bsa A10 IGNITION

[BSA59]

Hello,I'm sorry I live in France and i don't speak english very well
I want to know the ignition advance for my BSA A 10 Road rocket of 56
I need this information but not in inch but in degrees
I hope you understand me
Thank You!
good afternoon
Fred

[a10gf]

Bonjour, et soyez le bienvenu ici. N'ayez pas de doute, votre anglais est très bon, et ne posera aucun problème. Maintenant la France est representée sur le forum, excellent!
Moi, j'ai passé beaucoup d'années en France, banlieue de Paris et les Alpes Maritimes. Dans quel département habitez vous?

Erling
admin

ps, we will keep the forum in english, this is just a welcome note to our new french member.

[dpaddock]

Fred: Try 32 degrees BTC, equivalant to 5/16-inch.

[BSA59]

Hello
to a10gf: thank you for your welcome note,I'm living near Valenciennes- I have a recent bike(TRIUMPH TBIRD BIRD) and old bikes (SAROLEA 30R, NSu 200lux,MOTOBECANE R 44 C,BSA M20...)
to dpaddock: thank you for your information
Fred

[a10gf]

Some GF timing I picked up somewhere, think it was recommended by SRM using their timing disc:

35 deg btdc for super98
33 deg btdc for 95

Fred, post a few pictures of your bikes? (other than a10 pics welcome as well, especially BSA's, as long as you own an A10 too, BTW, I have a Triumph 900 Legend, good stuff ! )

Erling

[Beezageezauk]

Hi Fred,   

Welcome to our BSA A7/A10 forum and congratulations on your English.  We can understand you very well.

I have just done some calculations using the Ignition Timing Converter and these are the results.

Using the A10 stroke of 84mm....3.307 inches and the conrod centre distance of 6.469 inches the ignition timing conversions are as follows.

5/16in. before top dead centre is 0.3125inches or 32.5deg.
11/32in. btdc is 0.344inches or 34deg.
3/8in. btdc is 0.375inches or 35.5deg.
13/32in. btdc is 0.406inches or 35.5deg.

You decide what your ignition timing should be  in inches before top dead centre and the answer you are looking for is here.

Beezageezauk.

[Alan @Ncl]

I just came across the post quoted below and realised I was probably using the wrong data in my calculation (posted yesterday and now corrected).  Can I just seek confirmation of consensus that A10 con-rod length between centres is in fact 6.469inches (I was using 6 inches which obviously gives a slightly different answer).

Also, can anyone say how many degrees the autoadvance mechanism normally provides?  I did some measurements (gap to be taken up by the centrifugal action, about 6mm, and the diameter across yoke about 60mm).  This indicated an equivalent of about 23 crankshaft degrees.  On this basis, fully retarded would be about 12 degrees BTDC.  Does that sound sensible? I seem to recall seeing somewhere that it was nearer TDC.

I have just done some calculations using the Ignition Timing Converter and these are the results.

Using the A10 stroke of 84mm....3.307 inches and the conrod centre distance of 6.469 inches the ignition timing conversions are as follows.

5/16in. before top dead centre is 0.3125inches or 32.5deg.
11/32in. btdc is 0.344inches or 34deg.
3/8in. btdc is 0.375inches or 35.5deg.
13/32in. btdc is 0.406inches or 35.5deg.

Beezageezauk.