400ex engine mod help

[DaSandMan]

Have a 2000 Honda TRX400EX with a wight Bros pipe and tuned and rejeted stock carb. Looking for a High comp. piston and cam set. Mt step father sugests a JE 415cc 87MM 10.8:1 piston and Hot Cams stage 1 cam kit. If you have any sugestions on better parts please reply. I looking only to spend about $500.00 on parts, valve tune and boring. Doing rest on own w/ help. If you have any sugestions on parts and places i can get boring and valve tune up Please post. I live 45 min. North of grand rapids Michagan. Thank you agin.

[416exfreak]

hey man if u want the power, u can get a complete 440cc kit from wiseco, with a new high comp pistin(i think its a 13.5-1 or 15-1) somthin like that, and all the gaskets and other s**t u'll need like the wrist pin and other bearings, its wat im doin to my 400 and i have that same cam, but im goin to stage 2.

[F-16Guy]

Listen to your step dad. My only suggestions would be to think about maybe going with the new stage 2 cam (it's in between the old stage 1 & 2). I like my stage 1, but sometimes I wish I had a little more top end. I would also think about going with an 86mm (406cc) piston. You want to keep as much meat on the sleeve as possible, and I highly doubt you'll miss those 10cc's. The good part about this engine, especially with a high compression piston, is that it has a huge amount of torque, so you don't have to worry about losing too much with a longer duration cam. Stay away from those 440 "kits", you're not going to get the kind of results you think you are. My advice would be to buy an OEM XR400 top end gasket set from Service Honda, and a piston and cam from whoever has them for the cheapest. Piston brand is mostly preference, but I'd probably go with J.E. or Ross.

[icy1155]

Just remember that with the higher compression pistons you are going to need to use an octane booster every time u fill up on gas. The higest you can go with pump gas is 11:1 ratio... wich is the super (93 octane)

[F-16Guy]

Originally posted by icy1155
Just remember that with the higher compression pistons you are going to need to use an octane booster every time u fill up on gas. The higest you can go with pump gas is 11:1 ratio... wich is the super (93 octane)
True, if you're going over 11:1, but if you get the J.E. 10.8:1, you should be fine. If you have any doubts, use the thicker 400ex head gasket instead of the XR400; I personally would run the XR.