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
Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Twin oil breather modification
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="Nigel Spaxman" data-source="post: 178494" data-attributes="member: 2907"><p>My bike has such a strong vacuum in the crankcase it sucks the oil out of the primary case by the lip seal that I have behind the engine sprocket. Little oil comes out the breather, it mainly just spits out some emulsified oil on start up, when the air in the crankcase is evacuated. After my trip to California, I took the primary apart and put the seal in backwards (spring towards the primary sprocket) so that it should better prevent the oil being sucked into the engine. In 4000 miles of riding I never had to add any oil to the engine, I did add about 1 liter to the primary. The oil added to the primary didn't leak out it was sucked into the engine. </p><p></p><p>The reason my bike has a strong vacuum in the crankcase is I don't time the breather the standard way that it is advised in Richardsons and most other Vincent books. The trouble with the standard way is the breather valve closes right at the point of minimum crankcase volume. This is when the breather valve should remain open for a bit longer. The time when the crankcase pressure must be highest is at this point of minimum crankcase volume. Also the breather valve opens when both pistons are up high in their stroke. Probably air rushes into the breather when it first opens with the standard timing. The standard timing of the breather has it open for about 150 degrees. I time it so it opens and closes about 75 degrees before and after the point of minimum volume in the crankcase. Quite a few other people have had great results with this timing. You will have less oil leaks. No extra breathers are necessary.</p><p></p><p>I have that drip from behind the kickstart cover plate. I should have put an O ring on the gearbox selector shaft. I will do that one day.</p></blockquote><p></p>
[QUOTE="Nigel Spaxman, post: 178494, member: 2907"] My bike has such a strong vacuum in the crankcase it sucks the oil out of the primary case by the lip seal that I have behind the engine sprocket. Little oil comes out the breather, it mainly just spits out some emulsified oil on start up, when the air in the crankcase is evacuated. After my trip to California, I took the primary apart and put the seal in backwards (spring towards the primary sprocket) so that it should better prevent the oil being sucked into the engine. In 4000 miles of riding I never had to add any oil to the engine, I did add about 1 liter to the primary. The oil added to the primary didn't leak out it was sucked into the engine. The reason my bike has a strong vacuum in the crankcase is I don't time the breather the standard way that it is advised in Richardsons and most other Vincent books. The trouble with the standard way is the breather valve closes right at the point of minimum crankcase volume. This is when the breather valve should remain open for a bit longer. The time when the crankcase pressure must be highest is at this point of minimum crankcase volume. Also the breather valve opens when both pistons are up high in their stroke. Probably air rushes into the breather when it first opens with the standard timing. The standard timing of the breather has it open for about 150 degrees. I time it so it opens and closes about 75 degrees before and after the point of minimum volume in the crankcase. Quite a few other people have had great results with this timing. You will have less oil leaks. No extra breathers are necessary. I have that drip from behind the kickstart cover plate. I should have put an O ring on the gearbox selector shaft. I will do that one day. [/QUOTE]
Insert quotes…
Verification
What was Mr Irving's Christian Name?
Post reply
Home
Forums
Forums: Public Access
Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Twin oil breather modification
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