New 400ex owner have a few questions!!!!!

[marco1478]

Hey all Im getting my first 400ex today for cheap it has a 440 kit in it but it has a blown head gasket. The guy said it has had the 440 kit for a few years never had a problem with it, it blew the head gasket and he changed it with a 3 metal for a 440 kit. He took it out and about 5 min into his first ride it blew again. I have done 2 stroke rebuilds before but have never done a 4 stroke, Does anyone have a idea why it blew should i get hd head studs and what gasket should i use i am looking for a manual right now. Im sure its not to bad to do a head gasket on these bikes but just have never done one. any who just lookin for some advice

thanks all
Marcus

[01exrider87]

Ive heard some of the higher compression pistons pulling the stock studs out causing the head gasket to blow. That could possibly be the problem. Some companies make higher strength studs to compensate for it.

[marco1478]

Yea i have been doing a bit of research on that, how can i tell if the ones in it are stock or hd? whats the diffrence? sorry for all the dumb questions but i just want to get it together right and not have to worry about it

[bkelley]

You should be able to tell just by looking at the studs. The HD ones are about twice the size of the stock ones.

http://www.gtthunder.com/400ex_studs1.JPG

[01exrider87]

This should give you somewhat of a good idea of the difference.

http://www.gtthunder.com/400ex_studs1.JPG

[marco1478]

ok cool thanks for the info, should i use the stock nut or get some better ones?

[rocky_mtn_honda]

marco, check your pm's

[marco1478]

ok so here is the deal picked up the bike today bat. is dead so im charging the bat. tonight but the oil leak that the guy was saying is a blown head gasket looks like its coming from the spark plug area. The nut that is right in front of the spark plug is loose....I can twist it with my finger... what does that stud go to? and what is the torque of that nut??? Could that cause the leak I might be shooting in the dark but Im going to charge up the bat and see how it sounds tom. Also what size socket do you use to get the spark plug out I cant seem to get any deep socket to fit on the plug to get it out... And what kind of oil does the bike run im have not checked it but im guessing it is low hence leaking everywhere lol

thanks
Marcus

[tri5ron]

Originally posted by marco1478
ok so here is the deal picked up the bike today bat. is dead so im charging the bat. tonight but the oil leak that the guy was saying is a blown head gasket looks like its coming from the spark plug area. The nut that is right in front of the spark plug is loose....I can twist it with my finger... what does that stud go to? and what is the torque of that nut??? Could that cause the leak I might be shooting in the dark but Im going to charge up the bat and see how it sounds tom. Also what size socket do you use to get the spark plug out I cant seem to get any deep socket to fit on the plug to get it out... And what kind of oil does the bike run im have not checked it but im guessing it is low hence leaking everywhere lol

thanks
Marcus
I hope you got this quad for real cheap, because you are about to put some money into it.
Your stud is pulled out, and needs to be fixed first.

Don't waste your time or even the few dollars on an oil change right now,....
your stud is pulled out,and needs to be fixed first.

and dont even mess around starting it up, to "see how it sounds"...
your stud is pulled out,and needs to be fixed first.

forget about trying to tighten the nut back down right now...
your stud is pulled out, and needs to be fixed first.

buy a service manual, or use one of the online manuals,...
because your stud is pulled out, and needs to be fixed first.

take the head and cylinder off, and send it to GTT,...
because your stud is pulled out, and they will fix it right.

but the reason it needs to go there is because,...

Your Stud Is Pulled Out, And Needs To Be Fixed First.

[marco1478]

lol ok well the stud is pulled out i got that part, I thought that the stud threaded into the head not the bottom end. I believe you 100% but i cant seam to find a manual anywhere online to check it out at... well for free atleast lol and yes i did get the bike real cheap and even if it cost me a bit i still dont mind. I just would like to get it done and get it done right