400ex engine problems

[whiteclipse16]

Hey guys, hoping for a little help here. I'm working on a 2000 400ex for a kid.
When I got the bike the kid said it was running and knocking, so he tore it apart and put a new timing chain in it. He tried to start it and said it wouldn't start so I started working on it.
I pulled the motor out and turned it over by hand and noticed it would not make a complete cycle it would stop.
So I pulled the top cover off the motor and took the timing cover plug off the flywheel and found it was 2 teeth out of time . I put it in time and the motor cranks over fine now but won't even fire or start.

The other thing is, the hose that comes out of the crankcase in the back by the swingarm has a lot of pressure coming out of it. If you hold your finger over and crank the motor over, then stop take your finger off it lets a lot of pressure off.
I don't know if it has a bent valve or what.
Let me know what you guys think.
Thanks

[katch26]

I dont know what to tell you other than the crankcase breather tube is just that as it vents pressure from the crankcase

[whiteclipse16]

I realize it vents pressure from the crankcase, but I don't think there should be that much pressure.
With the hose on there and just hanging in mid air, there is enough pressure coming out of the hose to push the hose back and forth.
I hope that makes sense, its hard to explain.

Oh and it has spark, and seems to be getting gas, but it wouldn't even fire on starting fluid, not even once.

Also the kid said he put a hot cam in it. Does the hot cam use the stock cam gear, I'm thinking that possibly whoever put the hot cam in it, has the cam 180' off. Can someone tell me if the cam comes with the gear or it uses the stock gear.

[katch26]

at tdc the lobes should be facing downwards

[whiteclipse16]

I can't look at the bike to verify how the lobes are. If someone had to put the cam gear on the hot cam, its possible that is wrong, but if the hot cam comes with the gear on it, then I doubt that part is wrong, need somebody to verify that.

[big95xj]

ITs "impossible" to install it 180 out as long as the lobes are down when you install it. On this motor if the motor is at TDC its at TDC, when you install the cam YOU determine if it is the compression or the exhuast stroke. I hope that makes since. On a different note when i went into mine for the first time i had about the exact same problem. Check your valves for the proper clearance. My intake valves were about three turns too tight. I figured hey i didnt touch them when i took the cover off so they must still be right. WRONG. Give it a try and let us know...

Bryant

[whiteclipse16]

Hey thanks man, I thought about the valves being out of adjustment. The kid told me they checked the adjustments and stuff, but the bike also wasn't timed properly so its hard to tell if the valves are adjusted right.
I won't be able to update until next weekend, as I'm at school and the bike is at home.

What I was thinking when I said the cam is 180 out. Was that the cam lobes should be facing down when all the marks are lined up.
Well if they installed the cam gear on the hot cam so that the marks were lined up but the lobes were facing up, then wouldn't the cam be 180 out. I could be wrong, but it was just a thought in trying to answer why it wouldn't run.
Thanks for the replys, keep um coming though.

[drew416ex]

if it was 2 teeth out of time, it may have bent some valves.

[whiteclipse16]

I was thinking along the lines of bent valves or them not closing all the way and its putting the compression into the bottom end of the engine, which would account for the extra pressure coming out of the crankcase breather tube.
Not sure though

[big95xj]

I had mine way off too, like three teeth and it didnt hurt anything. I corrected that then the valves were way screwed up. After that she fired right up! As far as the breather tube thing i dont know...but if you leave your timing plugs out of the case and try to start the engine you will notice that there is ALOT of compression in the crankcase aswell. Im not sure but this "problem" may be normal. Get it running then see what happens...

[YELLOW_TRX400EX]

i think u should check compression it sound like it have a blown gasket and its loosing the compression thru there. i dont know how bent valve would send the compression to the crankcase ... ?? dont understand that????

[big95xj]

Originally posted by YELLOW_TRX400EX
i think u should check compression it sound like it have a blown gasket and its loosing the compression thru there. i dont know how bent valve would send the compression to the crankcase ... ?? dont understand that????

The only way the head gasket would be able to get compresion into the crankcase would be if it BLEW out into the timing chain tunnel. I dont recall that being a common place to blow out but it is possible...worth a look...

[whiteclipse16]

Update guys:
I got a call earlier while I was in class and the kid said he got it running tonight. I'm not sure what he did, I haven't been able to get ahold of him.
I cranked the motor over by hand kind of fast a few times with those timing plugs out and did notice a lot of air coming out there, so maybe it is normal.
Thats why I'm asking you guys, I know you know a ton more about the bike than I do.
As for a bent valve sending compression into the bottom end, I didn't know how to justify it either, but it was a thought since it was out of time and I know the valve was hitting the piston at some point.

I'll see what he did to get it running and let you guys know, maybe it will help someone else in the future,
Thanks for the input guys its much appriciated