Hitchcocks Forum

Hi,
Would anyone know the right settings for ignition timing and points gap on a 1959 big head bullet? The manual and handbooks all give different answers. Its the coil ignition version with distributor and not the magneto.

Many thanks

Bandit

Hi Bandit, I timed a 500 non Big Head Redditch Bullet the other day, with SR1 mag and auto advance, but just like yours with a distributor, it wants to be 5/16" BTDC @ full advance. I got this from an original Redditch manual. If you want crankshaft degrees, aim for around 35 deg BTDC, with 32 as a minimum and 38 max. It is more important to have correct full advance timing than the retarded setting, so if there is wear in the ATU mechanism, the engine can't over advance and a slightly over retarded tickover is usually nice and steady, if you end up with one as a result. Regards, Paul.

Many thanks bullet whisperer I'll give that a go and let you know the outcome.

Bandit

Points gap 0.012" Plug gap 0.024"


Timing depends on cams and piston? ie; Compression 6.25 - 7.25 ~ 3/8" - 5/16" Btdc. fully advanced.


Opening points gap in 0.001" steps to a max of 0.014" will advance timing across the specified range. Conversely, closing the gap down will retard the setting.


Depending on your setting technique, it is usually easier to start from the more advanced setting and retard as indicated. Keep in mind that drive-train clearances (back lash) will retard any initial static setting.


IF the motor misfires at higher rpm, close the plug gap down 0.002"


If you need a plug-gap of less than 0.020" to eliminate any high rpm misfire, try a hotter plug, otherwise replace the coil if the bike is still fitted with the original large Lucas item?

Great advice guys and my bullets running sweetly now. Thanks Tim for the tips re hotter plug etc, I have just replaced the coil with a lucas 6v from our hosts and I have a plan to do a 12volt conversion with electronic ignition over the winter.

Bandit

Hi Guys-----interesting point that TIM has inadvertently touched on and is worth remembering ie}------ as the points gap closes so the ign. timing retards...Remember that the quality / grade of fuel also has an impact on timing..