Gearing Changes

[chasdom]

Hi dlaing,

 

thanks fo the good info. on the swing-arm lengths. Actually, I wished I had used a V50 as the donor bike, for a variety of not terribly important reasons. There's just something about 500cc's if you know what I mean. As I mentioned above, I too have read the axiom about max efficiency at max torque, but again, if you get a chance go to the Craig Vetter Mileage tests, and what they found there seems in contravention to that. In essence, the slower they had 'em popping, the better mileage they got. After more time on this project/patent than I'd care to admit, I've learned a number of things - not the least of which is some of the 'conventional wisdom' out there, may be off the mark. The airplane fuel mixing is interesting - but I have no doubt I'd end up cooking this little goose! That's an art... and in that case ... I'm not Picasso! Anyway, one of my thoughts of the last year, is that along with our standard gearboxes, virtually all road bikes should have either a very tall high gear, or a two speed rear-end/final drive so that under the right conditions, we could lope along at lower rpm, and save a bit o' gas. Anyway, thanks again, and oh - another advantage of a V50 is the carb... inferior to fuel injection, save when a simple peasant like me wants to tinker out in the garage. Thanks Again

 

The V65 swing arm is longer than the V50, and the V65 Lario is longer than the both the V65 and V50.

Paul M. did some interesting swing arm modifications.

 

If your goal is MPG, RPM may not be such a big problem.

Efficiency is theoretically greatest somewhere near maximum torque, which I guess is about 5000 RPM

Of course that is theoretical, and assumes a fairly heavy workload on the engine.

Your streamline and lean wheels won't add up to a heavy load until you reach pretty high speeds.

There was an interesting forum thread back a while ago discussing how airplanes will lean out to A:F ratios of about 16:1. At 16:1 the engine runs cooler than at 14:1 (where there is risk of burning valves)

I have meant to experiment with this, but I fear damaging the engine by running in the map transition areas.

I think forum member Raz may have experimented with this.

You would have to run rich of stoich at some points just for drivability.

Theoretically a toggle switch could be made with a fuel injected Guzzi to quickly lean it from 13:1 to 16:1 for extended touring.

At 16:1 you would be losing power, which is probably OK, since your RPMs will be up.

Just food for thought. It may not really be doable.

 

Also I am sure the combustion chamber has room for improvement.

If you want to run 16:1 dual plugging may help????

Best of luck!

 

FWIW, my V65 got pretty good gas mileage, so I don't think it is such a bad choice for an MPG project.

[dlaing]

No doubt lower RPMs than peak torque get better fuel efficiency in the real world when you have power to spare.

Lowering the RPMs would be my strategy if easy enough. I am just thinking there may be other strategies...

Even a V35 should give you adequate power, and better MPG! But the Nevada engine will give you much more reserve power, and possibly greater durability????

I'd like to take Buell Blast and turn it into an aerodynamic recumbent, but I don't have the skills for such madness.

Keep us posted with the project!

[GuzziMoto]

Heck, I was getting over 70 mpg out of a stock Buell Blast. H-D's seem to have a much more effiecent combustion chamber then Guzzi does.

[Skeeve]

Heck, I was getting over 70 mpg out of a stock Buell Blast. H-D's seem to have a much more effiecent combustion chamber then Guzzi does.

 

Yep. Big twins post-Shovel & post-Ironhead Sporties (aka "Evo Sporties", altho' that term is technically only appropriate applied to the BTs...) had motors that were specifically redesigned for combustion efficiency [aka "better power & lower emissions."] I believe I've posted repeatedly that Guzzi would benefit greatly from similar efforts applied to their antiquated hemi-heads, but so far the factory has chosen to go the dual-plugging route [applying a metaphorical Band-Aid to the emissions problem...]

 

The Buell Blast essentially uses the front head of one of the Buell "Thunderstrike"(?) heads that Erik found gathering dust in Harley's old race shop: they were a set of Jerry Branch heads that had been tested for something, and then left on a shelf. Dropped onto the ~50hp Sportster motor of the late 90s, they immediately pumped out about 20 more ponies, which made them pretty much perfect in Erik's eyes for his bikes, so he got Harley to put them into production.

 

They've since been superseded by more modern designs, but they're essentially what comes on the current 883s & Blast, iirc.

 

Anyway, that's your totally non-Guzzi history lesson for the day...

[Skeeve]

... As I mentioned above, I too have read the axiom about max efficiency at max torque, but again, if you get a chance go to the Craig Vetter Mileage tests, and what they found there seems in contravention to that. In essence, the slower they had 'em popping, the better mileage they got. After more time on this project/patent than I'd care to admit, I've learned a number of things - not the least of which is some of the 'conventional wisdom' out there, may be off the mark. The airplane fuel mixing is interesting - but I have no doubt I'd end up cooking this little goose! That's an art... and in that case ... I'm not Picasso! Anyway, one of my thoughts of the last year, is that along with our standard gearboxes, virtually all road bikes should have either a very tall high gear, or a two speed rear-end/final drive so that under the right conditions, we could lope along at lower rpm, and save a bit o' gas. Anyway, thanks again, and oh - another advantage of a V50 is the carb... inferior to fuel injection, save when a simple peasant like me wants to tinker out in the garage. Thanks Again

 

WRT the Vetter mileage tests:

 

The faster an IC motor spins, the more fuel it burns, it's as simple as that. In normal usage, keeping the motor spinning near it's torque peak will provide the best combination of mileage and responsiveness.

 

For simply seeking best mileage, a good fairing and the tallest gearing the motor can pull on level ground while putting down the road at minimal rpms will be the answer, as substantiated by Vetter's mileage competitions.

 

Your comment about an overdrive top gear is pretty much why all the "I never use top gear" comments over on Wildguzzi are there: the speed limit in the States is unsuited to maintaining the minimum rpms that the tall stock gearing on the Guzzi 5-spds requires! Of course, we've heard less of that the last few years since the 70mph national limit went into effect for the majority of the interstates, and enforcement in some areas has allowed a slight "hedging" of 5 to 10 mph over the limit before stopping you for "road tax."

 

Good luck w/ your experiments!

[chasdom]

Thanks for the info and the encouragement.

WRT the Vetter mileage tests:

 

The faster an IC motor spins, the more fuel it burns, it's as simple as that. In normal usage, keeping the motor spinning near it's torque peak will provide the best combination of mileage and responsiveness.

 

For simply seeking best mileage, a good fairing and the tallest gearing the motor can pull on level ground while putting down the road at minimal rpms will be the answer, as substantiated by Vetter's mileage competitions.

 

Your comment about an overdrive top gear is pretty much why all the "I never use top gear" comments over on Wildguzzi are there: the speed limit in the States is unsuited to maintaining the minimum rpms that the tall stock gearing on the Guzzi 5-spds requires! Of course, we've heard less of that the last few years since the 70mph national limit went into effect for the majority of the interstates, and enforcement in some areas has allowed a slight "hedging" of 5 to 10 mph over the limit before stopping you for "road tax."

 

Good luck w/ your experiments!