Calling Paul, are you there Mr Compton are you there
I have some questions about the running of the bike after a weekend of setting up the carbs and checking plugs etc.
1. Being a 1977 sport is my bike (as the manual keeps referring to) an older model or the newer model? I ask this because my timing looks to be set from the lower engine marking (checked with strobe).
2. Is it then possible that the bike would run if I had (previously) set the tappets using PMS1 and PMS2 using the camshaft axis as the mark? I figure this could not be the case and worse it would result in metal meeting metal but I just want to check with someone that has done a lot more of this.
Well I remember doing that at the time and I am fairly sure that with PMS1 in line with the cam centre, the piston was TDC. Is it the case than on the earlier bikes the PMS1 was set by the camshaft mark but the timing was set by the lower case mark?
I have two 78 models (pre electric start) and as far as I know, the difference was in what style of flywheel you have.
Prior to the electric starter bikes, they all came with a machine finished flywheel (as per your avatar) that referenced the punch mark at "9 0'clock" - this is for both TDC and max ignition advance. A simple check with a protractor will show that the PMS1 and ANT1 marks are 34 degrees apart.
With the introduction of the electric starter bikes, the flywheel became die cast with a drum for the starter shoes and the timing case gained the window at the top. On these, all references are to the cam centre line.
Where things can get muddied (and I don't know the whole story) is with the Kanguru's and Camels, which gained the die cast flywheel but not the starter drum, and these also used a timing cover very similar to the earlier kickstart only bikes.
The waters are made even murkier in that the 500 flywheel and stator will bolt straight onto a 350, and while the TDC marks remain the same to cam centre reference, the max ignition advance is less. (30 degrees instead of 34 degrees!)
With a 40 year old bike, unless you are lucky enough to have owned it from new, there is no guarantee that you still have the original flywheel on it.
So, back to your original question, would it run OK? For the tappets, the difference of approx. 90 deg of crank rotation (= 45 deg cam) in terms of cam lift could give a bigger than thought inlet valve clearance but not by much, while I would not expect to see any appreciable difference to the exhaust clearance.
For the ignition timing, I doubt it would run with the timing 90 deg out.
Hope that this helps,
George
George
350 sport 1978, 350 Strada 1978
650 Norton 1967, 650 Kawasaki 1977 and 650 Enfield 2019
Thank you for clearing some points up for me. I rechecked my timings on my 1977 Sport which has no starter and they are all taken from the "9 O'clock" mark. Using a strobe confirmed that all was well when using that mark. I just had the horrible feeling that I had set timing from the "9 O'clock" mark but PMS1 and PMS2 from the cam centre. This however must not be the case because once I started to get the carbs closer to balance the bikes power said hello and also the whole in the rev range at around 4500rpm also vanished.
Last Sunday I was able to take the bike for a 5 mile run and she pulled with a noticeable hunger through to 8000rpm cleanly. I have now ordered 48 and 46 idle jets to try and stop her stalling when coming back off power.
The 250 twin always used the cast rotor and uses the rearmost alignment mark, so I think the distinction is between electric start and non-electric start versions.
The e-start models have an inspection plug you remove to view the timing marks, so the vertical position makes sense.
Just for information, pre Kokusan Excaliburs have dual marked rotors with timing marks for 350 and 500.
Paul Compton
http://www.morini-mania.co.uk
http://www.youtube.com/user/EVguru
