Static timing 76 400/4

[Oggers]

Folks

Retiming the bike. Not completely happy with it as it seems to hesistate a tad in lower/mid range. Could be something else of course, but for now let's eliminate the timing.

Still not got round to purchasing a strobe, so static will do for now. My basic procedure is as follows

Align F mark for 1 and 4
Ignition on
Voltmeter across 1 and 4 contact terminal and earth
Turn plate slowly, and as soon as you see battery voltage, lock the plate off.
Repeat for 2 and 3

A few points.... pun intended

Once battery voltage shows, is this the point where you lock off? is there any recommendation to advance or retard it a little from this point. If so, by how much?

Points gap as per the book says 0.3/0.4mm. Seeems quite wide...Do we go with this?

All plugs were quite sooty- Could be the timing was out, I have given the carbs a good spray with carb cleaner and advance mechanism looked fine. New air filter ordered. Anything else it could be? Plugs themselves perhaps?

[Bryanj]

Aim for 0.35(14thou) gap, you will need a big set of feelers so you only use 1.
Its easier with a bulb than voltmeter
Always recheck gap afterwards as the plate is never a good fit in the cases, normaly takes quite a bit of juggling to get both correct

[K2-K6]

All seems ok for technique as you've stated.

No need to advance or retard from voltage change if you've got it switching at the marked point. Could double check with a continuity "beep" with power off and by rotating the crankshaft,  beep should cease as timing mark lines up.

Gap,  yep ok as stated.  Too low / more closed will alter the switch speed to the detriment of clean cut off.

Ignition wouldn't usually affect jetting ( other than in extreme case) so after timing you're probably looking at airscrew setting to trim. They effect mixture change surprisingly far into throttle opening range on these carbs. 

Also they are not an absolute from manual listed settings but a competent start point to allow you fine tuning to accommodate local conditions.  Try riding it with them turned in a 1/4 and then out a 1/4 from current set point to assess if it runs more without glitches.

Suspect you need to be further out on screw to clean up sooty plug observations.

[JezzaPeach]

In case you find the same, I thought my right set of points were out of timing adjustment, opening too early, until a helpful forum member pointed out what a big difference it makes to the advance of the whole assembly when you open up the gap of the left set slightly nearer 0.4

[Oggers]

Gents

Many thanks - Points gap of 0.35 it shall be. Noted about airscrews. I did indeed think they basically affected things up to around 2000 and then main jets took over. All are set to 2 1/2 turns from bottom. I'll try 2 3/4 and take it from there.

I did try a test lamp initially but got a few sparks! No idea why. I didn't pursue it as I did not want to wreck a capacitor or something....I then just used a multimeter instead.

[JezzaPeach]

With the lamp, was one croc clip on the engine casing, and the other purely on the capacitor/output lead soldered tabs, and not touching the metal of the points mounting in any way?

[Nurse Julie]

Gents

Many thanks - Points gap of 0.35 it shall be. Noted about airscrews. I did indeed think they basically affected things up to around 2000 and then main jets took over. All are set to 2 1/2 turns from bottom. I'll try 2 3/4 and take it from there.
.

At 2¾ turns out, you will be bordering on running very, very lean. 1½-2½ is the desired range. Running slightly richer is far more desirable than running too lean. Have the jets or needle position been changed in the past by anyone that you are aware of?

[Oggers]

Nurse

I've set them at 2 3/4, and it runs better. No hesitation, better torque. Fully appreciate rich is better than lean, but if the plugs are sooty at 2 1/2 , then it is too rich and no good.  I'll check plugs again sometime.