[Diedav]

looking to replace origanal tillotson carbs with mikuni I don't have the tillotsons so looking for correct size to replace with Any info would be great

[mach9]

Hello, welcome.

This may help.
By 1977 skidoo 440 f/a model switched to:
mikuni VM-36-53,
main jet 320,
needle 159 p-2,
pilot jet 40,
needle ID# 6FL14-5

Cheers
_________________
Mark (mach9)
Shiny side up! Rubber side down!
To visit the store...
www.doodecals.com

[_FIII]

may be hard as the 77's had a single carb and the 74-75 TNT free airs ran dual Tilly's so that spec may not work

[mach9]

Ah yes duh..
36mm might too big anyway. (maybe)
But dual Mikuni 36s do go on sleds like the 79 blizzard 9500. 454cc
While the 76, RV-340 models use dual Mikuni VM-34s but the main jet size and needle settings will be off.
Then take into account the intake boots that need to line up to the jugs etc.
I've never attempted this setup but I'm sure someone has done it.
_________________
Mark (mach9)
Shiny side up! Rubber side down!
To visit the store...
www.doodecals.com

[_FIII]

I would go with at least 34's. I would think that if you got 34's that were from a 503 fan off a 5500 blizz they would be real close. If you do any porting or bump up the compression it would handle 36's for sure and maybe even 38's. My 77 RV cross country is a 340 with dual 38's on it but is a super stock motor. The little 292 single racer I built for my son has a 38 on it and it could go to a 40 but it is a mod drag motor in his roll o flex. Basically measure the bore on the old tilly and then that is the size carb that should work for you. You can make any carb work but just remember that the smaller the orfice is the faster the air will travel thus providing better throttle response, but conversely will not flow as much volume which will result in less top end. Depends if it is for drag racing or ovals