E: Engine Breather Timing: A long description of a different way (Part 1)

Michael Vane-Hunt

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VOC Member
Best to stay on topic. We are trying to find and fix oil leaks. Nigel will help us pull apart the timing chest on our bikes every evening and adjust our breather pinions while we have dinner.
 

vibrac

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VOC Member
I did not mention but I have before that the racer did not have any de compressor hole and my road twin has RE de compressors in a second plug hole that's one leak permanently stopped and a source of future problems solved
 

BigEd

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VOC Forum Moderator
I did not mention but I have before that the racer did not have any decompressor hole and my road twin has RE decompressors in a second plug hole that's one leak permanently stopped and a source of future problems solved
Getting a little off topic now but for those that don't have a spare plug hole the VOC Spares Co do very effective spacer and seal kit that stops leaks from the valve lifter.
 

Vincent Brake

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I have 10 motorcycles. I have only had the crank pin (crankshaft out) on 6 of them. Anyway that standard of ownership was Roberts not mine. When you have had the whole bike apart it does give you a certain mastery that you can only have that way. Anyway it will be really interesting to hear if some of you get some positive results from this. It makes sense in theory and I have tried it and it works. It may not make a noticeable difference on a bike that is already working well. When I first did it I was hoping it would stop the leak from my decompressor mechanism, it didn't. In the end to stop that I installed an additional spring to put more compression on the rubber, that stopped it. I think my bike probably drips more oil than some of the ones with the standard breather set up, but I think the leaks I have have little to do with the breather. Last year the problem I had was with my McDougalator leaking! Also until I put in the Cometic gasket my primary leaked. I do get some white emulsified oil dripping out of my breather when I park the bike. I notice very little oil consumption at all. I like the idea of a reed valve breather. Jim Comstock did experiments on Nortons with different reed valve and timed breathers using a very high speed pressure sensor attached to an oscilloscope. From that he designed a few different reed valve breathers for Nortons. Probably you can't do any better than what he has done.

I will try this summer:
get away with an ugly Indian Elephant and only a pipe from the original hole, already at the overhaul i did do in a new gasflowed spindle and enlarged the troughput all the way.
I am curius how it all will turn out:D
 

Monkeypants

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Non-VOC Member
What I would love to see is a Vincent with a dry back tire after a 300 mile ride on a hot day.

They all seem to put a little oil on the tire.
My 1360 is promising, but I haven't done a 300 mile summer day with it yet.
On a long group ride some years ago a friend who was new to Vincents commented on this. " Every bike here has some oil on the back tire " was his comment.
There were about ten twins plus a Comet present.
I had a good look around and he was correct.

Maybe a catch bottle is the only way to eliminate this. A better breather will only add a bit more mist to the rear tire problem.



Glen
 

vibrac

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VOC Member
A catch tank of 500cc is mandatory on a UK racer to be honest a 50cc one would have lasted us the season

A thought comes to me perhaps Graham has shot himself in the foot. Looking at a well written tome such as we have at the start of this post. This is perhaps the reason why we have so few technical items in MPH nowadays. in contrast, the other VOC (Velocette owners) have masses of technical stuff in their mag but use a Yahoo (ugh:eek:!) for an intermittent discussion group.
Time to put some of this in the mag with the note "part of the technical discussions on the forum" perhaps?
 
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vibrac

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VOC Member
Sounds like an excelent idea Tim. Are you volunteering to write something every month?
What does the exec think? and does this forum content carry the same inclusive license on content as MPH?
Having just reached parity on the copyright fees for my Book after two years I am well aware that this is an important factor
if all that seems clear "Fragments from the Forum" could be something I could warm to.....;)
 
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