Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board 69 b44 tightened up crank

Had built the b44 lower end up to the point of the timing cover a few months ago. New bearings, bushings seals etc, all was good crank turned freely.

All set up to put the primary and upper end on but some frame difficulties stalled that, so moved on to other things. Just sat on the bench under some rags ready for assembly
Now crank barely moves with a big adjustable on the rotor nut. Tried oiling and a little wd40 thinking maybe the assembly lube tightened up due to the much colder conditions in the garage. Not very confident with this turn of events

No clutch or primary or barrel on. Just fitted the rotor nut when it wouldn't turn by hand.
(Was all excited to put the extra plate clutch conversion in. )

Thinking maybe the oil pump? It was rough originally but good after I dressed the end plates .

Could be as simple as a cold shop ?
try heating the engine case with whatever is handy
or bring the case inside your house for a sleepover
and see if a little warmth loosens things up .

It's a plan. I'll put it by my wood stove. It was in the 20's the last few nights. Really unenthused about another project going backwards

If you used CN instead of C3 main bearings then the cold could be affecting the internal clearance and giving some drag. A couple of days near a fire would tell you if that is the issue.

I pulled the inner and it spun freely again. That was my first successful oil pump rehabilitation and I was getting kinda disappointed. But on closer inspection the cam bush is ever so slightly either misaligned with the pin (my error) or the notch is just slightly narrower than the pin (manufacturer error) holding the top hat from being home fully. It's very close but a few cold unlubricated thousandths is probably all it takes. Going to clean the yamabond off dress the top hat a little and dry fit it again. Just glad my oil pump job wasn't the cause.

Tried again, test fit, everything spun freely (was cutting a corner by using the 2 center screws. Bolted it up fully with goo and it got tighter yet still turned ok
BUT.....( the inevitable big but)
Holding my finger on the tappets while rotating it the outer tappet (closest to the gear) doesn't smoothly ride the ramp of the cam. It hangs then snaps down when it's finally at base circle.
My theory is the distance between the bushings when the inner timing case is bolted up is pressing the cam into the tappet. Either because the outer bushing isn't fully home (as above) or the hat was manufactured thicker. The outer looks to be fully home and the inner bush is flush with the case, there's no thrust washers or endplay setting that I know of.
Or I'm tightening up the case screws too tight. There's no torque spec in the book or a gasket to make any space and it's supposed to seal the oil from getting out and crossways to keep gearlube out of the engine.
They're pozi driv screws except the one by the kicker.

Engineers bearing blue is your friend in these situations ( some cheapskates' , myself included, i have run out of the good stuff, just use blue felt tip pen to mark up the surfaces adjacent to the rotating parts) that will tell you where the high spots are when you wind it over a few dozen times.

Was searching the service manual.
Should have reread Rupert ratio book. He suggest whacking ithe case with a hide mallet if it binds or tapping the bush inwards if the float is excessive. Going to try whacking, if that doesn't work then on to the blue
Thanks!

I've never put a unit single back together with NEW bearings ( last couple of decades) where I didn't have to remove some material from the bearing to get it to spin freely.

BUT......once it did spin freely I've never had that change just sitting there?????? That's a puzzler.

Not sure what's going on with the tappets.....never had that problem either

I don't think you could over tighten a pozi screw unless you were using some kind of an impact driver?

Keep after it.......you'll get it sorted. Sometimes you need to just walk away..........give it some thought and go after it again. That light bulb will come on eventually
.

Sounds like a good theory. Do you have any camshaft end float without the tappets in the way?
That outer bushing, the sintered bronze one with the timed breather hole in the side, the flange is usually too thick and almost always needs to be machined down to get some end float. As Gordon has experienced, I too have routinely reduced the flange thickness to get the cam to spin freely with a few thou of end float. I even made a simple mandrel/fixture to do it in a drill press with the cases bolted up so the machined surface was perpendicular to the cam bearing bores.

Another issue worth mentioning is the lack of interference fit on the outer bushing, probably due to case wear. Most replacements I have seen are too small and fit too loose in the case, so I usually make my own oversize ones for a more secure fit.
That can be good advice, but I don't think the whacking is going to help you much on this situation. It really sounds like the outer bushing flange is too thick.

Gordon, yeah it is possible that I had put a couple screws in checked that it it spun put the rest in and set it aside to cure and never touched it again. I was flabbergasted when it was so tight-thus my checklist thread. Just an actual pozi driv screwdriver.
I think the tappets just binding on the face
Just forgot what I'm dealing with-old stuff that needs to be sized
My first impulse (wrong) is new parts should work like new.
I had carefully reamed both bushes so the cam would fit with the inner cover bolted on when I had the cases apart, why would I think there wouldn't be any other fiddling? Yup just walked away. At least I didn't ignore it and proceed.
Retune the mindset
Thanks guys!

Sorry to say but any book that suggests taking up excess end float by smacking a "top hat" bush in is just a good fire starter ... that is incredibly bad fitting practice!

but by all means give the cases a bit of a tickle as you button them up ... dowel pins on an old motor cant be relied on but working clearances should NOT be so marginal that one needs to resort to such measures

BUT as John Wayne would say " a mans gotta do what a mans gotta do"

Dave.....I'm no mechanic (but I do know some) or machinist (just ask my friends) but............the last two unit singles I put together from a complete strip down......I installed NEW crank bearings. I would bolt up the cases and the crank would bind......split cases, remove the bearing and use a glass plate with emery cloth (glued on). Figure 8s with the bearing and try again. I really don't have an accurate way of measuring end float so I would just keep repeating the process until the rod dropped freely on it's own. (probably 3-4 attempts) I know that wasn't the "correct" way a real mechanic/machinist would do it but it's the only way I'm set up........and I did a lot of miles on both of those engines.

WHICH IMO is a testament to the design of the BSA unit single ........if I can make one run.......just about anyone could....hats off to BSA for designing something for the working man.

Last unit single engine I did........I had Ed V do the crank for me and had him install it in the cases.....working man got lazy.

Gordon, I interpreted your earlier comments to be about cam bearings but your clarification made me think of something less related to this thread. Was your bearing issue on a B44/B50 or C15/B25's?

I rebuilt my B50 with a Carrillo rod kit from Ed V. He warned me that in his opinion the crank would true up a little wider than stock using the parts he sold me and that I might need to machine a small amount off the crank to get the main bearings to fit.

My crank trued up normal width and therefore I didn't have that problem but I also torqued the nuts after each round of truing during the later stages. This ensured that the crankpin was fully seated in the flywheels so they weren't inadvertently too wide. It's possible that was the problem with your main bearings if you were working on a B44/B50.

Stuart, it's been a long time.....but one was my sidecar's tug's engine. Readers Digest version....1967 B44R.......cracked cases. I swapped out all the internals into a different set of cases so I could get the stock cases repaired. Replaced ALL bearings with new. Had to relieve one of the crank bearings to keep the crank from binding. THAT could have easily been the different cases fault??? But by removing some of the material off the back of the bearing (band aid?) worked. Put several thousand miles on that engine before I finally got the cases fixed ( very long story)

Other engine was my B25 Trials special. I don't remember what year that engine was (pre OIF).....maybe 68? Maybe a TR25W? It's been gone too long. Funny when you're working on one it's all you can think about. Now I vaguely remember riding it. That engine I built from scratch and had the same problem. IT COULD again have been an issue with cases vs internals not being the correct parts. I tried doing my homework and get things straight......but I had to relieve those NEW bearing too. Now that I'm talking about this I seem to remember the new bearings I was using were a "bit" thicker than the stock bearings. (for those cases) But my measuring skills lack ( as can be ascertained by my motorcycle friends.....don't ask me to size a piston!!)

That's one of the problems with having a lot of spares to choose from......they are not all the same.

So when Dave mentioned his crank binding........I've had that happen the last two engines I worked on......got no clue WHY really, just know what I did to make them work.

Sounds like you had a couple of mix and match type projects going on so dimension problems could happen. My B50 was a basket case with a thrown rod but the crank and cases were from the original factory build so they probably fit correctly before I got involved.

That's the main (pun intended) reason I sent the repaired (thank you Mr Healy) cases to Ed V. I wanted to be sure they were done correctly. When I gathered the bits to install back into those cases I didn't use the bearings I had messed with. I left them in those temporary cases....Ed used new.