BSA C15S - Torque Settings

[bobby12]

Hi
Just fitting the clutch side of my rebuild and as I cannot find any BSA torque settings I came across a video which stated that the clutch basket centre nut should be set at 60 flbs, this seems very high, anyone know if its correct?

[Spaceman]

I'm sure it would take an even bigger torque without any problems but I would personally go with the torque specified for my other old non-BSA bike which is 55 ft lb or 75 Nm.

[JulianS]

This is the only factory C15 clutch torque I have seen.

[Spaceman]

It's interesting to compare the accepted ways of working on bikes from different eras. On my modern Triumph Tiger and another 35 year old bike I ride, every nut and bolt on these bikes is always tightened to a specified torque - I wouldn't dream of doing it any other way and I have tables of torque values printed out and pinned to my shed wall to make life easier.

In contrast, I have worked on countless BSA, Norton and Triumph bikes over many years and have never considered using a torque wrench on any of them and have never had a problem as a result. There's nothing wrong with trying to use a torque wrench on a BSA but experience tells me it is not normally necessary as the engineering built into these bikes is pretty tolerant to how tight you do up nuts and bolts. With a clutch centre nut in particular, I find it's normally a case of doing it up as tight as I can make it with a normal socket wrench!!

[DAVE BRADY]

Hi,

I must admit that I tend to do things up by feel but making sure that I do not use a spanner that is too long.  I have some small size Gedore ring spanners that are quite long when compared to other makes and to open ended spanners.
As they are longer it is very easy to strip a thread or even to snap bolts so I try to match the leverage of the spanner to the size of the bolt.  Things like oil pump stud nuts, carb. stud nuts, small rocker cover nuts etc, can easily be over tightened so either a good 'feel' can work instead of a torque wrench but it is surprising how easy it is to go over, say the 10 lb/ft specified for A65 carb flange nuts. 
I suppose the other thing to consider is the consequence of something not being tight enough.  A slightly loose carb. nut is easily detected and rectified but a loose oil pump may not be until damage has been caused.  Likewise a clutch that has come off its taper is a pain to put right and even the slightest movement in an alternator rotor can damage the slot in the crank before you notice the noise.
So if you have a good feel for the correct torque use a spanner, otherwise remove the doubt and use a torque wrench on nthje most important fastenings.

Dave.

[Bess]

Hi,
    With a lack of info you could use the BSA workshop recommended C25 settings, the values listed seem to be right for the components across the range.

Best wishes...

[Spaceman]

It should be borne in mind that most torque values are specified to prevent over-tightening of nuts and bolts - this is the case for the clutch centre nut. With experience, you learn not to over-tighten them which is why you can then normally work on old classic bikes without using a torque wrench.

[bobby12]

Hi
Many thanks for your various comments, I will use the info wisely.
I have fitted the clutch plates , have a new primary chain and clutch springs. When in neutral I can turn the engine only part way with kickstart, it just seems to be sold. If I put the bike in a high gear I can turn the engine over by turning the back wheel, the clutch turns ok , so is it just the friction between the plates which is stopping me using the kickstart or something else? Any comments would be appreciated.

[DAVE BRADY]

Hi,

When holding the clutch lever in does the kickstart move through its full movement?  If so then that is unlikely to be the problem but if not then investigate the kick start mechanism.
What compression piston have you fitted?  A high compression may seem like the engine is locking up if not enough force is put on the kick start lever.  Try it with the plug out.  Using the back wheel gives a much greater mechanical advantage so the compression can be overcome. 

Dave.

[bobby12]

Hi
I haven't fitted the clutch lever/cable yet, thought I could just try turning the engine over with the plates fitted to make sure all is ok. Before the clutch was fitted the kickstart mechanism worked fine. As I say using the back wheel and in gear all seems ok, maybe it is the compression.

[Spaceman]

If you take out the spark plug, the engine should turn over freely. If everything moves ok when you rotate the back wheel then the problem will not have anything to do with the clutch or primary drive.

When you say you can only rotate the engine a short way with the kickstart and the engine in neutral, what happens when you put the gearbox in 1st gear? If you get the same problem then it may well be the kickstart mechanism locking up.

[Bess]

Hi,
    As its a new primary chain, have you checked its tension throughout its travel. They have been know to have tight spots.

Bes wishes...

[bobby12]

Hi,
Quick update and another question.
Checked all items, took off the clutch plates, springs etc, re-fitted and now all is ok, in neutral the engine turns over fine using the kickstart, so not really sure what the problem was.
This may seem like a silly question, I am nearly at the stage of trying to start the bike, it has a PVL electronic ignition fitted.
Can I fill the engine with the correct amount of engine oil but with no oil in the gearbox and its cover not fitted as with the primary side, no oil or cover. In neutral can I try and start the engine; will this do any harm? Thinking if there are any adjustments to make everything will not be covered in oil.
Comments would be appreciated.

[Spaceman]

Don't you need to fit the outer timing cover before you can fit the electronic ignition system?

You have to be careful running the gearbox without any oil because it contains plain bushes. However, if you oil the plain bushes before assembling the gearbox, it will probably ok to run it for a short time.