Installing Mikuni carbs

mrbindc · 12-07-2012, 11:50 AM

I took the leap and ordered up the Mikuni carb kit from Rocky Point Cycle. The old Bings were in need of a rebuild, which I am planning to do, but I thought I'd try out the RPC kit for a comparison. The difference in the colour of the floats in the Bings was interesting.

The Mikuni carbs are very slick, I like how the RCP kit uses two different models so you can set them up with the idle screws on the outside. RCP recommends soaking the rubber connectors in hot water to make the installation easier. After a soak they went on without any drama.

I think I may just JB weld them to the rubber connectors instead of using the clamps...

oldroadie · 12-07-2012, 12:02 PM

Do yourself a favor and pull the choke(enrichner) valves out and give them a shot of silicon lube. Keeps them from hanging up and giving you false plug readings. Took me a while to figure that one out...

photorider · 12-07-2012, 01:46 PM

Well? How do you like 'em?

hardwaregrrl · 12-07-2012, 02:38 PM

Another Mikuni convert!!!!

disston · 12-07-2012, 03:17 PM

Those look like nice carburetors.

mendoje · 12-07-2012, 04:39 PM

Subscribed! I've been thinking about doing this too.

What bike is this on? (Edit: I checked your profile, an R65?) Do they come jetted for your bike? How's it run?

Beater · 12-07-2012, 04:40 PM

I love my Mikunis. I will be putting them on my GS when the cash presents itself. Dead simple, reliable, no diaphram, and the parts are widely available. Better throttle response ... about the same milage. Me likes.

mrbindc · 12-10-2012, 06:23 AM

Sorry for the delay, work was taking up too much time so I couldn't tinker last week... Nice to have a job but when it gets in the way of tinker time, frustrating...

Anyway, back to the fun. The Mikuni carbs are on a 1982 R65, my Frankenbeemer with the K75 front end.

The bike fired right up, I still need to dial them in a bit and adjust the cables but the installation was pretty straight forward. Now all I need is Charlie to stop by sometime and show me how to tune them by ear.

I ended up using a couple of my OEM hose clamps. The clamps provided in the kit are decent but a couple of them seemed to be defective. The flat blade screwdriver slot on the head wasn't stamped through enough to get a good bite, I could have made them work with some effort but I said eff it and used my OEM clamps.

btw, I was kidding about the JB weld...

PS, the rear secton of the front fender is off the bike for painting.

oldroadie · 12-10-2012, 07:23 AM

You'll find the air mix screw hard to get to on the left carb. I've been using a bit from a screwdriver set for that (you can count the flats as you turn between your finger tips).

hardwaregrrl · 12-10-2012, 09:14 AM

So sync them with a drill bit. Here's how....warm the bike up. I ride for about 15 mins. Then pop the carb elbows off. Grab a bunch of small drill bits. Insert the no business end in the back of the carb until it barely slides under the slide at a 90degree angle, I think i use a 3/16" so have several sizes at the ready. Then take the right size bit to the other side and using the throttle adjust screw, adjust the other side to be the same. It works much better that adjusting on the fly. Then if you need to bump the idle up or down, just make sure to turn the screws the same.

On the air screw i find it easier to take the carb off to adjust.

dvblue_2000 · 12-10-2012, 10:06 AM

Quote:

Originally Posted by oldroadie

Do yourself a favor and pull the choke(enrichner) valves out and give them a shot of silicon lube. Keeps them from hanging up and giving you false plug readings. Took me a while to figure that one out...

I had that problem. I had fits tuning this thing and getting it to idle before I figured out. I push the little plungers down with my finger each time I use the chokes.

Kai Ju · 12-10-2012, 12:39 PM

Silver solder or braze a one inch extension to the airscrew and cut a screwdriver slot in the end so you have a reference on the number of turns.Then slip a piece of vacuum tube over the extension. Now you can adjust it by reaching up from under the float bowl, no need to remove the carb.
I'm also using the stock clamshell airbox and adapted the stock choke actuating mechanism to the Mikunis, beats having to turn the chokes off individually.

mrbindc · 12-11-2012, 07:24 AM

RPC sells a choke adapter kit for the Mikunis. I haven't bought it but I'm wondering how did you make your stock cables work for the choke?

Rapid Dog · 12-11-2012, 10:28 AM

what size Miks did you buy?

Kai Ju · 12-11-2012, 10:30 AM

I didn't use the stock cables. I made my own out of a couple of throttle cables I already had.
Since the Mikuni choke plunger is spring loaded I didn't need the single wire cable to push the mechanism closed like the Bings do.

12-07-2012, 11:50 AM	#1
mrbindc ^OP Adventurer Joined: Apr 2012 Location: Alexandria, VA Oddometer: 74	Installing Mikuni carbs I took the leap and ordered up the Mikuni carb kit from Rocky Point Cycle. The old Bings were in need of a rebuild, which I am planning to do, but I thought I'd try out the RPC kit for a comparison. The difference in the colour of the floats in the Bings was interesting. The Mikuni carbs are very slick, I like how the RCP kit uses two different models so you can set them up with the idle screws on the outside. RCP recommends soaking the rubber connectors in hot water to make the installation easier. After a soak they went on without any drama. I think I may just JB weld them to the rubber connectors instead of using the clamps...

12-07-2012, 02:38 PM	#4
hardwaregrrl Shit for brains Joined: Jan 2006 Location: Atlanta Oddometer: 5,014	Another Mikuni convert!!!! __________________ Trans Lab RR-broke down in Ontario-2 stroke fun for 200 bucks- TCAT R100 GS racks For Sale My life aboard an R80ST

12-07-2012, 03:17 PM	#5
disston ShadeTreeExpert Joined: Mar 2011 Location: Silver Spring, Md Oddometer: 5,229	Those look like nice carburetors. __________________ Never memorize something you can look up. ---Albert Einstein

12-07-2012, 04:39 PM	#6
mendoje Gnarly Adventurer Joined: Jun 2009 Location: Los Angeles Oddometer: 137	Subscribed! I've been thinking about doing this too. What bike is this on? (Edit: I checked your profile, an R65?) Do they come jetted for your bike? How's it run? __________________ 2004 BMW R1100S / 2003 Ducati M800Sie / 1986 R80 G/S / 1981 BMW R100RS (Sold ) / 1977 Kawasaki KE100 (1st Bike )

12-07-2012, 04:40 PM	#7
Beater Scope Creep's Victim Joined: Sep 2009 Location: Decatur, GA, USA Oddometer: 2,291	I love my Mikunis. I will be putting them on my GS when the cash presents itself. Dead simple, reliable, no diaphram, and the parts are widely available. Better throttle response ... about the same milage. Me likes. __________________ Fred '85 R80RT G/Sified '91 R100GS Bumblebee Airhead Zen: Ride-Maintain-Repair-Ride On.

12-07-2012, 12:02 PM	#2
oldroadie /5 dirt road wannabe Joined: Feb 2010 Location: North Alabama mountains Oddometer: 349	Do yourself a favor and pull the choke(enrichner) valves out and give them a shot of silicon lube. Keeps them from hanging up and giving you false plug readings. Took me a while to figure that one out...

12-07-2012, 01:46 PM	#3
photorider Gnarly Adventurer Joined: Nov 2008 Location: Chicago and Guatemala Oddometer: 128	Well? How do you like 'em?

12-10-2012, 06:23 AM	#8
mrbindc ^OP Adventurer Joined: Apr 2012 Location: Alexandria, VA Oddometer: 74	Sorry for the delay, work was taking up too much time so I couldn't tinker last week... Nice to have a job but when it gets in the way of tinker time, frustrating... Anyway, back to the fun. The Mikuni carbs are on a 1982 R65, my Frankenbeemer with the K75 front end. The bike fired right up, I still need to dial them in a bit and adjust the cables but the installation was pretty straight forward. Now all I need is Charlie to stop by sometime and show me how to tune them by ear. I ended up using a couple of my OEM hose clamps. The clamps provided in the kit are decent but a couple of them seemed to be defective. The flat blade screwdriver slot on the head wasn't stamped through enough to get a good bite, I could have made them work with some effort but I said eff it and used my OEM clamps. btw, I was kidding about the JB weld... PS, the rear secton of the front fender is off the bike for painting.

12-10-2012, 07:23 AM	#9
oldroadie /5 dirt road wannabe Joined: Feb 2010 Location: North Alabama mountains Oddometer: 349	You'll find the air mix screw hard to get to on the left carb. I've been using a bit from a screwdriver set for that (you can count the flats as you turn between your finger tips).

12-10-2012, 09:14 AM	#10
hardwaregrrl Shit for brains Joined: Jan 2006 Location: Atlanta Oddometer: 5,014	So sync them with a drill bit. Here's how....warm the bike up. I ride for about 15 mins. Then pop the carb elbows off. Grab a bunch of small drill bits. Insert the no business end in the back of the carb until it barely slides under the slide at a 90degree angle, I think i use a 3/16" so have several sizes at the ready. Then take the right size bit to the other side and using the throttle adjust screw, adjust the other side to be the same. It works much better that adjusting on the fly. Then if you need to bump the idle up or down, just make sure to turn the screws the same. On the air screw i find it easier to take the carb off to adjust. __________________ Trans Lab RR-broke down in Ontario-2 stroke fun for 200 bucks- TCAT R100 GS racks For Sale My life aboard an R80ST hardwaregrrl screwed with this post 12-10-2012 at 12:43 PM

12-10-2012, 12:39 PM	#12
Kai Ju Beastly Adventurer Joined: Jul 2009 Location: So Cal Oddometer: 1,068	Airscrew mod Silver solder or braze a one inch extension to the airscrew and cut a screwdriver slot in the end so you have a reference on the number of turns.Then slip a piece of vacuum tube over the extension. Now you can adjust it by reaching up from under the float bowl, no need to remove the carb. I'm also using the stock clamshell airbox and adapted the stock choke actuating mechanism to the Mikunis, beats having to turn the chokes off individually.

12-11-2012, 07:24 AM	#13
mrbindc ^OP Adventurer Joined: Apr 2012 Location: Alexandria, VA Oddometer: 74	RPC sells a choke adapter kit for the Mikunis. I haven't bought it but I'm wondering how did you make your stock cables work for the choke?

12-11-2012, 10:28 AM	#14
Rapid Dog bikes, booze, broads... Joined: Oct 2003 Location: Strangel Living West of Hell Oddometer: 8,340	what size Miks did you buy? __________________ '08 R1200R / '10 WR290X/R '81 R100RS Rattlecandy Red '06 950 ADV Orangeboom '05 R12GS Wedding Bike '91 R100GSPD Derelict

12-11-2012, 10:30 AM	#15
Kai Ju Beastly Adventurer Joined: Jul 2009 Location: So Cal Oddometer: 1,068	I didn't use the stock cables. I made my own out of a couple of throttle cables I already had. Since the Mikuni choke plunger is spring loaded I didn't need the single wire cable to push the mechanism closed like the Bings do.

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