Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board First BSA, 1972 A65L, Engine troubles

A lot of good ideas in this thread, one other possibility for the noise is a bent valve stem , this would cause lazy closing and a bit of clatter, a compression test with a gauge will show any big differences up. or possibly a broken spring.

I think , after a compression check a top end strip may be a good idea.

The occasional kickback may be a sticky advance /retard mechanism if it is still fitted with points.

I agree. While you can make styling changes which are easy enough to reverse, making a competitive racing bike is an all-or-nothing effort.


Not even the stock frame, a Trackmaster. I've never seen an OIF used for this purpose.

I was tempted..

Good luck. I put 8500 miles on my OIF this last year riding all over the country.

There were a lot of smiles in all those miles. :bigt

I helped build several Triumph based OIF flat track bikes in the 70's/early 80's. No one wanted them, we didn't have the money for an XR750. For a junior class bike, a Triumph in a stock frame would get the job done. Longer Shocks, Betor front end, glass seat/tank, and remove every unnecessary bit. We also played around with Trackmaster, Astro, and Redline swing arms to improve the handling.

I also had my own Trackmaster Triumph. What a sweet handling bike. Very predictable, very stable, and awesome hole shot frame......never rode anything that would start better. I still liked the Astro better for pure handling. Never rode anything on dirt track that would set up like an Astro in the corner. And was more forgiving. But the Trackmaster was pretty close.

And the OIF bikes......not bad, maybe a touch slow steering, but not bad. I know where 2 of the bikes I helped build are still sitting....too bad really, they did work surprisingly well

Tracker aesthetically, without any irreversible changes, no I don't plan on racing it, for those who keep bringing up the tracker thing up.. didn't mean to step on any toes haha.

Anyways, some more info on the bike: title says its a 1972 lightning, and the engine has a little over 2000 miles on it.

Engine knock is still there! Rockers and everything appear to be assembled correctly, and valve clearances are correct as per the manual.

Oil is getting to the top end, I know this because I ran it without the rocker cover on :p. Nothing dangling around in the tunnel. Everthing simple seems to be out of the question, however I haven't checked for the loose rotor, though it just seems to top - endy to be that, but may be worth a check anyways..



https://www.youtube.com/watch?v=WFYl1_bhl-8&feature=em-upload_owner


any other ideas before I have to really dig into this engine and remove the head! thanks in advance!

it still sounds like a single in the video.

The rotor nut is worth a check before you open up the top end.

Which cylinder is missing?

Zoltan, good buddy, getting back to what I said about the air boxes being upside-down in your first pic, I am really dubious of the abilities of the previous owner(s), so I wouldn't be surprised if there are many "surprises" awaiting you as you dig further into it. If it wuz me, I'd have the primary cover off and both right-hand covers as well, for starters. You can only tell so much without opening it up. Further running might could cause damage. Just my opinion based on my recent A65L experience.

So, some bad news! I called a british bike shop in Connecticut (maciag) and they have the bike on file and it had piston slap. Called a couple places and a full engine rebuild is really out of my budget. One place said that the piston slap is probably from something about starvation of oil and the crank, a 3-4 thousand dollar job. Now I could tear the engine down, maybe get the cylinders honed / bored with new pistons, but it seemed that the crank issue is what most likely caused the piston slap in the first place, so I don't wanna put a bunch of money into the top end and have the same issue not too far down the road. Do you guys think it'd be worth it too tear it down anyways?

Are all A65 engines interchangeable from various years? Was thinking it might be worth just finding a new engine entirely as a full rebuild would be far more expensive... than even an entire new bike really. Let me know what you guys think.

The new engine would need a rebuild.

This engine runs on one cylinder only making this racket.
It could be clogged pilot jet in one of your carbs or lack of compression in the cylinder, you can start with finding which cylinder doesn't work.
You can do it by touching lightly exhaust pipes after you start a cold engine. Only a few minutes id necessary to find out which exhaust pipe is getting hotter.
If you do not have a pressure tester you could just take spark plugs out and by covering their holes with a thumb during a few kicks determine if you feel any difference in pressure between cylinders, if you get any gas or oil on your thumbs from working and not working cylinder.

It's quite obvious this engine needs a rebuild, and you can make this cheaper for you doing all the dismantling and cleaning work and using machine shop for measuring and machining.
After machining work is done you can build the engine yourself with a help of this forum.
These are easy engines to build if you have a proper information.

I paid $1100 for my 1971 A65L, then spent at least $1500 to get it roadworthy. And now the motor is apart, another $2K? "In for a dime, in for a dollar," as we say hereabouts.

Piston slap is not typically caused by lower end problems; it's typically caused by excessive clearance between the piston and cylinder wall.

That's not to say you DON'T have lower end problems.

Yes, if you call a shop and say, I want a total engine rebuild, the price tag is going to be staggering. If, however, you do all of the disassembly and assembly yourself, and only farm out the things you can't do, you might get away with in the vicinity of $1K. And, if you take your time, you can dole out the money in smaller doses, which may be less painful.

Here are the things you'll probably need to contract out: 1. Cylinder head refurbishing. 2. Replacing/fitting the timing side main bush if it needs it. 3. Crank journal grinding if it needs it (let's hope not). 4. Cylinder boring/honing/fitting pistons.

On my last couple of rebuilds, I had the rebuilder assemble the crankcase - not the timing gears, oil pump, gearbox, primary drive, clutch, etc., just the crankcase with crank and camshaft. This is a quick operation and doesn't add much to the bill.

But be prepared to become a motorcycle mechanic, to acquire tools and materials as needed, and to devote a few hundred hours on this project.

thanks for the input everyone

Yes I know it is still firing on only one cylinder, the left ones not firing... didn't think it had anything to do with the noise, and its hard for me too notice the difference I'm not use to bsa's idle - along with this engine clammer..

I just ordered some 2 dvd course off eBay on a65 engine rebuilding haha... manual finally came in the other day as well..

looks like I got myself a project ahead of me... I'll be posting lots of pictures in hope for suggestions.

pulling the engine tomorrow

right, i was just quoting what this shop in nyc was trying to say to me I'm not exactly sure what they were talking about but works engineering in brooklyn was saying something about a crank issue causing oil starvation and ultimately piston slap... he was talking about 3-4 grand for a complete engine rebuild... forr 'worst case scenario' it climbed to 8-$10,000 .... lol wtf... i really don't know if he was feeding me some bs or what

Yes, he was feeding you bs .

Good plan. I hope that's the genuine FACTORY service manual you are getting. A parts book is a good item, too, I find it essential. I, too, bought the DVD before tearing my A65 down. It is helpful, my words of caution have to do with the ease with which he swings a hammer -- maybe OK if you've done it before. Also, I felt queasy as the motor rolled around on the workbench while he went at it -- you can build a simple box of short 2x4 lengths for the lower end to sit in (I think it is mentioned in the factory service manual.). (I also cringed at the shots showing the open electrical box above his workbench, but my shop is no showplace, either haha).

One thing I did to make the heavy lifting a little lighter was to strip the motor in the frame before unbolting the lower end, like this:



But you can pull it out in one piece, too, someone to help lift it out is a good idea, frame clearance is tight.

that does sound bad, first i would do a compression test on both cylinders to see haw they compare,left side might be well down stopping it running on that side,if comp is good on both check carbs and electrics if poor you need to pull the top end off check the head and bore sizes but to me that does not sound like piston slap.

how did you do that? weren't the seats cut oversize to fit the oversize valves?

Cool i'm glad it was useful either way haha.

WOW, thought that taking the engine of the frame would be the easy part.. those bolts near the center back bone are impossible to reach and loosen.. especially when you are alone.

Engine is off the bike and I let the frame and engine drain oil over night, going to bring it in the house tonight and hopefully get a little start.

found a random free washer in the valves.. someone threw this thing together

pistons look good no hot spots, also no cracks in valves.. the most "burnt" looking one is individually picture below.

still need to check spring sizes and bore size















Sort of disappointed by the DVD as one of its slogans was you just need basic tools...yet theres about 5-6 tools he made himself / bought.

Also I don't feel any play on the rods so fingers crossed i don't have to split the cases...

having trouble getting the pistons of the rods

however I believe the pistons look a bit scored? However it feels smooth theres not pitted scoring

not pitted scoring on the cylinders either..



cylinders:
























Some advice I got about the noise and rebuild:

Zoltan,
If you're going to pull the head off, I should tell you this: If the engine did not suffer oil starvation, and simply ran enough miles to wear the cylinders past normal wear limits, then with just the head off you'll see cylinders that look reasonably smooth. They would be actually worn oval, but you'd probably need to measure them to tell they were worn oval shaped.
If, as you were told, the problem was oil starvation, then you will no doubt find severe scoring and grooves worn into the cylinder wall. If you do see such scoring, then you may well need more than a top end rebuild.


Zoltan,

Without having the engine here to look at, this is all guesswork, but, I can tell you that I've seen very few A65 engines suffer from oil starvation. Also, I haven't run into a lot of those engines that have cylinders worn so far that you hear the piston slap about in the cylinder. It is much more common to have loose gudgeon pins, AKA wrist pins. It isn't actually the pins, but the small end bushing or the hole in the piston itself that gets worn and the noise is referred to as 'loose wrist pin'.

There is a way to get a good indication of whether or not you need a total rebuild versus just a top end rebuild and it's not very hard to do.

Do this: Remove the round cover located in the primary case over the alternator rotor. It's just forward of the brake pedal and has the BSA logo cast in it. (Of course, this assumes that no one has put a different year cover on your engine.) With the cover off, you be looking a the end of the crankshaft and a large nut holding the alternator rotor in place. Now, get a large pair of vise grips and lock them onto that nut. Once you've got a firm hold on that nut, push and pull it back and forth to see how far the crankshaft will slide, in and out. You should find almost no movement as the proper end float should only be 0.001 to 0.003 of an inch. If you find the crank moves only this small amount, then the crankshaft assembly is probably ok. Putting an oil pressure gauge on it to test the running pressure would be the next procedure, but that would be more involved.
If the crank moves in and out much more, like 0.050 inch or more, then you may need a complete rebuild. I say 'may need' because I have seen engines with way too much end float on the crankshaft, but the top ends were just fine.

bottom of followers


no wear on the cam though

from what I've been reading I am starting to think its small end bush wear but the manual is pretty vague about how to determine if wear is there or not, any help would be appreciated.

It also states that small end bush wear can cause high pitched tapping sounds. hm

You need lifters and a cam.....holy crap that is ugly