BSA B50 -500 APG Build

[wobblywalrus]

All of that, including the roller bearing on the crank and the pump feeding the crank end is similar to the cure for the twin's rod bearing problems.  Maybe the rod bearing is something that works OK and simply must be scheduled for regular inspection and renewal.

Sometimes the springs would sag on the old Lucas bob weight spark advances.  The sudden power pulses of a big single at idle would slam the weights outward against their stops every couple of revolutions and this was noisy.  I took apart an engine a few times before I figured this out.  It sounded like the cams were worn flat on the lobe tips.     

[Koncretekid]

Wobbly,
The bob weights slamming out against their stops would also fully advance the spark at the same time.  Maybe some of the noise you heard was detonation.  In my case, the pinion gear was loose and could move as much as about .020" on an 11/16" diameter. If my calculations are correct, that's 10 degrees!  The cam gear would then follow suit, and the timing trigger is fastened to the end of the cam, so maybe some kind of funky spark causing detonation could cause a noise.  Or maybe, I just assumed that I heard a noise because the old BSA couldn't possibly still be running after about 21 runs (6 at Bonneville in 2010, 5 at Loring, and 9 at Bonneville in 2011.)
Tom

[Koncretekid]

Before I left Colorado, I fabbed up an oil squirter with the help of my friend/machinist Doug, because the piston pin and rings were blued from overheating.  I used an unused threaded hole in the front upper side of the case, which was probably used for a timing plug at some time in the evolution of the B50 motor.  We/Doug made a long hex headed short bolt to fit the threads (1/2"-13, luckily) with the top of the hex drilled and tapped 1/8"npt.  I soldered a plug into the end of a 1/8" copper tube, and had Doug drill a .025" hole just above the plug.  When fitted into the cases, it aims upward towards the inside of the piston.  A test just using the starter rollers with the bike in 2nd gear shot oil at least 6" into a plastic cup, and with the oil pressure gauge showing around 30 psi.  Again, this was without a spark plug, and just spinning the motor over with the rollers.  I'm hoping this will keep piston and pin a bit cooler.
Tom

[Koncretekid]

After I re-assembled the motor and the rest of the bike, I started thinking about making streamlining bodywork for next year.  Starting from scratch sounded very difficult, so I searched Airtechs LSR fairing for something that might work.  Everyone of them seemed too big except for the little CamAm 125 replica fairing from the '70's  bike that set the records.  I decided it would be easier to start with this and modify to suit.  This is how it looked set on the floor next to the bike.

[Koncretekid]

After a 3-1/2 day haul, I'm back in NS, and having waded thru most of the "honeydo" list, I've starting trying to fit the CanAm fairing.  The first photo shows the front end before I try to fit the fairing - - yes, I know the forks are upside down - - someone told me that upside down forks are better.....
I've reached a sort of an impass, and am hoping somebody out there will have some brilliant ideas on how to make the proverbial silk purse out of a sow's ear!  I've got the fairing mounted at the front, although most of the front will have to be cut away in order to see where I'm going.  But the fairing is so narrow, that I can't possibly turn the handlebars.  I'm convinced that the original CanAm rider (Bob Barker?) must have been a lot smaller then.  If I spread the fairing with a prop, it just bows outward at the top.  Looks to me like major surgery is going to be required.  Hopefully, one of our local boat builders will be able to help out, 'cause we sure don't have any bike builders around here!
Tom

[nrhs sales]

If you are going full bodywork why not just move the handlebars up higher (if possible) to clear the fairing easier?

[bak189]

1973 Can-Am rider Bob weight 135lbs at the time......that fairing started out as a roadrace fairing for a Ossa......with lots of mods to it during tunnel testing......Gustafson in Florida still has a windscreen for that fairing in stock......try to use as much of the fairing as is, wind tunnel testing made it slick...................................................................

[bak189]

In order to retain as much of the fairing as tested in the tunnel......cut it down the middle and add a section in the middle to make it somewhat wider, that is what I am doing to our fairing in order to fit it on our new Rotax powered 125c.c.................................................................

[55chevr]

That is a low bike ... are you going to put a window in the nose ?....  you already look thru the steering neck to see forward.

[wobblywalrus]

In the past I had the same task with a fiberglass fender.  I ordered two of them and cut and spliced them together to get a fender for a wider tire.  I cut one in half lengthwise and cut the center section out of the other.  I spliced all three together to get the wider one I needed.   

[Koncretekid]

If you are going full bodywork why not just move the handlebars up higher (if possible) to clear the fairing easier?

Dan, I can move my handlebars up, but they will still be wider than the fairing.  I can also cut holes for my hands and forearms, but that doesn't seem like the best way.  Making it wider at the front would seem to be better to me.

In order to retain as much of the fairing as tested in the tunnel......cut it down the middle and add a section in the middle to make it somewhat wider, that is what I am doing to our fairing in order to fit it on our new Rotax powered 125c.c.................................................................

Thanks, Bak189.  I have considered doing this, but it already seems wide enough at the bottom.  Maybe I can add a wedge shaped  piece, 0 at the bottom, and wider, about 6 more inches at the top.  Then again, that Gustafson windshield wouldn't work. By the way, is the Rotax 125 you're going to use the same as the old CanAm 125?  I believe they were all made by Rotax originally.  Also, was the rider, Bob Barker, the same one that now sells Dunlop racing tires for vintage racers?

That is a low bike ... are you going to put a window in the nose ?....  you already look thru the steering neck to see forward.

Yes, I am going to have to cut the CanAm fairing down almost to the point at which it turns under to form the fender area.  That means a custom bubble type windscreen, for sure. I'll chip away at these issues over the winter -- at least I have time.

In the past I had the same task with a fiberglass fender.  I ordered two of them and cut and spliced them together to get a fender for a wider tire.  I cut one in half lengthwise and cut the center section out of the other.  I spliced all three together to get the wider one I needed.   

Bo, thanks for the suggestion.  I am even considering using sheet aluminum to fab up the rest of the fairing, maybe only as a mold.  Know any good sheet metal workers?
Tom

[bak189]

Yes, the same Bob Barker that sells the Vintage racing tires....when Bob set those 125c.c records back in the 1970's he worked as a development engineer at Can-Am in Canada.  He now lives and has a machine shop
in Gainsville, Florida.  Bob and I go back to the early 1950's when we both had Whizzers riding in So. Cal. and later in the 50;s we roadraced
solo bikes (before my switch to sidecars) with the AFM.........No, not the same engine Bob used to set those records....this one has twice the horsepower, but still build by Rotax.
A interesting point regarding that fairing and how well it works.....on Bob's return run for record at Bonneville...the engine seized in the middle of the timed traps....Bob pulled in the clutch....stayed down inside the fairing and coasted out of the timed area 1 mile slower than  entered.  However, it should be pointed out that in addition to the fairing (front) a lot of work was done in the tunnel to the back end of the bike.

[wobblywalrus]

The book I often refer to "The Racing Motorcycle" Volume 1, ISBN 0-9512929-2-7 has a lot of info, including pictures and a table of wind tunnel test results, for a Can-Am.  Kevin Cooper from Canada did the development.  I think this is the bike you are discussing.

Sheet metal bashers were fairly common when cars were metal.  Now is is sort of a lost art.  This evening I will say something on the build diary about this subject.

[Koncretekid]

Bo,
I have read both volumes of John Bradley's "The Racing Motocycle."  They were part of the inspiration to build my own land speed bike.  I have also done some searching for more information on the little CanAm bike, including viewing photos on the Airtech website.  Bak189 (sorry I don't know your name) knows the bike and the rider very well, and has responded above.) I now see that part of the problem is that the fairing narrows prematurely in the handlebar area.  Perhaps the rules were different then, as it appears they had cutouts for the hands and forearms, which are not required now. The following photos show this concavity quite well.  I'm thinking of cutting out both sides and reforming this area by simply continuing the curve of the front out further, similar to what they have done at the lower extremities which I think are intended  to continue back to fair the foot cutouts.

[bak189]

Also keep in mind to keep the air-intake for cooling the engine as small as possible.....on the Can-am bike there was no air intake.....the engine was water cooled with no radiator....the cylinder had a water sleeve around it that was filled with water prior to the run and would boil off during the run.  The only holes in the fairing were for the narrow front fork tubes.......back then there was a black line down the course....Bob did not look out of the windscreen but stayed down and looked thru the fork tube holes at the black line to stay on course. The engine had all of 22 horsepower with a top time of 138mph. It ran on methanol....it took some to get the carburation worked out.....but with the great help of Don Vesco it all got worked out in the end
On our 125c.c. I plan to pick up cooling air for the radiator on the far backside (bottom) of the fairing using a Nacca duct (the radiator will be behind the engine)  the same could be done on the BSA.......using flex hoses to the engine for cooling