KLX 250 S w/ 300 kit

Hello again, after your great recommendations on jetting my last bike I am back for more.

I recently added a big bore kit to an 06 KLX 250, there is also an aftermarket header and exhaust, a Dynojet kit and the usual free mods.

Before the Big Bore I was running a 128 mj, 3rd pos Dynojet needle and all was pretty well. Now though there is a bit of surging in 4-5 gear at 80% power and the bike pops when I chop the throttle comming to a stop. It does not pop if I keep 1/8-1/4 throttle on deceleration though.

I cannot tell if I am missing anything at the top end as there is way more of everything everywhere with the 300 kit.

As usual, any advice is greatly appreciated.

Cheers :thumbsup:

Anyone ?............

go to the 4th clip.

does the bike idle well?

Before the 300 kit was installed the did start better, now I have to choke everytime when cold. The bike does however idle fine unless I let it sit 2-3 minutes after start-up.

I will try 4th pos as you have recommended.

what happens after you let it sit after start up?

It just stalls after 2-3 minutes after cold start up.But does idle steady until then


128 on 3rd w/ 2.5 turns out.

Needs choke w/ every cold start (local temp 75 degrees/ sea level)

Surges at 80% throttle in 4th and 5th gear

Backfires (alot) on deceleration

Thanks again.

my bigbore did the same had to drop the main two sizes, cleaned righte up.

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