Gearing Changes

[chasdom]

As a former owner of three V11 series bikes, I'm just wondering if anyone out there has done any 'gearing up' on their V 11 or other 'large block' Guzzi. My reason is that I'm presently working on a prototype for a fairing I've developed which is an improvement (with full lock-to-lock) steering capability, upon the dustbin fairings of the 1950's, but I erred in using a small block Nevada, for which gearing options are near zero. I have used a circa 1980 rear-end off I believe what was one of the old V50's, and also a 21" rear tire, but my rpm is still far too high for the power reduction allowed by the fairing. So if anyone has experimented with gearing on the bike block bikes, I'd love to hear from you. Also, has anyone out there ever lengthened a driveline and housing? Would love to know. Oh, if you're curious, you can see what I'm up to at my personal project page at toytotransportationcom my goal is to have a practical 100mpg full-sized bike. Thanks for your time, Best Wishes, Charles

[Guzzirider]

By coincidence I know the guy who is selling this:

 

http://cgi.ebay.co.uk/Moto-Guzzi-special-d...A1%7C240%3A1318

[raz]

The V11 introduced the new 6-speed gearbox along with completely different ratio final gears in the bevel box - the gearbox has much lower speed at the output. Not much to choose from I'm afraid.

 

The 5-speeds have more options, if you can source them. I believe most people that change ratio do it by replacing final gears. The most common ratios are 7/33 and later 8/33. Both of these are easily available, and has German (I think) aftermarket alternatives. The highest ratio I know have been used is 9/34 used by the 1000 Convert in late 70's and early 80's.

 

Then there is the primary ratio in the gearbox. Since there are three shafts and the primary gear is also the third speed gear, I'm not sure it's sensible to try and alter that. But you could choose a whole box from a suitable bike. The tallest I know is the 1100 Sports, but there may be others.

 

Some examples of original ratios:

[font="Courier New"]                      highest
[/font][font="Courier New"]Model       primary   gear      final   total[/font][font="Courier New"]
V11         19/32     27/23     11/32   0.2396
1100Sport   17/23     26/19      8/33   0.2452
Centauro    17/23     26/20      8/33   0.2329
Cali II     17/21     28/21      7/33   0.2290
[/font]

Then again I'm sure it's possible to use a V11 final gearset and a 5-speed box, for a very tall ratio... Maybe using some special driveshaft similar to the Convert one mentioned in the previous post. Maybe that's not even needed, I have no idea.

 

Just to get a feel for the ratios: My Sporti makes 242 km/h at 8000 rpm, highest gear, 70 profile tyre. With final gearing from a Convert it would theoretically do 265 km/h and with V11 final gears it would be... 344 km/h

 

Incidently, the 1100 Sport gearbox has straight gears, most other 5 speeds have helical. For a 100 Mpg bike that may be of benefit...

[jcbooghs]

That's the way to go, Charles! Thumbs up for your project.

 

I believe the late Le Mans 1000 gearing was the highest (primary 18/23, gear 27/19)

[chris a]

[ I erred in using a small block Nevada, for which gearing options are near zero.

 

Charles ,

the gearing on the small blocks is altered by changing the primary gear sets .these are the two gears that are between the clutch housing and the gears per se.The final drive 's are all the same I think as are the gearbox ratio's. The slines on the shafts vary according to the vintage so a partial sawp may not be feasable.

If you look in Guzziology , chapter 14-11 to 14 15 covers all the small block gearing options . They are as follows

13/24 for v 35

13/23 for v 35 imola and gt

12/24 v35 111. ntx and early tt

12/25 late tt and ntx

13/24 350 nevada

14/23 v 50, v50111 and custom

15/22 v50 monza

15/22 monza 11, v75, v65 , sp, custom, gt and florida

16/21 v65 lario, florida,750 targa, nevada 750 and 750 sp

14/23v65 tt and ntx

The easiest way to go would be to simply swap the gearbox for one with the desired ratio and as the boxes are pretty cheap and available second hand( at least here in europe) that would be a cheaper solution than getting a big block and starting all over again !

another way to go is also to adapt a big block swinging arm to the sb frame which is the option the factory took with the Baja desert racer- They only hand built 17 or so of theses and the swinging arm mounting points on the gearbox were a constant failiure point in the design so they grafted on the big block one. I'd say that the larger and stronger UJ was also a consideration as they are known to fail dramatically in the small blocks and especially on the enduro models as the swinging arm is more steeply angled due to the longer shocks.

I have a few baja pics if you are interested

Chris

[chasdom]

By coincidence I know the guy who is selling this:

 

http://cgi.ebay.co.uk/Moto-Guzzi-special-d...A1%7C240%3A1318

 

 

Hey 'Guzzirider" thanks very much for the link, but by the time I got to it Friday it was gone,

thanks again, Charles

[chasdom]

Hey Raz,

 

thank you a bazillion, as you are a wealth of information, or at least a wealth of possibilities... now I have LOTS more research, but at least a few ideas to perhaps ask the right questions - thanks again, Charles

[chasdom]

Hey "JC" thanks very much for the encouragement. Also, I checked out your link, and my compiments on your shop as it's first rate. Tell me- did anyone see what kind of bikes are the escourts for our P. Obama llimosine as he spins around your neighborhood...? It would be nice if they were Guzzi's, but I suppose they're Beemers, which is fine. I just hope he didn't haul some Hardley's over the pond! Again, best wishes, and I do hope all is well in Belgium.

[chasdom]

Hi Chris

thanks for getting me the primary ratios on the small blocks. you're idea of actually just "swapping" gear boxes is an intriguing one - if they're compatible with the later model Nevada, and also doing some back of the envelope math to see how much "taller' that would get me. As to the 'Baja", it sounds like a 'fix' with an added set of problems. Although to date on the project - every time I do something to this bike, it's like Newton's third law of physics ... they're ALWAYS a reaction in the form of a NEWLY created problem! Oh... to have the resources to be able to start from scratch...

Oh, I had no idea Guzzi ever even made a "Baja" ... that's great. Coincidentally I had one of the 'orignal' Bajas, that is back in 1971 I bought a brand new Harley Davidson (Aermacchi) 100cc Baja. Sold it about ten years ago as it was literally out in the barn for a couple hundred bucks. Probably a mistake. Although a friend told me he saw one in the area - most probably my old one - so maybe I should go buy it back. It would probably make a fun little cafe racer.

Oh well - again, thank you for the good info. and I will check it out. Chaz

 

 

Charles ,

the gearing on the small blocks is altered by changing the primary gear sets .these are the two gears that are between the clutch housing and the gears per se.The final drive 's are all the same I think as are the gearbox ratio's. The slines on the shafts vary according to the vintage so a partial sawp may not be feasable.

If you look in Guzziology , chapter 14-11 to 14 15 covers all the small block gearing options . They are as follows

13/24 for v 35

13/23 for v 35 imola and gt

12/24 v35 111. ntx and early tt

12/25 late tt and ntx

13/24 350 nevada

14/23 v 50, v50111 and custom

15/22 v50 monza

15/22 monza 11, v75, v65 , sp, custom, gt and florida

16/21 v65 lario, florida,750 targa, nevada 750 and 750 sp

14/23v65 tt and ntx

The easiest way to go would be to simply swap the gearbox for one with the desired ratio and as the boxes are pretty cheap and available second hand( at least here in europe) that would be a cheaper solution than getting a big block and starting all over again !

another way to go is also to adapt a big block swinging arm to the sb frame which is the option the factory took with the Baja desert racer- They only hand built 17 or so of theses and the swinging arm mounting points on the gearbox were a constant failiure point in the design so they grafted on the big block one. I'd say that the larger and stronger UJ was also a consideration as they are known to fail dramatically in the small blocks and especially on the enduro models as the swinging arm is more steeply angled due to the longer shocks.

I have a few baja pics if you are interested

Chris

[chasdom]

Hey Chris, I went and pulled up the page from Guzziology on the small block gearing and unless I'm being a "blockhead" which is entirely possible as sometimes gear ratios seem counterintuitive to me - when I take into account primary, high gear, final drive etc... it's almost like looking in a mirror with a mirror. I can be a wee bit slow! Anyway, just a cursory review suggests to me that the bike is already geared about as high as the small blocks go. I did add a slightly higher speed final-drive from a 500 (I don't recall the exact model offhand) that was about twenty years old, and I got an additional six percent. I also had laced (Buchanon Spoke and Rim) 21" front rim to the back wheel, and then covered it with disks - for an additional six percent or so. Still, I probably may just have to go to the big motor and transmission.

[chris a]

Hey Chris, I went and pulled up the page from Guzziology on the small block gearing and unless I'm being a "blockhead" which is entirely possible as sometimes gear ratios seem counterintuitive to me - when I take into account primary, high gear, final drive etc... it's almost like looking in a mirror with a mirror. I can be a wee bit slow! Anyway, just a cursory review suggests to me that the bike is already geared about as high as the small blocks go. I did add a slightly higher speed final-drive from a 500 (I don't recall the exact model offhand) that was about twenty years old, and I got an additional six percent. I also had laced (Buchanon Spoke and Rim) 21" front rim to the back wheel, and then covered it with disks - for an additional six percent or so. Still, I probably may just have to go to the big motor and transmission.

Charles

Ahhh ,I think you do have the highest ratio available for the small bloc .I always have a problem working out gearing !

I've two decent photos of the baja in the museum at mandello which show how the bigblock swinging arm fits on .Hopefully they come up here !I would have thought that that would be cheaper and quicker than going for a complete engine and box transplant , especially as you seem to have extreamly competant fabbing skills .Again , no idea what the ratio's work out at but logically you should be able to get what you want useing the big block final drives .

By the way your project looks amazing - i 've allways liked the idea and esthetics of the dustbins and it's really neat to see someone grappling with their issues.if you can get the faults ironed out your onto a winner .

Chris

ps

cant upload the effing pictures...Pm me and i'll send them.

[raz]

Charles, I'm curious what rpm you are targetting for the engine and what speed you'd like at that rpm. It seems to me a Guzzi is not the best engine to make mpg records with, though like with tuning, getting relative enhancements is easy and maybe your fairing is most of the trick.

 

My experience is you got to exceed 4000 rpm to get best mileage with my injected 1100. On the other hand, mpg is only my second or third priority so I haven't really experimented a lot with that in focus.

[dlaing]

Also, has anyone out there ever lengthened a driveline and housing?

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.

[raz]

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.

Yes, I reckon a bigblock is too powerful for this project unless we want 100 MPG in 100 MPH

 

Here is that thread you mentioned: http://www.v11lemans.com/forums/index.php?...0&hl=stoich

I did experiment a little with very lean mixtures but I gave up early because a Guzzi 2-valve bigblock is about the worst candidate in the universe for such things. Maybe a 4-valve smallblock is a better option?

 

I'm still keen on the idea of measuring CHT and EGT while [home-]tuning just for the hell of it. But I've yet to get a Round Tuit. The equipment is readily avaliable from the cart world.

[chasdom]

Hey Raz: To give you an exact answer is impossible, as the whole thing is an empirical process. Yes, on the one hand I've read before that maximum "efficiency" is at maximum torque rpm. HOWEVER, in real world circumstances taht may not be the case, as posited by Craig Vetter in his experience with his fuel mileage contests of the early eighties. If you're not familar with them, check them out by simply searching for Craig Vetter Mileage Contest, and there's a ton of information there. Basically, what the contestants empircially found was that high gearing/low rpm at then highway speeds (55mph for the era) were the most efficient. This seems in direct contravention to "conventional wisdom", but alas many of those guys were getting well over 200mpg, and several bested 300, with the best example at 471mpg.

As to picking the goose - it was probably a poor choice overall, but I thought the aesthetics of the bike would help. From what I have learned, today I would go with either a 500 Kawasaki or preferably Suzuki parallel twin, and just swap sprockets. Yes, a 125 or 250 would get better mileage - but what good would that do if nobody would ride them?

So my theory is - settle for a bit better than 100mpg at freeway speed, but have enough "snort" that the bike would have some roll'on power, and decent top-end - more or less 120- 135, so that a fellow could run with his pals and no get left on a weekend, but still have a PRACTICAL commuter vehicle for weekdays. Gas is cheap now - but who really believes that's going to last long?

 

Charles, I'm curious what rpm you are targetting for the engine and what speed you'd like at that rpm. It seems to me a Guzzi is not the best engine to make mpg records with, though like with tuning, getting relative enhancements is easy and maybe your fairing is most of the trick.

 

My experience is you got to exceed 4000 rpm to get best mileage with my injected 1100. On the other hand, mpg is only my second or third priority so I haven't really experimented a lot with that in focus.