V50 Gearing

[Jacks the lad]

Hi
 I have a problem with a Ex police '79 V50 MkII. The overall gearing seems to be very low i.e.  50mph at 5000 rpm.
Perceived wisdom tells me that I need to change  the input shaft (From the clutch) and the intermediate gear (on the end of the main shaft) from 13 - 24 teeth ( as shown in my parts manual - Varianti Polizia) to 14 -24 teeth.
Problem is once I got the gearbox of I found that 14-24 is what I already have! Is the change of gearing done somewhere else? Seems unlikely, but who knows? One other point, again according to my parts list the  the input shaft is 23mm Dia. and has a 32mm AF nut, but what I have is 20mm Dia and a 27mm AF nut.
If anyone is able to throw  any light on all of this, I should be most grateful.
Also, after more searching on the web this is what I have come up with:-
Assuming a circumference of 82.31" for the rear tyre, at 5000rpm
V35 with a 13/24 input gears, overall ratio 1:6.502 = 60mph
V50 ditto   14/23      ditto             ditto     1:5.783 =67.3mph
Monza      15/22      ditto             ditto     1:5.166 = 75.25mph
Sadly there is no one in my local club with a V50 to compare these figures with, maybe there is someone out there who could  comment if I have got my sums anywhere  near right. 

[boatdetective]

Jack- sorry- I don't know what to say other than it was my impression the gearing was decided by the pinion/ring gear at the rear drive (are you using Guzzi terminology and calling it the "transmission"?).

I own a V50III and the gearing isn't quite as tall as a Monza. I never ride the bike on the highway anyway- so it's not that big a deal to me.

[Jacks the lad]

As far as I can see from the parts manuals all of the small block Guzzi use the same gearbox and rear bevel drive (8/31). Makes sense when you think about it, using standard parts through out  the range makes assembly easer, cuts down the stock holding  and helps to keep costs down. Two (relatively) small spur gears would be cheaper to  produce  than different bevel and pinion gears. Overall ratio could be simply changed as required by putting the required pair of gears in during assembly, Again from the parts book they would be 13/23 for the v35, 14/23 the v50 and 15/22 the Monza

[Guido Valvole]

Your 79 police model II sounds like it's geared the same as my civilian 79 II. As I tell people, it'll cruise happily at 100 all day long -- that's 100 kph. Happy zone is between 5 and 6000, short bursts to 7, runs  like an Israeli drone… Monza gearing is better for highway, it's like having an extra gear there. But on appropriately tight and twisty roads the II is geared better. III with a little more power (maybe, yeah there are gearing differences but the II and Monza feel pretty much the same, with the higher gearing of the Monza masking the extra power) would be a hoot in the appropriate old smallblock habitat.

Monza will happily bury the needle of its Joan Claybrook Memorial 80-mph speedometer right into the stop. At which point I'm still being passed by more than I'm passing so definitely Vaguely Accurate.

Getting the gear off of the gearbox input shaft is a lot of fun. Impact driver is your friend.

Does anyone know what the recommended cruising revs and redline for V50s might be? iirc without going out to the garage, red for II is 7000 and Monza 8000 or so. Which seems high.
cr

[Jacks the lad]

Hi Guido,
100kph or about 62 mph, that would be nice but I would need to be revving quite fast to do it. The only other V50 that I know of near me is Monza and his is doing 70mph plus at 5000rpm. I would not have thought the gearing between the two models would make over 20mph at that revs. Maybe next time you (or anyone else out there who might read this) are out on your machine, you might let me know how fast you are going at that number of revolutions. Thanks

[Guido Valvole]

They were and are meant to rev, so 5-6000 keeps them happy. As I said, the Monza feels like it has a sixth gear -- 4th on the Monza is the same as 5th on the II. I'm not sure my Monza is doing 70 at 5000, I'll check over the weekend (any excuse for a ride!). But probably close. Also remember that there are plenty of differences between the V50 II and III engines -- II has bigger valves and carbs, different ignition, many castings are different… so the III and Monza should have a little more power. Hard to notice on the Monza because of the gearing.
cr