416 vs 426

I am going to be building my brothers 400ex motor in a couple weeks. I am eyeing the 416, or the 426. I do not want to have to sleeve the cylinder, and besides mx, we ride glamis and I'm afraid the 440 would get too hot on long rides.

I already have a hotcam(stage 1) in mind, and maybe some mild porting. What would be best reliability wise, a 416 or a 426? Also Will the cylinder need to be nikasil plated, and what mm will the cylinder need to be bored to for each engine size? I also saw some kits were for 11:1 sompression, and some 12-5:1. Which is better?I don't want to have to run just race gas.

I know it is a lot of questions, but I am new to the 400ex and I want to do this right. Thanks in advance for your help.

i'd do a 416 bc it will run cooler and if anything would happen to go wrong u can always bore it out to a 426... i built a 406 so i still have a 416 and 426 on this sleeve...

if u want to run on pump gas (93 octane) go with 10.8 or 11 :1


and u may want to stay away from hotcams... to many horror stories that i've read... they say they are fixed but i would never trust one... i'd go with a TC or HRC cam...

If I had it to do over again I would put the HRC cam in mine. It is a Honda part after all so you keep the Honda reliability. Rico has one he seems to like it.

With the new 4 stroke semi synthetic oils out there you can run a 426 no problems.The stage one cam and porting/valve job with the pipe and jetting create nice power increase and a sweet sound.

Go with a 416 so you can bore the cylinder again.

anything over 10.8:1 will require race gas so forget about the 2 compressions you mentioned.

Stage 1 will suck in the dunes I would think, go with a stage 2 or the HRC Cam. The HRC costs more than 2 hotcams but it's a reliable honda part.

Don't worry about the size of the bore, you'll get some paperwork with the piston you buy that will tell the machinist what to bore the cylinder too.

ya listen to him,dune riding is not my thing.