E: Engine More Adventures with the Comet
- Thread starter manxman
- Start date
Biggest problem was excessive wear in tunnels so no stock rocker bearing would be available to suit. So homemade bearings were to be made and I came up with the two part bearings for easy milling the slot for the rocker to size for each individual rocker after surface grinding them to get the lot into acceptable shape. There were a few things I did not like with the whole rocker bearing and oil ways over heads , no wish to weaken rockers for these feed bolt nuts anyway. So I ended with all-o-ring seals in all joints along the oil lines . I had only very knackered collection of spares in the boxes so instead of spending a lot of money on new spares with details I did not really love it was another job in my workshop - ahhmm, sort of my living room really. Securing these grub screws is in my head, thanks, a bit of mild Loctite was used here, but a little punch in the thread end would do as well. Don´t think it is as critical as in that design with split bearings because the grub presses on o-ring material, basically quite shakeproof in similar cases.
Vic
Vic
Peter, although common sense indicates that there must be some distortion it was never enough that you could feel it when moving the rocker by hand. Probably worn pins in worn bushes giving lots of clearance anyway.
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One can't help but admire Vic's work and engineering skills, but I am not convinced by his rocker bearing mod, the bearing has lost its annular integrity and it is hard to understand how a couple of squashed segments of O ring rubber could possibly retain its effectiveness over any significant period of time, I would have thought with Vic's skills a metal to metal ramp system would be better. I fitted the captive rocker feed bolts literally years ago, probably when they first became available, it seems like the only solution that I will ever need.
Peter, in real life the o-ring rubber hydraulics are just an extra, the fit of the two part rocker bearing is less than one thou play, just a nice push fit. So that fit is just like the factory hoped to achieve with production parts fitted in new engines. I certainly have rocker feed bolts with front diameter going into countersunks in the bearings to position the lot . The o-ring effect just presses any play out to the top of the tunnel, so no fretting should happen.
Definitely I did not want to weaken the rockers in the center part for clearance for feed bolt nuts, not my liking really.
Maybe a misconception: Rubberlike material may appear too soft for purpose but rubber only has soft properties when there is space for deformation. Once all space is taken up by rubber then it behaves like iron, no more give. I could have used bathroom silicone and filled up the o-ring grooves to the top and let it completely cure. After that the grub screws would do the hydraulics even better to lock all up . There is no way to go or disappear for silicone or NBR rubber so I cannot see a problem with this idea but only time can tell. Most likely I will not see any problems in my lifetime in this matter and unlikely after myself there will be somebody in need to care for old engines due to wear. Sorry for being a bit negative , but any optimist is merely somebody with uncomplete information .
Vic
Definitely I did not want to weaken the rockers in the center part for clearance for feed bolt nuts, not my liking really.
Maybe a misconception: Rubberlike material may appear too soft for purpose but rubber only has soft properties when there is space for deformation. Once all space is taken up by rubber then it behaves like iron, no more give. I could have used bathroom silicone and filled up the o-ring grooves to the top and let it completely cure. After that the grub screws would do the hydraulics even better to lock all up . There is no way to go or disappear for silicone or NBR rubber so I cannot see a problem with this idea but only time can tell. Most likely I will not see any problems in my lifetime in this matter and unlikely after myself there will be somebody in need to care for old engines due to wear. Sorry for being a bit negative , but any optimist is merely somebody with uncomplete information .
Vic
All makes sense to me. Not that you should find comfort in that.... I’ve been told I’m a little weird too.
Cyborg, no I'm trying like hell to avoid that! But we'll see. I've been pulled away from the bike for the moment so haven't yet been able to pop off the head and have a look at the cylinder/piston directly. Also I'm trying to do all that I can myself, and I've never done open heart surgery on a crankcase. Taking it apart would be easy, but putting it back together... ¯\_(ツ)_/¯
No Manxman or Manx, unfortunately. My last name is of Manx origin, from way back when (it starts with the tell-tale "Q"), so I thought it a fitting nickname on a forum for a British mark.
It was the valves, I believe. Specifically, the exhaust valve.
Removed the head. Intake valve perfectly snug in the guide. Exhaust valve has as much as 1/16 inch of play–or wiggle? Whatever the word. In bad condition.
Attaching pictures and a video below. I think the piston/cylinder wall look good. The scoring I saw before was vastly exaggerated by the endoscope I was using, I think.
Probably best just to replace the valves and guides entirely. I can’t do that work myself (I need a oven and women in my life who wouldn’t care if it reeked of oil, which I don’t have), but my thanks to others who have given me recommendations in the New England area.
Also, looks as though I’m losing oil between the muff and ET 21? Bolts seemed to be plenty tight. Is there another solution to cure this, or am I misreading what I’m seeing?
Removed the head. Intake valve perfectly snug in the guide. Exhaust valve has as much as 1/16 inch of play–or wiggle? Whatever the word. In bad condition.
Attaching pictures and a video below. I think the piston/cylinder wall look good. The scoring I saw before was vastly exaggerated by the endoscope I was using, I think.
Probably best just to replace the valves and guides entirely. I can’t do that work myself (I need a oven and women in my life who wouldn’t care if it reeked of oil, which I don’t have), but my thanks to others who have given me recommendations in the New England area.
Also, looks as though I’m losing oil between the muff and ET 21? Bolts seemed to be plenty tight. Is there another solution to cure this, or am I misreading what I’m seeing?
Sorry, But it has to be something more than the Ex valve, Messing up the spark plug,
The Ex valve would make smoke out the exhaust, But the oil would not get on to the plug,
From there.
Cheers Bill.
Your video won't work on my computer.
The Ex valve would make smoke out the exhaust, But the oil would not get on to the plug,
From there.
Cheers Bill.
Your video won't work on my computer.