Tim, did you curve the deflector in the top of the oil filler neck when using the twin start? I quite literally used a piece of baked bean can, or similar, and let the oil follow the curve of the can surface. I know sprinting is not as hard on the system as racing but I use the same system on a road bike and just don't get splash.
Misc: Everything Else Starting Problem - Series 'C' BIG Single
- Thread starter Jez Nemeth
- Start date
Jez, I have been following your progress with the Renwick Comet engine with great interest, and as you know I had some early involvement with the project, but do you really think you need a water jacket round the cylinder to progress towards a usable fast road Comet, I think I would sit down, take a deep breath of that clean Welsh air, and perhaps sink pint of SGWARNOG GWYN ALE. Roger and Anne normally turn up for the Far Far North Rally, and I notice they are booked in for the Outer Hebrides Rally in 3 weeks, I have attended a couple of Rallies with them previously, I am pretty certain that Roger rides a Bob Dunn big bore Comet, I am not sure if it is one of the biggest bores that Bob did, 665cc or something like that, and with no ghastly electric start off the ESA with extended primary chain case, Roger manages to kick it into life, and I know Rogers knees are knackered as we discussed our ailments last year, mine now fixed for life (I hope)
Rogers Comet goes very well indeed, he keeps up with us twin boys without to much difficulty, he is always 2up, as I am, so it is working plenty hard enough, I just wonder, for the additional 135cc if it is worth all the expense and aggravation, perhaps I am just getting old and lazy. I notice Alan Millyard is running larger pistons than your Comet, I think 2.5 litre per cylinder, being a home crafted 5 litre V twin, using the barrels and heads from a Pratt and Witney engine, worth a look on youtube, Alan is a seriously clever chap, I don't know what carb he is running, but it does not look to be anything out of the ordinary, as I say, take a look, no water cooling either.
P.S. He runs his carbs very rich, they look to be a huge bore, and he made them from scratch, with float bowls that he can raise and lower to adjust the mixture, this chap is one clever dude.
Peter
Rogers Comet goes very well indeed, he keeps up with us twin boys without to much difficulty, he is always 2up, as I am, so it is working plenty hard enough, I just wonder, for the additional 135cc if it is worth all the expense and aggravation, perhaps I am just getting old and lazy. I notice Alan Millyard is running larger pistons than your Comet, I think 2.5 litre per cylinder, being a home crafted 5 litre V twin, using the barrels and heads from a Pratt and Witney engine, worth a look on youtube, Alan is a seriously clever chap, I don't know what carb he is running, but it does not look to be anything out of the ordinary, as I say, take a look, no water cooling either.
P.S. He runs his carbs very rich, they look to be a huge bore, and he made them from scratch, with float bowls that he can raise and lower to adjust the mixture, this chap is one clever dude.
Peter
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yes dangled a half round shield from under cap
Mine was fixed in place by the screw adjuster for the chain oiler. Couldn't move.
I had oil pouring out of the cap until I fitted a clear plastic deflector that almost seals off the filler neck above the return.
Nothing coming past now, the area stays clean and dry.
Not sustained high revs though.
Glen
Nothing coming past now, the area stays clean and dry.
Not sustained high revs though.
Glen
It is quite easy to lose oil from the vented oil tank cap, even on modern roads, but more prevalent if you are riding a D Comet, I thought I had completely solved the problem with a blanking disc fitted above the oil return outlet, but if I have been particularly exuberant with the throttle I can still coat the RH side of the rear tyre with oil, quite worrying really, I am now experimenting with very fine brass mesh, a good friend of mine, ex racer and engineer, tells me the problem is air bourne oil droplets, and suggests a catch tank similar to an engine breather catch tank, but I can't see an easy way of doing this, space under the seat is very limited.
Hi Peter,
Just thinking aloud that's all Peter, tend to do that, can all be done -but practical to do in only one lifetime? Nope.
Air cooled is ok, convinced of it too, but lower revs and as said fitting a well hidden oil cooler, which along with a pump scavenging and squirting an oil jet at the underneath of the piston simultaneously might not be a bad idea at all regardless, cooler is simply going to be better. So a bit more durability, and a smidge cooler -closer to the temp of running meths perhaps? And then I think we're good to go again.These are easy additions once have split cases to go hunting for bits of piston.
Alan Millyard is a bit of a legend -aircooled, and it's fine, but would bet (nearly) each of those extra cylinder engines, or his big twin runs a pump significantly higher flow than what's in the case here. But then JR did do some very high rev range testing on this unit, and it survived, so it can cope in those conditions. Perhaps the constant changing of revs and other factors met on the road are less favourable to a unit which likes a more linear and possibly graduated rev experience.
Fueling -now that's the one that's got me scratching the rain detector -but 'run what we brung' and see what can be done with/to the 36mm got presently, opened up with bigger main and get it fuelled closer to what it wants -38 would be better of course!
Ignition + twin spark is absolutely superb, think we have timing 'rightish'...although maybe too much retard? We'll get there.
Other projects are taking over my time presently, so putting this one on simmer for the mo. Omega pistons are back next week, so will pick up then -but have found a compromise of a solution with liners methinks.
Jez,
I've been following your thread with interest as I've just finished my Comet special and was playing with carb and ignition issue.
I'm now happy with the bike so far, even though it has only 200 miles under its wheels.
I don't know if this can help you but here are the bike's spec:
90mm bore, 8:1 Omega
1034 concentric: 30, 106, 250, 622/122 needle 2nd groove, 3 1/2 valve.
I'm not sure about the main jet at the moment as all is brand new I don't want to try WOT until it's run in.
Ignition: Ford Fiesta points (by François Grosset), single plug, Lucas condenser.
The bike start first kick cold (don't like to be over flooded though), warm or hot. I mention "warm" because I have a Sunbeam twin which start readily cold or hot but is real pig when just warm.
After 34 years I never solved this problem so I just live with it every day as this bike is my ride to work, I don't own a car or a modern bike.
Cheers.
I've been following your thread with interest as I've just finished my Comet special and was playing with carb and ignition issue.
I'm now happy with the bike so far, even though it has only 200 miles under its wheels.
I don't know if this can help you but here are the bike's spec:
90mm bore, 8:1 Omega
1034 concentric: 30, 106, 250, 622/122 needle 2nd groove, 3 1/2 valve.
I'm not sure about the main jet at the moment as all is brand new I don't want to try WOT until it's run in.
Ignition: Ford Fiesta points (by François Grosset), single plug, Lucas condenser.
The bike start first kick cold (don't like to be over flooded though), warm or hot. I mention "warm" because I have a Sunbeam twin which start readily cold or hot but is real pig when just warm.
After 34 years I never solved this problem so I just live with it every day as this bike is my ride to work, I don't own a car or a modern bike.
Cheers.
Not sure if it helps , But I have had " warm " start up problems for some years,
I now think the bikes need flooding or choke,
Being an old mechanic , The thought of flooding a warm engine to me is wrong,
But I think this petrol we use has something to do with it,
I often go to the coast "Chilly " and the bikes get cold very quick with the wind.
I now think the bikes need flooding or choke,
Being an old mechanic , The thought of flooding a warm engine to me is wrong,
But I think this petrol we use has something to do with it,
I often go to the coast "Chilly " and the bikes get cold very quick with the wind.