Can any one point me to a detailed source of how to adjust this, as it appears to be beyond me or at best trial and error. 

 

In that the cam is on the flywheel and the flywheel covers the screws that adjust it the timing. 

 

So you can check BTDC once its on but have to take the flywheel off to adjust it then assemble to check it and see how close you have got? 

 

Or am I being daft !?

 

G :-) 

It's a long time ago so I might be wrong.but I put a bultaco pursang motorplat ignion on my bultaco trials bike in place of points and there was a hole though flywheel and back plate that you could put a rod through to line the up in the right place then take the flywheel off tighten back plate then put flywheel back and tighten sorry if I'm wrong as I said it was a long time ago good luck

Hi Stanmet - These have points but there are no alignment holes (just the long slot to adjust the points through)? 

Hi isn't there slots in the fly wheel to adjust the points very fiddly but possible sorry about before thought it was electronic

Yes there is a slot but don't think its possible to adjust the back plate through it, just the points.

 

 

 

and no worries, I have been looking at switching to electronic but the £240 that Electrex want reminded me that the originals were still working fine!   

First clean the points and set their gap, taking your time to get it exactly right. Then with a dial test indicator (DTI) in the plug hole turn the flywheel until the piston is the required distance BTDC. Where the flywheel is close to the engine casing "chisel" a very light slot in the casing. At the inner end of the slut centre punch a shallow dot in the flywheel. Fill the dot and the slot with black marker pen or something else so they stand out clearly.

Using a strobe light check the alignment of the dot and the slot. Adjust the stator backplate until the marks align correctly under the strobe light. Having these permanent marks makes points and timing setting / checking easy in future. I used to find my Monts stayed in time for many months whereas Bultos used to go out of adjustment after about 6 trials.

Remove flywheel. Bolt backplate in original position, or centre of slots if not sure. Replace flywheel. Slacken points screw and set points to correct gap through slot in flywheel ( yes it's a bit fiddly but when you've adjusted it a few times you get the hang of it), then retighten screw. Check timing using a dial gauge in the plug hole. If it's fairly close to correct adjust points to retard or advance. If it's a long way out move backplate one way or t'other to advance or retard and reset points.

When you've got it right check again when backplate screws, points screw and flywheel nut are all fully tight.

Mmmmm so unfortunately it was 'designed' that you have to pull it to bits adjust it and assemble it to check it !  

 

Still thanks for the tips on setting it all useful stuff.

 

G :-)  

Additional minor tip on this to speed up the process - an electric screwdriver with a socket on effectively turns the engine over for the strobe once the plug is out to test how close your getting!