Mikuni carbs on a R65

[Hunsta]

 Recently I was on a road trip and came across an R65 with Mikuni carbs on it. I wondered how they would go. They were also attached to a set of airpods. Now I have asked a few questions of the enlightened and thought I`d run it past the R65 crowd. Ive heard that with the Mikunis you get a crisper throttle responce and not the slight lag from the diaphrams of the Bings. However the cons are that like most slide type carbs there is a tendancey to get flats spots in excelleration, especially with the larger slide carbs, if not tuned right.
 So the questions are, has anyone done this mod to there R65 or other Bing lunged BMW? If so, was there any major differance in cabling (apart from the obvious lengths). Anyone have a prefered size Mikuni and needle settings.
 Any help would be great. And for the anally faithfull, Im not trying to make an R65 go faster. Just better.
 Cheers
Craig

[tvrla]

My hopped up (850cc) LS came to me with 34mm flat slide Mikunis.

It's got independent floats that sometimes just leak. I've heard that's just how it is and nothing you can do about it.

They are very simple carbs but not sure I'd convert if it hadn't already been done. The cables were pretty easy - I just modified some old ones lying around here. The chokes are independent, but there's a kit to make them cable operated. After it died at night in traffic one time (still not totally warmed up, but chokes turned off) and wasn't able to restart it quickly, I converted to cable operated.

I don't know much about the jetting, but think the jets are fairly inexpensive.

Mine came to me poorly attached and it took a while to get the plastic air tubes to connect everything properly. I may have dug through my box of air tubes trying different ones till something worked.

Supposedly the flat slide Mikunis flow better than other carbs, so a smaller size is needed than you'd think. My 850 pulls really strong, but having never ridden it with Bings I have no comparison.

My previous 650 was stock and it accelerated just fine, so my advice would be to get yours sorted before changing carbs. It can be a tedious process setting up new carbs properly.

[Altritter]

Happy coincidence! I punched onto this forum this evening to ask a question about Mikuni carbs on an R65.

About a year ago (Feb. 2010 sticks in my mind) there was an article in the BMWMOA Owners' News about Mikuni carbs on airheads. Like a dumba$$, I didn't clip and save it, and had forgotten about it until my airhead-owning friend mentioned it.

What I've learned this weekend is that (1) the Mikuni rep in USA is Rocky Mount Cycle in New York' (2) RMC's web site offers kits for a lot of airheads, but does not mention R65; and (3) the RMC kits might not permit full use of a single choke control on the left handlebar, as the later R65 Bings do.

If I have a spare moment this week, I hope to calll RMC and ask if their kits include R65. For my part, though I'd like to install a less finicky, more stable twin-carb configuration than the Bings, I lack the time, skill, or inclination to attempt to design and install such a modification myself. Anyone out there ever done it?

[Justin B.]

I was looking into this when I was bringing the "Junkyard Dawg" back to life as the PO had disassembled the carbs and all I got was the carb bodies when I took delivery.  Luckily he was able to find the baggie full of bits so I didn't need to.  From what I remember this has been done before and is not that difficult.