416 kit on its way a couple questions on what I am buying

I have decided to order the Hot Cams stage 2 cam and an 11:1 compression piston for my 2000 400EX. I plan on doing the installation myself. I am not sure about all the decompression stuff I must remove on the stock cam and do not install when I put the new cam in could someone please explain this? My understanding is its just a small spring. I will be using stock valve springs and rockers.

Also I would like to get the 11:1 for some more top end. Has anyone found the 10:8:1 piston better? If I do get the 11:1 do I need to run a 50\50 race gas mix? I do a small amount of drag racing but I ride alot of hard, fast, tight woods riding so would the 10:8:1 be better?

My current set up is White Brothers R4 complete pipe and silencer, 158 main jet, 38 piolet, needle 2nd clip from bottom, K&N w outerswear, with lid. I plan on removing my choke plate. Anyone have any ideas on where to start with jetting? I live in Nebraksa. If anyone could please clear these few questions up before I start to rip apart my motor. I would greatly appreciate it.

[Ex'r Marlin]

Originally posted by Honda4hundredEX
Also I would like to get the 11:1 for some more top end. Has anyone found the 10:8:1 piston better? If I do get the 11:1 do I need to run a 50\50 race gas mix? I do a small amount of drag racing but I ride alot of hard, fast, tight woods riding so would the 10:8:1 be better? If you have not ordered the piston yet.... I would recommend either a 10.5 to 1 or 10.8 to 1 compression piston per your comments on how you will be riding your atv. Going to the 11 to 1 compression will most likely force you to run race gas... At least 50% pump and 50% race. I do not live in Nebraska (wish I did though), but I do similar terrain like you commented on. I went with the 10.8 to 1 and found that Sunoco 94 is working good for me... But I heard some riders on here noticed an improvement with 50/50 mix on their 10.8 to 1.

BTW, If you did not order your piston yet, and you plan on doing all the work yourself, I would highly recommend getting a stock bore piston with your compession request. But if you know how to bore a cylinder... Have fun with the 416.

Good luck!:)

I was told by many people that the 11:1 piston really wakes up the 400EX. I was also told that the 11:1 increases torque and I would like some more torque for trails. I already have the 14 tooth sprocket. I do not mine running a 50-50 mix of gas. Is the main reason for the 10:8:1 piston just because of the gas factor. Are their any other pros and cons to the 10:8:1. Thanks for your help and I can have the cylinder bored for $45 for the 416. Thanks again

[400exRacerX]

You wont even notice the difference between 11:1 and 10.8:1. I have the 10.8:1 je 416 piston and mine pinged on super unleaded, so I run 50/50.

Beleive me you will mind running race gas, even at 50% at $7+ a gallon. It adds up after awhile and quick.

[Ex'r Marlin]

Definetly going to a higher compression is going to "wake" up your atv. The negative of going to a higher compression piston is two things... It may require race gas and if you are out trail riding, and need gas.... You may be out of luck!:( It is worth it for me to keep the atv running on pump gas. The other negative, is that the higher you go, the more stress you put on your connecting rod, and other parts. I am not saying that going to a 11 to 1 is a bad idea... But like 400exRacerX stated, is it going to be a noticeable difference between a 10.8 to 1 and a 11 to 1?

Thanks 400exRacerX for your reply. :) Do you mind telling me what pump gas you use and what race gas you use for your mixture? Sorry to hear that you have a ping using just pump gas with the 10.8 to 1!:(

[Blake24]

hey Honda4hundredEx where in nebraska do you live..........i live in kearney..........maybe we can go ridin sometime........

well, i know this for a fact on 2smokes, but high comp is increasing BOTTOM end, not top, thats what power valves are for, they lean the compression out so it can still hav top end, im not sure about 4's, but thats the way it is in 2's.

[VegasEx'r]

Higher compression does increase bottom end, but you won't feel a difference between 10.8 & 11. I have 10.8 & run 50/50 fuel. Neither CR is high enough to really worry about the additional stress. I have the Hot Cam stage 2 cam & for jetting I use Dynojet's (http://www.dynojet.com/pdf/Q107.pdf) recommendations. I use a 40 pilot since I have removed the choke, & that seems to work pretty well.

being able to run pump gas is saweet but you can always switch between high octane or pump or mix them. i notice a differnenc when I run pump vs. 110 octane,,the 110 makes it pull stronger and it only cost's me $4 a gallon..woo hoooo

im ordering the 416 kit from marcums with an XR400 cam and hmf slip on. im going to run the 11:1 compression so i should be ok on high octane pump gas and octane booster if needed. its only .2 difference between 11:1 and 10.8 so im not worried. but a question to anyone who can answer it, am i going to need anything special to do the cam and piston job? i know the obvious but are there any tricks or special tools that will help? thanks for your help

[nakomis0]

Rico what compression piston do u run? 10:1?

[Tommy 17]

rico is 10.8:1


i am also 10.8:1 and run on 94 octane fuel...

[Punk13rym]

Originally posted by 400ex21
rico is 10.8:1


i am also 10.8:1 and run on 94 octane fuel...



does that 94 octane fuel work good for you?

Well, I guess I will have to run pump gas with either 10 or 11 compression. If I have more stress on parts with the 11:1 then I will go with the 10. Thanks for your help guys. Any tips or tricks as far as removing and installing the cam would also be great. Thanks for your help

[400exRacerX]

Ex'r Marlin,

I run VP C12 and Gulf super unleaded 50/50.

[Punk13rym]

this is kind of an odd question but, does anything move or fall when you take off the cam's cover? if i were to take mine off would i have to worrie about moving something back to its origional position? thanks

[400exRacerX]

All you have to do is make sure the engine is at TDC and the valves are loose, then pull the cover off.

Just remember not to lose the dowel pins and seat them in the holes and set the gasket before you reiinstall the valve cover.

[Ex'r Marlin]

Originally posted by Honda4hundredEX
Well, I guess I will have to run pump gas with either 10 or 11 compression. If I have more stress on parts with the 11:1 then I will go with the 10. Thanks for your help guysI'll let you be the judge of this one, but I strongly feel that either one will still power your atv without too much stress, going to a 12 or 13 to 1 compression ratio might definetly change my thoughts!!

Thanks 400exRacerX on the fuel mix you use on your 10.8 to 1!:)