UL MPG!

[Rhysmort]

Hey all,

New to this forum, but frequent some of the other "knowns" I've got myself a lovely 47UL (it's a chop so I won't post photos!). I was wondering what sort of MPG they achieve on a M51 link. I know there's a shed full of variables, but engine is rebuilt low miles and nice and tight. My 54 pan wasn't that great on fuel but I'm wondering if these lazy old gals are!

cheers!
Rhys

[kitabel]

30

[Buddhahoodvatoloco]

MPG

[Rhysmort]

Not sure why it's so funny? It's a pertinent question, I live in the middle of nowhere, and have a 2.4US gal tank.

Thanks for the reply man, 30 isn't too shabby.

[kitabel]

1. accurate wheel alignment (fluorescent tube, laser)
2. highest tire pressure you are comfortable with
3. good chain adjustments
4. chain and wheel bearing lube
5. NEVER "close ratio" 1st gear
6. tallest sprocket ratio that allows acceptable traffic manners
7. lowest cruising speed that gets you there
8. if you have hand spark control, arrange the full advance position to give MORE than the factory 29° setting, like 32° (.41" BTDC). No, this is not safe for hard throttle or low speed but it will definitely improve mileage at constant speed light throttle. After some practice, slightly rolling the spark back as you open the throttle becomes automatic
9. anything to reduce exhaust backpressure, NOT drag pipes with baffle insert

[Speeding Big Twin]

Rhys, I cannot help regarding petrol consumption for Flatheads but welcome to the forum. (I saw your bike on another site.)
Eric

[Rhysmort]

Hi Eric,

Pleasure to be here!

Thanks for the replies, I'm not looking for best MPG, of course I appreciate there are 1000 factors, just a general average consumption of where I can look to be. It's not the end of the world I was just hoping for people to chime in and say they get 28,30 etc.

Thanks again all!

[RUBONE]

High 20s (27-28) on my 44UL sidecar rig operating pretty consistently above 7000ft.

[Rhysmort]

High 20s (27-28) on my 44UL sidecar rig operating pretty consistently above 7000ft.

Hi Rubone, cheers, so without sidecar 30ish isn't in the realm of impossible. Great news. I'm pretty high where I am as well. Will I get skinned for posting chopper photos? haha.

[ixtee]

Not by me! please post m....

[Rhysmort]

Chobba now.JPG (422.54 KiB) Viewed 183 times

How she looks currently. tank change pending!

[flatheadmatt]

Rhys! Good to see you on here! Im running a CV carb on mine so no input on linkert mileage. I have noticed that with an intake leak mine was doing less than 20mpg.

[rocket ron]

Rhys
A US gallon equates to 1.2 UK gallons, so 30mpg over there is 36mpg over here.
On my U with bog standard engine I can easily do 80 miles before reserve and sometimes (when I couldn't find a filling station) 100 miles. I cruise at around 60mph.I seem to recall working out that I average around 45mpg.
I can understand that with your small tank mpg is critical.
Like your bike, by the way.
Ron

[Rhysmort]

Rhys
A US gallon equates to 1.2 UK gallons, so 30mpg over there is 36mpg over here.
On my U with bog standard engine I can easily do 80 miles before reserve and sometimes (when I couldn't find a filling station) 100 miles. I cruise at around 60mph.I seem to recall working out that I average around 45mpg.
I can understand that with your small tank mpg is critical.
Like your bike, by the way.
Ron

Hi Ron!

Very good point, of course I wasn't taking into account the US>UK conversion. Ah that's great news, if I can get 65/70 miles to a tank I won't be overly concerned! It proves difficult when I ride to Sweden or Belgium for the shows as fuel stops become a chore!

Have to post a photo of your U Ron, what fantastic engines they are, I was worried I would miss my pan, but I don't at all! haha.

[kitabel]

There is a quite reasonable tendency to assume that leaner cruising mixture will yield better mileage.
This is true, however as Gordon Jennings said "motorcycles are also liquid cooled, and that liquid is gasoline". Leaner mix will raise head, cylinder, and exhaust valve temperatures slightly. Do not retard the spark to compensate for this - less fuel needs more spark lead.
In my modest experience, Marvel Mystery Oil added to a full tank of gas allows slightly leaner mix to be used without penalty. YMMV.