BSA 650L

Psychopasta

Member
Finally, an update! Got all the frame parts back from powder coating, and fitted the center stand to the frame, loaded it up onto the ramp:




Getting the center stand spring on was an almighty pain, until I read the service manual and used that method...who'da thunk it? Also, I forget I needed split pins for the center stand pivot, so I rednecked a split pin with a nail:



Although 'rednecking' may not be fair, it's not far from factory o_O. Proper split pins coming soon...

Here's the trial build of the engine. I haven't added the sealing goo between the halves yet, this was a trial build to check end float. Now happy with it, so final assembly should be coming soon:





The plan is to complete the bottom end rebuild and then put the engine into the frame whilst there's nothing else in it, on the basis that that's the easiest way to get the engine in and bolted down. Then I'll complete the engine rebuild in the frame. Wish me luck!
 
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pidjones

Well-Known Member
I jamb pennys into the spring before taking it off to make it easy to put back. They can be jambed in with slip-joint pliers, even after removal.
 
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Psychopasta

Member
The factory method is to put a phillips screwdriver through the end ring of the spring, and put the end of the screwdriver in the retainer for the spring. Then lever the screwdriver down, extending the spring and moving the end ring towards the retainer. Once it's all the way there, and final twist of the wrist sees the screwdriver removed and the spring end ring on the retainer. Really crafty method.
 

ridesolo

You only bear responsibility for your own actions
I jamb pennys into the spring before taking it off to make it easy to put back. They can be jambed in with slip-joint pliers, even after removal.
Gotta be one of those, "Wish I'd thought of that!" things. Nice.
 

Psychopasta

Member
Ok, so today was get the engine back into the frame day. It's much easier if you do this before the swing arm goes in. Start off with fiuxing the engine mounting plates to the motor:



Use a lifetime's supply of painters' tape on the frame:



And in she goes, with the help of a rubber hammer to center things and a heavy-ish hammer to knock the bolts through:






Pleased with this. No scratching of the newly-painted frame, and I'm now in a position to work on several parallel jobs if one job gets held up by something unforeseen
 

Psychopasta

Member
Ok, time for an update. Lets just say this: the engine has been back out of the frame twice to fix various cockups. On reflection, I should not have tried to get it back in the frame so early. Live and learn.

Anyways, I put the timing gears back on




And fitted a new oil pump made by SRM in Merrie Olde England:




'tis a much better pump, and good oil circulation is essential for these old girls. I then disassembled the clutch entirely to check it and was glad I did. The cush drive (shock absorber) part was horribly worn, with the cush rubbers having given up all hope, and the basked having the strangest grooving I've seen:



It looks like the wrong size plates have been used at some point, and they have jumped out of the grooves. A nice new one was cheaper than the sum of the parts to repair this one:



and nice new ball bearings in the clutch:



Voila!


Now before I can assemble the clutch onto the engine I need to replace the gearbox. This was stripped down and all bearings changed, one selector fork replaced and then rebuilt from scratch:





and reinstalled in the bike




I had the cylinders measured up and they have been rebored +.02 but are still in spec for that size, so new rings and back on with the head:






My only concern at this point is that I cannot get the gearshift to change gear. Prior to putting it back in the engine I could change gears from top to bottom with just a little rotation of the gears by hand. Now with it installed, the gearchange is very stiff and does not move at all, even if I rotate the gears by rotating the output sprocket. Does anyone know if this is normal, or an indication I have messed up and need to pull the box again? I'm leaning in that direction but have done enough for one day.
 

goldy

Active Member
DTT BOTM WINNER
They can be a bit stiff to move when assembled mostly due to the pressure from the detent plunger , but you should be able to get it to move through the gears while turning the input shaft, while at the same time holding the sprocket.
 

Psychopasta

Member
Yep, I found out that the plunger can have a sticky point in its range of travel, so now I'm cleaning up my hole and polishing my plunger, so to speak.
 

doc_rot

Oh the usual... I bowl, I drive around...
DTT SUPPORTER
DTT BOTM WINNER
Yep, I found out that the plunger can have a sticky point in its range of travel, so now I'm cleaning up my hole and polishing my plunger, so to speak.
theres a joke in there somewhere! haha. Seriously though, nice work.
 

Psychopasta

Member
So I rebuilt the gearbox several times and got the same thing every time. BTW, the plunger moves in the hole very smoothly now. I'm at a bit of a loss for a simile, but its motion is real smooth. I decided that was as good as the box was gonna get, so I hooked up the gearshift mechanism and the old gear lever:




and the whole thing worked snickety-snick. It just needed the right leverage, I guess. So with all that done, it was time for the other side. Drive chain tensioner installed:



and then on with the clutch and rotor/alternator:



Rotor is in the wrong way round but is fixed now so the timing marks are on the outside, not the inside. Twat move. Clutch plates reinserted and then I added an upgrade to the clutch from SRM Engineering. This little fellow:



fits inside the clutch rod hole like so:



and then a much stiffer clutch cover goes on:


Springs and cups go back on as normal


Once the springs are screwed in, tighten the central screw until it contacts the bearing, then back it off a turn and set the lockscrew. Job done:
 

Psychopasta

Member
Did you catch the deliberate mistake? I put the alternator rotor on the wrong way round so the timing mark was on the inside. Quite impressive. Anyway, all fixed now:


I put the cover back on loosely, just two bolts and no gasket for now:

I had intended for the cover to be replated and polished but that will have to wait for the end of the Great Shutdown. I also did a trial fit of the timing side plate and end cover:


Intend to get that done properly tomorrow.
 

Psychopasta

Member
So today I fitted the gasket on the timing side (needed a little trimming)



and on she popped:



The kickstart spring seems 'good enough' but I'd welcome conformation as it just seems to sit there when the kickstart is not used. It does engage with the kickstart, and hence I think it's good enough, but would welcome comments. The timing cover is all screwed down now and I put the outer cober on with just one bolt for now:

 

Psychopasta

Member
Someone on the Britbike forum pointed out I have the spring washers on the head the wrong way round, so I fixed that:



All washers correct and in place sir!

Also, I need more tension on the kickstart spring, so I took off the inner timing cover to fix the kickstand spring properly. I had a spare gasket. This time, I fitted the kickstart ratchet into the cover, and then fitted the washer and spring. I then used a small pipe wrench to turn the spring to tension




Little bit of jiggling to get the kickstart ratchet to engage the gear pinion and in it went. Remove the wrench and everything stays in place:



Pleased with that. the kickstart lever is under tension at all times. Then I disassembled the clutch puller mechanism in the outer timing cover, and greased everything and rebuilt it:






Job's a good 'un. Unless it's not. In which case, I do it again.
 

Psychopasta

Member
So with the inlet rockers in place, it was time to put the head back on:


Nice new copper gasket with a little copaslip added:


and on she went:


I put the exhaust rockers on:



and in went the pushrods:



Rotating the engine shows all rockers and valves moving as they should. I set the gaps very approximately, as I hate the square-sectioned adjusters and will replace them with an Allen key version.
 

Psychopasta

Member
I then did a trial fit of the new exhaust, which is the 'Siamese' 2into1 type



Am I right that there are no exhaust gaskets, and the pipe just pushes straight into the port? That was the arrangement it had originally. I was able to get the RHS pipe sitting nicely



but the LHS isn't playing ball:



I hate getting mediaeval on things, so I'd be grateful for any tips and tricks in exhaust fitment you might know.
 

3DogNate

"You Meet the Nicest People on a Honda"
Man! This is looking good. You are at the point where I get pretty excited once that rocker box gets sealed up it goes pretty quick for me.
 

Psychopasta

Member
Well, the head's coming back off soon because I forgot two small orings that fit over oilways. But that's not hard with a clean engine with nice new nuts and bolts. It's onto the wheels next.
 

Psychopasta

Member
So, after a week of Honeydew lists and garage tidying, I stripped the head back down to anneal the copper gasket and add the two missing O-rings:



Top tip: when choosing a container for the quenching water, choose one that doesn't leak. Anyway:


Annealed washer, O-rings and nicely cleaned up cylinder edges. Rebuilt head, and then I checked the exhaust rocker end washer. This is the exhaust cam and final washer in place:


and this shows how far the bolt protrudes (actually it looks like the image is cut off, but the bolt is just flush with the nut:


I replaced the tappet adjusters with nice new ones with slotted ends:

and larger, hardened faces:


and then reassembled the whole thing. Got teenage son to turn the engine over with a spanner on the rotor nut and checked out the movement of the top end:


and all seems good to me. The tappet clearances are not yet set properly, I'll do that once I have the ignition installed and I do the static timing
 

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