well i finally got my fmf powercore 4 installed
and have been running it with stock jetting kdx snorkel and smog lines removed
i just pulled my plug and it is clean as a whistle
i dont think i will re-jet
the bike is factory jetted at sea level with a 118
i live at 3500 feet and ride up to 8000 regularly even around town we vary to about 4500
well with my elevation the bike would run very rich stock but with the intake and exhast i think im about perfect
again the plug is very clean there is no detonation on decel
all in all i think its about right
the only question i have is about the adustable needle in the dyo jet kit
will it improve anything?
or am i just itching to take on another project?

 

I really don' know how you got that to fit ........after all the work I had to do.....

 

That looks like either a stock 250 header with an extension or a stock 300 header, I can't quite make it out.

 

factory 300 header

 

Did you have to do anything special to get it to fit or was it a true "slip on"?

 

its a true slip on with the exception that the fmf is about 1/4 inch short still so i had to come up with a way to seal it tight
i used tin foil and made a sleeve about two folds thick
i put the whole assembly together
then i used some of the graphite from inside my stock headpipe and cut it into strips and put the strips into the cut grooves on the 300 headpipe
and clamped it all together
clean and tight

 

Stupid question but, it looks as though the FMF is moutned with a rubber/metal strap. Couldn't you slide it ahead that little bit to close the gap?

 

not if you want the other mount to line up
there is one tig welded to the pipe under the plastic

 

It is known that the FMF has fitting issues on the KLX300.If you search on Thumpertalk you will find some seem to fit up fine and others are short like yours. it's not an issue because you have a 250S. One of my riding partners hasthe FMF and it was short on his stock header and his Four Stroke Works header.He had the FMF pipe extended at a machine shop to fit up right. You can't tell were they added on at all. It was a fabulous job. The FMF sounds real good to me by the way.

 

i really like the sound of it
nice and low but doesnt scream when its reved up
makes it a little harder to sneak around the neighborhood though