Max bored 40mm Mikuni racks & throttles

[lancelarue]

Well, this is interesting. On a Summit, with 40mm rack carbs bored to the max, stock throttle won't open carbs all the way. I'm sure there's a ton of people know this, I sure didn't. I had only run these carbs on a 860 on the dyno,with a different throttle, not on a sled.
So, race sled throttle will work but kill switch gremlins etc. (race kill switch is junk).
Believe it or not, an old I think "Touring" 670HO or some such sled with 44mm round slide carbs works awesome!!!!!!!!! I bought this throttle like 16 years ago to put on my old horse, 99' 670HO Summit and just never got around to it. They had a nasty throttle pull and these "cruising sleds" throttle was dual action to soften up the beginning part.
Use your same kill switch / thumb warmer etc.
Probably no one interested, but there it is!!!!!!!!!!!!!!

 

[lancelarue]

max bored Mikunis

Well, this is interesting. On a Summit, with 40mm rack carbs bored to the max, stock throttle won't open carbs all the way. I'm sure there's a ton of people know this, I sure didn't. I had only run these carbs on a 860 on the dyno,with a different throttle, not on a sled.
So, race sled throttle will work but kill switch gremlins etc. (race kill switch is junk).
Believe it or not, an old I think "Touring" 670HO or some such sled with 44mm round slide carbs works awesome!!!!!!!!! I bought this throttle like 16 years ago to put on my old horse, 99' 670HO Summit and just never got around to it. They had a nasty throttle pull and these "cruising sleds" throttle was dual action to soften up the beginning part.
Use your same kill switch / thumb warmer etc.
Probably no one interested, but there it is!!!!!!!!!!!!!!

Gave up on the Mikunis. Leaking through the aluminum, inconsistent. Back to stock 40's for now.
This will be good enough for the trail / spring time sled.

 

[BBP]

How big did you bore them & where were they leaking, around the slides?

 

[lancelarue]

big mikunis

I can't find any signs they're leaking around the slides and believe me I've looked hard.
I had Larry at Crankshop bore these for me as he's done them a lot and I haven't.

 

[BBP]

I believe mine are bored to 41.7mm. It's been a couple of years but I'm pretty sure they open all the way. Stock throttle on an XP. Now I'm going to have to go doublecheck.