what compresion

[jiffers]

i'm new to this 4 smoke thing but have just brought a 2002 440ex
i and read that the head gaskets have a chance of blowing so what is the normal compresion should i be looking for this engine

jiff

[TC426EX]

Do you know the compression of the piston thats already in it? It varies... If it is a 440, then its gotta be at least an 11:1 compression. If theres any way to get in contact with the original owner to get a list of mods done to the engine in detail that would help out. If you find youre blowing head gaskets, then youll need to replace the head studs with oversize ones. Its important to know what compression you got there to at least know what kind of gas you need to run. If its over 11:1 you need to run race gas....

[jiffers]

thanks for the info but what i'm looking for is roughly what p.s.i am i looking for

jiff

[Rider#11]

a stock 400ex should be around 125lbs or so...but for example my race quad is 240lbs..just checked it the other day.