..yes u need to be very careful when doing this,need to put a few rags in there to catch any metal shaveings. Soak them in water or something...."whatwasthat" let me explaing again why youd want to do this. Iv had this probelm with my ex and Mickey Dunlap even talks about it somewere...If you sleeve fits to tight in the lower cases it puts pressure on the sleeve,and when things heat up it puts even more pressure on it,makeing the sleeve no longer round,thus binding up the piston and cracking it...Hope this helps

 

When resleeving a cylinder with a bigger bore, yes the outside diameter is bigger, however, most reputable companies who produce sleeves will have the outside portion of the sleeve that fits into the cases slightly smaller than that which fits in the cylinder. This is what i have found with my 440ex, perhaps you had gone with a bigger bore where as the material of the sleeve was to thin to fit without machining the cases.

 

..no my sleeve didnt need machining the cases done. I got everything from Thumper raceing with a lightned piston. I think everything was a Wisco set up?

 

you need a gap between the sleeve and case. otherwise you won't have a good quench area. also, when the metal expands from the heat, you could be putting added stress on your piston. i hear some of the sleeves are fine without boring the case though.

 

..here now this can be put to rest..."Mickey Dunlap ....One other thing to watch with the 440 sleeves is about 80% of the 400EX I have worked on the cylinder sleeve touches the cases where it goes down into the cases right in the back between the 2 case halves. A way to check for this, is to remove your dowl pins from the cases, set your cylinder down into the hole and try to move it front to back. It should have about .020 clearance front to back. If it doesn't, you will need to grind the cases to give it clearance. Otherwise, the cases will push into the cylinder sleeve and cause a hot spot at bottom dead center with your piston which will lead to your cylinder cracking or your piston scuffing - or both. A good way to keep the metal shavings out of your bottom end if you have to grind it is to stuff paper towels down around your rod and crank and then fill about 1" layer of spray foam insulation (Neat Stuff) on top of the paper towels. When you are done grinding, you can vaccum all the metal out, pull the insulation out and then the paper towels. I hope this helps you with your next big bore kit."............hmmm 80%...more common then ppl thought.. heres the link http://www.exriders.com/vbb/showthre...threadid=83162