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
Fogging for Mosquitos; Valve Guide Issues and Solutions
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="ClassicBiker" data-source="post: 85145" data-attributes="member: 1632"><p>Here's a little update. I unscrewed the crankcase drain plug. Approximately 250 cc ( 8 ounces in old money <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite2" alt=";)" title="Wink ;)" loading="lazy" data-shortname=";)" />) of oil poured out, I then unscrewed the chain case level screw. Normally nothing pours out of this but in this instance 125 cc did. I then checked whether the breather assembly was still an assembly or not. I removed the ATD cover and plugs and placed the bike in fourth gear. I placed my airline with about 20 psi up the breather pipe and listened as I rotated the rear wheel. The hiss of air entering the crankcase could be heard starting and stopping as the wheel rotated. Next to make sure the return pipe was clear I blew air through it with no problem.</p><p>Now the leak down test. The good news is my home made leak down tester works. <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" /> After setting the line pressure to 100 psi I checked that both gauges either side of the restriction read the same. Now setting each piston at TDC and fiddling to get it so the air pressure didn't drive the piston down the bore was a big headache. Setting is close and wrapping a strong cord around the rear wheel with the bike again in fourth and tying the other end to the front wheel to stop rotation and gradually shortening the cord finally paid off. The line pressure on the feed side dropped to 90 psi when I opened the valve to allow air through. This is where it gets ugly.<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite3" alt=":(" title="Frown :(" loading="lazy" data-shortname=":(" /> On the front cylinder the with feed side of 90 the air pressure on the down stream side dropped to 80 psi, with the air exiting from under the front right head nut. Trying to tighten is didn't help it was already tight. So that head will have to come off to see what's up there. The rear cylinder was 90 on the feed side and the downstream was a little over 80. Took me a bit to realize the air I could hear escaping wasn't going out through the valves because the air had moved the piston and thus opened the valves, but was escaping into the crankcase. When I took the ATD cover off again I could hear it clearly.</p><p>So now I'm wondering if it is worth temporarily bypassing the oil feed to the rockers to see if the excess oil is being sucked down the valve guides. If I'm taking the front head off to see why air is escaping from under the head nut I might as well double check the valves and install seals on the stems. Along with that I'll double check the radi (as mentioned in the latest MPH) on the rockers and probably install the modified rocker bearings and feed bolts from the VOCS for good measure. If doing that to the front head I'd be foolish not to do the same to the rear. At that point I might as well lift both the barrels and check all the ring gaps. Guess I know what I'm doing this fall and winter.<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite3" alt=":(" title="Frown :(" loading="lazy" data-shortname=":(" /> It is already sounding expensive. </p><p>Thoughts?</p><p>Steven</p></blockquote><p></p>
[QUOTE="ClassicBiker, post: 85145, member: 1632"] Here's a little update. I unscrewed the crankcase drain plug. Approximately 250 cc ( 8 ounces in old money ;)) of oil poured out, I then unscrewed the chain case level screw. Normally nothing pours out of this but in this instance 125 cc did. I then checked whether the breather assembly was still an assembly or not. I removed the ATD cover and plugs and placed the bike in fourth gear. I placed my airline with about 20 psi up the breather pipe and listened as I rotated the rear wheel. The hiss of air entering the crankcase could be heard starting and stopping as the wheel rotated. Next to make sure the return pipe was clear I blew air through it with no problem. Now the leak down test. The good news is my home made leak down tester works. :D After setting the line pressure to 100 psi I checked that both gauges either side of the restriction read the same. Now setting each piston at TDC and fiddling to get it so the air pressure didn't drive the piston down the bore was a big headache. Setting is close and wrapping a strong cord around the rear wheel with the bike again in fourth and tying the other end to the front wheel to stop rotation and gradually shortening the cord finally paid off. The line pressure on the feed side dropped to 90 psi when I opened the valve to allow air through. This is where it gets ugly.:( On the front cylinder the with feed side of 90 the air pressure on the down stream side dropped to 80 psi, with the air exiting from under the front right head nut. Trying to tighten is didn't help it was already tight. So that head will have to come off to see what's up there. The rear cylinder was 90 on the feed side and the downstream was a little over 80. Took me a bit to realize the air I could hear escaping wasn't going out through the valves because the air had moved the piston and thus opened the valves, but was escaping into the crankcase. When I took the ATD cover off again I could hear it clearly. So now I'm wondering if it is worth temporarily bypassing the oil feed to the rockers to see if the excess oil is being sucked down the valve guides. If I'm taking the front head off to see why air is escaping from under the head nut I might as well double check the valves and install seals on the stems. Along with that I'll double check the radi (as mentioned in the latest MPH) on the rockers and probably install the modified rocker bearings and feed bolts from the VOCS for good measure. If doing that to the front head I'd be foolish not to do the same to the rear. At that point I might as well lift both the barrels and check all the ring gaps. Guess I know what I'm doing this fall and winter.:( It is already sounding expensive. Thoughts? Steven [/QUOTE]
Insert quotes…
Verification
What was Mr Vincent's Christian Name?
Post reply
Home
Forums
Forums: Public Access
Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Fogging for Mosquitos; Valve Guide Issues and Solutions
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