bing to mikuni

[Dale Sonnenschein]

My Bing carb isn't in great shape so I was wondering what it takes to fit a mikuni to my 75 250. Anyone have this setup? Or,Does anyone know where I can get a bing 36mm slide and needle?

74 puch 175 SD
73 Husky 360 WR/RT
75 Penton 250
10 ktm 250xc
02 bmw r1150r

[Gordon Brennan]

These folks have everything you need. They have helped me with both my Penton and Husky Bing carburetors.
Bing International.
[email protected]

[brian kirby]

Normally I am very pro-Mikuni, I am very happy with them on my Maico and Can-Ams, but with the KTM engine Pentons its a lot of work to get one to fit. Probably better off rebuilding your Bing.

Brian

[tomale]

yea it is alot of work, but it is so worth it, I was shocked how much of a difference it made. I made the switch on my 76 and this is what I did, I bought a spare intake manifold and I cut a half an inch off of it, then I ground down the hump that is on the top of the manifold. Next I bought a 34mm carb the company I bought it from offered one that bored out to a 36. this allowed me alot more room than the standard 36 to mount the carb I bought a piece of gas filler tube. and a local auto parts store, they sell it by the inch but is alot cheaper by comparison. Being a big guy, when I first started riding the bike again I ended up going to a 13 countershaft sprocket to get it to pull out of the corner, once I got the bike set up with the mikuni, it rev'd so fast and pulled so hard that I found myself shifting too often and I went back to a 14 boy what a difference.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
74'250 hare scrambler (project)
74' 1/2 440 maico
78' 440 maico
72' cr125 Husky (project)
93' RMx 250 suzuki

[chicagojerry]

hey tom (tomale) i am very happy with how my bing performs but hopefully you can supply some vital info to some folks here.  (and who knows i may try a mik myself in the future) can you post where you bought that modified mikuni along with the jetting specs?     chi jer

[Dale Fisher]

Is the Amal Jackpiner intake adaptable to the Harescrambler?  There are rubber Amal to Mikuni flanges available and the 2" can be worked around with an adaptor plate (Speed and Sport).  But, would this type of arrangement leave enough room to hook onto the air boot?

Dale Fisher
POG Membership
74 Berkshire 100
70 Six-Days 125
72 Jackpiner 175

[Jeff D]

I used Sudco when I needed a Mik for my Ossa.  The Bing was so shot that purchasing the Mik was cheaper than buying the individual rebuild parts to make the Bing serviceable again!

Jeff DeBell

[Mick Milakovic]

I made the switch to a 34 Mikuni this summer.  I did the manifold mods that Thom recommends, but stayed with the 34 body.  Radiator hose from the auto parts store connected the carb to the manifold nicely.  Only drawback is getting the intake bell into the stock rubber boot from the air box.  Only way I can do it is to get the boot warmed up and flexible, then take the air filter out and slip it on from inside of the box.  Tough to get on, but I know it's not coming off!  I only ride cross country with the bike and it's great!  Starts easy, pulls hard, and has more top end than I can handle, so the bigger 36 is not necessary for me.  

We did the same thing to Ambr's 175, but used a 32 Mikuni and it works well, also.  Once again, she's more a low-end power band rider, so the smaller carb works well.

Mick

[Dale Sonnenschein]

Mick,WHere do you start with the jetting? I'm at around 1100ft asl. What throttle cable do you use?

74 puch 175 SD
73 Husky 360 WR/RT
75 Penton 250
10 ktm 250xc
02 bmw r1150r

[Mick Milakovic]

Dale, I'll check the specs tonight and get back to you.

Mick

[john durrill]

Dale Fisher,
 This is what we did to mount a Lectron to a KTM 175 cylinder.
It gives you an idea how to do it one way.
We used a standard Mikuni intake manifold adapter to mount to the modified intake manifold.

We moved the carb as close to the cylinder as we could and still have good flow and clearance. We turned the intake bell down on the Lectron also to help with the air boot fit. The enrichner air passage will limit you some on how small you can make it but it makes things fit a lot better if you can do it.
Good-thing is, if you use a standard Mikuni intake adapter, it bolts right up and is easy to find.
The one that fits the Amal intake is and expensive one.
john d.

[tomale]

Jerry, I will pull the carb off and list the specs here.. I will have time on wed. afternoon PST and I will list it as soon as I get finihsed, I think I have actually listed them before and you might try a search. I will try that too.
A 34 might just work fine, I have a friend who put 34 mikuni's on both of his 400 CZ's and they work great.. I nearly pullled off my first hole shot on one of the bikes.. besides if I remember right, most guys only use about 3/4 of the throttle anyway..

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
74'250 hare scrambler (project)
74' 1/2 440 maico
78' 440 maico
72' cr125 Husky (project)
93' RMx 250 suzuki

[tomale]

I found these specs from a post of mine on 2/22/2009
Main jet 290, Pilot 30 slide 2.5, jet needle 6DH4,
Needle jet 159 Q2, elevation, 500 feet above sea level. at 1100 feet you should be able to adjust with an air mixture screw. I don't think I used any air jets..
this bike runs really crisp and starts on 2nd or third kick, even cold. you might want to try a bit larger pilot and see how it runs before dropping down to a 30, if you have to adjust the air mixture screw out more than 2 full turns the pilot is too large, it should how ever be large enough for the bike to start easy. Better to be a bit large than too small.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
74'250 hare scrambler (project)
74' 1/2 440 maico
78' 440 maico
72' cr125 Husky (project)
93' RMx 250 suzuki

[Bob Bean]

I only rode 1  250 with a Mikuni on it a dozen years ago.
It was a 76 250.  
I was really really impressed with that bike.
It came out of a corner and ripped !  Great bottom and mid range power that built into good top end..

My 74 250 motor is not even close.  It does not have the bottom and midrange power like that.  It carberates cleanly, no stutter or hesitation, just doesnt build power unless clutched.
So what is the reason for the big difference ?

Carb ? Porting? something else ?  
I wish I knew.....   I wish my 250 ran like that 76 motor did.
It sure was a lot easier to go fast on.

Bob Bean

1986 ISDE Italy
1987 ISDE Poland
1989 ISDE Germany

1970 125 Six Day
1973 100 Berkshire
1973 Jackpiner 175
1974 Penton 250 Harescrambler
1976 Husky 250CR
1985 Husky 400WRX
1985 Husky 400WR

[Dale Sonnenschein]

THanks guys. I guess I better get a carb and do some measuring. I have a friend that has a machine shop. I was thinking of having him machine the stock intake and shorten it a little for the mikuni.

74 puch 175 SD
73 Husky 360 WR/RT
75 Penton 250
10 ktm 250xc
02 bmw r1150r