The Spares Company
Club Shop/Regalia
Parent Website
Contact Officials
Machine Registrar
Club Secretary
Membership Secretaries
MPH Editor and Forum Administrator.
Section Newsletters
Technical Databases
Photos
Home
What's new
Latest activity
Forums
New posts
What's new
New posts
Latest activity
Information
Bike Modifications
Machine Data Services
Manufacturers Manuals
Spare Parts Listings
Technical Diagrams
Whitakerpedia (Vincent Wiki)
The Club
MPH Material Archive
Flogger's Corner
Obituaries
VOC Sections
Local Sections
Local Section Newsletters
Miscellaneous
Club Assets
Club History
Club Rules
Machine Data Services
Meeting Documents
Miscellaneous
Essential Reading
Magazine/Newspaper Articles/Letters
Adverts and Sales Brochures
The Mighty Garage Videos
Bikes For Sale (Spares Company)
Log in
Register
What's new
New posts
Menu
Log in
Register
Install the app
Install
Home
Forums
Forums: Public Access
General Chat (Vincent Related)
5 Speed Gearbox
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="Black Flash" data-source="post: 772" data-attributes="member: 433"><p><strong>altered gearing</strong></p><p></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">Hello Tom, I feel I have to answer your post concerning the altered gearing.</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">First off all I fully appreciate your opinion, 5 or even 6 gears is much better than 4 gears, there is nothing to discuss about!</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">but I also think that comparing a highly tuned Manx Norton raced in eager to a bored and stroked Comet, even with much higher power compared to the standard engine is not appropriate. If I understand Mick alright he is guiding tours of motorcyclists around the countryside at more or less road legal speeds <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite8" alt=":D" title="Big Grin :D" loading="lazy" data-shortname=":D" /></span><span style="font-family: 'Times New Roman'">. He is now helped by an extremly torquy engine to do so. With much increased torque on a touring bike, there is in my opinion no real need to change to a five speed box. Also there are two other reasons that spring in my mind why to alter the gearing.</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">1. engine speed. When I was working with Jaguar cars, the safe long time (10 min to 20 min) rev limit for the straight six 4.2 ltr. Engine with 106 mm stroke was ca. 5700 rpm. On german autobahn where you have no speedlimit even this figure was too much and travelling at this speed with an standard engine was calling for trouble (I learned the hard way holing pistons). It was wise not to exceed 4800 rpm on long fast journeys. From this time I know that an average piston speed of 20 m/s is sort of an universal figure in standard piston engines, you should avoid to go beyond that point consistently. On a standard comet with 6000 rpm, your piston speed is already 18m/s, with the stroked engine you already reach this magical 20m/s, so increasing the gearing by 10% makes sense, just for that reason. </span></span></p><p><span style="font-size: 12px"><strong><span style="font-family: 'Helvetica'">2. </span></strong><span style="font-family: 'Times New Roman'">More than that and even worse, you also have a 5mm shorter rod with the longer stroke, which again adds up to the piston acceleration. This puts even more stress on the piston, rod, bigend… so this is another good reason to alter the gearing beyond the 10%</span><span style="font-family: 'Times New Roman'">It would be best, if it was possible to change the engine sprocket, therefore speeding up the poor Burman box and reducing the torque in the box to make for easier gearchange, but with the Vincent ESA it is easier to change the gearbox sprocket from 18 to 21 to start with. In my opinion it is the easiest and cheapest and fastest way to have a go and try out.</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">I will ceratinly certainly try out once my bike is finished, but there are still many things to do before I can put it together.</span></span></span></p></blockquote><p></p>
[QUOTE="Black Flash, post: 772, member: 433"] [b]altered gearing[/b] [FONT=Times New Roman][SIZE=3]Hello Tom, I feel I have to answer your post concerning the altered gearing.[/SIZE][/FONT] [FONT=Times New Roman][SIZE=3]First off all I fully appreciate your opinion, 5 or even 6 gears is much better than 4 gears, there is nothing to discuss about![/SIZE][/FONT] [SIZE=3][FONT=Times New Roman]but I also think that comparing a highly tuned Manx Norton raced in eager to a bored and stroked Comet, even with much higher power compared to the standard engine is not appropriate. If I understand Mick alright he is guiding tours of motorcyclists around the countryside at more or less road legal speeds :D[/FONT][FONT=Times New Roman]. He is now helped by an extremly torquy engine to do so. With much increased torque on a touring bike, there is in my opinion no real need to change to a five speed box. Also there are two other reasons that spring in my mind why to alter the gearing.[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3]1. engine speed. When I was working with Jaguar cars, the safe long time (10 min to 20 min) rev limit for the straight six 4.2 ltr. Engine with 106 mm stroke was ca. 5700 rpm. On german autobahn where you have no speedlimit even this figure was too much and travelling at this speed with an standard engine was calling for trouble (I learned the hard way holing pistons). It was wise not to exceed 4800 rpm on long fast journeys. From this time I know that an average piston speed of 20 m/s is sort of an universal figure in standard piston engines, you should avoid to go beyond that point consistently. On a standard comet with 6000 rpm, your piston speed is already 18m/s, with the stroked engine you already reach this magical 20m/s, so increasing the gearing by 10% makes sense, just for that reason. [/SIZE][/FONT] [SIZE=3][B][FONT=Helvetica]2. [/FONT][/B][FONT=Times New Roman]More than that and even worse, you also have a 5mm shorter rod with the longer stroke, which again adds up to the piston acceleration. This puts even more stress on the piston, rod, bigend… so this is another good reason to alter the gearing beyond the 10%[/FONT][FONT=Times New Roman]It would be best, if it was possible to change the engine sprocket, therefore speeding up the poor Burman box and reducing the torque in the box to make for easier gearchange, but with the Vincent ESA it is easier to change the gearbox sprocket from 18 to 21 to start with. In my opinion it is the easiest and cheapest and fastest way to have a go and try out.[/FONT][/SIZE] [FONT=Times New Roman][FONT=Times New Roman][SIZE=3]I will ceratinly certainly try out once my bike is finished, but there are still many things to do before I can put it together.[/SIZE][/FONT][/FONT] [/QUOTE]
Insert quotes…
Verification
What was Mr Vincent's Christian Name?
Post reply
Home
Forums
Forums: Public Access
General Chat (Vincent Related)
5 Speed Gearbox
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
Accept
Learn more…
Top