thinking the same thing Moose, maybe vertical rod slop or the cylinder was machined before. Oh well as long as it runs.