Everything has to be right for the timing

So the new plug was in, and sure, she was trying to fire but she just wouldn't run.
I gingerly (i didnt want to strip any threads again) tightened things down in the attempt to ensure that there was no air leakage in or out of the barrel (weak fuel mix / low compression) but to no avail.
I checked the contact breaker points gap, and investigated the advance/retard timing.  A fellow Manurhin owner and regular rider (so therefore knows what he is talking about) had told me that the easiest thing to do was to rotate the stator plate hard to the left (anti-clockwise) - no timing adjustment required "it works for all versions" - but it wasnt working for me - so I spent a long time finely adjusting the timing - bearing in mind that each adjustment required the starter mechanism to be removed and refitted - it was all very boring - and nothing was helping my engine to run correctly.

Eventually I reasoned that my condenser was knackered, and having the spare engine from the old black donor Manurhin, I looked into exchanging the condensers (and perhaps the stator and flywheel)
I should have guessed..... it was never going to be that easy!

My flywheel on left,   donor bike flywheel on right

It turns out that I have 2 manurhin engines of different designs.  Which, while didn't help me resolve my problem, was interesting to discover and learn about.  I don't know for sure yet, but I think I am looking at the difference between what the spares manuals call "Polygone coupling - cone 1.75" and Polygone coupling cone BNA 15%" This has always baffled me - The exploded parts diagram shows the crankshaft with 2 part numbers and these two descriptions.  I need to strip the latest engine to investigate further but for now the 2 first obvious differences are 1. my engine has a pin dowl to position the flywheel on the crankshaft while the other engine has a woodruff key, and 2.  My engine has a far smaller diameter crankshaft than the other - which means I couldn't swap the flywheels even if I wanted to without swapping the crankshafts too.  This investigation; to be perused one day when my scooter is on the road and my bench is clear.

More importantly though, as I removed my flywheel from the shaft I found, to my horror, that the pathetic alignment dowl (that i had had machined especially) had sheered!
When had it sheered?... and then I started to wonder...... if the flywheel was out of alignment due to a sheered pin then maybe this is why the engine wasn't running correctly?
I wondered how the pin could have sheered - granted it is a pathetically thin pin - 2mm dia - and I had only used silver-steel for the pin (preferring this to be damaged if anything was going to be damaged - So actually this was a perfectly designed fail!) - but I wondered if I had tightened the flywheel onto the tapered shaft enough? The trouble with 'experimental' rebuilds (as opposed to a known rebuild) is you are always fitting and removing so sometimes don't do a proper tighten-up of nuts...... had I let the flywheel run loose?
Whatever the reason for the fail, I was motivated again to see if this was the simple solution to my running problem.  A quick drill out of the sheered pin, another pin made up, some careful refitting and lots of tightening, and....... bugger me, she started and ran like a dream!
I've said it before, and I'll say it again...... I am a nobhead! ;-)

Kids, do as I say, not as I do

Been trying to get my engine running.  The bike is all set up on the bench with my new 'prototype' electrical loom in place.  I've replaced the head that I stripped (grrr :-( and I've lashed up a gravity fed fuel supply from an old baked-bean can - So why isn't she starting properly?

DKW workshop manual - note someones penciled reference

a little historical time line of all my sparkplugs

Well first up, Ive been a bit concerned about my spark plug after seeing that it doesn't seem to be long enough to reach well into the firing chamber (should it?)  I looked back at my emails to The Green Spark Plug Company who I first turned to for advice for a new sparkplug.  They were very helpful especially as they didn't know the bike and I had very limited information to offer them.  At the time (remember this was way before I had access to manuals, handbooks, and fellow Manurhin owners) the only thing I had to go on was the old spark plug in the engine.  I ASSUMED that this was an original specification [you wouldn't think that I made my living out of helping people to overcome their assumptions would you?].  Now with the benefit of workshop manuals, my assumption was in doubt

The DKW Hobby workshop manual (that I now have) suggests either BOSCH W225T1, or BERU 225/14u2 (and in the copy of the manual I have, someone has penciled CHAMPION L85 and BOSCH W5AC as well)  And just to make the whole picture even more mud-like, My scooter was fitted with an AC 44-5, and the old black manurhin that I acquired has an NGK B6HS

All this additional data is of course a good thing, but it did have me pulling my hair out for some time (interestingly, none of the owner handbooks give a sparkplug reference - though they do state an electrode gap)  Fortunately the Green Spark Plug Co have a very good comparison table on their website and so with a bit of detective work I got to a point where it dawned on me that I have been trying to run the scooter with the wrong spark plug type (it should be a 12.7mm reach and not a 9.5mm reach)  I had foolishly ASSUMED that the plug in the bike as I had bought it was of correct spec! Will I ever learn?

For sake of completion on this topic - I have now fitted an NGKB7H-S

Crisis of confidence

I've been having a crisis of confidence recently at work.  I am worried that I am losing my touch, and I am seeing people coming on line who are bigger, better and brighter than I am - I'm not so sure I can cut it for much longer.  This can make me feel a bit low sometimes, but I can usually brighten myself up with the comfort that actually I am quite good with a spanner.  Sometimes I can feel quite proud of the progress I make with projects in the garage.......  Well that was until today :-(

After spending a good hour yesterday trying to fit my new starter cable (£10 +£10 delivery from Greiner-Oldtimerteile :-(  and fettling a fastening device (that failed hopelessly) in the starter handle, I spent the rest of the day trying to start my engine.  She fires, but wont run.  Thats fine, its just a case of tuning everything to run in harmony.
I cant tell you how many times I had the carb and starter housing off.
The carb kept flooding.  I cleaned and cleaned the float valve (it always worked correctly on the bench!) until she seemed to hold the fuel in as designed.
And I kept checking and fine tuning the timing and points (which means taking the starter case off.... and putting it back on to start the thing to see if you've got it right) - its a slow old process.
She would fire ok (I had yards of spark) but I was getting some backfire now and then, and my plug was always soaking.  And after every firing (but not continuing to run) i felt like i was getting a smokey emission from places other than the end of the exhaust - was this simply oily surfaces burning off, or had I not tightened everything down enough?
I ended the day feeling a little disappointed at not having got her running, but hopeful for solving it tomorrow.
Tomorrow (thats today) came and sadly its been hopeless

I used to comfort myself that while I was feeling crap at my job, I was pretty good in the garage.  Today I realise I'm not good at that either :-(
I made a fatal error today.  A schoolboy error.  An error that I dont think I've ever made before.
So embarrassed am I with myself, I wondered wether to avoid reporting the story in this blog - I reasoned eventually that I am not trying to prove anything here so I have to add the 'moment' as part of the ongoing story (which is getting a bit boring now isnt it).

As I say, every now and then, when the engine fired I thought I saw a puff of exhaust smoke emerge from around the engine.  I tightened down the head nuts a little, and even put a little gun-gum around the exhaust pipe manifold.  I had had the spark plug in an out numerous times (to check the spark, clean the fuel sodden electrode and to air some of the wet out of the barrel) - and it was as I replaced the plug for the umpteenth time, that I felt that dreaded sensation of not-quite-tightening-down.  Bugger! (actually I think I said something far more appropriate for the moment) I had stripped the sodding head.
I have never stripped a cylinder head before, and I was well pissed off with myself that it should happen now.
On reflection, I have trying to work out why this happened.  I am sure I am not an absolute idiot, so why did this strip?  I never tighten a spark-plug harder than a 'nip', and this might well have been a reason for the exhaust leak that I was seeing (equally it might have contributed to poor compression and air-in leak), so I was certainly tightening the plug more than I had done previously - but even then it was only a 'hard-nip'.  The head was also pretty damaged in the first place - cooling fins smashed and pitted mating surfaces so it could be that the plug thread was not at its best anyway.  But the thing that really bothered me - and I hadn't noticed this before was that my spark-plug (which I believe is the correct spec, but I need to check now) only screwed in to about 66% of the head - ie the electrode was actually inside the threaded part of the head, and not the domed space, so there wasn't much thread to tighten up in the first place - is this how it was designed?  surely not.
Whatever the reason - it really got me down.
On the upside though, it would appear that I am having a crisis of confidence in EVERYTHING, and not just work! so maybe work isn't that bad after-all ;-)

I gave the day up as a 'rubbish day' - but not before I pulled out the engine that I have from that old black manurhin basket case that I and a friend bought for spares.  The head on that has been abused too, but at least it had a spark-plug thread - it might just get me out of trouble.
The picture here shows my original head with my new spark-plug along side the spare head with the spark-plug that was in it (I am not suggesting that this is the correct spec either). You can see my plug on the right does not come all the way into the head void as it does in the assembly on the left.

Time to go and investigate spark plugs (again) and see what is right.  However not before I go to a cocktail making class this evening - maybe this will be one thing in my day I can do well.  And if not...... I shall simply regain all confidence in myself by getting terribly drunk ;-)

Everything has stopped (well, it certainly cant start!)

Manurhin things seem to have slipped a little lately.  I've been away for work, I had a daughters 21st Birthday party to prepare for, and I went to a conference in Italy that ended with me on a 3 day drive back  over the Alps and through France in an old London taxi (but thats another story).
Actually, small things have been happening on my scooter whenever I can grab 10 minutes in the garage - but none of those things seem significant enough at the time to report on.

I am hoping to soon get back to the garage in earnest,  So heres a little summary of where I am at right now;

new cables

I reported a few blog posts ago that my brake and speedo cables were both too short.  Well, I decided in the end to just get new ones made.  Fortunately, I found the perfect cable company only an hours drive from me in the heart of Warwickshire farming country.  JJ Cables don't have a website (no, really, they dont!) so you have to do it the old fashioned way and phone them (01926 651470)..... but its worth the effort, they have a fantastic cable capability and make any cable to any spec - by comparison to most of the stuff they do, my cables were childs play.
Within the week - 4 cables (throttle, speedo, front & rear brake) - £40.  OK, so they might not be original stock, but they are all brand new, modern materials and made to fit my scooter :-)

I have also been working on the scooter electrical circuits.  This is taking far longer than I had imagined it would - I am a bit frustrated that I dont have the correct handle bar switches, but I can live with that.  I will report on the electrics when I have something more to say than 'why have i made this so much more complicated than it looks in the circuit diagrammes??'

I did manage to get to a position a couple of weeks ago where I had rigged up all the electrics and was in a position to test them - which meant starting the engine.  Because the scooter is on a bench in my garage, I decided that in order to prevent me dying of carbon-monoxide poisoning, I would rig up an extraction system that would pull exhaust fumes directly out from the exhaust pipe.  With the aid of several lengths of flexi ducting and bits of drainpipe, I created quite an impressive adaptation of an old shower extractor fan.  The engine seemed reluctant to fire up - and every time i did get a hope of a start, I found that the engine seemed to smoke profusely - i was a bit anxious (I certainly didnt want an engine fire in my garage).  It took me about an hour of nervous engine adjustments before I realised that I had installed my extractor fan in back to front!   Doh! so instead of sucking the exhaust fumes out of the engine - I was blowing them back in!  what an idiot.

So with the fan turned round I enthusiastically attempted to start the engine again....... and promptly pulled the starter cable right out of the starter mechanism (exactly as I had done when I first started the engine several months ago) - clearly, I am unable to fit a tight enough nipple to the end of the cable.  So I gave up for the day....... and this is how the bike has remained for the past 3 weeks - though I have ordered a properly nippled starter cable, and I do have plans to get back to the garage this weekend - so hopefully a little more progress to report in the forthcoming weeks