Comet Crankcase Breather

[b'knighted]

Thats great if you can identify the difference between 2.175, 2.3 and 2.425 revs once any backlash gets in. Thats if I've correctly sussed out what difference a tooth each way would make. A timing disc on a spindle inserted into the big end quill should permit you to recognise the 4.6 revs (1656 degrees) and know if your one wheel rev makes 92 degrees too much or too little.

 

[Howard]

Thats great if you can identify the difference between 2.175, 2.3 and 2.425 revs once any backlash gets in. Thats if I've correctly sussed out what difference a tooth each way would make. A timing disc on a spindle inserted into the big end quill should permit you to recognise the 4.6 revs (1656 degrees) and know if your one wheel rev makes 92 degrees too much or too little.

Good point Ian, but we've already established the wheel sprocket is right, so the difference would be a tooth on the gearbox sprocket which would make a bigger difference.

H

 

[Phil Baker]

OK. Here we go again. Retimed the breather so that it opens and closes at the correct times - when I say 'closes' I mean that there is more resistance to my breathing into the pipe and, on the same planet, open means a lot less resistance to my breathing - and fitted the Burgess silencer. Goes like a freakin' dream. Keen, raunchy LET'S GO BOYS!!!. However.... you note that there is ALWAYS a however, don't you? however, a slight seizure (petered to a stop and felt tight when I tried to kick it tho' it might still have been in gear, thinking about it). Left it five minutes to cool down and it started up again fine and I rode it home. All seemed OK until I looked at the rear tyre and in the oil tank. Lots of oil and not a lot in that order. Started it up and watched what's happening ....... oil is leaving the breather pipe that bends over the top of the dynamo at a fine fast healthy drip (I think we all know how that should be described, don't we children?). So much so that I felt like calling the Yanks with I'VE STRUCK IT!! enthusiasm. Well, gentlemen.... WHY OH WHY OH WHY ME??

Sorry, broke down there just a bit! Any ideas, please?

Phil

 

[Phil Baker]

Sorry

Apologies to anyone who finds the term 'Yanks' in any way offensive....

Phil

 

[Phil Baker]

And, whilst we're here, any ideas how to widen the hole from 10mm to about 2 inches in my lovely chromed Made in England Vincent silencer - please avoid the crasser forms of 'stick a pole up it and belt it with a hammer' if you can! Phil

 

[bmetcalf]

Apologies to anyone who finds the term 'Yanks' in any way offensive....

Phil

I can just imagine the feelings of GIs from the southern US being called Yanks during WW2. It is typical that southerners are 12 or so before they find out that damn yankees is two words.

 

[davidd]

Phil,

I am sticking to my original answer. If you are only feeling change in resistance when blowing in the tube, something is leaking and itis most likely the rings. The blow-by at or near idle is the most likely cause of the oil being transported out the breather. A leak down test is the best tool.

I assume that you are saying the Burgess is less restrictive and that it may have wanted the needle up a notch. Did you check the plug at any point?

David

Phil Irving's article on breathers is 252MPH at 15.

 

[Phil Baker]

If it seized at all it was only momentary because as soon as I felt it losing power I pulled in the clutch and drifted to a stop as it ticked down to full stop. After 5 minutes cooling it started again, no problem, and I rode it home. The breather problem may be because there is no oil returning to the tank now, for some reason. I fitted an undrilled oil cap and wonder if, now that it revs a lot more eagerly, there is an airlock forming and the oil just goes into the sump and out of the breather as soon as the sump is full. Do I need to somehow prime the oil pump again?

Jetting : I just refitted the 29/3 (had a 29/4 in it) slide and put the needle on 3rd slot and it's ticking over far too fast (can't slow it with tickover screw and eight-stroking.

Silencer - I poked a piece of pipe down each end and there's only about 150mm of baffling with the 10mm hole...... what happens if I bash it, then?

Phil

 

[b'knighted]

Hi Phil,

I am going to be no help at all but will answer one of your questions – “ WHY OH WHY OH WHY ME??”. That’s easy, its because you bought a Vincent and intend to ride it. By the time you have it sorted you will know it inside out (because you will have had most of its insides out) and every ride will have the dreaminess of today’s coupled with the satisfaction that comes from having eventually sorted it yourself. Don’t let it get you down – just shrug, remind yourself that you only do all this because you enjoy it, and put it down to the joys of motorcycling.

Keep it up,

Cheers,

 

[nkt267]

I fitted an undrilled oil cap and wonder if, now that it revs a lot more eagerly, there is an airlock forming and the oil just goes into the sump and out of the breather as soon as the sump is full. Do I need to somehow prime the oil pump again?

Does the oil return with the cap off? If not remove the drain plug from the crankcase to check if all the oil is in there, if not it may have all blown out the breather and you will have to recheck the timing of it again( closing just before BDC)..John