Keihin PWK 38 Airstriker on 85 KX500B1?

[VMXSteve]

I am looking at replacing my Mikuni VM40 carb with a new Keihin 38mm PWK Airstriker, as recommended by JDJetting.
Is this a straight bolt on replacement?  Or will I need airbox adaptors etc?

[don46]

I have used them in place of the stock 39 kehin never a 40 mikuni though. The 38 is shorter, which is one of the advantages, better throttle response. the 38 will require an extension on the back of the carb to the air boot, I machined one out of Aluminum