440 big bore....problems

[sledneck696]

So im trying to help out a buddy here. He recently bought a 2002 400ex with the 440 big bore kit in it. Its got the stage 2 cam and edelbrock carb. Now from day 1 since he bought it it hasnt ran right. Its gutless, has a bog in the mid range, the starter has screwed up twice, and fouled some plugs. I checked his plug the other day and it must be running real rich because it was black, and that was a new plug. Now I have read these bikes when running properly should walk all over like kfx 400's and this wont touch one its that gutless. Im not sure what compression hes running but he put 94 octance in it and dumped some octane booster in there and didnt seem to help much so maybe you guys could chime in and help us narrow this down.

[speedfreek]

I think it may be his carb. I don't know much about this setup but I would put back on the stock carb and re-jet it just to see if it makes a difference.

There is not much to screw up with the big bore kit. I think it is in the carburetion.

[sledneck696]

Maybe...hopefully he got the stock carb with it, ill ask him but I know the carb thats on it now looks like one hell of a nice carb but maybe its not setup properly. The other thing he is unsure about is he read the cdi needs to be upgraded and were not sure if it has been or not.....but i dont know if it could cause all these issues too. By the look of the bike it hasnt been cheated money wise though lots of expensive parts on it

[sledneck696]

He does have the stock carb what jet size should he be running?

[speedfreek]

I would say start with a 185 main.

[sledneck696]

Alright hopefully this helps.....the only other thing is his frigin starter keep blowing for soem reason so we will prob have to keep bump starting it to figure this issue out

[jasonwayne222]

tell him to invest in a repair manual, i downloaded one offline for 20 bucks, some librarys have them u can checkout for free, in the repair manual it shows you how to troubleshoot the ignition system, if the carb isnt the problem i would troubleshoot the coil, it wont cost u anything to check it if u know how to operate an ohm meter and follow instructions, also theres always that chance that whoever timed it got it a tooth off, thats probly not the problem but if you check everything and cant figure it out i would take off the valve cover and check it, the cam lobes should be down with the marks on the cam gear lined up with the head when the fly wheel is at the T mark. and check your valve clearance, .005 on the exhaust and .004 on the intake.