Author Topic: low mpg where to start?  (Read 949 times)

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Offline Ayrity

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low mpg where to start?
« on: June 19, 2009, 03:13:32 AM »
hey so the bike runs pretty well, I really don't think it is running rich, plugs look fine, but I am getting not great mpgs around 29ish, and thats with basicly all highway driving, I thought I read that these should be getting around 40+? What are the first things i should look at?
1976 Honda CB550k

Offline donny

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Re: low mpg where to start?
« Reply #1 on: June 19, 2009, 03:29:55 AM »

... tune up..
... dragging brakes ?
... clean carb & kits.....
2007 Husqvarna self propelled lawn mower    1976F    1971K    1974K      1990 FXRS-SP

Offline OldSchool_IsCool

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Re: low mpg where to start?
« Reply #2 on: June 19, 2009, 03:53:53 AM »
Bike Setup:
+1 on the dragging brakes.
+1 on the tune-up
- proper tire pressure
- balanced carbs (don't want them fighting each other)

Driving Style:
- use higher gear for lower RPM (the faster the engine rotates, the more gulps of gas its taking)
- coast to a stop or at least use greater stopping distances where the engine can idle
- better yet, adjust your speed to time the lights so you don't have to stop at all
- gentle accelerations
- use wheel brakes with minimal engine braking (downshift to stop)
- coast down hills with engine idling

Cargo:
- skip the Krispie Kreams
- carry less
- pack your cargo in a aerodynamic fashion (no loose cloths, no barn doors)
Can I have a motorcycle when I get old enough?
If you take care of it.
What do you have to do?
Lot’s of things. You’ve been watching me.
Will you show me all of them?
Sure.
Is it hard?
Not if you have the right attitudes. It’s having the right attitudes that’s hard.

Offline Ayrity

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Re: low mpg where to start?
« Reply #3 on: June 20, 2009, 06:08:02 PM »
love the doughnut comment made me acutally laugh out loud! Ill look into the breaks dragging, but the carbs are def in sync, just had them vacuum synced. Would a wind shield help with aerodynamics? I would think it must me less of a drag on the bike to have a shild on it than the air all hitting me, be a bit more comfortable at high speeds too despite the full face helmet...
1976 Honda CB550k

Offline andy750

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Re: low mpg where to start?
« Reply #4 on: June 20, 2009, 06:35:20 PM »
Check your plugs and see if you are running very rich (black sooty plugs).

cheers
Andy
Current bikes
1. CB750K4: Long distance bike, 17 countries and counting...2001 - Trans-USA-Mexico, 2003 - European Tour, 2004 - SOHC Easy Rider Trip , 2008 - Adirondack Tour 2-up , 2013 - Tail of the Dragon Tour , 2017: 836 kit install and bottom end rebuild. And rebirth: http://forums.sohc4.net/index.php/topic,173213.msg2029836.html#msg2029836
2. CB750/810cc K2  - road racer with JMR worked head 71 hp
3. Yamaha Tenere T700 2022

Where did you go on your bike today? - http://forums.sohc4.net/index.php?topic=45183.2350

Offline Johnny5

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Re: low mpg where to start?
« Reply #5 on: June 20, 2009, 07:26:48 PM »
Might be a silly question, but you're not leaking any gas? All your floats are in good shape and youre not overflowing?

Is your bike stock? I have pods and larger jets, and my mpg is high 30's low 40's.
www.kerosenecycles.com
1971 CB350
1973 CB350F
2006 Harley Springer Classic

Offline ofreen

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Re: low mpg where to start?
« Reply #6 on: June 20, 2009, 09:35:07 PM »
How many miles on the engine?
« Last Edit: June 20, 2009, 09:36:53 PM by ofreen »
Greg
'75 CB750F

"I would rather have questions I cannot answer than answers I cannot question." - Dr. Wei-Hock Soon