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V50 gearing

Printed From: guzziriders.org - moto guzzi forum
Category: Technical
Forum Name: Small Blocks
Forum Description: V35 up to V750 including B750, V7 etc.
URL: http://www.guzziriders.org/forum_posts.asp?TID=10650
Printed Date: 08 Dec 2019 at 05:12
Software Version: Web Wiz Forums 12.03 - http://www.webwizforums.com


Topic: V50 gearing
Posted By: drøn
Subject: V50 gearing
Date Posted: 29 Oct 2019 at 21:02
How do I change the gearing on my V50 III?
it revs into the red long before it run out of power.



Replies:
Posted By: Chris A
Date Posted: 29 Oct 2019 at 22:26
Primary drive...maybe try a 650 box or perhaps you have the wrong one anyway.


Posted By: drøn
Date Posted: 30 Oct 2019 at 11:36
Thank you Chris.
I'm not experienced with the more involved works on motorbikes so I was kind of hoping I could get away with changing the final drive to a different spline count.

Is there a way to calculate/estimate what primary drive is in there?


Posted By: c13pep
Date Posted: 30 Oct 2019 at 11:52
Most of the V50 gearbox's are the same ratios internally and as mentioned it's only the primary drives that are different. Hence its a gearbox out job for any changes as the bevel box spline would a none starter.
The Monza box would be the easiest alternative

CHRIS   

-------------
you can`t have any fun in a straight line

Monza
BMW R1150RT
1200 Sport


Posted By: Barry
Date Posted: 30 Oct 2019 at 11:54
Surely the first questions should be: what is it rev'ing to? Followed by: is this acceptable within the parameters of the owner's manual?

It may simply be that the rev counter fitted is not correct for the bike, or that - if manufacturer fitted - it did not accurately show the 'red limit' for that specific model.

I had an early 600 Ducati Pantah - it came, from factory, with a rev counter that red-lined "too early". The owner's manual very clearly stated that it could be rev'd to higher limits than shown on the fitted rev counter. (Rev counter, I think, was as fitted to 500 models, and subsequently changed during the 600 production run).


Posted By: c13pep
Date Posted: 30 Oct 2019 at 12:34
Originally posted by Barry Barry wrote:

Surely the first questions should be: what is it rev'ing to? Followed by: is this acceptable within the parameters of the owner's manual




The simple answer to revs question is that maximum power is at 7500rpm as quoted in the workshop manual

CHRIS

-------------
you can`t have any fun in a straight line

Monza
BMW R1150RT
1200 Sport


Posted By: drøn
Date Posted: 30 Oct 2019 at 12:34
I just compared the gearing values here: http://www.thisoldtractor.com/mg_manuals/owners_manual_v50-iii_de.pdf" rel="nofollow - http://www.thisoldtractor.com/mg_manuals/owners_manual_v50-iii_de.pdf with my observations from this summers trip.

It seems like i'm missing the 5. gear. Or I have the gearbox or Primary drive from a V35. Sigh


Posted By: drøn
Date Posted: 30 Oct 2019 at 12:40
Now looking at this: http://www.thisoldtractor.com/mg_manuals/owners_manual_v35-ii_de.pdf" rel="nofollow - http://www.thisoldtractor.com/mg_manuals/owners_manual_v35-ii_de.pdf
Apparently the primary drive, each individual gear ratio as well as the final drive are exactly the same between the V50 and V35.

How come the overall ratios between engine and wheel differs between the two?


Posted By: c13pep
Date Posted: 30 Oct 2019 at 12:41
Did you not realise there should be five gears surely not
The difference is in the primary drive ratios (the only 2 helical gears in the box)

CHRIS

-------------
you can`t have any fun in a straight line

Monza
BMW R1150RT
1200 Sport


Posted By: c13pep
Date Posted: 30 Oct 2019 at 12:45
Check out the different primary drive ratios in the manual


CHRIS


-------------
you can`t have any fun in a straight line

Monza
BMW R1150RT
1200 Sport


Posted By: drøn
Date Posted: 30 Oct 2019 at 12:47
I must admit that I've never counted my gear changes. But I always tried shifting for a gear more and when that didn't happen assumed I was in fifth...

The manuals say: (Z = 13/24) 1 : 1,846. for both...


Posted By: c13pep
Date Posted: 30 Oct 2019 at 12:49
The primary drive ratio for a V50/3 is 14/23

CHRIS

-------------
you can`t have any fun in a straight line

Monza
BMW R1150RT
1200 Sport


Posted By: drøn
Date Posted: 30 Oct 2019 at 12:50
I can't open that link.
I have mine from thisoldtractor site as linked in my earlier posts.


Posted By: drøn
Date Posted: 30 Oct 2019 at 12:53
A printing error in the manual then. hah.

This smells like I need to source a correct primary and book a mechanic.


Posted By: drøn
Date Posted: 30 Oct 2019 at 13:04
Or it's time to put on knobbled tyres and a motocross handlebar and enjoy the great traction off road...


Posted By: Brian UK
Date Posted: 30 Oct 2019 at 13:15
According to my paper V35/50 manual, the V35 primary is 13/24 (1.846) and the V50 is 14/23 (1.642).

The V50 III is the same as the V50, but the Monza is higher, 15/22 (1.466).

All the beval drives are the same, 8/31.


-------------
Brian.

Better 5 minutes late in this world than years early in the next.


Posted By: c13pep
Date Posted: 30 Oct 2019 at 16:19
Originally posted by drøn drøn wrote:

A printing error in the manual then. hah.

This smells like I need to source a correct primary and book a mechanic.


As usual it ain`t that simple as one of the gears is on the lay shaft while the other is on the input shaft and comes complete (big job to change)
First check is to make sure all gears are present as it may only be a selector problem.
What is the road speed when you are in the red as this will be the more accurate measure of your gearing (top speed is 170Kmh according to manual)
By the way changing the gearbox is the easiest option but it will have to be a V50/3 or Monza box as all the others have a smaller diameter input shaft with a corresponding difference to the clutch etc.

CHRIS

-------------
you can`t have any fun in a straight line

Monza
BMW R1150RT
1200 Sport


Posted By: Richard Hyatt
Date Posted: 30 Oct 2019 at 17:00
I know someone else has asked , but have / can you actually select all 5 GEARS???
 
are the linkages ok or are they fouling something or gear pedal catching on something??
 
from memory , there are 2 little drilled holes in one of the linkages , is that in the correct place giving you full travel???


Posted By: drøn
Date Posted: 30 Oct 2019 at 19:25
Thanks for the pointers everybody.
I will need to employ a much more academic approach if I want to know whats what.
I recall to be going 80 kmph at 4000 rpm, but I also recall going just off 140 kmph at 8000 rpm.
That could not be in the same gear so I need to look into eliminating some error sources like my memory etc.


Posted By: Richard Hyatt
Date Posted: 30 Oct 2019 at 20:20
I think someoñe has already mentioned , but have / can you actually select all 5 gears ?
Are the linkages ok and not fouling anything?
Is the gear lever not fouling?
From memory , one of the linkage arms has 2 options of holes drilled in it , are you getting full travel for all five gears ?

Just  re-reading your last post , 4000rpm for 50 mph is about what my v50 is doing in 5th
140kmph equals 87mph


Posted By: Mike H
Date Posted: 30 Oct 2019 at 20:37
Originally posted by Richard Hyatt Richard Hyatt wrote:

Just  re-reading your last post , 4000rpm for 50 mph is about what my v50 is doing in 5th


I.e., 800 rpm per 10 mph (16.1 kph).

On which basis, 7,500 rpm = 94 mph (151 kph)





-------------
"Chicken nuggets don't dance on a Tuesday."


Posted By: c13pep
Date Posted: 30 Oct 2019 at 22:12
Originally posted by Mike H Mike H wrote:



I.e., 800 rpm per 10 mph (16.1 kph).

On which basis, 7,500 rpm = 94 mph (151 kph)





I would have thought that 94mph was the more likely `real world` figure for a V50/3 with 105mph only likely with a thump up the ar-e from a Boeing 747

CHRIS

-------------
you can`t have any fun in a straight line

Monza
BMW R1150RT
1200 Sport


Posted By: Chris A
Date Posted: 30 Oct 2019 at 22:51
Beware trying to change the primary ratios as the shafts and bearings are different sizes between the v 50 2 and monzas...spline counts are also different so mixing and trying to match can be an absolute nightmare...I've been there ! it should be reasonably obvious if the ratios fitted are v 35 ...first gear will be virtually unusable......As an aside i have a standard NTX 650 enduro...the gears are v 50 as is the clutch as factory fitted. Goes really well and very unlike any other guzzi I have ridden...it took a while to get used to and it totally runs out of steam at 160 kph.


Posted By: Mike H
Date Posted: 31 Oct 2019 at 18:32
Originally posted by drøn drøn wrote:


I recall to be going 80 kmph at 4000 rpm, but I also recall going just off 140 kmph at 8000 rpm.


Could be your speedometer is under reading at the higher end. My LM's one did, it also was km, being a second hand import. Not had it long, then speedo would not go past about 80 - 100 (kph).

I bought an English speedo for it with trip odo.





-------------
"Chicken nuggets don't dance on a Tuesday."


Posted By: c13pep
Date Posted: 01 Nov 2019 at 14:44
As a follow up have you checked out the frame and engine numbers are V50/3 ie. they should begin with PF to confirm bike is not a `bitsa`
Gearbox numbers are not as straightforward and I have never been able to work them out

CHRIS

-------------
you can`t have any fun in a straight line

Monza
BMW R1150RT
1200 Sport


Posted By: drøn
Date Posted: 08 Nov 2019 at 13:48
Hi everybody
Thanks for all the insights and suggestions.
I have now determined that the bike has the correct gear ratios.

The front tyre is slightly larger than stock at 100/90 which gives a slightly lower speedo reading.

My want og higher gearing is now down to the two facts that I am very light weight and that I feel there is a lot more throttle to give and power to get when cruising at 7500 rpms.

Messing with primary drives and gear boxes are too extreme for me, on a chain drive bike I would change the sprocket so I am looking at tyre sizes now to increase gear inches.

The rear tyre is a 110/80 which gives a circumference very close to the original 100/90 (?). The general recommendation is that you can fit 110/90. This will increase speed by about 3.75% in a given gear. I am now thinking of umping that up to 120/90... This is one size over what was stock on the V65 that had the same rims so I don't think it would be entirely unsafe...


Posted By: Chris A
Date Posted: 08 Nov 2019 at 14:10
Good news that you have the right box....Playing with the rear tyre sizes would be the logical thing to do but wider ones could well compromise the handling...these bikes were designed for skinny tyre and handle really well with them...I had no choice but to put a 130 on my T3 once as nothing else was available and the one on it was shot....and it was awful!The drive boxes on the more recent small blocs do have different ratios too , different rim sizes too there is scope there too.



Posted By: c13pep
Date Posted: 08 Nov 2019 at 15:45
A 120/90 rear tyre is what my Monza came fitted with, however they make it extremely difficult to remove the rear wheel without letting air out of the tyre or removing the bevel drive, as the cush drive fins make the gap very tight for oversize tyres.(ask me how I know    )
The big tyres definitely compromise handling as I experienced on my first V50/3, very ponderous especially on white lines.
Cruising at 7500rpm would mean that the engine is at its maximum output, according to the factory specs, so not much point in going higher and I doubt there is much throttle left if any at all.


CHRIS

-------------
you can`t have any fun in a straight line

Monza
BMW R1150RT
1200 Sport



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