MPG Transmission Mods

Not wanting to hijack the 'Weight & MPG mods' thread I thought that I would put this out for discussion. Anyway, my 2¢:

The best mileage I ever got was when I was using a Sumitomo rear tire. The larger diameter of the tire altered the transmission ratio  to the point that my cruising RPMs dropped ~500 rpm. That was over and above the overall RPM drop already achieved by using 30gm Dr Pulley sliders.

All of that speaks to the fact that the major obstacle to better economy with the Silverwing is inefficiency of the CVT transmission. Transmission being the drive line beginning with the crankshaft output and ending with the rear wheel. There are plenty of 600-750cc motorcycles out there which consistently get better MPGs due to their geared transmissions.  

So the trick to better MPGs then is to reduce the CVT slippage and/or alter the transmission ratio. A Dr Pulley HiT Clutch reduces clutch slip by locking up the shoes to the clutch bell, and variator sliders alter the variator 'timing'. However there seems to be no way to reduce the belt slipping --which is the major inefficiency.

Aftermarket variators not only alter the variator weights 'timing' by changing the weight-ramp angle but may also alter the belt-face of the moveable pulley sheave. Traditionally those after market variators do not change the fixed sheave of the variator. So maybe it is possible to 'tune' the variator by altering the face of an OEM variator sheave and effect how the belt acts at various RPMs. And given that at cruising speed the belt is riding close to the maximum diameter of the drive pulley, then if the pulley could be altered so that the belt rides at the max diameter then the drive ratio should be reached at a lower RPM and/or the drive ratio changed. Much like changing to a larger sprocket on a chain driven motorcycle.

Tim

The major obstacle to better economy with the Silver Wing is the OP buying a scooter that has been in production for 14 years which has had a reputation of being a gas guzzler since it was introduced. The later versions are less thirsty, but there are other maxi scooters out there that are more fuel efficient and advanced in design if better mpg is a priority.

Considering you pay buttons for gas in the US compared to what we have to pay in the UK, I can't understand why you'd want to throw more even money at the Silver Wing to save a few cents a gallon when the latest 400’s from SYM, Kymco, or Yamaha would be cheaper to purchase and be better on fuel economy.

I can't understand why you'd want to throw more even money at the Silver Wing to save a few cents a gallon when the latest 400’s from SYM, Kymco, or Yamaha would be cheaper to purchase and be better on fuel economy

Perhaps, people who choose to modify their Silverwing to increase power and fuel economy do so because the ergonomics of the Swing are better than the models you mentioned (for them), and because the 400cc engines on those models do not have sufficient power to climb 14,000 foot mountains where they live, or maybe they just want to experiment with various ways to optimize the performance and efficiency of their scooter.  Not everyone is 5'8" and 150 pounds.  A few of us are actually quite large in stature and some of us live more than a mile above sea level, so the mods we added to improve power and efficiency are barely enough to restore the power lost due to altitude.  Everyone else might think I'm crazy, but fortunately, the last time I checked, each of us has the freedom to decide how we choose to spend our money and it really doesn't matter what anyone else thinks or says.  It seems to me that some people have a hard time accepting that fact...

\"Meldrew wrote:

<> I can't understand why you'd want to...

Thank you for your, well stated, alternative view, Meldrew.

However I am trying to address the Silverwing's lackluster fuel economy from the vantage of my suppressed engineering genes. Sure there are later versions of the Silverwing which have remapped ECUs, and other scooters available with different size engines and different ergonomics. But I have this one, recognize the inefficiencies, and am speculating on remediating those shortcomings.

Tim

The forum member who wants to save fuel and weight lives in Texas where there isn't any 14000 ft mountains, the highest mountain in Texas is Gaudulupe Peak at 8749 ft and he hasn't mentioned he needs these mods to ride up there, even if there's a road up to the summit.

If you're a bit large for your Silver Wing that's your problem, and if it doesn't matter what anyone else thinks or says why are you responding to my post?

Since I'm a nice guy I won't mention the reason you edited your post is grammar, not grammer.

Have a nice day.  

Hmmm - Meldrew:
There aren't (plural) any 14,000 ft mountains (plural again) in Texas. At least we agree on that point.
-You stated that you couldn't understand why "anyone" would modify thier Swing, not just some guy in Texas. I offered three reasons why people may choose to modify their bikes.
-The ergonomics of my Swing are quite good actually - for me - but I can't say the same about the three other machines you listed.
-And clearly I don't need to worry about spelling when I have you available to make corrections... Happy now?

The bottom line is you are entitled to your opinions and so are the rest of us... Have a nice day...

Grammer?...My grammer died several years ago. She was a nice sweet old lady who loved all us kids and use to bake us cookies and other treats. I still miss her..

Gotta love it Cosmic!   

My grandma baked molasses cookies. Man were they good. As to the OP, that sounds interesting, although more tech / engineering than my business background covers. No, in my area along the gulf coast we don't even have 1400 ft elevations much less 14,000.

As to why, I chose the SW because I wanted at least a 500cc bike in case I do something crazy like ride to Daytona or Sturgis or anywhere else outside of Texas. For that matter, even some places in Texas since you can travel 885 miles without changing roads or leaving Texas.

Why not something else? Most were smaller than I wanted. Some of them would have done the job, but with less reserve available. The Bergman 650 would also have been a very good option, but about 10% heavier and 20% plus more expensive. Mine being a leftover 2012 I saved a little over 20% off it's msrp.

I'm very happy with my bike. I really like the low cg and how easy it is to handle. I like the ride now that I've got the rear suspension properly adjusted. I may do the front spring mod and from all reports will like the ride even more.

I've seen video of the Leo Vince exhaust. It sounds really good with a little more voice but not at all objectionably loud. Being 8-10 pounds lighter is a great bonus.

I may or may not make any more changes. I may or may not eventually migrate to a different bike. I definitely will enjoy my SW for as long as I have it if this introductory period is any indication.

For what it,s worth  it is impossible for the belt to slip it is constantly rotating free until the driven clutch engages or there is grease on the belt .Count your self lucky your spelling  of Burgman  did not catch his attention . I was corrected 4 times of the word Bergman which I miss spelled 3 times deliberately. :lol!:

Too funny tinman! But I think we underestimate how difficult it is to be perfect. Oops/Horrors Upon Horrors - Did he spell Guadalupe Peak???

"the highest mountain in Texas is Gaudulupe Peak"

Oh well... Gotta smile at life...

On my second new SilverWing---secret to decent fuel mileage=light throttle hand.

Had 2 new Burgman 400's---they get about 10 US mpg better than SilverWing, ridden at the same speeds---performance is just fine.

john grinsel wrote:

<>---secret to decent fuel mileage=light throttle hand

While it's agreed that a light hand / light foot will deliver better fuel economy, we are not always able to maintain travel speeds at 4500-5000rpm.

What I would like to do is to figure out some teaks or mods to the Silverwing's transmission which would reduce cruising RPM. Think overdrive.

Switching scooters isn't an option.

Tim

Hmmmm..... If there were a way to disengage engine braking....
You could coast farther, and also downhill....
Could reduce gas use, but might correspondingly increase brake wear.....

My take----leave transmission/drive train stock---Honda did good job, remember SilverWing is old design.

Gas is probably one of the cheapest things involved in Maxi Scooter ownership/use.

Leaving stock gives you the option of almost any Honda dealer looking at bike and getting parts----when you get stuck in middle of nowhere and something breaks.

My current SilverWing gets 50mpg US average even with hard throttle use sprinting to 90mph often to get out of the way of the idiots we share the road with. Recent trip to Maine--63 mpg one tank, 60 another time---so I am happy. Tailwinds and slow speeds big help.

Want good bike gas mileage---TU 250 Suzuki, mine gets 70mpg in hard use, ridden slow like on Blue Ridge Parkway 90mpg!! Cheapest gas, no performance mods. Best to leave it alone.

tinman wrote:

For what it,s worth  it is impossible for the belt to slip

V-belt drives can lose a lot of the power input to heat due to slippage.  V-belt drives are typically 85% efficient at power levels nearing the tensile strength of the belt and can be as high as 95% efficient under lighter loading.

Realistically, the Silver Wing's v-belt drive is probably about the same efficiency as a conventional geared transmission at normal highway cruising speeds.  In a geared transmission you have viscous drag issues, and friction from constant mesh gears between the main and counter-shaft that eat up as much of your power and fuel as the v-belt.  At full power output I would expect a manual transmission to be slightly more efficient (probably around 90%).

So I don't think the SWing's gas mileage characteristics can be blamed on the CVT from an engineering standpoint.  It is a heavy bike.  Combine that with a heavy throttle hand and your mileage will probably suffer. You could probably add this to your owner's manual under Operation and it might help:

Dan, Back in the 60's I had several two-stroke Saabs. When you lifted your foot off the gas it shifted into neutral (coasting), more so to prevent the engine from seizing due to the lack of lubrication than for economy of operation. It was a mechanical device in the trans that made that change. I don't think that a SW drive train (transmission) could hold up to the stress of going from no-load coasting to abrupt re-engagement at cruising RPMs of ~6000rpm. That'd be really slamming the gears.

Mr Grinsel, Thank you for your comments. Regrettably not all of us are able to purchase a new scoot as frequently as you, nor are inclined to leaving things as they are.

Chris, While your facts regarding belt drive systems may be spot on, the fact remains that the SW cruises at ~6000rpm when most geared bikes cruise at 3500. It's not the weight which drives the need for the high RPMs, it's the inefficiency of the drive train (transmission) -IMHO.

The fact is that any time you increase your RPMs over 5000 fuel consumption increases in direct proportion to the tach reading. The best fuel efficiency seems to be between 4000 & 5000rpm

Tim

Cosmic_Jumper wrote:

Back in the 60's I had several two-stroke Saabs.

What about long hair and bell bottoms?

BTW Tim, did you get the stator done?

Cosmic_Jumper wrote:

the fact remains that the SW cruises at ~6000rpm when most geared bikes cruise at 3500. It's not the weight which drives the need for the high RPMs, it's the inefficiency of the drive train (transmission) -IMHO.

I think that's inherent to the design of the engine though.  At 3,500 rpm the SWing's engine doesn't have sufficient power at highway speed.  It's almost square with a 72mm bore and 71.5mm stroke.  It needs to run at higher speed to maintain the power required for hills, etc or it will fall flat on its face. Torquey v-twins that can run at lower rpm have a long stroke, but the Silver Wing is not one of those.

If you've ever rode a CBR600RR, those turn about 4,400 rpm at 60 mph in 6th gear. But it barely can maintain road speed unless you're going downhill in 6th. The CBR600 is much happier at 90 mph in 3rd gear, and in race trim those engines turn 14,000 rpm. The bore and stroke is 67 x 42.5.

It takes a specific amount of power to move your bike down the road to overcome resistance from wind, etc.. You can only get horsepower two ways - either torque or speed. SAE HP = torque x rpm / 5252. So if you reduce rpm you have to increase torque. The Silver Wing's engine does not have a long enough stroke to increase torque sufficiently at lower rpm's on the highway by opening the throttle further and increasing mean cylinder pressure.

bigbird wrote:

Cosmic_Jumper wrote:

Back in the 60's I had several two-stroke Saabs.

What about long hair and bell bottoms?

BTW Tim, did you get the stator done?

Pre-bell bottoms. Beatle hair was long hair.

Still waiting for the new stator. Due to arrive on Tuesday

\"Chris Olson wrote:

I think that's inherent to the design of the engine though.  At 3,500 rpm the SWing's engine doesn't have sufficient power at highway speed.  It's almost square with a 72mm bore and 71.5mm stroke.  It needs to run at higher speed to maintain the power required for hills, etc or it will fall flat on its face.  Torquey v-twins that can run at lower rpm have a long stroke, but the Silver Wing is not one of those.
If you've ever rode a CBR600RR, those turn about 4,400 rpm at 60 mph in 6th gear.  But it barely can maintain road speed unless you're going downhill in 6th.  The CBR600 is much happier at 90 mph in 3rd gear, and in race trim those engines turn a14,000 rpm.  The bore and stroke is 67 x 42.5.
It takes a specific amount of power to move your bike down the road to overcome resistance from wind, etc..  You can only get horsepower two ways - either torque or speed.  SAE HP = torque x rpm / 5252.  So if you reduce rpm you have to increase torque.  The Silver Wing's engine does not have a long enough stroke to increase torque sufficiently at lower rpm's on the highway by opening the throttle further and increasing mean cylinder pressure.

Thanks for that explanation Chris

Tim

Cosmic_Jumper wrote:

Thanks for that explanation Chris

Tim, I think your theory is good. And there are ways of increasing mean cylinder pressure of a specific engine design at lower rpm. But I don't think those ways are practical because it requires doing things like reducing valve timing duration and overlap to increase effective compression ratio , increasing valve lift slightly to provide better volumetric efficiency at lower mass air flows, and slightly advancing both valve timing events and ignition timing. And consequently use a slower burning fuel (higher octane number) since the Silver Wing already has a static 10.2:1 compression ratio and it would likely start to "ping" at lower speeds if you increased the cylinder pressure too much.

I don't think the means to do most of these things exist in the performance or aftermarket worlds.

So what I'm saying is that retuning for lower rpm MIGHT yield better fuel economy under some conditions and riding style. But it is likely it won't make a significant difference, and only be detectable with a fuel flow meter on a dyno.

If I could find a set of 30gr rollers I'd like to try that to lower the clutch engagement rpm and reduce engine speed a bit around town by making the CVT shift up faster. My clutch starts engaging at 2,200 rpm and reaches full lock at 2,500 rpm. And I don't like how it disengages all the time when making a slower turn around a corner behind a car or something.

I wouldn't mind if the clutch started coming in at 1,800 and reached full lock at 2,200 rpm. For my riding style, I'd like that. My wife is different, however - she likes a more revvy engine and she's a little more aggressive around town riding than I am. We came from Rice Lake last night, for instance, and there's these roundabouts there. They're not real roundabouts like you see in Europe. They're toy ones. My wife zips thru that roundabout dragging her centerstand lever on the blacktop and I back out of it a little more and the clutch disengages halfway thru it. I don't like that.

Chris, To change the RPM when the clutch shoes engage you'll need to install weaker clutch (shoe) springs. I have been unable to find out what "weight" the OEM springs are rated at.

It sounds as if you have quite a background in mechanical 'stuff' and, perhaps, you can determine what the actual (gram) ratings on the OEM clutch springs. Honda won't divulge that info.

Cosmic_Jumper wrote:

Chris, To change the RPM when the clutch shoes engage you'll need to install weaker clutch (shoe) springs. I have been unable to find out what "weight" the OEM springs are rated at.

Actually, the clutch engages depending on the driven pulley speed. If you put in heavier rollers the driven pulley runs faster sooner and enhances clutch lockup.

I got my Silver Wing all tore apart and the variator off it, doing some experiments. I may have come up with a mod for the stock rollers that does what I want to try it out. I'll keep you posted.

Back in the 60's I had long hair and bell bottoms. I'm lacking one of them now days.
If you can't find the heavier rollers you want you could possibly try filling the center of the rollers with lead then maybe drilling with a small bit until you get the weight you want.

What I achieved:
- clutch no longer drops out when rounding a corner slow.  Huge improvement.  Engagement is just slightly below 2,200 rpm.  On decel the clutch stays in until 1,800 rpm.

- around town riding, the bike is MUCH more like a bike with a manual transmission.  Not near as much revving going on.  Largest improvement from 25 to 40 mph where I now get 500 rpm less at 40 mph than I had before.

- at highway speed there is no difference other than reaching high gear sooner than before.

- acceleration, no discernible difference from stock.  At highway speed still get a very nice downshift and can go from 55 to 85 mph passing a car, no problem.  I think acceleration is actually IMPROVED from 55 mph to 85 mph, but that may be subjective without measuring equipment.  What I notice from the seat is that the CVT now holds the engine at peak torque under full throttle from 55 mph longer than it did before, and doesn't let it rev quite as fast.  The seat of the pants feel is that the engine is running more on its torque curve than into the hp curve when the torque sensor (driven, or rear CVT pulley) is active under heavy throttle.  And peak torque is where you want to be for acceleration.

I don't have a gram scale, and the weight mentioned in the video is incorrect. I used the data for Type K tubing but when I didn't get the results I thought I would I did some calculations on centripetal forces and came up with the actual weights based on rpm's. I then realized I had used Type M tubing (.028" wall). 1/2" Type M copper tubing is 0.203 lbs/ft. This is 92g for 304.8mm, or 0.302g/mm. The inserts are 14.8mm so I calculated 4.5g added to each roller. The calculated weight of the inserts agrees with my engineering calcs on the centripetal forces vs observed rpm, so I'm reasonably sure the rollers now weigh 32.5g.

Yeah, it would be MUCH easier if I just had a gram scale. But I don't.

After I thought about it, the centripetal force on the weights is a function of not only mass but also velocity and radius from center of rotation.  Except that the velocity component is squared.  So addition of mass has less effect than velocity (or rpm).  This is why the clutch engagement didn't change much, but it holds longer on decel rounding a corner - the rollers are further out from the center of the variator (the radius component) so the combination of the radius component and mass component makes them tend to want to stay there in a higher ratio CVT configuration at lower engine rpm on decel.

You can't believe how extremely pleased I am that the clutch doesn't drop out turning corners on streets anymore. Also improved decel coming up to a stop sign instead of the clutch dropping out and coasting the last 50-60 feet.

In the video I only did four rollers to try it.  After making the video, and while it was processing and I was doing a bunch of engineering calcs to figure out why I didn't get quite what I expected, I tore the variator down and did all 8 rollers.  The results noted above are with all 8 rollers with 4.5g weight inserts.

Honda Silver Wing Variator Mod - The Movie.

Chris,

Could you be more 'technical' so us extremely intelligent people can understand this?   

Just kidding. Are you an automotive engineer or something? You gave a very technical post. Thanks.

JeffR_ wrote:

Are you an automotive engineer or something?  You gave a very technical post.

Mechanical Engineer. Cummins Power Generation.

Great video Chris. So if the moveable sheave were shaved at the narrowest face -say by 1mm- allowing the variator to close tighter together at higher RPMs would that allow the belt to ride higher in the pulley and therefore change the overall drive ratio? And assuming that the belt didn't come off the pulley, wouldn't that allow XX cruising speed to be achieved at a lower RPM?

The thought being to get the top of the belt to ride as high as, and no higher than, the variator diameter

I wouldn't use an impact wrench on the variator nut. My training tells me the bearings for the crankshaft are not meant to be subjected to the lateral pounding from the impact tool. Impact guns are for nuts, bolts, studs, etc that do not ride in bearings. I use the spanner tool and a breaker bar.

bigbird that reminds me that I still need make a spanner tool to hold the variator nut. I wonder if anyone has ever posted how to make one.   

Cosmic_Jumper wrote:

The thought being to get the top of the belt to ride as high as, and no higher than, the variator diameter

The belt already climbs to the top of the variator. If it climbed any higher you would lose traction surface on the belt that is in contact with the sheave halves.

bigbird wrote:

I wouldn't use an impact wrench on the variator nut. My training tells me the bearings for the crankshaft are not meant to be subjected to the lateral pounding from the impact tool. Impact guns are for nuts, bolts, studs, etc that do not ride in bearings. I use the spanner tool and a breaker bar.

While using the spanner and a breaker bar is probably the recommended way to remove it, the impact wrench is easier as my spanner tool is too long to flip around the other way and it's hard to step on it and hold it down.

Actually an impact wrench can't subject bearings to anywhere near the dynamic loads and vibration that the reciprocating assemblies do when the engine is running. We have some high frame-rate videos of internal engine parts when the engine is running. For instance, you hold a h-beam connecting rod in your hands and you think it looks like a pretty stout piece of iron. In the videos those rods develop a bow in them that can be seen with the naked eye when the cylinder fires. They pretty much look like a limp noodle connecting the piston to the crank pin in the videos.

Cosmic_Jumper wrote:

The thought being to get the top of the belt to ride as high as, and no higher than, the variator diameter

Cosmic_Jumper, I can see your thoughts are to get the engine rpm down at highway speed in an attempt to increase fuel mileage. But I don't think anything can be done with the stock CVT that way. I'm pretty sure the belt is about as low as it can go in the driven pulley, and I know for a fact it can't go no higher in the drive when its in high ratio. The only other options are changing the gears in the final drive or a bigger rear tire.

I don't even know if what I did in the video is good or bad for fuel mileage. I've checked a few tanks and I think the highest I ever got yet was 52.6 mpg. But I haven't written it down or kept track of it religiously or anything.

Since I added some weight to the rollers I plan on filling up the SWing tomorrow and keeping track of it for a few days. I usually burn a tank of gas off every two days here with a combination of around-town and hiway riding. I sort of doubt that what I did will change it much. But I am pretty happy with the other results - especially running the engine a bit slower for the around town stuff.

I think my wife wanted to ride someplace for breakfast at sunup so I might get enough miles on tomorrow to see what it did to fuel mileage.

Chris Olson wrote:

Actually an impact wrench can't subject bearings to anywhere near the dynamic loads and vibration that the reciprocating assemblies do when the engine is running.  

I would think the bearing loads from combustion and those from an impact wrench would be perpendicular to each other. AFAIK, crankshaft bearings are designed to take loads radially, not axially. But what do I know? I'm no mechanical engineer.

Chris Olson wrote:

<>I can see your thoughts are to get the engine rpm down at highway speed in an attempt to increase fuel mileage.  But I don't think anything can be done with the stock CVT that way.  I'm pretty sure the belt is about as low as it can go in the driven pulley, and I know for a fact it can't go no higher in the drive when its in high ratio.<>Since I added some weight to the rollers I plan on filling up the SWing tomorrow and keeping track of it for a few days.  I usually burn a tank of gas off every two days here with a combination of around-town and hiway riding.  I sort of doubt that what I did will change it much.  But I am pretty happy with the other results - especially running the engine a bit slower for the around town stuff<>

It seems to me that any time I've taken note of the belt rising in the Drive Pulley at a no load, high rpm (4000+) test the belt never rose to maximum diameter of the pulley. On that same note I've never been able to see that the two pulley sheaves were in contact at that approx RPM. However that the sheave faces are galled at that location indicates that they do have contact. Maybe just close contact but, well...

I once had a set of 35gm Dr Pulley sliders. On a freeway test they reduced my 65-70mph cruising speed to ~4000rpm. That would have done wonders for fuel economy but the acceleration, or the lack of it, was suicidal in the local traffic. It was worse than an old 36 hp VW bug in a head wind. In retrospect, no doubt the Driven Pulley torque spring needed to be upgraded or shimmed. But, way back then, who knew?

BTW I agree with BigBird's comment regarding using a spanner & breaker bar vs an impact gun --but without the snarky remark.
Tim

I'm still inquisitive about the quest for lower cruising rpm. As stated many times already, the sweet spot for the engine is between 4.5k - 5k rpm. Why would anyone want to bog the engine and run it at a lower rpm? What's wrong with a 5k engine speed at a true 65mph? If someone wants to cruise the interstates at 75+ mph, there are far better choices than a Silverwing.

My wife and I went on a breakfast ride this morning. 114 miles. I checked my gas mileage and got 51.8 mpg. My wife got 53.1 mpg. I think mine got worse, not better, since any time I've checked I've always been withing a half mpg of her bike. Of course, it's just one test, can't always fill the fuel tank the same, etc etc.. And 80% of our ride this morning was hiway instead of around town.

I think I have to agree with bigbird here - the SWing's engine is obviously tuned for 4,500-6,000 rpm on the highway. Reality is that 50 mpg with a 600lb bike is not bad. The tuning is not easy to change because it involves everything from the bore size selected for the throttle bodies to valve timing events. I don't really see how 35g sliders could cause 4,000 rpm @ 65-70 unless they were pushing the belt well above the variator sheave faces at full high ratio. If you watch in my video you can see plain as day that the belt gets all the way to the top of the sheave faces. That is as far as you can go without causing damage to the belt. If your variator is not doing that, then the ramps in either the pulley or the splined ramp are worn excessively and need to be replaced.

On the impact wrench issue, let's not get too far off-topic. But basically, plain journal bearings such as used in the Silver Wing's engine have thrust surfaces ground into the crankshaft that mate with thrust surfaces on the crankcase halves. The SWing only has two main bearings instead of three, and the mains are basically similar to Briggs & Stratton lawnmower engine main bearings. You can't hurt 'em with an impact wrench taking the variator bolt out. That being said, I'm sure the recommended procedure is to lock the pulley with the tool, then use a breaker bar. But even for changing car wheels the use of impact wrenches are not recommended in any service manuals. There is always torque specs published and the use of a torque wrench is recommended for those too.

Impact wrenches are "cheater tools" used by technicians to beat published flat rates, since they usually get paid on a flat rate basis. You will not find any engineering documents on machines where their use is recommended.

I'm not sure what to think of this. Because I would've never believed it.

I put a power plug in my bike today. Late this afternoon I decided to take a ride to charge up my cell phone with it. Yeah, that's a pretty lame excuse. But it was the best one I could think of.

So I went to the gas station and filled the bike up and reset my Trip A to 0.0 miles. I rode to the County Fair and rode around town there for awhile. Then zipped up the freeway to the next little town where they had a truck pull going. Watched that phenomenon for a bit. Then cruised Main in that little town a couple times and rode all the backroads home. I pulled into the same gas station with my Trip A showing 64.8 miles. I filled up the bike, and using "burst squirts" at the end to get it full all the way to the top of the filler neck, I got 1.007 gallons in it.

I'm sure that if you think about it, you were spending a whole lot of time at, or below, 4000rpm; had little, or no, stop & go stuff (like traffic or a multitude of Stop signs); and kept a steady throttle hand. Maybe even had a tank full of that famous Wisconsin non-ethanol fuel.

I had a similar experience a while ago after leaving this urban area and riding upstate PA with some friends. I ended up the day getting 63 mpg.

Tim

Yeah, I think most of the time 4,000-4,500 on the highway, closer to 5,500 for my 14 mile jaunt up the freeway, and 2,500-3,000 riding around town.

I think the reason I always get worse fuel mileage than my wife when we go riding is not only because of the weight difference (I'm 190lbs, she's 135), but also probably because she always rides lead and I'm trying to pace her. So I"m on and off the throttle more than she is.

I put 117.6 miles on my Trip A today since the last fillup, and this was mostly hiway riding.  I filled up this evening and got 2.144 gallons in it using the same method of fillup.  So once again I got slightly better fuel economy with heavier rollers in the variator.

Not sure I totally understand why because 95% of my riding today was on the hiway and I see no change in rpm from what I had with the stock rollers in the variator.  And I find it doubtful that reducing rpm in the midrange speed, which is basically all the heavier rollers did, can make a difference of 2-3 mpg that it appears I'm getting after adding weight to them.

This is where a dynamometer would come in real handy.  Too many variables on the road that can change to say 100% for certain that any sort of a modification does [whatever].

Sort of an update on putting those pieces of copper tube in my stock rollers - after three more tanks of gas I think it continues to provide a little increase in fuel mileage from before. I say "I think" because I never kept real good track of it previously. Just a few random checks. And my fillup results are better than the random checks I did before. Haven't gotten below 52 mpg with the extra weight in there and 50% of my daily riding during the week is in town.

And I continue to be happy with the lower rpm's around town.

We're going to Sturgis on the 2nd, and we usually run the 701 miles from our place to Mystery Mountain in one day. If the Silver Wing can get 50 mpg on that one it will be the most fuel efficient touring bike I've ever owned. We'll see. I remember earlier in the last decade sometime we rode our GL1500 to Sturgis two-up. We rode 23 down thru Pipestone and jumped on I-90. The wind was blowing 30 mph out of the west in South Dakota and all the Harleys westbound for Sturgis were running at 80-85 mph. So we turned it up and ran with 'em. Had to stop in Mitchell and take on gas and the big 'Wing didn't even make 19 mpg.

I'm very curious to hear about your tank range and what kind of MPGs you'll get, both coming and going --as well as your RPMs at various steady cruising speeds.

Have a safe trip.

Tim

I haven't seen any difference in rpm's at highway speed with the heavier rollers.  Just that the bike shifts up to high gear quicker.  When we rode our Lake Superior Circle Tour over the 4th weekend we went 150-170 miles between fillups and still had plenty of reserve.  So I don't expect that to change either.

My wife was talking that instead of taking I-90 to Sturgis we should run 23 thru Minnesota from St Cloud to Pipestone, then take 34 along the Missouri to Pierre.  That sounds good to me - we haven't been that route for several years and it's all two-lane road.  It skips going thru the Twin Cities to get to to I35 south during morning rush hour and is a more laid back pace.  So we'll get better fuel mileage taking that route, without even a doubt.

Wife's preferred route

I looked thru some of our photos and I have a photo of my bike at Pipestone.  Don't remember when that was, but the picture was taken for an IBA ride I was doing at the time.

I ran a 500 mile round trip today to the southern part of the state. Cruising rpm's on the freeway are 4600 @ 65 mph and 4800 @ 70 mph. Got 48.00 mpg right on the button for the round trip, almost 100% freeway riding.

Chris Olson wrote:

I ran a 500 mile round trip today to the southern part of the state.  Cruising rpm's on the freeway are 4600 @ 65 mph and 4800 @ 70 mph.  Got 48.00 mpg right on the button for the round trip, almost 100% freeway riding.

Is that GPS or speedometer speed? The older Swings read high by at least 10%.

bigbird wrote:

Is that GPS or speedometer speed? The older Swings read high by at least 10%.

GPS speed and mileage.

Then that is equivalent to a very significant reduction in overall gearing. I would say you got your desired results. Good job.

bigbird wrote:

Then that is equivalent to a very significant reduction in overall gearing. I would say you got your desired results. Good job.

The thing is, I don't remember what it was before at highway speed. I only know that when I ran it in the shop on the centerstand that the full high ratio was achieved at slightly over 4,100 rpm and the heavier rollers dropped it to 3,600.

I can't see how that can make any difference at highway speeds when the rpm's are 4,500 or more - UNLESS due to load on the CVT the torque sensor (rear pulley) is causing the CVT to run in a slightly deeper gear ratio with the stock rollers because of load on it. So with the heavier rollers it forces it into the high ratio at the same torque load on the highway now. It would almost have to be run on a dyno with a strobe tach on the pulleys to bear that theory out, or prove it. But it's my best idea of what's going on.

Regardless, I don't think it improved fuel mileage any. I know I can get 50+ on two-lane roads because it did that before on our Lake Superior lap. But 48 mpg is about what I'd expect from a ~600 lb bike on the freeway running 65-70 mph. So I remain pretty happy with it and I'm not going to press the weights back out of the rollers and change it back.

It doesn't seem my speedo is quite that far off. At 55 indicated my GPS shows 53. At 65 indicated the GPS shows 62. So I think the speedo is about 5% optimistic, and that's about what every bike I've ever owned has been.