best mpg factors

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rgrigutis

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i was amazed that i was getting 64 mpg on my '72 w/jrc carbs and 19 tooth mss. this was on avgas and i've since reloaded w/ american 93. long ride tommorrow and reload will reveal if mpg holds up.
i ride twisty/turny/up;/down roads and have a heavy throttle hand. can't quite figure out my mpg.

what kind of mpg do you guys get?
 
WOW! When I had my '71 back in the day (19T sprocket) I never got more than mid-30's MPG. My roadster was good for about 50 miles before looking for a gas station. Of course, back then, as a young guy I never lost an opportunity to red line it in any/every gear possible, even if that just meant WOT in 1st across the interesection! :)

I haven't seriously checked my 850 (22T) here in Mexico but in NY, before I did all the work I've done here to make it actually run like it should, I don't think it ever did better than around 40MPG.

I'll be riding it from Mexico City to San Miguel de Allende fairly soon (I hope). That's about 170 miles so I'll be interested to see if the fastback tank can get me there without stopping for gas...
 
When my '69 was running, I remember getting around 50mpg highway mileage. No ethenol, straight high octane gas, as high as I could find it. Conoco had multiple grades and higher grades as I remember? 19 tooth sprocket.

Dave
69S
 
50-55 mpg (US gallon) with my 1974 Commando 850 Roadster at moderate speeds on 92 octane. 22 tooth rear sprocket. 36 mm Mikuni with K&N filter. I can go about 120 miles before hitting reserve.
 
I get 55-60 on my '74, but I think I'm a bit lean on the needle. My brother gets about 50 mpg on his 72 750.
 
I get around 75 Imperial mpg in normal use. The best so far is 85.4 mpg on the slower first day run at the Norton International rally in Colombres in Spain, followed by 65.5 mpg on the next tank with some more spirited riding over the mountains and a dash along the motorway two up.

Phil.
 
Hard for me to get one running a IS tank worth to measure, but when I did on half Combat Peel, ~50 mpg, upper 50's cruising, lower 40's 'racing'.

A lot of HD riders keep track too and they report the same range as Commandos
in the 50-60's. Scooters in 250-600cc size get 60-70's mpg.

85 mpg is amazing efficiency. I wonder what Cdo combo allows this?
Just keeping throttle open a lot to gain speed can raise mileage by ~15%.
One reason diesels are considered more efficient per gallon of work.

hehe even if Commandos got 10,000 mpg, they'd still be an expensive luxury item
with no hope of using economy as excuse to own one, or more.

hobot
 
I get around 60mpg(UK gallon) cruising at approx 60-70mph and around 65mpg if I can keep it down to 50mph. Thats on my 1995 MK3(starter motor removed) no air filters(bellmouths) and PW3 cam. :)
 
JAYMAC said:
I get around 60mpg(UK gallon) cruising at approx 60-70mph and around 65mpg if I can keep it down to 50mph. Thats on my 1995 MK3(starter motor removed) no air filters(bellmouths) and PW3 cam. :)
Click to expand...

Sorry that should be 1975 MK3 Roadster.
 
Get about 46 mpg on my 74 Mk II during daily commute (45 miles both ways) but a fair portion is spent in 2nd or 3rd gear negotiating traffic. Seem to remember that back in the 70s & 80s when I took longer highway rides it was more on the order of 55 mpg. I would usually stop at about 120 miles to fill up.
 
Should have said - mine's a '72 Combat 750 running 32mm Amals and old Boyer analogue. Chain primary, standard secondary (not o-ring). Just over 10000 miles since complete rebuild. Runs reasonably lean, but doesn't pink unless I open the throttle too much around 2500 rpm. Opening the throttle a bit more nicely quenches the pre-ignition indicating that up to 1/3 (cut-aways) are very slightly lean. But of course backing off for gentle cruising is just at that lean spot. The most I've done on a tank is 203 miles as a Roadster (mind you I had to tip it over then ultimately push it to the service station as I'd put the fuel taps on the wrong side!) and 387 miles when it was an Interstate (as original).

Phil.
 
Phil, appreciate the report that pre-detonation or light detonation can be heard in the lower speed rpm ranges engines are most prone to this. I've been plotting to use electronic stethoscope but may not have too, cool.
I'm expecting ~60 mpg average on lightened tall geared Ms Peel if i keep below the ton. I'm afraid tire mileage will be her kicker to monitor and back off for.

hobot
 
Just back from a 3200 mile trip, around 50MPG (imperial) on a heavily laden Interstate with small screen (looks shit but does a great job for the wind and the MPG) Thats with a single 36mm Mikuni and mostly sitting between 75 -80 mph, 23 tooth gearbox sproket and belt drive. I suspect its a bit overgeared but this is the bike I use for longhauls and it eats up the miles whilst purring along.
 
23 tooth sprocket is not overgeared. Thats the perfect gearing for Commando in my opinion - when you get on the freeway. Why run out of gear and why overrev? Its also the gear for top speed - if you've got the HP to do 130mph. Its the same gearing I run on my cafe Atlas.

You can run lower gearing if you never get on the hiway.
 
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