where is the part number on the head? and if i take the top head cover off to look for it, do i have to put all new gaskets/seals in??

i just bought a 03 prox 440, and the guy claims it has a trail head, but i dont think it does, so i wanna confirm ths before i put any more gas in it.

dont pull the head cover off just yet..just do a compresion test.....now if the compresion is ###(i dont know what low or high comp should be), that should tell you if its low or high comp heads, but if you decide to take off the head cover, the part number is next to the water pump
mine low comp says
3021299
02
QX

and if you take off the head you should replace the gaskets to help retain compresion

Koz

how do i do a comp. test? and i dont no what the compression is supposed to be

There is a tool used to test comperssion.. check with a local car shop or anyplace that rebuilds/works on motors....In my case the local high school...HA
I think the high comp heads are in the 160s but thats an estimate...but i know they are in the mid 100s sorry i dont know the numbers but if you P.M Akiqpilot im sure he will know
Koz

i believe i got about 125-130 with my low comp heads on my 440, and with the high comp i believe it should be in the 155-160 range and thats if the rings and pistons and gaskets are all good and holding pressure.

just checked it 125 one cylinder, 126 on the other

this is doing a compression test while engine is cold

u more than likely have the low comp heads then, i did mine when it was cold and warm and i didnt have any difference in compression

When you check the compression, it is imperative that you hold the throttle WIDE OPEN. Otherwise, you will not be providing alot of air to compress. On my '03, compression with the race head is at 185 PSI, and with the trail head, it is right around 150. It is that way on both my '02 and '03.

ya i held it w.o.t, so should i rebuild the top end in summer? do i have to do pistons or just rings?

It all depends on how the cylinders and pistons look. I would replace the pistons as well, depending on how many hours are on the engine. Rings should take care of it, but you don't want to crack a piston down the road when you could have prevented a catastrophic failure beforehand.