Fuel consumption

[ROGSLATER]

My 86 R80RT fuel consumption has dropped from 47/48mpg to 38/39 within 3000 miles.
Replaced the old crackomatic ign coil for the late type together with the matching ign controler. This cured poor starting and some vibration but had no effect on fuel consumption. Then changed diaphrams, checked float levels, dropped needles one notch to second from top and checked valve clearances. Small improvement to 40/41mpg. Performance and general carburation both excellent. Total mileage 38,000
Any ideas?? What is normal average consumption.

Roger

 

[20774]

Have you changed the air filter?

Have you resynched the carbs after performing the carb work? Have you dropped the jet stack and checked for crude on the jets? Maybe you should consider more than just bits-n-pieces of the carb work.

Check the gaps on the plugs... Ensure the tires are properly inflated...

 

[dduelin]

Did the fuel distributors in your area begin selling 10% ethanol fuel? Where I live there are 3 or 4 regional distributors of gasoline and until recently I could still buy non-ethanol gas. Now we have no choice and all gas stations have ethanol 10% with less mileage in the bargain. Just a thought. You may have fixed the original problem but mileage not going to be the same as it was before.

 

[zoridog]

Check how your wheels spin. I fixed a dragging front brake caliper and went from about 30 mpg to 40 mpg.

 

[osbornk]

Did the fuel distributors in your area begin selling 10% ethanol fuel? Where I live there are 3 or 4 regional distributors of gasoline and until recently I could still buy non-ethanol gas. Now we have no choice and all gas stations have ethanol 10% with less mileage in the bargain. Just a thought. You may have fixed the original problem but mileage not going to be the same as it was before.

Yep. My final holdout for real gas went to the ethanol blend last week. He said it was mandated for all stations June 1. You will probably lose about 10% of your mileage.

 

[ROGSLATER]

Yep. My final holdout for real gas went to the ethanol blend last week. He said it was mandated for all stations June 1. You will probably lose about 10% of your mileage.

Thanks fellers for all the tips, yes been there, done that, on every one of them including strobing the ign timing, and plug readings at varios fixed thottle settings up my big long out in the boonies test hill. I will check out the latest adulteration of the local fuel but really can't see that bringing my consumption down as far as it has. My R1200RT on the same fuel, if ridden in the same manner as the 80 manages 9 to 10mpg better, formally they were about the same.
I will now try complete carburetor over haul with all new bits but I have reservations about that due to the relativly low miles and they appear to be perfect in every respect.
Thanks for the ideas

Roger

 

[20774]

My R1200RT on the same fuel, if ridden in the same manner as the 80 manages 9 to 10mpg better, formally they were about the same.

Yes, but your RT has a computer to control the ignition for optimum performance...all you have on your Airhead is your right hand!

In the February 1994 ON, there's an article on testing for the amount of alcohol in the gas. Steps are:

- uses 1 liter of gas, 100ml of water, a graduated cylinder, and some food coloring
- add 2 drops of food coloring to the water; mix
- put 1 liter of gas in the graduated cylinder
- add the colored water
- put hand over the top of the cylinder and shake
- observe how much colored water is at the bottom of the cylinder.

If the new amount of colored water at the bottom is now 150ml, then you have 5% of alcohol/ethanol in the gas (100 to start, 50 more shows up in 1000ml).

Be careful doing this and do it outside with proper ventilation.

 

[AnnapolisAirhead]

Check how your wheels spin. I fixed a dragging front brake caliper and went from about 30 mpg to 40 mpg.

I've wondered about brake drag and fuel consumption. Your brakes are ATE or drum? I don't see anyway to adjust Brembos. Is there?

 

[zoridog]

I've wondered about brake drag and fuel consumption. Your prakes are ATE or drum? I don't see anyway to adjust Brembos. Is there?

My caliper needed to be replaced. Even used Brembos are expensive.

 

[AnnapolisAirhead]

... Even used Brembos are expensive.

...but less expensive than a brake that doesn't work. ;-)

I don't think the Brembos are adjustable, the pads basically float in the caliper. The rebuilds are dead simple but I've always wondered how the pads can last so long the way they are held. Seems to me they are very lightly dragging all of the time. That can't be helpful for fuel economy--not that I check it all THAT much.

My bike will stop on a dime though. I installed a new master cylinder and braided stainless lines from the calipers to the junction box under the tank, and another up to the master cylinder (my is on the handle bar).

 

[ROGSLATER]

Yes, but your RT has a computer to control the ignition for optimum performance...all you have on your Airhead is your right hand!

In the February 1994 ON, there's an article on testing for the amount of alcohol in the gas. Steps are:

- uses 1 liter of gas, 100ml of water, a graduated cylinder, and some food coloring
- add 2 drops of food coloring to the water; mix
- put 1 liter of gas in the graduated cylinder
- add the colored water
- put hand over the top of the cylinder and shake
- observe how much colored water is at the bottom of the cylinder.

If the new amount of colored water at the bottom is now 150ml, then you have 5% of alcohol/ethanol in the gas (100 to start, 50 more shows up in 1000ml).

Be careful doing this and do it outside with proper ventilation.

Kurt
Yes seen that one, there is a most intersting test done on four cars usuing varios ethanol mixes. www.ethanol.org.
The average drop in fuel consumption was 1.5% on E10 (ten% mix)
2.2% on E20, 5.1% on E30. However on E10AK which is a denatured ethanol the average milage IMPROVED by 1.7%.
Interesting.

Roger

 

[seniorasi]

Kurt
Yes seen that one, there is a most intersting test done on four cars usuing varios ethanol mixes. www.ethanol.org.
The average drop in fuel consumption was 1.5% on E10 (ten% mix)
2.2% on E20, 5.1% on E30. However on E10AK which is a denatured ethanol the average milage IMPROVED by 1.7%.
Interesting.

Roger

I have not had the Beemer long enough to check but I went from 19.2 mpg down to 15.3 in my Z71. Substantial drop!

 

[Polarbear]

Get in the REAL world?

Drive your bike across country and buy a LOT of ethanol gas and see the drop in mpg's. Its "huge", not 1 or 2% as any may suggest! I've done so many cross country trips(dozens) and the gas mpg used to be fairly good until the ethanol showed up. Its more like a 15-20% difference in my bikes when I get the alcohol added. No fool'in. Its quite the BIG difference, according to my bikes. I'm kind of miffed by it too, as we are getting the shaft by corn folks and our wonderful Gov't, subsidizing this crap! Randy......Those who ride a lot know the change in mpg's is not small....Randy

 

[ROGSLATER]

I have not had the Beemer long enough to check but I went from 19.2 mpg down to 15.3 in my Z71. Substantial drop!

The testing was done by, or paid for by the ethanol producers so I view the numbers with much suspicion. However my RT1200 shows no noticable negative effect compared to the 15% drop to my RT 80 with fuel from the same pump.

Roger

 

[seniorasi]

The testing was done by, or paid for by the ethanol producers so I view the numbers with much suspicion. However my RT1200 shows no noticable negative effect compared to the 15% drop to my RT 80 with fuel from the same pump.

Roger

It may have something to do with computerized fuel injection versus calibrated normal aspiration.

 

[lkchris]

Check your compression.

When Wife's RT had bad compression in one cylinder, mileage fell noticeably.

 

[ROGSLATER]

Cured It

Check your compression.

When Wife's RT had bad compression in one cylinder, mileage fell noticeably.

Cured it
With needles in the top notch I did 224 miles today on 4.62 gallons which translates into 48.48 mpg. It would appear that despite the low mileage the needles and needle jets are worn. Dropping the needles a notch has restored the clearance so mixture in the mid range is leaned off to approx the correct setting.
Getting parts out of BING is like getting a Federal bail out as they will not respond to my request for costs.

Roger