performance upgrade question

[SunDevil]

I am new to this site and find most post really helpful. I want to put a new piston and cam in my 400ex but do not want to resleave or bore out the cyclinder. Can this be done? I was looking at the kits from LRD performance and they seem reasonable. I was think about a JE piston at 11:1 and a hotcam stage 2. I have a powerbomb header and a e series to round out the exhaust. How much power gain will i get from the piston and the cam? Is this a good setup or do i need to go a different route? thanks for your help...Tom Duer

[airheadedduner]

Unless you are boreing way out you will not need to resleave unless you sleave has no bores left on it. LRD would be a good choice for mods. They know what they are doing and are great to deal with.

[remlapr]

Give C&D, the site sponsor a call. They can hook you up with either a stock bore kit or a .80 over (416) kit that will work great with a stage II hotcam. They have a lot of experience with these kits and will take great care of you. Also remember, that with a 11:1 you may have to run 50/50 race gas mix.

[wgbanks]

You can go with an 11:1 stock bore, but the cylinder is going to have to come off no matter what. So IMHO if I am going to the trouble of tearing into the motor there is no reason not to go to a 416. That is a simple bore process and shouldn't cost more than $50.00. If you do stay with the stock bore you are still gonna want to hone the cylinder walls. Tearing into your motor just for compression increase, again IMO, is not worth it. Go to a 416 and then later, if need be, you can still bore it one more time and go to a 425. Call Dusty @ C&D Racing she will hook you up.

[hook]

416 jepiston hotcam stg 2 port&polish head 41fcr yousi exh loving it:devil:

[airheadedduner]

Originally posted by remlapr
Also remember, that with a 11:1 you may have to run 50/50 race gas mix.
I run at sea level, at 11:1 with my 440 and have no overheating or pinging problems. Thats with 93 pump gas, in the sand:huh

[400exdad]

My 400ex had little time on it so I went with a stock bore, 10.5 to 1 piston. I also bought a used xr400 cam for it. I love it! There is a very good post if the FAQ... do a search for Mike400EX I think and you'll see where there were a ton of posts about head gaskets and base gaskets. I went with a XR400 head gasket and a thinner (cometic) base gasket to get the compression where I wanted it to be. While I was in there, I did some mild port and polish work to bring it to life too. In my opinion, if you plan to keep the quad for awhile, I wouldn't bore it until I had too.

Welcome to the site!

[Colby@C&DRacing]

I really like the 416 kits they are the most popular kit that I sell. They are one of the cheapest ways to boost the performance of the 400ex.:)