Tuesday, 3 October 2017

Three minutes

October 2nd.

Spent a while going through the motions of hand cranking to check the timing and spark behaviours.

Became immediately obvious that LH is about two cogs advanced even though RH is spot on.
This equates to maybe 7 degrees of advance!
No sign of spurious sparks though.

Compiled this data set



.  










October 3rd

Started fine.  Knocked the choke off.  Let it settle.  Adjusted LH slow running a little   Rode her out up the road.  Went beautifully.  Pulled to 4000 cleanly.  No flat spots or hesitation, just the bike I remember.  For three minutes.

Turned round and trundled down the road, ready to take it out on the main drag.  Just before the pub on the corner it suddenly reverted into a spitting popping recalcitrant beast.  Turned round and struggled the 200m back to WH.  Decided it was probably running out of fuel so topped it up.

Went for a 5 mile walk to Eppleby and back with M whilst the sun shone and came back ready for another session.  But bike now positively unrideable.  Spit pop gasp fail.  Wouldn't even pull up the side drive.

Very deflating.


Spoke to the guys at Sachse about the timing.  They suggested it may be up to 2 degrees different at worst given the various tolerances in the total system.  But there is a problem if it is any worse. They suggested the usual round of swapping things over.  But added that if it persisted please ring back they want to help.   They said if necessary they would send another pick up.  They were stumped by the LH HT not strobing.

Tried a direct supply from battery to Sachse (as per troubleshooting guide).  The ignition cut out switch is a bit flaky although always works fine.   Anyhow it made no difference.  Had a think.

During the next course of running and strobing, I accidentally found out that when the LH HT lead if not connected to the plug it would fire the strobe!!  So was able to confirm that the LH is over advanced using the strobe on the marks.  Tried swapping the polarity round on the coils (each has one terminal that is marked with a red dot, I'd assumed this meant + terminal, nothing in the documentation).  Blow me down but both HTs now fire the strobe when connected.  At least that mystery is solved.  So the spark was jumping upwards?  Hence induction field opposite to requirement of strobe detector?




Timing sensor  output now connected to red terminal










Final nail in today's coffin - checked to see if alternator pushing 14v across battery.

No it's not.  Battery at 11.5V when running. 

Have ordered new bearings, gaskets and O-rings for distributor.  When all else fails spend money.

Next steps
Solder terminals on the wires that connect to the Sachse spade terminals.

Inspect fuel, and possibly carb internals






Sunday, 1 October 2017

The Shim's the Thing!

September 30

Steve J popped round to help trouble shoot.

We reviewed the static timing both cylinders.

Three things emerged.  Firstly there is a lot of play in the distributor rotor.  Secondly the alignment beetween magnets and sensor only 50% of optimal.  So shimmed the backplate up with two small washers.  Thirdly the LH spark plug flashes at least three extra times per revolution.
And Steve adjusted the synch on the throttle slides - way out
Pressed the go button!
BOOM!!

Both cylinders away and hot!
Pick up v good and clean - so quickly put the needles back to centre notch.  Still good.
BUT
It seems clear that the LH spark is putting out spurious timings in addition to the TDC.  Evidence of blowback through carb AND through exhaust, indicating off compresssion combution.

PLAN
Ring Sachse to discuss.

But major progress today!!