400ex possible cam issues

[lilwhitetruck]

ok well i install a je 10:5 piston (stock bore) just to get a little more from my 04 400ex. as i was putting every thing back together i found a little pin approx 1/8 inch in diamiter and maybe 1inch long. anyone now were this goes. i keep reading about a spring and a plungger under the cam. i dont recal seeing this. after it was all together i tried to start it. i wants to start but just wont start. please help!!!!!!!!!!!!!!

ps cam is stock

have spark
have fuel (170main)
tried jumping of car tries to start very close just wont go please anything will help

[blackhole]

I havent messed with these atv engines much but i have messed with automotive engines a lot. I would say that the cam timing is off a few teeth on the timing chain. just a suggestion.

[lilwhitetruck]

i thought that to but checked it several times. at tdc all valves are loose just like they should be. cam gear only goes on two ways took digital pics just to make sure that i got it right. i think that it has to do with the decompression assy. just not sure how the system work.

[blackhole]

oh, ok. Like i said i havent torn into one of these motors yet, but plan to soon. If i think of anything else I will post it

[duke416ex]

That sounds like the decompression out of the head. Look under where your cam is by the sprocket and there should be a little hole under the mechanism on the cam where that pin goes, but it does have a spring that goes under it. If you need more help go to planet honda and look at the microfiche to see where it goes.

It will still start without the decompression mech. b/c many aftermarket cams do not use the mechanism. When it is tdc, are the lines on the sprocket lined up with the top of the head perfect?

[400exrider707]

Originally posted by duke416ex
That sounds like the decompression out of the head. Look under where your cam is by the sprocket and there should be a little hole under the mechanism on the cam where that pin goes, but it does have a spring that goes under it. If you need more help go to planet honda and look at the microfiche to see where it goes.

It will still start without the decompression mech. b/c many aftermarket cams do not use the mechanism. When it is tdc, are the lines on the sprocket lined up with the top of the head perfect?

It will NOT start like that. What is happening is he took the decompression pin out. That pin is what DISENGAGES the decompression mechanism. If that is not in it WILL NOT start!! I just went through this same fiasco. If you look at your stock cam, near the sprocket there is a decompression mechanism. It is attached to the cam. Look under the cam in the motor, right in the head there is a little recessed hole. The spring and plunger go in there. Drop in the spring, then drop in that plunger, then put her back together and start it up!

[lilwhitetruck]

ok one more question i ordered a hot cam stg 1 will this fix my problem as well.

[400exrider707]

Originally posted by lilwhitetruck
ok one more question i ordered a hot cam stg 1 will this fix my problem as well.

Yes it will. The hotcams dont have the decompression mechanism on them so you can just drop in that hotcam. Dont forget to remove that plunger and spring out of the hole though, otherwise they will end up in your engine somewheres, and thats not good!

[lilwhitetruck]

well the sprign and plunger wont be a problem i never put them in
thanks for the info. what jet would you reccomend for my application.

stock carb
hotcam stg1
je 10:5 piston
wb rev box
custom dual exhaust
k&n filter and outerwear.

i have a 170 in the carb right now but i ordered a 180 just in case let me know thanks again

[400exrider707]

Originally posted by lilwhitetruck
well the sprign and plunger wont be a problem i never put them in
thanks for the info. what jet would you reccomend for my application.

stock carb
hotcam stg1
je 10:5 piston
wb rev box
custom dual exhaust
k&n filter and outerwear.

i have a 170 in the carb right now but i ordered a 180 just in case let me know thanks again

Sounds way too big. I dont know its hard to say with that custom dual exhaust. To give you an idea though I had a
Wiseco 11:1, stage 1 hotcam, FMF slip on, UNI filter w/ NO lid, and I was running 155 main, 42 pilot, needle in 4th position. 160 main possibly if yours is a full exhaust.

[lilwhitetruck]

ok thanks

[Chino886]

Originally posted by lilwhitetruck
ok thanks

I'm in KC MO and I had the JE 10.5 with stage II and I ran a 170 when it was 100 degrees outside and humid as crap and it ran good.....