The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: Duncan R on 23.09. 2010 17:55

Title: Timing Question
Post by: Duncan R on 23.09. 2010 17:55

My Shooting Star has an auto advance magneto fitted instead of the manual version. Should I set the timing as a standard A7 or Shooting Star spec?

Haynes manual states : Std A7 5/16" BTDC and Shooting Star 3/8" BTDC

Thanks

Duncan

Title: Re: Timing Question
Post by: muskrat on 23.09. 2010 20:53

G'day Duncan,
                       depends on your comp ratio and fuel used. I and others here have found that with unleaded fuel and reasonable comp (8.5-9.5) the timing needs to be retarded a few degrees. Try it at 3/8" but if it pings under load you will need to back it off until it stops pinging.
Cheers

Title: Re: Timing Question
Post by: Duncan R on 24.09. 2010 09:11

Thanks Muskrat,

Motor is running nice at the moment, good starting and idling and seems to pull in any gear. I have not opened it much above 50 MPH due to the  weak front brake(which has now been sorted) Plug colour is good. Engine is a bit of an unknown quantaty, I don't know the piston spec. At the moment it is set at 3/8 BTDC and there does not appear to be any pinging. I think I will run it for awhile and see how it goes. I am hoping to attempt an engine overhaul over the winter which will include rebore and new pistons

Cheers