Hi guys, I have a 2010 KLX250s which I bought to learn how to ride on the road, learn the rules etc and get my motorcycle license down here in Australia. Current mods include FMF Megabomb header, a straight through slip on exhaust branded "Rooster", modified airbox sans snorkel, Uni filter and some mods to the carby performed by the dealer workshop. I've got a Kustom Kraft 330cc BB kit I'm going to install in the winter months ( May - July down here ) and a KX250f carby I want to graft on as well. I'm a machinist so any adaptors etc are no problem. I was thinking of doing some port work while the head was off as well as running the bigger intake valves. Putting the feelers out about any problems I may have bumping up the comp ratio or if I'm heading down any wrong paths. Has anyone had any worries doing these mods ?Any feedback is appreciated

 

Welcome to the forums! Glad to have you aboard. I left my bike pretty much stock since I bought it in November of 05, with the exception of the 13 tooth, new exhaust, airbox lid off, and jetting. I'm really happy with my bike. You'll have to post up some build pictures when you get started. Later man!

 

The squish is pretty tight now and hi comp piston I couldn't find. Careful measuring you may be able to cut or deck a hair. Another option, if your changing the valves you might use a filled face (vs dimpled face) valves to reduce the chamber cc. I did my crf this way so I could run cheaper stock pistons. For cam timing you can run a reduced base circle stock regrind, shim spacers are available and valve springs depending on how wild you go. How far over bore will depend on how much you want to rev it and the weight of the pistons available at that bore. Trying to burn the distance across the bigger bore starts to limit things also if you don't have control of the timing.

 

Hi guys, thanks so far for your responses. Thought I would upload a couple of pics of the big girl as she sits at the moment.