Comet Crankcase Breather

[Phil Baker]

OK, I've got it running again now - can't tell how well it goes or whether it's going to throw vast quantities of oil out of the breather on a run because, just for a change, it's raining!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Oil is recirculating and pumping back into the tank. I have refitted a vented oil tank cap. I am now running it on a VOC stainless steel silencer loaned by Stumpy. Put all the carb stuff back as it was before I got excited and changed it all - 29/4 slide, 2nd needle slot. Ran it up and it ticked over at about 2500 revs. Stopped it and buggered about with the tickover setup screw so that it does useful things like adjust the tickover - ditto throttle cable adjuster. Adjusted the points back to 12 thou. Starts easily. Makes one HELL of a bang if one doesn't hold the kill button down long enough - that's worth remembering!!!

I only do all this because I crave attention, you DO know that, don't you?

Phil

 

[Phil Baker]

OK, back to the silencer problem. There is about 6" of baffle with a 10mm hole running through it and this seems to rpoduce too much back-pressure for the Comet. How do I go about modifying it whilst avoiding the temptation to bash and hope? Shall I try drilling a few holes in the flat plates that surround the central hole each end of the baffle?

Phil

 

[Phil Baker]

Been out for a quick thrash betwen the raindrops and it goes much better with Stumpy's exhaust (not quite as wel as with the Burgess virtually straight-through!). Oil's returning OK, went up hill at quite a lot more than 25mph. So, that would seem to have been the power problem all along......

Phil

 

[b'knighted]

"How do I go about modifying it whilst avoiding the temptation to bash and hope? Shall I try drilling a few holes in the flat plates that surround the central hole each end of the baffle?"

You could try a holesaw fitted with a spigot to locate in the 10mm hole. Better still put it on a long spindle located in the front and tail pipes. Doing it that way you could try increasing the bore a bit at a time, although I think that you may as well go as big as you can straight away.

 

[Phil Baker]

The problem I am having is that I cannot visualise the construction of the baffle. It seems likely that it is like a tin can with both ends intact and a 10mm bore pipe welded along the centre. If that's the case then drilling the centre hole out to a larger size will result in the centre pipe falling out...... anyone know for certain what's in there, please?

 

[nkt267]

I understanding is that this should have be a spiral baffle silencer. The baffle should be a spiral welded around the 10mm tube, at least the one on my brothers Meteor is, and that is good for over 80mph with very good acceleration.Very little restriction to the flow of exhaust gases as they flow around the spiral,at least on a single anyway. At 70mph you can see the top links rise when you open the throttle.John

 

[Phil Baker]

Tried diamond holesaw and long drillbit at the local HSS Toolhire place (found a motorcycling manager!) but couldn't make any impression on it so went to Armours yesterday and bought one that looks very much like the Burgess internally. We'll see how that goes..... Then I'll have to set up the carb to match it and it should all be done. (Obviously I don't believe that!)

Phil

 

[Phil Baker]

Went for a 60 mile blast today and it's going fine now! (Apart from a few carburation issues which will take the usual methodical sorting out... some very amusing bangs from the exhaust in the meantime!) Phil

 

[Howard]

Phil, I've had some pretty naff silencers over the years, but if that's all that was making your Comet so gutless, it's got to take first prize. I don't know about a diamond hole saw, I think I'd use a roadroller on it.

H

 

[Phil Baker]

Silencer

Yes, Howard, it was most annoying - it looked so bright and shiny, too!!

Phil;-)