Inappropriate advances

 October 30 2022

For some unknown reason it occurred to me that I just needed to have a look again at my electronic ignition settings.  Workshop manual says 2 degrees up to 1000 RPM, rising to 33 degrees at 4000 RPM.

So I looked up in the manual to see where the correct setting for the T3 advance curve is.

First off I lifted the seat to have a peek at the installed setting, here's the picture.

So it looks like the arrow is pointing at #8 (red dot)

Here's the settings chart.

It's blindingly obvious that the correct setting is the curve highlighted by the  green arrow, which corresponds to setting 3 as far as I can tell, or possibly 2.  

However the current setting is at #8!  So the engine has been labouring (?) with the wrong advance curve.

A very wrong one!

So priority job for Spring 2023 will be to correct this and see how the engine runs.  I'm expecting to feel some  difference given that the motor is behind the curve, by as much as 5 degrees in the main operating range (2000 - 4000 RPM).

How did that happen?  I have obviously failed to pay attention to which way the arrow is pointing.  The only consolation is at least the setting is the same at the low RPM setting (2 degrees BTDC).

Going Somewhere

 Friday 23rd September

Ideal weather for a spin out.  Rather than just tour aimlessly around the local by roads, decided to actually go somewhere so rode over to Stockton for a cuppa with the Dyes.  

Great cruisy ride, bike running very well after recent effort with Carbtune, longer way back via Neasham.  35 mile round trip.  No glitches.  New matching BUMM wing mirror arrived too late for the ride but looks good.  Two small oil patches on return parking, smelt a bit like Hypoid.

Feeling more confident about getting back now!

On the railway bridge, Hurworth

Balancing Act

 11th July 2022

Balancing Act

Following short vid and exchange of messages with HC/FA  (The go-to Moto Ears in the SW) have obtained Carb-tune manometer to aid balancing.  Had to get threaded ports cut into manifolds at the local engine shop.  Now all ready set about adjustments (carb tuning may be a bit of an exaggeration).

Restored jets, barrels and needles to as supplied by Mikuni agent (Allens).  (this was simply a needle swap).  Aim was to return to an as-supplied baseline.

Checked timing, spot on 2 degrees advance at tick over.

Checked throttle cables and adjusted until there was about 3mm slack both sides, the LH seemed to be a bit tight.

Released carbs from m/folds to allow for eyeball inspection of slide synchro, adjusted until appear to move together.

Fitted carb-tune, started engine, minor tweak to cable adjusters to get both columns moving together.  Adjusted tick over until columns level.  Checked synchro again

Disconnected one cylinder and adjusted fuel screw for optimum rpm.  (first needed to set throttle screw in about half a turn to get a tick-over).   Note that unlike VHB Del Orto, the Mikuni VM slow running screw adjusts fuel supply, not air supply.  Hard to find best setting, finished at 2.5 turns out.  Probably close to max fuel from pilot jet.  Repeated operation on other side.  Same result. Reset tick-over.

However found that motor fluffed when snapped open and picked up poorly on slowly opening throttle.    Sounded strangled and revs just died away as throttle slowly opened.  No amount of fuel screw adjustment made any difference. 

On the last outing the motor pulled well with the alternative needles in.  These are less aggressively tapered and look more like the profile of the original Del Orto VHB needles.  So I let the motor cool, then put the alt-needles in (easy swap with these carbs, round screw top, rubber gasket seal).

Repeated process above, results much better, quick pick up on a throttle snap, an even pick up on slow opening.  Fuel screw now 1.75 turns out (RH) and 2.0 turns out (LH).  

No test ride, too warm and a bit tired after three days away.

UPDATE - TEST RIDE

About 12 miles, mostly country lanes, a bit of open road, and a blast down the dead straight Roman Road back, up to 5500 rpm in top, pulling well, sounding clean.  Good engine braking indicating decent shut-off.  Link below to short video of current state of motor.

Link here

The carb synch was a bit out on return, I tweaked it back, not quite perfect nearly there though.

There was a definite pick up when I turned the pilot screws out by a quarter turn.

2022 is open for TWX

 May 21/23

Put 6 litres of fresh in the (empty) tank

Fitted two new plugs (7ES right, 6ES left).

Good start, even tickover.

Monday - got togged up and went out for a twenty minute 11 mile trip.  Pulled well.  No glitches on low throttle opening.  No spitting or popping once warm.  A bit of tappet rattle.  Tick over a bit lumpy once hot.  But overall all good.

But seeping engine oil from bell housing drain hole