Mikuni manifold question

Friend of mine recently bought an '06 Fatboy with several engine mods including 95" conversion, SE heads & a 45mm Mikuni carb. It had an intake manifold leak 'cause the carb didn't fit to the manifold right & the dealer ground down the fins on the engine so it would. They told him Mikuni said to do that - I ain't buyin' it. Surely there's a longer intake manifold for that application, so the carb's not right up against the engine & I figured some of the BT guys would know.

This time Art the Dealer was telling the truth, check the installation guide

Mikuni American Corporation

2.Carburetor hits cylinder fins on Twin Cam

About half of Mikuni/Twin Cam installations have an interference between the cylinder fins and the float bowl of the HSR carburetor. A small portion of the cylinder fin material must be removed from both front and rear cylinders to clear the float bowl. Failure to make this modification can result in alignment and wear problems.

A small file can be used to flatten the corner of the fins enough to clear the carburetor's float bowl. The modification is not visible with the carburetor mounted.

Thanks Lucifier! That "solution" really surprises me - can we say "vapor lock", boys & girls? On a nice hot day, it ain't real smart to have the float bowl nearly touching the cylinders! The other thing is my friend mentioned there were 2 manifold part numbers listed in the paperwork he got with the bike, so I figured there was another manifold for the Twin Cam that would move the carb out a little bit - it's not an issue on Sportsters or Buells. I think we'll make him a spacer.

It's not an issue on my Evo either, a fix I was thinking of would be to use a S&S type manifold with a flange carb mount and attach a spigot adapter like Ive seen in either the V-Twin or MidWest catalog and that would move the carb out enough to give it proper clearance.

Good idea, Lucifer, thanks.

Art do you think that your friends build really needs a 45mm Mik?? Wouldn't a stock CV40 be able to feed enough air for a 95" even with SE heads, and do it at a higher velocity giving better cylinder fill than a 45mm at the RPM range he'll probably spend most of the time?? or at the most a 42mm MIkuni. Just want to pick your brain a bit

No, he doesn't need the 45, a 42 would be better & he doesn't need the cams the engine has either, but all the modifications the previous owner had done - the dealer even told the guy he was going with too much cam. But he got a good deal on the bike & having spent all his "mad money" on it, he's going to leave the big things alone for now.

Grinding the fins evidently did get the carb to fit so the intake manifold leak is gone & the next thing is pipes, as the bike came with 2 sets of drag pipes - 1.75" & 2". He took the 2" pipes off & slipped some baffles in the 1.75" pipes for now, but he'll get a better setup - he's leaning towards a 2-1 SuperTrapp. That's not what I would put on a Sportster, but the way his bike is set up, that would be good choice as the powerband of the engine & the pipe is in the same range & he likes the idea of a longer pipe so the sound exits behind him - he doesn't like loud drag pipes (neither do I). So it'll be one step @ a time, just making changes as he can afford to & I think getting the carb off the cylinders is important.