mx set up

[foxracer5464]

my question is which would be better for mx the 416 or the 426 also what compression ratio would be best

[tar]

It all depends on how much money you want to spend. It's really not about the displacement but how well the motor is built.

[foxracer5464]

well what did u have in mind tar

[AutoRoc]

The difference is very small. You're talking about 10cc's of engine volume. Compression should be chosen based on what fuel you can afford. If you want a pump gas 93 octane setup, do 11:1, as MANY people say you can run pump gas with that....If you want to run race gas, do 12.5:1 or more.

Tar realizes that reliability is more important than any extra HP or 2 from increased compression or 10 more CC's of engine. Finishing the race is better than winning the holeshot and blowing gaskets in the next turn.

[foxracer5464]

how much of a diff power wise is there between the 11:1 and 12.5:1 i think im leaning towards the 11:1 for reliability

[drew416ex]

Ive had both in a 416. There was a noticable difference in lowend torque but other than that there wasnt much difference.

[gcart2]

you do not have to bore the motor over to race it. i race b class open and am a regular compettior. I am the only 400 running eith all 450's. My motor is built but there is no bore over. I run a 11:1 hi comp piston from wiseco.

[tar]

What I would do if I had money to spend is a 416 12.1 JE piston with a stage one or two hotcam, HD cam chain and port and polish. This would be a pretty expensive build if your not doing the work yourself. And you have to remember if you run anything over an 11.1 you have to run atleast a mix of race gas which is $6.?? a gallon.

But if you want to keep the cost down do an 11.1 with a stage 1 or 2 hotcam and a HD cam chain for reliability (or crf450 cam chain)

EDIT:also a 450r carb