The New And Improved Unofficial R65 Forum V2
General Category => Chit-Chat => Topic started by: Mainerider on May 29, 2014, 08:23:14 PM
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So I've been loving riding my R65 but I was a little disapointed when I calculated my fuel consumption and it's just over 30 MPG. My '82 Honda Nighthawk gets over 40. Maybe I'm just spoiled by the 100+ MPG I get on My SYM Symba.
So what kind of gas mileage do you guys get?
Steven
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Mid 40s is typical, I've gotten as high as 51MPG, but usually it is around 46-47 assuming that I am riding reasonably smooth and no more than +5 MPH over the speed limits. If you are just making alot of short ~2 mile trips around town, it will be worse.
If you hear from the Brits - they will get even higher MPG numbers of course because their British Imperial Gallon is more than our wimpy American Gallon.
Also, if your carbs aren't setup right, or you've got some Mikunis on there, your mileage will be lower and running rich. What do your spark plugs look like?
~30 MPG is about what you can expect to get on the R65 if it is dragging a sidecar along.
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If you hear from the Brits - they will get even higher MPG numbers of course because their British Imperial Gallon is more than our wimpy American Gallon.
I would have to flog mine to get it below 60MPG Imp (50 MPG US) My average this year is 66 MPG Imp (55 MPG US) Besides the bigger gallons we have the small advantage of less ethanol in the fuel and possibly higher compression engines.
Lots of things you can do to improve consumption. Start with the carbs as just over 30 MPG US means there is something wrong with them. I would check float levels, wear on the needle jets and my old hobby horse properly set (not overly rich) idle mixture settings which have a significant impact on consumption in moderate use given the idle circuit is still making a big contribution at up to 1/4 throttle. On my back road cruising at 50mph I'm using only 1/8 throttle so it really does make a difference. I'm not talking excessively weak to the point where it affects performance as that doesn't work. Best performance and efficiency go hand in hand.
I also use thinner semi synthetic 10W40 in the engine and semi synthetic throughout the transmission which all helps a little to reduce drag. The whole airhead transmission has bigger losses than a chain driven bike where the gearbox is running in much hotter engine oil. Our bikes take longer to warm the transmission oils and never get to engine temperatures so the oil drag is particularly higher when cold.
Try this little experiment. Spin the back wheel by hand when cold and do the same when you get back from a ride. The difference in oil drag is huge. Now try the same thing on a chain driven bike.
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I'm getting about 43mpg out of my LS with combined city and highway riding. I'm pretty liberal with the throttle both in town and on the freeway though. When passing (especially trucks) on the freeway I usually approach at cruising speed and try to stay in the driver's mirrors... and then when close whack it wide open to get ahead of said vehicle.
Rider/luggage weight it a factor too. At about 230 pounds geared up I don't expect to get as good mileage as the test riders. My front brakes also drag a bit and aren't helping.
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Last time I checked I was getting low 30s in US mpg.. but that was before the transmission rebuild. I'm very, what's the word, open to using the throttle.. and my speedo is busted too.
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Also, if your plugs come up looking OK I'd make sure that your odometer is working. Plan a route on google maps and see how your meters match up to the calculated distance.
Two other things than can hurt mileage are lots of hills and consistent wind.
The factory manual says BMW's German DIN 70030 standard for measuring fuel consumption requires that the bike be up to temp and ridden on a course with no more than 1.5% grade and wind not exceeding 6.7mph and loaded halfway between unladen and gross weight. Speed should be 3/4 of top speed but not exceed 68mph and be as uniform as possible, and tires should be of correct size and properly inflated. Oh, and no brake drag allowed.
Under those ideal circumstances (without ethanol in the gas) the manual says machine should get 51.1 mpg. They say to allow a 10% deviation for unfavorable circumstances... go figure
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The factory manual says BMW's German DIN 70030 standard for measuring fuel consumption requires that the bike be up to temp and ridden on a course with no more than 1.5% grade and wind not exceeding 6.7mph and loaded halfway between unladen and gross weight.Speed should be 3/4 of top speed but not exceed 68mph and be as uniform as possible, and tires should be of correct size and properly inflated.Oh, and no brake drag allowed.
So that's what the figures in the riders manual are based on. At least it's a benchmark so that if you ride moderately as described and don't achieve the prescribed consumption it's a good indication that there is something amiss with the bike. The figure for mine is 62.8 Imp (52.3 US) I can achieve that figure ridden like that.
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Sounds like I have some work to do. That 30 MPG was riding to the Downeast Rally. 10 miles on the interstate, the rest on secondary roads going 50 - 55. Not many hills. I did have some luggage and camping gear. Maybe another test run this weekend. :)
Steven
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I've had my '81 R65 since January, '81 .
I lived in the Chicago area at the time and 5% ethanol was in the fuel supply .
I averaged 45 mpg then, speed limits on the rural highways was 55 mph, I could squeeze an occasional 50-52 mpg, with all interstate highway type riding for a full tank .
I moved to Phoenix in October, '93, there was MTBE in the fuel instead of ethanol, I was getting a consistent 45 -50 mpg then, still 55 mph highway speeds .
10% ethanol was added to the fuel supply and speed limit increased to 75 mph on rural highways about 12 years ago, fuel consumption is now at 38-40 mpg, I hit reserve around 190-200 miles now .
Increased speed and alcohol don't make a good combination for fuel consumption .
I even replaced the main jets on the '81 R65, from 143, to I think 135 or 137 and saw no difference in fuel usage .
Get alcohol out of the fuel, and back into beer, where it belongs !!!!!!!!!!! ;D
My first suggestion, would be to replace the needle jet, it takes a beating from the needle .
Check the float level and condition of the float needle valve, it has a rubber tip and gets hardened with age .
Then a full carb synchronization .
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BUT FIRST - make sure that the valve lash is properly set before messing with the carbs!
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I changed out my throttle cables recently and did not do a carburetor balance. I dropped my mileage from the high 40s into the 30s for in town riding. Did a careful carb balance and got close to 50 on the last tank. I would not have believed it could make that much difference if I had not seen it for my self.
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I changed out my throttle cables recently and did not do a carburetor balance. I dropped my mileage from the high 40s into the 30s for in town riding. Did a careful carb balance and got close to 50 on the last tank. I would not have believed it could make that much difference if I had not seen it for my self.
That is a surprising difference. With out of balance carbs one cylinder is dragging the other one along. The one being dragged will run weak and the one doing the dragging will run rich and neither will be running efficiently.
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I have an airline pilot friend who lives in Georgia and said he would help me sync my carbs. I'm waiting for him to have a layover in Portland. He owned an R100 for years and told me he'd teach me how to do it.
Latest fill-up was 32MPG
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Latest fill-up was 32MPG
In my experience one of the most often overlooked things that can greatly increase the amount of fuel you use is the condition of the carbs generally.
Unless something happens to block them up solid, you simply do not notice the slow deterioration in mileage and performance as carbs wear out.
The newest R65 is long past the date where the carb internals should have been completely renewed, especially the floats, float needle and seat, main jet and main jet needle.
Caveat, Snowbums article says several times to not us Stromberg diaphrams and also mentions Bing USA in less than supportive tones.
Aside from buying a manual from them I have never bought anything from Bing USA, but I find it incomprehensible that BING would manufacture the same parts to two different engineering standards, in fact given that BING USA's (and indeed BING worldwide, main interest is in making and supporting aircraft carbs, the idea of multi-standard replacement part manufacture is up there with "we didn't land on the moon" or "the government has been taken over by aliens". Not I hasten to say that I want to detract from the rest of Snowbum's article, which is 1st class.
The other small difference of opinion I have with him is that I have been using Stromberg diaphragms since around 1983 and am yet to have a problem with one, noting that on average they cost less than one third of the BMW variety.
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The previous owner of my bike had the carbs rebuilt at a shop a couple of years ago. I'd need to check the receipt but I know it had new jets.
Interestingly the Danish motor I have in my sailboat, a Vire 12, has a Bing carburator.
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Not to mince words but unless you are really thrashing the bike 32 MPG US (38.4 Imp) is truly appalling. While you are waiting to have the carbs tuned I would be inclined to try a a few simple adjustments.
First and most important thing is check the float levels as there is no point in attempting to tune carbs unless the fuel level in the bowl is correct and the same both sides. The official method is set the floats to shut off when parallel to the carb flange. This probably works well enough with new floats but I wouldn’t trust it if they are a few years old as they are known to get heavier and not necessarily by the same amount or at the same time. Unless they really are sinkers that doesn’t mean you have to put in new floats every few years but it does mean the parallel method won’t work accurately as this is an inferred method of setting fuel level that relies on identical weight and volume of the floats.
For older floats remove the float bowls quickly and measure the depth of fuel above the centre well. 22-24mm is the accepted target figure. Rather than use a ruler I find it best to scribe a line on the inside of the bowl. I use a vernier depth gauge to measure the overall bowl depth at 36.35 mm and subtract the target fuel depth to determine the distance from the bowl edge.
For 24mm depth of fuel scribe 12.35mm from top
For 23 mm depth of fuel scribe 13.35 mm from top
For 22mm depth of fuel scribe 14.35 mm from top
To scribe the lines I use a good old fashioned woodworkers marking gauge to ensure accuracy and more important to mark both bowls at exactly the same depth.
The next thing I would do is mark the position of the idle mixture screws with a dab of paint and then turn them clock wise in small increments the width of the screw driver slot alternating between the two carbs. Keep doing that for as long as the idle speed remains stable. Once the idle speed slows or starts to sound rough back the screws out until it runs smooth again. As long as you mark the original position of the screws you can't go wrong doing this and it could easily net you several MPG if they were set rich which many are.
After this it will depend how comfortable you are going into the carbs and whether or not you want to do a full overhaul and tune up. A lot more can still be done though with the carbs mounted on the bike. Checking the needles jets for wear and the needles for correct position and wear would be the next steps. Also check and clean the air space around the emulsifiers which depending on use could have started to block up after only a few years. These are the main things that have an impact on MPG. Only the needle jet wears to any significant degree so I wouldn't worry about the others provided they are correctly sized.
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Barry can I bring my bike over for a tune up? ;)
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You'd be very welcome Tony but somehow I think you have more than enough experience to do it at least as well as me if not better.
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Interesting disparity in the fuel usage of each bike. Those owners reporting very low mileage really should consider trying a few of the easier checks and adjustments to improve performance and fuel burn. With a bit of study and research, the overhaul and tuning of the CV Bing carburetors is not really a black art and can be accomplished by most anyone.
Besides bringing the carburetors back up to specification, there's also the need to balance the throttle cables while the engine runs at idle and then with the revs held at approx 4K rpm. The enrichener cables will also need to be confirmed for full off with the engine running.
Even the position of the carburetor in relation to an X-Y axis can effect carb function. Stand behind the bike and eyeball the Bings. If one or both are tilted too far off the vertical, the floats can be hindered in operation and float bowl fuel levels may be at odds.
There are many small details outside of the carburetor's body. One may not be an issue but several can leave you scratching your head. And in the course of 30+ years, previous owners most certainly may have changed any number of Bing bits. If you decide to do a full overhaul, replace everything that is not marked as to the OEM number for your bike's carburetor model number.
I'll leave you with a reminder that plays a large roll in reported fuel mileage. Most of us ride the R65. There's an R45 amongst the crowd with an engine two-thirds the size of the 650cc R65. Avoid comparing apples to oranges. My full-size Ford truck does not nor will it ever get the same fuel mileage as my Cabriolet.
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There's an R45 amongst the crowd with an engine two-thirds the size of the 650cc R65. Avoid comparing apples to oranges.
I wouldn't let em off that easily Monte. An R45 is exactly the same weight and has the same frictional and aerodynamic losses as an R65 so should need the same amount of power to accelerate or cruise at any given speed. The only benefit I have is better part load efficiency but to balance that I lose out on overall gearing. Even the factory consumption figures are near identical at 61.4 MPG Imp For the R65 and 62.8 for the R45. If I can match the factory figure so should an R65.
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You'd be very welcome Tony but somehow I think you have more than enough experience to do it at least as well as me if not better.
Barry mate you are doing yourself down there, my experience is more associated with ECUs and individual coil packs and injectors none of which you find on an R65 :o