big bore

[koschak]

I just installed an 11:1 wiseco 440 kit in my 1999 400ex. also a stage 2 hotcam was added at the same time. when riding, if in too high a gear or not on it hard it gets really boggy. This is all that has been done to the motor and stock jets are still being used. I am running 98 octane in it. any suggestions would be helpful. I am assuming i need a better intake and exhaust.

[2muchquad]

you'll definately need an exhaust to take advantage of the improved breathingabilities of the bigger bore.you'll need to rejet as well for sure.your fuel requirements have changed as well.ask around on here for the 400ex specialists;)

[eganracing]

I did the same thing and i found the doug eichner 38mm carb really woke up my engine.

[prepracing]

it could just be your clutch slipping that makes it feel like its bogging, usually that large of a bore on the motor requires some clutch adjustment. Mine did, just a thought though

[koschak]

but doesn't the doug eichner carb require 110 octane? what kind of clutch adjusting do you mean? Also what would i jet my stock carb up to in the mean time...i think it is running a little lean now because its a cold starter and doesn't like to idle at first but once it is warmed up it idles really high.

[K_Fulk]

Changing the carb dosent change your octane requirement.

[Colby@C&DRacing]

Stock jetting will not provide enough fuel for a big bore kit. You need to rejet. If you are still running stock exhaust though jetting will not really help, the stock exhaust is to restrictive for a high comp piston and cam.

[koschak]

i read somewhere the edelbrock 440 doug eichner series carb requires 110 octane....?

[eganracing]

thats wrong! mine ran fine with 91.

[K_Fulk]

Originally posted by koschak
i read somewhere the edelbrock 440 doug eichner series carb requires 110 octane....?

Just beacuse you read something dosen't mean its true. ;)