Boxerworks.com

Hummmmmm
I rebuilt a 32/11
when when my Bings wore out I installed Mickuni 32mm
when the point system went south, I installed a Dyna III

Compression is over 130
no clutch slip
Nice plug color, smooth runner BUT 25 MPG??????????????????

I know the Gas is Piss..................... but 25MPG???????

dragging brakes?
retarded timing?
aggressive driving?
did you check the accuracy of the odometer (mpg calculation)?

Mikuni's have a reputaion for useing more fuel than Bing CVs.

Perhaps some tweeking in the midrange can help. No mater how hard we think we ride, the carbs are pulling through the midrange most of the time.

Seth nailed the obvious,except perhaps tire pressure-they'd be awfully low...

Motorhead wrote:Hummmmmm
I rebuilt a 32/11
when when my Bings wore out I installed Mickuni 32mm
when the point system went south, I installed a Dyna III

Compression is over 130
no clutch slip
Nice plug color, smooth runner BUT 25 MPG??????????????????

I know the Gas is Piss..................... but 25MPG???????

How does the timing mark look under a stobe? Is it nice and solid? A slightly bent cam nose will cause every other spark to be out of time. This causes over heating and reduced mpg. Switching to a crank mounted ignition boosted my mpg considerably.
Does the 32/11 match the speedo/odo ratio? When I put a 32/11 on my bike I found that the odo was off by 10%. Funny thing was that the speedo used to be off by 8 mph at 60mph (with the correct drive). With the 32/11 it's only off by 1 or 2mph.
I get 45+mpg with Dellortos, when I'm just cruising the super slab. That's going to change with some of the mods I'm doing now. I still hope I can get close to 40.

Given the record of BMW Motometers, I had grounds to get them off my bike...... I did install a nice Electronic Tachometer and installed LED idot lights for neutral, High beam . oil and tun with a Generator mod with a 330 watt resister and a Light changeing LED for Charge level

Red now FRed is more Cafe or sport traveler

My recent trip to Texas and back was the proveing ground

with the Rockey point Mickuni kit, and Stans advice from the Ohio Cafe web site I had my needles bottomed out still a nice light tan heat tape on motor showed no heat level over 220 degrees

Dyna at installation was spot on with the timeing strobe

and the drum brakes test smooth and no drag

although my First BMW had 36mm flat slide Mickuni with the same gearing I got 50MPG

Yes I am usually heavy on the throttle but as I traveled this time I started looking for answers

last time out on a trip Red was 70# heaver had 37/11 gearing and points and got just over 30MPG as gas stations and filling take on I recoreded the same way

I always chose a distance from the place of start as distace was maybe 15 to 20 miles different between stops I took them for face value Like Van Horn to El Passo was 138 miles gas at the fill up was just over 4 gallons maybe 4.6 that time

I am gona review the timeing and valve setting then carb's again

Garnet wrote:Mikuni's have a reputaion for useing more fuel than Bing CVs.

The Mikuni VM is one of the best slide carb designs ever produced.
A carb can only perform as well as the set-up will allow.
The reputation that you speak of is undeserved and speaks to the tuner's ability –
rather than anything inherent in the carb's design or it's performance capability.

Motorhead wrote:Given the record of BMW Motometers, I had grounds to get them off my bike...... I did install a nice Electronic Tachometer and installed LED idot lights for neutral, High beam . oil and tun with a Generator mod with a 330 watt resister and a Light changeing LED for Charge level

Red now FRed is more Cafe or sport traveler

My recent trip to Texas and back was the proveing ground

with the Rockey point Mickuni kit, and Stans advice from the Ohio Cafe web site I had my needles bottomed out still a nice light tan heat tape on motor showed no heat level over 220 degrees

Dyna at installation was spot on with the timeing strobe

and the drum brakes test smooth and no drag

although my First BMW had 36mm flat slide Mickuni with the same gearing I got 50MPG

Yes I am usually heavy on the throttle but as I traveled this time I started looking for answers

last time out on a trip Red was 70# heaver had 37/11 gearing and points and got just over 30MPG as gas stations and filling take on I recoreded the same way

I always chose a distance from the place of start as distace was maybe 15 to 20 miles different between stops I took them for face value Like Van Horn to El Passo was 138 miles gas at the fill up was just over 4 gallons maybe 4.6 that time

I am gona review the timeing and valve setting then carb's again

Very puzzling...looks like you've covered the bases. Please keep us posted if you find the problem isn't in your use of the throttle.

although the motor seems tight and uses no oil or blows no oil it failed the compression check
left 110 right 95

adding oil didn't change the readings so rings are sound

valves settings spot on and motoring didn't seem to point to the cam operation

seems strange but I guess this was comming with the low milage with the sturgis trip to the 20,000 miles after rebuild now 25,000, looking into the chamber through the spark plug hole seemed normal

but will take pulling the heads that were rebuilt at the San Diego outfit advertized in Airhead ABC magazine

maybe just a clean up of the heads..................... who knows just what we are making fuel from these days maybe its the USA getting us to junk these ole bikes

Motorhead wrote:although the motor seems tight and uses no oil or blows no oil it failed the compression check
left 110 right 95

adding oil didn't change the readings so rings are sound

valves settings spot on and motoring didn't seem to point to the cam operation

seems strange but I guess this was comming with the low milage with the sturgis trip to the 20,000 miles after rebuild now 25,000, looking into the chamber through the spark plug hole seemed normal

but will take pulling the heads that were rebuilt at the San Diego outfit advertized in Airhead ABC magazine

maybe just a clean up of the heads..................... who knows just what we are making fuel from these days maybe its the USA getting us to junk these ole bikes

Do a leak down test before you tear anything down.