Need help with wr 400 engine

My buddy recently blew up his 01 wr426 and didn't have the funds to rebuild it so he bought a wr 400 motor off ebay. Were having some trouble figure out what the brass pipe outlet is for that is on the cylinder head in between the head and the carb. I know somebody out there has one and will be able to save the day.

I think he means the hot start fresh air inlet (first picture,from the hot start knob horizontally to the left following the black tube)

this thing is found only on 98 nad 99 models, since 00 has hot start already incorporated on the carb

how much did he pay for the 400 engine?

Its in the first pic the tube that goes from the head to the hot start. is there any way to bypass that and use the carb off his 01?. Not sure what exactly caused his old engine to blow but all 5 valves broke and nicely mashed themselves around in the cylinder and did some pretty good damage to the head. He paid 800 us for the engine off ebay which supposedly has been rebuilt with only 10 hours on it. Came complete with wiring and carb but he said it wasn't the carb that was originally on it so......

Bonus for me tho because he's doing a wr to yz conversion and he needed a seat so i traded him my seat for his stator,flywheel,headlight and all the electrical stuff, his tank and seat i think i got a good deal. but anyways if anyone knows off a way to bypass that or if he has to get the origanal carb and airbox??it would be greatly appreciated.

In my opinion, If he wants to use 426 carb, it should be enough to just block the hole in the cylinder, but block it good, solid and permanent

I d use some tight fit rubber plug and then put a hose over it, that is closed at the end - like the one, used to remove excess water from the airbox

and than there would be no need for outer hot start system, since 426 has it on the carb body

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