416 wont start!! I need help!

[dirtbikerider5]

I just put my 400ex back together last week! I just got it bored to a 416.(I also have a HMF pipe on it) I only had 3 hours on the piston and when I was riding home it just died!:mad: I thought it might have something to do with the spark..... but it doesnt because I took the wire off and put it on another plug and I could see the spark. I then thought that maybe the timing chain broke.....but it didnt! I took the valve caps off and the valves are moving fine. But when I had my hand over the exhaust valves I could feel air coming out of the valves is this normal??

Then I thought maybe the timing was off some how....but when I turn the engine with a wrench the cam is only off by 1 tooth!! It is getting gas and everything! I am not sure what to do! I dont think anything is wrong witht he piston b/c its brand NEW! PLEASE ANYBODY HELP ME!!

[dirtbikerider5]

anyone PLEASE!!!:eek2:

[GPracer2500]

Is it getting fuel?

[dirtbikerider5]

yes its getting fuel! I even sprayed starting fluid into the carb before I took the head off

[KrazyKarpet]

Check your compression. Just because your piston is new doesn't mean you didn't break a ring or maybe they are lined up and your getting blow by.

[dirtbikerider5]

maybe but it was just running fine and it just stopped!

[boricua]

wait! the cam is off by one tooth? that cant be good, that should throw your valve timing off.....enough to stop the motor! you said you felt air coming out of the exhaust valves? was that from the same hole you would adjust the valves from? if so, that doesnt sound good either. unless its crank case pressure. i would check the timing chain, start there. i would say its critical for that to be in tune.
adjustable cam gears i thought only changed the cam timing by a few degrees, not quite a full tooth.

[GPracer2500]

I had a freind with a 300EX. He got the timing off by one tooth and the engine ran. It didn't run very well--but it was certainly rideable. [shrug]

You took the head off? Or do you mean the valve cover?

Have you removed the old plug do inspect it? Have you tried a new plug?

[400exbiggun]

Originally posted by boricua
wait! the cam is off by one tooth? that cant be good, that should throw your valve timing off.....enough to stop the motor! you said you felt air coming out of the exhaust valves? was that from the same hole you would adjust the valves from? if so, that doesnt sound good either. unless its crank case pressure. i would check the timing chain, start there. i would say its critical for that to be in tune.
adjustable cam gears i thought only changed the cam timing by a few degrees, not quite a full tooth.
one tooth is not enough to stop a 400ex motor. My buddy timed his motor up with that F on the flywheel instead of the T which is 1 tooth off i think or a little more. it ran, but ran like ****. We thought we bent a valve, but pulled the head and it was fine. Now that same head is on my 416 and running harder than ever

[dirtbikerider5]

Well I just blew air into the spark plug hole and the air was coming out the pipe when the valves are closed! I did not have time to rip it apart last night but I will do it tonight. Does anyone know how the timing chain is suposed to fit on the cam gear because on mine it doesnt really sit like it does on a normal sproket. It seems like the timing chain is sticking up a little bit off the gear but it wont go down! O boy I hope i didnt break a vavle and mess up my piston!! ONLY 3 HOURS on it!!

[boricua]

there was another post on here about the heavy duty chain, the masses say it ok......
about air leaking through your pipe when blowing air in the cylinder.....what about the decompression plunger, could it be stuck? if not, maybe you have a bent valve sticking open.....:confused:

[dirtbikerider5]

hey guys I just took the head off and both vavles were sticking out about 3 milameters and there are 2 marks in the piston! I am not sure how the vavles hit the piston but they did!! I am not sure if I need a new piston. I am having a local shop look at it. Does anyone have and sugestions to what kind of vavles I should get?

[boricua]

maybe it jumped more than one tooth, hit the piston, bent the valves and somehow ended up jumping back to the one tooth mark you saw........possible.

[dirtbikerider5]

yea maybe but the guy at the shop said that even if the cam was backwords the valves shoulnd never hit it. He also said that he never saw this before!

[patches85]

Sounds like the cam chain is way stretched! Put a crf chain on it.