Sorry man, it IS driven off the gearbox. That's the small wires coming out of the cases near the rear exhaust head pipe. Gearing affects the ODO quite a bit.

I used Factory Pro's baseline settings and adjusted from there. I'd have to look at my notes to see where I am right now, but mine probably isn't a good example because of the internal changes I've done. The needles at the 4th clip position sounds like a lot. The idle screws should be less than 2 turns, maybe 1.5-1.75.

When I take my bike to the track I get only about 4-5mpg less than "normal" riding. Maybe when those cops tell me that I'm using the streets as a racetrack they are onto something....

 

Maximum efficiency is achieved between max torque and max horsepower. Not sure where this is on a 'Hawk but I imagine its around 5k rpm. Low revs (<3k rpm) are not efficient because the vibrations in the engine increase friction amonst the moving parts.

The regular speed ranges on this ride were 50-70 mph and L8RGYZ stated he was using all 6 gears to keep the rpm's low. Reaper stuck to 3rd. Not sure what mine was doing cause my friend was riding it. If it was me on it I would have back and forth between 3rd and 4th due to the -1 +2 gearing. Reaper has the ignition advancer on his. I think his mpg's were affected mostly by his size and the higher octane fuel resisting combustion. Tire pressure would also definitely be a factor and I don't know what he was running. Mine are ~36 psi.

 

And at least in my vocabulary this is what is meant when you say "lugging it" and I say again... Just above this is the most efficient for long not to brisk runs... Not for canyons though...

 

no no no, I said I had luggage! Oh, you said lugging.....

 

Next time you find yourself on a slight hill or even doing 80+ on the freeway at 5000 rpm, try something...

Check your speed. Now downshift, and notice that the bike requires less throttle to maintain the same speed, but the rpms are higher.

The reason I say maintain speed, or do it on an incline is that your hp won't change.

Anyhow, I'll let it go, no need to cloud the thread up.

 

Question, so if my speedo is reading too high, does that mean my odo is too high also?

Or is the speedo intentionally inaccurate?

I guess it's possible I have a different sprocket, I'm not the original owner. How many teeth stock?

 

We all know lugging is not good for engine longvity. The additional wear on bearings is enormous verses that of smooth operation. That said, is the assumed incremental friction enough to countermand the additional efficiency of an unthrottled intake? And is someone lugging their bike for a significant portion of the operation? I think the theory is shakey and in practise would not likely have a measurable impact.
Hotbrake - Maximum efficiency is obtained at max torque period. Torque is directly related to pumping efficiency. More power is possible (and is available on a Shawk) but this is developed at decreasing efficiencies. Power is simply Torque*rpm/5252. As long as torque falls off slower than RPM builds, HP will increase. At some point (about 9000 rpm for us) pumping efficiency falls off faster than rpm increases and the out put begins to fall.
But there is another significant variable here - throttle opening. Not sure what a typical Superhawk's max torque rpm is, (68 ft/lbs?) I'm sure someone can tell us, but that MaxT RPM is based on a fully open throttle. MaxT is different and occurs at a different RPM for every possible throttle openning. That means Max T at 1/2 throttle is (obviously) less than fully open throttle, but less intuitive, is that it occurs at a different RPM. Generally a lower RPM (most likely the case on the S.Hawk), but sometimes not, for a trick tuned intake. Tuned resonance frequencies of the incoming air charge (known as Helmholtz) can create significant changes in the expected MaxT and the RPM it occures relative to various throttle openings. Exhaust is part of this too, and adds a whole new level of complexity.
This is fairly general description to a very complex system, but I think it adds to the basic understanding most everyone on this forum has - that simply opening up the intake and removing (or lowering) exhaust back pressure doesn't always result in what we want. Might give us good top end (and might not! even more to that.) but is likely to hit us in the mid range. This is noticeable say during a roll on. What is a real killer of gas mileage is the part that is almost imposible for us to notice - the reduction of torque (and thus efficiency) at part throttle openings. I say almost imposible because who knows what the power at 1/2 throttle is? If the power isn't what we want, we open the throttle slightly more. Throttle opens, RPMs change - Allowing more air and thus fuel in (read consumption)
Who gets a dyno run at 1/2 throttle? at 3/8?
That is the kicker. 1/4 throttle to maybe 1/2 throttle is where our bikes spend all their time - at least for what we would call "hiway" riding.
Describing all this exactly is a rather complex (at least for me!) set of differential equations.
I know there are people on this forum with the grey matter to take this further. Me, I have an engineering degree but went into marketing be cause I was better at describing the system to others than integrating it.
Oh and also cause marketing is where th REAL money is!

 

16-41 is stock and yes, speedo and odo are of by equal margin (within a few %)...

 

BTW I know how that works... I'm pretty sure we are talking about the same thing... only simplifying on both parts, and drawing slightly different conclusions...

I know that in theory you are 100% right in saying that "lugging it" or whatever terminology used is more fuel efficient... I'm not disputing that...

What I'm saying is that in a real world application is that just above the line is more usefull and in the long run probably even more effiecient as then you have a little higher consumption than lowest possible, but also less "waste surges", when you need to roll on power there is a little lag, when you are overconsuming gas... and that eats up the "savings" awfully fast...

Smoothness counts... And lugging it doesn't make for smooth...

 

Stevebis1- Ok, I agree that max torque is the most efficient. So max "power" or performance would occur between max torque and max hp, or the most efficient max power.

My 15/43 gearing gives me a 20% (19% to be exact) difference in speed and odometer reading. The RC51 with one tooth down in the front puts me at a 10% difference. And the VFR with stock gearing is 9% off. All this was tested with GPS which is accurate to 21 feet (.4%). At first I was concerned about the additional mileage, but my 'Hawk has over 30k miles, and I have no intention of ever selling it. After a minor crash last year which somehow ended up getting it "totalled", I bought it back for $1100. Accruing additional mileage with it already over 30k wouldn't really have any affect on resale value anyway.

 

Interesting. I read up on BSFC (brake specific fuel consumption), haven't seen that since college.

Anyhow, most of the graphs show peak efficiency just below peak torque rpm, and at about 75-100% of peak torque.

Here's an example of a bsfc graph on a VW:

http://s3.amazonaws.com/mark_trancha...s/tdi-bsfc.png

 

I bought mine at 21K in July, and am almost up to 30K now. Agreed, might as well keep the bike forever at that point, because it's not worth anything to anyone else no matter how well you take care of it.

 

I failed to mention that I did add the FP 4 degree ignition advancer a couple of months ago. My tire pressures cold were 40 rear and 40 front.

I do a good job managing the throttle when ride, either super slabbing or riding the twisties. I allow the engine to provide a great deal of braking for me when entering a turn and I do not enter a turn slow and then gun it out I tend to enter and maintain a consistent speed throughout the turn.

The bike is well maintained and the carbs get sync'd before every ride after the bike has been warmed up to operating temperature.

This thread has motivated me to pull the carbs off tomorrow and see what I have done and make some minor adjustments to the pilot screws, clip position, etc. I do know that the bike is running a bit rich, so we will see what happens.

I am curious about what other SH riders are getting for mpg, based on rider weight plus gear and any modifications made. My information is as follows:

average mpg: 33
weight w/gear: 270#
mods: FP carb kit, 4 degree adv., K&N filter, -1 on drive sprocket, yoshi slip-ons cut down to 14"

 

Told y'all he syncs the freakin carbs more than he rides it! LOL.

Try running a tank of 87 through it before you go changing things, thus eliminating multiple variables.

 

Should start a new thread for that! Tell everyone to trim the fat and just post the pertinent info.

 

You know... I hate synching carbs... It makes me frustrated... Doing it before every ride would put me in the toon farm in short order...

I agree with Hotbrakes... Try it on 87... It's not going to make anything worse I can promise you that... If it's running rich on premium it's going to be less so on 87... Probably still less than perfect, but in the right direction probably...

 

Okay I will try a tank of 87 and see if there is any improvement before digging into the carbs.

Tweety, I have the bike setup now where all I have to do is remove to rubber caps and attach the vacuum hoses. Simple as that.

Honda part #16214-MB0-000 joint booster $3.77. This replaces the hex bolt that sits below the carb housing on the front cylinder head and $0.50 worth of hose to complete the job. Sync the carbs all day long with no hassle.

 

The VTR makes peak torque (about 67 ft. lbs.) at 6250-6500 rpm. Some guys are gonna think that 75% of that is 4800-4900 rpm. Nope.

75% of peak torque (67 ft. lbs.) is about 50 ft. lbs., which the VTR makes or exceeds at every rpm from about 2200 to the rev limiter.

I'm pretty damn sure the best possible mpg will be obtained in 6th gear at the lowest rpm usable without lugging the engine.

 

Central Coaster - You are correct. I was wrong to say "max torque is max efficiency Period" I was oversimplifying somewhat to make the point that it wasn't occuring at a higher RPM level.
Hey oversimplifiying is what us marketing guys do!
Your graph is interesting and supports my position that there is much more to what is going on than any simple answer such as "keep the engine between max torque and max HP"
The recipe to real world max mileage is still stay in the lowest gear posible (numerically low) keeping the revs low but not lugging.

As far as differences between bikes on the same ride I think most every one has hit the high points - Weight, acceleration, carb setup, overall state of tune are all going to be the biggest contributors

 

I have never understood where folks get these concepts. Ok, sure, the maximum efficiency is in the range you suggest, I'll buy that. However, do you realize that you are referring to the power output specification of the engine? How was this measured? AT FULL THROTTLE!!! At partial throttle the hp and torque curves look a lot different. You would need to pull and infinite number of dyno runs and plug that into a database in order to determine the exact optimum for the particular throttle opening you are using. Way too complicated. I'm sure there is a guy at Honda somewhere who has done all of this.....

What's the answer then? I don't know. The stock, or close to stock, gearing seems to work for me. I know that cruising along in 5th gets worse mileage than being in 6th. That's about all I need to know!

 

Jamie;

I wasn't promoting any concept about efficiency at 75% of torque peak. I was commenting on a previous post- pointing out that the motor is capable of producing that 75% through the whole power band so I wouldn't know what to do with that info.

Like I said, my experience and belief is that pulling the tallest possible gearing at the lowest possible rpm without lugging the motor will return the best possible mpg.

 

Agreed!

 

HA! that is pretty funny. the things you have to do when you don't have a garage!

 

Reaper did you see this in the other thread?

http://14point7.com/Widebands/JAW_1_03/JAW_1_03.htm

 

I did and I Googled widebands but not really sure what this does. Do you mind explaining how it works with the SH?

 

I think it's a digital circuit that monitors exhaust. You mount the little display thing to your fairing and hide the circuit board under the seat. You have to buy a probe from an outside source that is cited in the directions. Once you have the probe you put it in your ***. The circuit board measures the exhaust. If you're shitting a brick every minute or so you're driving really fast and your gas mileage will register very poorly. About 28 - 32 or so. By contrast if you're just loafing along like the church lady - just farting around - the air box will intake the methane and you'll be getting fantastic mileage. Like 43 or something. It really is a clever device.

 

Nuhawk great description

in a nutshell the wideband measures the air fuel ratio. With this infromation you can determine if you are rich or lean.

 

Seriously where are the measurements taken?

 

 

The exhaust gasses.