how much to shave 300ex head?

[Jake250ex]

I was wondering if anyone has tried to mill the surface of their 300ex head to gain some compression. I am wanting to get a .80 over wiseco "11:1" piston, but I hear they arent a true 11:1 and test like low 9:1's. Im looking for about 12:1-12.5:1. I know I will have to run race gas, but do you think the bottom end will hold up ok?

[Cody_300ex]

.020 with a 11:1 compression wiesco piston with give you little valve to piston clearance. I cant remember what mine was exactly but it wasnt much. I know I have quite a bit of compression cause my starter that was replaced when I bought the quad in 01' is about shot.

[Jake250ex]

so I should go .20? Does the stock batter and starter work ok with that?

One more question, I am building a XC sport class motor, what would be a good drop in cam where i wouldnt have to change all the rockers and springs?

[Cody_300ex]

Originally posted by Jake250ex
so I should go .20? Does the stock batter and starter work ok with that?

One more question, I am building a XC sport class motor, what would be a good drop in cam where i wouldnt have to change all the rockers and springs?

I would say, It should last its just the combination of high comp. and me being hard on starters. My battery hasnt have bme any problems, charge wise. Any time you but a cam in a 300ex you going to want a higher rev CDI and h/d rockers and valve springs. The CDI cause the engine is going to want to rev faster, higher and pull the powerband up some. The h/d springs are beacause w/o them you are going to float the valve when you do get in the higher RPMS cause the stock ones can't handle the lift and duration.

[Jake250ex]

I know someone has to make a drop in cam for the 300 though, if you add it all up you end up spenging $300 (and thats being optimistic) just to change cams. The cam ends up being the cheapest part of it all too. I have no prob with the cdi.

[Cody_300ex]

Yes they make drop in cams for them but that dosent mean its going to work right. I had a stage 1 web cam which is supposed to be drop in for about 2 weeks before I got tired of floatin the valves every time I got on it hard. Left two nice marks on my piston two due to my low piston to valve clearance. I soon sold for a stage 3 cam and h/d valve springs.

[Jake250ex]

I might go with curtis sparks then

[300WheelyKing]

web cams makes' a cam for 300's?
Is the powerroll any good?

[ZeroLogic]

i dont think web cam makes cams for the 300ex

powroll is good i havnt seen anything worng with them but yet i dont know anything from them:p

[Cody_300ex]

Originally posted by ZeroLogic
i dont think web cam makes cams for the 300ex

powroll is good i havnt seen anything worng with them but yet i dont know anything from them:p

Lol web makes 4 different cams, hardened rocks and valves for a 300ex/250ex.

[bwamos]

Originally posted by Jake250ex
I was wondering if anyone has tried to mill the surface of their 300ex head to gain some compression. I am wanting to get a .80 over wiseco "11:1" piston, but I hear they arent a true 11:1 and test like low 9:1's. Im looking for about 12:1-12.5:1. I know I will have to run race gas, but do you think the bottom end will hold up ok?

I think you're thinking of the 400ex with the thicker head gasket and base gaskets in comparison to the dirtbike.

I have a 330 11:1 and the piston as is had to be clearanced for the valves. If you shave the head you're gonna want to really check for valve clearances.