Sometimes the dealer mechanics will fill the holes in the slides before the customer takes delivery. Another case could be the previous owner was flush with green and just replaced the OE slide with a KLX 300 item.(No holes.) You'll need to completely remove the grey crankcase breather hose to remove the restriction. It's set right in the centre of the hose. I just pushed it out with my socket extension bar.

 

You are correct.

 

Thanks.

 

I have a 2007 klx250. just put the bill blue mikuni carb and big gun on it. Take the smog stuff off it will fix your back fire. i had the same issue. I left my air box lid on though.
I have a tendancy to find the deepest "muddle puddles" around. I went this morning with a friend who has a ktm450exec. We were out on some town run trails which are all pot holed up from 4wheelers. I saw a medium sized puddle which would have been more work to go around then go through. it looked like it was only about 5-6inches deep. Then water rolled over my lap and I lost sight my front blinkers until i jumped on the throttle thinking OH SH&T....

I am curious how you will make out with the stock carb. Big Gun says go 1 larger than main.

Bill Blue sells an alluminium plug to fill the hole on the side of your head when you take the exhaust stuff out. He charges 5.00 for it.