brucey Posted June 26, 2011 Report Share Posted June 26, 2011 After 18 months, I finally fired up the Cub today. This is the 1st bike engine I have assembled and although pleased to hear it run, was slightly dissapointed at the amount of smoke and various oil leaks that need sorting. I have the following questions: How long does the engine need to run before it stops smoking? Mine has run for about 5 minutes which I thought would be enough to clear any assembly oil but it still smokes! The barrel had a good bore (hone marks still evident) and I fitted a new piston and rings during the rebuild. Is there meant to be a small quantity of oil seeping into the RH (Side point side) case? There is a vent hole near the bottom. My engine has the Alan Whitton Gear Shaft Seal Mod and Breather in the top. About an egg cup full of oil came out when I removed this cover to relocate the kickstart return spring. The oil was found before I started the engine but after I had pushed it for about 50 yds with the spark plug out to get the oil circulating. Do the rocker cover feed pipes normally have copper or fibre washers. For some reason I am finding it hard to get them to seal. I modified the pipe to fit my top tube oil tank and have just fitted 'dowty' washers to the outside to see if that helps. Looking on the bright side, it starts and it moves! It may need a bit more running time to identify some other leaks and sort the faults. Bruce. Quote Link to comment Share on other sites More sharing options...
alan Posted June 27, 2011 Report Share Posted June 27, 2011 (edited) How long does the engine need to run before it stops smoking? Mine has run for about 5 minutes which I thought would be enough to clear any assembly oil but it still smokes! The barrel had a good bore (hone marks still evident) and I fitted a new piston and rings during the rebuild. Don't panic yet, triumph used to run them in on a rolling road for about 30 minutes. However in my experience the triumph/Hepolite oil control rings struggle to cope with the amount of oil that a slider block oil pump throws around (let alone the morgo one). There are quite a few using japenese oil control rings to over come this problem Is there meant to be a small quantity of oil seeping into the RH (Side point side) case? There is a timed breather through the cam bush into this casing, the oil is meant to return to the sump via the drain hole. If you have the dizzy plug breather it is usual to block of the cam bush breather (rotate the bush to misalign the holes or fit a new blind bush) and plug the drain hole. (ps not a practice i entirely agree with, but it works for many others) Do the rocker cover feed pipes normally have copper or fibre washers. For some reason I am finding it hard to get them to seal. I modified the pipe to fit my top tube oil tank and have just fitted 'dowty' washers to the outside to see if that helps. Are the faces of the banjos in good nick? Copper washers are the norm, the manufacturing process work hardens the washers, heat them to cherry red and drop in a bucket of cold water to soften them. Edited June 27, 2011 by alan Quote Link to comment Share on other sites More sharing options...
stecks Posted June 27, 2011 Report Share Posted June 27, 2011 Interesting questions and first rate answer. Just a point if I may. I thought copper needed to cool naturally to anneal it? I may be wrong, its a long time since I annealed anything. Just found this link... Annealing washers...? Regards Peter Quote Link to comment Share on other sites More sharing options...
brucey Posted June 27, 2011 Author Report Share Posted June 27, 2011 Alan & Peter many thanks for your replies. Going back (many years) to my Toolmaking days, I'm pretty sure you let copper cool slowly to anneal it. I'll fire it up again tonight on the grounds of 'what's the worst that can happen?' It will also give me another chance to play spot the oil leak! I think I may have made a mistake on my return oil feed pipe to my top tube tank. The feed does not stick up above the oil level so oil tends to run back down the rocker feed pipe when the engine is turned off. As the top tube tank only holds about 1 litre of oil, I was thinking about fitting the oil filter kit sitting on my work bench to increase the capacity or even fit a new trials/alloy oil tank. I'll see how hot everything gets first. There is the possibiliy of fitting a mini K&N type filter direct to the top of the Alan Whitton Crank Case Breather but I'd have to be careful in wet conditions. However, it would match the bright orange main air filter that came with the Miccuni Pit Bike Carb! Interesting point about the timed breather. I'm running PVL so I put a cap head screw up the middle of the Cam Shaft to block it off as I have removed all traces of the points set up. On a side note, I also fitted Alan Whittons 'clutch lightening mod'. I'm no expert on Cubs but the clutch is as light as my friends 2009 Scorpa! Shame the brakes aren't as good though! Bruce. Quote Link to comment Share on other sites More sharing options...
goudrons Posted June 27, 2011 Report Share Posted June 27, 2011 Interesting point about the timed breather. I'm running PVL so I put a cap head screw up the middle of the Cam Shaft to block it off as I have removed all traces of the points set up. Have you just blanked the end of the cam up and left the oil ways cut further down the shaft free? I was under the impression that these oil ways in the shaft needed to be free and just blank up the hole in the end. If you've used a long bolt down the end it may have blocked them off. As for the oil in the side case, is the pump sealing against the case, I know the ball bearings that are under the pump can wear away the alloy in the side case and cause the pump to leak. Serco used to sell a kit with nylon balls, though I bet it was someone else's kit! Quote Link to comment Share on other sites More sharing options...
alan Posted June 27, 2011 Report Share Posted June 27, 2011 I think we are talking about the outer case, the inner case where the pump is is full of oil any way. You need a bolt in the end of the cam or the engine will breath into what was the points housing. there is a hole in the cam journal that lines up with a hole in bush to relief the pressure in the crank case as the piston descends. The hole in the bush breathes into the outer case, and is timed as the holes only align once every cam rev. if you hsve a dizzy plug breather, this is a much bigger hole and therefore easier route for the engine to breath through, the cam bush breather becomes redundant. it is normal to fit a blind bush and plug the drain, this stops any water getting into the engine. if you go to extremes you can then remove the outer cover completely. (check the pictures on the armac website.) Quote Link to comment Share on other sites More sharing options...
mcman56 Posted June 27, 2011 Report Share Posted June 27, 2011 I recently completed a C15 and had a difficult time getting the rings to seat. I was finally advised to assemble the cylinder dry and run it at 2500 or so rpm until hot. The result was no smoke followed by lots of smoke. After allowing it to cool, I restarted and it has been smoke free. The rings also had a very slight taper from top to bottom that was difficult to see on the first look. Quote Link to comment Share on other sites More sharing options...
brucey Posted June 27, 2011 Author Report Share Posted June 27, 2011 Thanks for your interesting replies gentlemen. I ran the bike again tonight for another 5 minutes or so with the following observations: I didn't cure the leakey rocker feeds so have fitted dowty washers both sides as a final attempt before buying new feed pipes. Oil flows back down my poorly designed Top Brace Oil Tank return pipe when the engine is stopped. The oil seeps into the rocker cover feed pipes until the level in the tank drops below the return pipe. This may explain why it is smoking on start up. I'm assuming this won't do any harm for the moment and the new Morgo pump should quickly return the oil to the tank. There is enough oil comming out the distributor hole breather to cover the bottom of the tank in minutes! I have now fitted a large diameter pipe running from the breather, up to the tank and back down the rear frame tube to just below the sump guard. My motto being, 'If you can't cure the oil leak, plumb it in!' So apart from leaking more oil than the Torrey Canyon and smoking more than Wintson Churchill, it's going well! I'll see what tonights fixes bring when I have another go on it tomorrow night. Bruce. Quote Link to comment Share on other sites More sharing options...
charlie prescott Posted June 27, 2011 Report Share Posted June 27, 2011 Hi Guy's. Hi Bruce, The best way to run in new rings on a Cub or BSA unit, is to run it for short while until it gets to hot (especially today), then let it cool, and repeat this operation until the engine changes to a much smoother note.You will tell when the tick-over revs increase, and the engine does not get so hot, Time is of the essence , as they say. You will not set up a "New" motor instantly, and the more breathing the motor has the better. Regards Charlie. Quote Link to comment Share on other sites More sharing options...
brucey Posted June 28, 2011 Author Report Share Posted June 28, 2011 Cheers for the information Charlie. This would make sense in so far that the exhaust front pipe turned blue after about 5 minutes of running (at which point I tuned it off anyway). Also the fact it seems to be 'breathing' so heaviliy through the new distributor hole breather pipe would indicate the rings aren't sealing properly yet. I can mod the top tube oil tank return pipe to prevent oil running back when the engine has stopped (or just dont fill it as high for the time being). I can also replace the leaking rocker shaft lube pipes but I don't want to start stripping the engine until it has had a good chance to bed in or I know there is definately something I've done wrong when I assembled it. I will run it up a few more times to see what happens. Bruce. Quote Link to comment Share on other sites More sharing options...
bashplate Posted June 28, 2011 Report Share Posted June 28, 2011 hi, you say the hone marks were still visable and fitted new rings......but did you glaze-bust the bore? this would be esential for getting the new rings to bed in. Quote Link to comment Share on other sites More sharing options...
pat slinn Posted June 28, 2011 Report Share Posted June 28, 2011 Talcum powder, Vim ? ! Quote Link to comment Share on other sites More sharing options...
alan Posted June 28, 2011 Report Share Posted June 28, 2011 Talcum powder, Vim ? ! a few drops of brasso down the plug hole, take the bike for a push in gear with the plug out... i didn't build TT winning engines without knowledge like that... no seriously i didnt build tt winning engines.. best of luck but i don't think that a hepolite oil control ring can handle the amount of oil a morgo pump throws around. With the barrel and piston off spin the crank around using the rod and see how much oil is picked up on the fly wheels, image how much oil is thrown up the bore at 2 - 3000 rpm.. As Pat will testify the C15 was "a new and improved cub", the C15 has a "scraper" to remove oil from the rim of the flywheels to reduce this problem. Quote Link to comment Share on other sites More sharing options...
brucey Posted June 28, 2011 Author Report Share Posted June 28, 2011 A couple of photos of the cub on its 1st run! I ran the bike on and off for about 25 minutes this evening. It seems to rev and pull o.k. The tube fitted to the distributor hole breather has solved the oil leak there and the dowty washers stopped the rocker feed oil leaks for the time being. It did start leaking from the top oil tank breather (mainly because I haven't fitted a pipe to this yet and was going down a few hills!) I was also getting some quite impressive pops and flames out of the exhaust on over run once hot. However the front pipe had become loose so I assume pulling air in. It still smokes on start up but clears after a while. I'll modify the return feed in the tank to see if this helps. Overall a succesful evening. Thanks for your advice to date. Bruce. Quote Link to comment Share on other sites More sharing options...
charlie prescott Posted June 28, 2011 Report Share Posted June 28, 2011 (edited) Hi Guy's Hi Bruce, Glad the motor seems to be bedding in. Pat is right , and he did build a TT winning motor, or two, and I once used Fullers Earth, (remember that) in a Triumph twin ,racing motor! and a tip from Dan Shorey's father, Bert, Was to always leave a newly bored barrel out side for a couple of days to let the bore get rusty before fitting it. And Dan's motors used to be quite quick, and he had the fastest Cub in the land at one time! I think it is still about somewhere? It used to live in the IOM museum. So you see the old tips are still the best. Just thought, after looking at the pictures. Is that one of Alan Whitton's super lightweight, front frame diamonds, that you have? Edit, to ask Question. Regards Charlie. Edited June 29, 2011 by charlie prescott Quote Link to comment Share on other sites More sharing options...
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