Here you go Ice! Careful what you ask for.
This was something I wrote some time back in response to Mark Hoyer's collumn in Cycle World (never even got a reply) about his 1954 Vellocette.
Guess I need to update it with the cracked head episode.
December 31st 2011
Bullet Trials
So I’m sitting here on New Year’s Eve reflecting on what I have and haven’t achieved for the year and I remembered that I had been intending to write a response to Mark Hoyer about his trials and tribulations with his 1954 Velocette – so here it goes.
I have been following his saga with some amusement and, not a little, empathy for I too own a 1954 British single that I ride, perhaps not daily, but often, on extended trips camping and to rallies, etc., as well as local stuff to the grocery store and occasionally to work and have covered some 9000 miles on it since it’s original rebuild in 2004.
My nemesis is a Royal Enfield Bullet 350 that I purchased in 1983 as a project, when I was (gulp) 21, still living in England and “between jobs”. I did ride it for several months before taking it off the road and disassembling it for restoration but it was shortly after this that I actually got a job, going back to sea and never to return to live in England again. So there the bike sat, in boxes, in my Mother’s garage.
Fast forward to the early 90’s - My Mother remarried, moved house and asked what did I want to do with the bike? In the meantime I had washed up on the beach in South Florida and also recently married and so I had Mother (and her new husband) crate up the pieces and ship them to me. When it arrived I bolted all the parts back together, mainly to make sure they were all there, fired up the engine (which was still in one lump) and rode it to the end of the street and back. The racket it was making indicated that something was catastrophically wrong in the lower end so it was once again disassembled.
Fast forward to the early 00’s - A change of career, a move to Georgia, other projects (including a ’70 Bonneville restoration) and life in general kept the bike in boxes again for the last ten years. Finally, having bought a new house and building a workshop, it was time to bring the old girl back to life. The initial restoration went quite smoothly, with most parts being available through Hitchcock’s in the UK, some parts coming from the “Indian” Bullet, and some rather delicate work needed to restore the rusted sheet metal. The first firing was in early 2004, just in time for her 50th birthday, and all seemed happy. Ha ha….
As with Mark I could give a blow by blow account of all the subsequent problems but that would take a week for me to write. A summary would include 3 magneto/dynamo rebuilds, 1 piston seizure, 1 rocker block coming loose, 1 failed main bearing, 1 burned exhaust valve, , etc., etc., - you get the picture.
By far the most serious failure was the drive side main bearing. While going on a charity run, with my wife on the back, the bike started emitting a terrible knocking in the lower end and I shut it down and coasted into the nearest parking lot. Fortunately we were not too far from a friend’s house and she appeared with a pick-up truck within 20 minutes of us calling her (thank you Margaret) and got the bike, and us, home.
During my initial rebuild the rattling in the bottom end appeared to be due to failure of the Enfield’s “floating bush” big end bearing which I replaced with a roller bearing setup. The main bearings seemed to be in good shape so I had made the decision not to disturb them - a decision I have since kicked myself for many times. Engine strip down on this occasion revealed that the main bearings, drive and timing side crankshafts and the drive side flywheel were toast.
New bearings, crankshafts and a used flywheel were purchased from Hitchcock’s and I eagerly pressed all the crankshaft components together and mounted it between centers to true it up. After a while it became apparent that no amount of beating with a dead blow hammer, or verbal encouragement, was going to get this thing true. So apart it came, all tapers inspected and cleaned, reassembled , beaten, cursed, disassembled, cleaned, assembled, beaten…….
In desperation I consulted Phil Irving’s “Tuning for Speed” to see what sage advice he had for truing crankshafts. One of his tips was to lap the tapers on the crankpins into the flywheel with fine compound (whilst keeping it true of course) which I did. Closer but not close enough. Apart again, lapped again, trued again and finally a maximum total indicator reading of 0.0015”. I would have liked to have seen a runout of less than 0.001” but on a 56 year old engine assembled from mismatched, old and new parts, a reading I could live with.
So with new bearings pressed into the crankcase and a trued crankshaft we’ll have this thing up and running in a day or so, right? Wrong! Every time I put the crank into the crankcase it locked up and again, no amount of verbal persuasion would make it do otherwise. But where was the problem? Individually all the components checked out fine but something was amiss when they are all assembled.
The timing side crank bearings on the early Bullet consist of a ball bearing on the inboard side of the case and a bronze bushing pressed into the outside of the case. After numerous attempts I assembled it with the bronze bushing removed and, after running a dial indicator around the bore it presses into, discovered that it was 0.003” out of true with the bore for the ball bearing. A quick hunt around the shop turned up a chunk of oil impregnated bronze, an hour on the lathe to make an eccentric bushing, high/low spots located on both the bushing and the case, new bushing installed accordingly and finally a rotating, true, crankshaft. Piece of cake – only took me about two months.
So Mark, you are not the only 1954 British single masochist out there and not all the poorly machined cases were exported to the colonies. So how is that crankcase casting coming along?
Topic: Bullet Trials (Read 2839 times)