MPG??????

Hi, how many miles do you guys usually get with your ROADSTERS?

With all the rural petrol stations closing in the UK not far enough, 100 miles and need to fill up. 850 MK2A with peashooters and blackbox air filter.

Since I put on new Amal bodies and chromed brass slides in 09 mileage has gone up. Mixed 75-80 cruising and slower minor road work but with regular use of throttle I'm getting 170 per tank with 11.8 litre empty to full. That's with PW3 cam, 9.3:1 and 32mm Mk1's. Gearing is 4.14:1 overall which helps. Easy riding adds 10 miles per tank.

I'm getting 50-60mpg on my '72 750 combat roadster. Amals sleeved in '98 by Mike Gaylord (stainless). The carbs have 28,000 miles since being sleeved. The motorcycle has over 48,000 miles, rebuilt at 20,470 miles and well maintained in the last 12 years. Supposedly the steel roadster tank holds 3 US gallons, so should go at least 150 miles per tank. I usually fill up around 120-130 miles.

illf8ed said:

I'm getting 50-60mpg on my '72 750 combat roadster. Amals sleeved in '98 by Mike Gaylord (stainless). The carbs have 28,000 miles since being sleeved. The motorcycle has over 48,000 miles, rebuilt at 20,470 miles and well maintained in the last 12 years. Supposedly the steel roadster tank holds 3 US gallons, so should go at least 150 miles per tank. I usually fill up around 120-130 miles.

Click to expand...

I get about the same on my 850 Roadster with PW3 cam, around 60mpg at 60-70mph so I normally fill up at 120 miles but have not had to use reserve yet.

There was a thread which covered mileage a little while ago...
best-mpg-factors-t7013.html

I get around 75 Imperial mpg in normal use. The best so far is 85.4 mpg, worst 65.5 mpg with more spirited riding over the mountains and a dash along the motorway two up. This is for a '72 Combat 750 running 32mm Amals and old Boyer analogue. The most I've done on a tank is 203 miles as a Roadster and 387 miles when it was an Interstate (as original).

Phil

I never got even 40 MPG on my 71 Commando in the 70's when it was new! I don't know how in the heck folks get the kind of mileage mentioned. But I still ride my 850 like I rode my 750 - like I stole it. Maybe that's the problem! I expect that changing from the 22T sprocket to a 20 won't improve things much!

55-57 mpg (US) consistently on my '74 850. My Garmin GPS has a "fuel gage" feature that I have set to warn me of low fuel at 125 miles. I seem to get that much before the reserve.

MexicoMike said:

I never got even 40 MPG on my 71 Commando in the 70's when it was new! I don't know how in the heck folks get the kind of mileage mentioned. But I still ride my 850 like I rode my 750 - like I stole it. Maybe that's the problem! I expect that changing from the 22T sprocket to a 20 won't improve things much!

Click to expand...

Before sleeving the carbs I was getting around 40MPG. I'm running a 21T counter sprocket. "Spirited riding" as low as 52MPG the the Gaylord sleeved carbs. In '73 on my first Commando...don't know or don't remember, didn't care.

Lately I've been getting around 47 or 48 mpg US, most of my riding is on an Interstate highway cruising around 75 mph, that works out to close to 120 miles to reserve for a steel Roadster tank. That's with sleeved Amals, probably 70,000 miles ago, I'm getting a little bit better gas mileage than I have in the past. For the life of the bike, I'd get around 44 mpg (around 110 miles to reserve on a steel Roadster tank), at the same speeds. At 60 mph, I'd get in the mid fifties, I think.

-Eric

I got stopped on my '71 Commado in Memphis (where I lived at the time) for 105MPH in a 70. I guess that explains my low mileage!

70-750, single 34mm Mikuni, 20T spkt., around 55mpg.

101 mph is the highest ticket that I've had on the Mk111. I was invited to sit in a Police Spec. Jaguar and given a full explanation of the 'Vascar' system. I had over a 'ton' on the clock so it didn't seem worth arguing.

I get around 60mpg (imperial) and reckon to run out of fuel and push the roadster at least once a year !

Just remember the difference between UK ("Imperial!") gallons and US measure. I guess there must be a difference in the temperature at which the two systems calculated the pounds to gallons conversion. There are 16 fluid ounces in a US gallon and 20 fl.oz in a UK gallon, so theoretically a UK gallon should be 1.25 x a UK gallon, but it's only 1.2 x.

Checking in my trusty "Machinery's Handbook, 19th edition", I've calculated, by comparing the two gallon to litres, that the UK fl.oz. is 0.96 x the size of a US Fl.Oz.

A friend reckoned he always got much better gas mileage in his car when he went to Canada (this was before Canada went metric). When I asked "Is it about 20% better?" he was surprised, until I told him that Imperial gallons were 20% bigger.

My fellow Brits sure had delusions of grandeur when they named their measurement system "Imperial"! Maybe at the time they had a big enough Empire to get away with it.

Boy Frank, now I'm more confused, I thought the rule was that a Pint's a Pound the World Around. A US pound fluid weight has 16 oz. A quart has 32. A gallon 128.
BTW big ole Harleys get same range of mileage as reported here for Cdo's.
I see em keeping records so have asked them. Ethanol fuel reduces mileage by a good bit 15-20% according to recent 2000 mile trip figures reported to me.

Sorry, Hobot. The equivalent saying in Englansd is "A pint of water weighs a pound and a quarter" (i.e. 20 ounces). That's where I got confused when we first emigrated.

It wasn't until I checked the two against the Metric standard that I realised that the fluid ounces were different. A US gallon (8 US pints, 8.0 pounds of water or beer, 231 cubic inches) is 3.785 litres. An Imperial gallon (20 British fluid ounces of water or beer) is 277.42 cubic inches and is actually 1.2009 US gallons. Consequently, a British fl.oz is 0.96 x a US one.

Wouldn't it be so much easier if we all used Metric? It gets so confusing when we use the same names for UK and US measures, but they're actually different.

As I said in my earlier post, the conversion from pounds to gallons must have been done at different temperatures. The British one is done at 60 degrees F. I don't know what temperature the US standard used. In aviation, they avoid the issue by using pounds, but then they get into trouble using tons, as a US ton is 2000 pounds and a UK ton is 2240 pounds. Just to confuse things even more a Metric "Tonne" (1000 Kg) is 2236 pounds! I was always surprised when my Bahraini airline customer used tonnes when defining their fuel loads.

hobot said:

Boy Frank, now I'm more confused, I thought the rule was that a Pint's a Pound the World Around. A US pound fluid weight has 16 oz. A quart has 32. A gallon 128.
BTW big ole Harleys get same range of mileage as reported here for Cdo's.
I see em keeping records so have asked them. Ethanol fuel reduces mileage by a good bit 15-20% according to recent 2000 mile trip figures reported to me.

Click to expand...

I was surprised to find out many years ago that one US fluid oz of water doesn't weigh 1 oz, it weighs 1.043 oz. It sounds like 1 UK fluid oz would weigh pretty close 1 oz.

-Eric

50-55 per US gallon with single 36mm Mikuni

Very glad we have the metric system in Canada (for more than 30 years now). To add to the confusion, in French a "Pinte" is a Quart so definitively not a Pint!!! No confusion with Liters though. Same with Ounces : can be weight and volume! and so on...

Barely a Nor-ton content!

Very glad we have the metric system in Canada (for more than 30 years now). To add to the confusion, in French a "Pinte" is a Quart so definitively not a Pint!!! No confusion with Liters though. Same with Ounces : can be weight and volume! and so on...

Barely a Nor-ton content!