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need help on 400ex

3389 Views 10 Replies 6 Participants Last post by  killer454
hello everybody im new to the 400ex and picked one up last week to fix up.

it has a bad piston and cylinder in it i have taken it apart and the piston did not messup that bad at all.the piston skirt just melted to the cylinder a little bit.its like melted alluminum on the cylinder wall.cant find no real bad scratches even in the cylinder,checked the rod and no up and down play at all.

i mainly do trail rideing and some hill climbing when rideing.

here is my question-im going to order a 440 kit for this 2000 400ex and need to know some info on it. has an aftermarket sylincer on it but they took the baffle out for some reason!!should i replace this and can i run just a stock sylincer with the 440 kit for a while till i get the money for a good one?

2.what jets should i put in the carb?the compression ratio is going to be 11.5 to 1 acording to the 440 piston kit on ebay. their anything else i will have to change to run this kit? this 400 has all stock cam and everything else.the timeing chain was tight to no play)

im going to buy a filter box and cover for it to off ebay,because i do get stuck in mudholes once in awhile.

thanks for the help everybody i have tryed a search on here but cant find the info im looking for on the 440 kit.i tryed bigbore kit,big bore,cylinder,440 cant find nothing.SORRY IF THIS QUESTION HAS BEEN ANSWERED 100 TIMES.

thanks for the help everybody:icon_ goofy:
1 - 1 of 11 Posts
With the money you will have to put into the ex to do it right. It will be cheaper just to fix it, sell it and get a 450r imho. Then you will have the power you want and it wont be broken all the time.
1 - 1 of 11 Posts
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