The 750 saga continues

I wouldn't be too fussed about any warranty offered by a retailer.

The DMC units don't go tits up very often. But even if it does, Uwe Witt generally provides good back-up. He was very helpful when my old blue box DMC1 fried its brains after it had been in use for probably around 30 years. 20 of those before I bought the bike. In all that time the bike never had a voltage regulator installed (just a rectifier) so I'm surprised the electronic box lasted that long on an un-regulated power supply.

If it were me, I'd grab Phil's and save a handful of money rather than pay full price and get a dealer warranty that you don't need, and which may only be for a couple of years anyway.
 
If it were me, I'd grab Phil's and save a handful of money rather than pay full price and get a dealer warranty that you don't need, and which may only be for a couple of years anyway.
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Good advice - but i would say that wouldn't I! - But Too late  - now sold - Regards - Phil
 
For the moment I am going to persevere with the original contact breaker system. 
When the brand new used plated arrive from Ernesto I shall (hopefully) install them and complete timing.
 
I have known the original points to last 40,000 miles, a drop of light oil on the ATD works wonders as well.
CLEM
 
I now have the new plates from Ernesto - indeed a complete distributor assembly bar the eccentric screw.
When it warms up a little I will persevere in trying to set the timing. ::)
Three sets of points should last a LONG time.
 

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Simon Yates said:
I now have the new plates from Ernesto - indeed a complete distributor assembly bar the eccentric screw.
When it warms up a little I will persevere in trying to set the timing. ::)
Three sets of points should last a LONG time.
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Guess it depends on how much you use the bike.  Replacement interval for points was around 10000-20000km, usually 15000km, "back in the day".  No reason for them to last longer now.

Of course you can leave them for far longer, and start elongating the mounting slots once again. :D

piet
 
At last got the chance to install the Ernesto supplied points onto the bike.  There is still an odd issue with the timing which I will try to explain.  I cleaned and checked the electrical operation of the points - all ok.
Installed the rings onto the bike with the screws at the slot centres and recorded the following timings.
Outer ring (RH) 24 deg BTDC, Inner ring (LH) at TDC (correct).    ???
At the end of the slots the outer plate records 10 deg BTDC (LH end) to 36 deg BTDC (RH end).
With the outer ring at the centre, the inner ring shows 10 deg BTDC to 15 deg ATDC (just about correct).
Question - why is there such a difference between the inner and outer ring timings?
This is the same issue that I had with the original non-flat plates.
I need to bring these closer together before moving the gears again.

I can move the timing gears one tooth and set the timing to TDC by having outer plate set to one end of slots and inner to the other end.
Obviously, moving the outer plate affects the inner timings.
 
Hi, Simon.
Question - why is there such a difference between the inner and outer ring timings?
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Though I'm absolutely sure you've adjusted them carefully, different gaps are the thing that
comes to my mind first.
I'll have a look this week. I should have an auto-advance unit left. I can lend you that for
trouble-shooting if you wish. Can't imagine but perhaps that plate is bent?

Ernesto
 
Thanks Ernesto.  I checked the plates and they seem to be flat.  The auto-advance unit cannot effect inner and outer plates differently.  Lets see if there are any other suggestions. 
I believe that a smaller gap, say 0.3 mm will retard the spark and vice versa.
As a matter of interest I will try changing the points gaps to, say 0.2 mm and 0.6 mm for the outer and inner rings. 

Surely it cannot be this critical a system.
 
Today I tried smaller and larger gaps to establish the effect.
Anyway, this morning the initial readings with  plates in the middle of slots and 0.40 mm gaps were - outer 45 BTDC, inner 25 BTDC.  Before adjusting the gear positions I was trying to get the inner and outer timings to read the same.
Anyway, I moved the oil pump gear 2 teeth CCW and re-assembled leaving the Jesus nut loose.
The new readings were outer 3 deg BTDC, inner 1 deg BTDC.  :D :DWhy so close to TDC and virtually the same I do not know but really please to find it. :o :o  Might be because I retired a week ago.
I shall now reassembly properly and hope to find the same readings before my strobe arrives to fine tune.

 
Well finally the 750 ticks over below 1000 rpm and sounds much better than it did before.
I am waiting for a strobe to arrive before I finally set the ignition timing.  One downpipe is warmer that the other - only to be expected as I now need to match the throttle lifts and tweak the bleed screws.
One observation during the reassembly regarding oil pump thrust washers.  The exploded diagram shows there to be one per side of the gear.  There is one on the inside of the pin but there were two on the outside.  This has resulted in some wear on the inside face of the oil seal boss.  I excluded the thinner shim which should stop any further wear. 
Still lots to do especially regarding securing the tank and seat.
 
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