Hot Cams Decompressor

[KAWSAM62]

IVE SEEN LOTS OF HOT CAMS BEING RUN IN VARIOUS 400EX ON HERE ANYONE HAD A PROBLEM WITH THE CAM NOT HAVING THE DECOMPRESSOR ON MEANING I DONT THINK THOSE CAMS USE THAT PART ON THE ENGINE ANYMORE LIKE THE FACTORY CAM DOES AND DOES NOT HAVING IT (DECOMPRESSOR) DOES THAT AFFECT ANYTHING TX IN ADVANCE.:confused:

[Scott400EX]

My 400 starts easier without the decompressor on the cam!!!

[KAWSAM62]

SO HOT CAMS DO NOT USE THE DECOMPRESSOR RIGHT?:confused:

[YZROOSTINYA]

no decomp on hotcam 1 or 2

not needed since the intake valves are partially open during the compression stroke, no probs yet 25 hours

[01_400exrider]

No problems, i love mine!!! Nope dont need the decomp, that baby will fire right up, easier than b4.

[hotex]

is partially correct. It's actually since the valves are open LONGER (from more duration) than the stock cam is the reason for it spinning over easier than the stocker. He is absolutely correct about it when he says "not needed" though! It dumps enough compression during cranking speeds to lower the compression to sub-decompressor levels because of the timing of the decompressor. The best part is....... they work!

Tony

[KAWSAM62]

SO YOU TAKE THE FACT CAM OUT PUT THE HOT CAM IN ROTATE THE VALVE TRAIN LIKE THE MANUAL SAYS ON THE T MARK AND SET THE VALVES AND YOUR DONE, ANYONE DONE THIS ON A FACT BORE STAND COMP, WHAT GAINS CAN BE EXPECTED?

[YZROOSTINYA]

is that tony from hotcam?


i didn't want to say that because i figured he wouldn't understand

you will not see as much of a gain with a stock bore/comp ratio

the reason why people high comp with wild cams is for the reason above, you gain some of what is lost

[YZROOSTINYA]

drop the caps man

[KAWSAM62]

HOTELX IS THE DUMPING AFFECT YOU MENTIONED WHY MOST PEOPLE ARE USING THESE CAMS WITH A 416 HIGH COMP AS A EXAMPLE TYPE SETUP MEANING BECAUSE YOU LOSE COMP BECAUSE OF THE VALVES BEING OPEN YOU MUST NOW ADD COMP BY THE PISTON BORE ECT CORRECT?

[KAWSAM62]

sorry camps dumped:rolleyes:

is that tony from hotcam?
You mean the only thing at Hotcams/pivot works thats worth a crap :)

Like we discussed b4 Tony you are a good guy that doesnt work for the most respectable place.

[Texan32]

KAW.

Your ezactly right.

[KAWSAM62]

so the fact decompresor bleeds off comp so the engine doesnt have trouble starting right, if thats correct i didnt know that tx all:cool:

[YZROOSTINYA]

the stock decompresser partially opens the right(sitting on bike) exhaust valve when the motor is cranking over

yes that is why people do high comp pistons in conjunction with the cam

[KAWSAM62]

tx:cool:

[hotex]

For some reason this board is very weird on the sign in. Sometimes I get under Hot Cams, other times I get in under hotex, most times I can't even use the board. Kind of frustrating.

All of the higher than stock performance cams rely on duration to make the things run better on top. The down side is that the more duration you have, the more overlap you have and less wide your powerband becomes, with an emphasis on the top end. That makes it easy to have the engine crank over easy though. We don't use a decompressor on the DR-Z because of this reason. Just like the 400EX, enough intake duration to bleed off some of the compression at cranking speeds.

Tony

[bmw500hp]

Tony from Hotcams.....

If you could suggest a book to bring a quad rider around to a real good understanding of compression/cam theory... what would it be....I would like to learn more about timing/duraion in regards to power curve and performance trade off....

thanks.. and thanks for your visit....

[KAWSAM62]

is the xr 400 cam everyone is buying have the decompressor already on it or do you need to remove it from the 400ex cam thats in the motor.tx :)

[frogburner]

OKAY,,, Well what is the stock Compression of the 400??? I thought it was 8-1.. Now if I have a Stage 1 HOTCAM,, and drop in an 11-1 compression piston with stock bore,, that should wake her up a little shouldnt it??

[Steve-o 400EX]

I think stock the 400 is like 9.5:1 but i'm not 100% sure, but an 11:1 piston and cam will definately wake her up!:devil

[YZROOSTINYA]

9.1:1

xr is 9.5:1 i beleive do to the thinner head gasket

the xr cam COMES with the factory decompressor