Pinking

Old fuel??.Low battery voltage affecting the Boyer? . Try a different brand/grade of fuel.

i agree try super unleaded.

Hi Mac,

Assuming that the 'pinking' is still in evidence when you use super unleaded,the other possibility is that the ignition is advancing up way too early,& checking it at 5000rpm might be misleading.

As the problem occurs at relatively low engine speed,try checking the ignition at around 3000rpm & it shouldn't really be much more than 18-20 degrees.If you're seeing more than this,then it may well be that the primary spring in the advance & retard mechanism is stretched,& the ignition is acheiving half its advance curve the momoent the engine starts.

Hope this helps!

Sounds like I have a wee issue with "pinking"

How far retarded has anyone gone with ignition timing to sort pinking?

I have a 750 with a single AMAL containing a 260 Main, and 107 Needle jet, a No 3 slide and the needle in the bottom groove.

Ignition timing is courtesy of an older type BOYER and has been set around 28 BTDC at 5000 RPM.

Bike seems to start quite easily except when it's been left for weeks on end then it takes quite a few kicks to fire it up, after that it's first or second kick.

It ticks over nicely but as you pull away you can hear what sounds like pinking, plugs are sooty round the body of the plug, porcelin nose light in colour and the electrode greyish.

Just wondering if it could get retarded a bit more?

Previously robert_waddington wrote:

Hi Mac,

Assuming that the 'pinking' is still in evidence when you use super unleaded,the other possibility is that the ignition is advancing up way too early,& checking it at 5000rpm might be misleading.

As the problem occurs at relatively low engine speed,try checking the ignition at around 3000rpm & it shouldn't really be much more than 18-20 degrees.If you're seeing more than this,then it may well be that the primary spring in the advance & retard mechanism is stretched,& the ignition is acheiving half its advance curve the momoent the engine starts.

Hope this helps!

Sounds like I have a wee issue with "pinking"

How far retarded has anyone gone with ignition timing to sort pinking?

I have a 750 with a single AMAL containing a 260 Main, and 107 Needle jet, a No 3 slide and the needle in the bottom groove.

Ignition timing is courtesy of an older type BOYER and has been set around 28 BTDC at 5000 RPM.

Bike seems to start quite easily except when it's been left for weeks on end then it takes quite a few kicks to fire it up, after that it's first or second kick.

It ticks over nicely but as you pull away you can hear what sounds like pinking, plugs are sooty round the body of the plug, porcelin nose light in colour and the electrode greyish.

Just wondering if it could get retarded a bit more?

Boyer does not use any of the mechanical auto advice unit parts. Low voltage at the black box style boyer due to bad connection, old wiring, bad earth or failing battery/ charging system is well known cause of premature advance of the spark timing.

A carboned up motor can also give pre-ignition,as can wrong plugs or a plug thread too far into the chamber.

Previously mac_macdonald wrote:

Has anyone found pushrod end fittings loose during a stripdown after having a rattly noise?

This is not unknown but tends to affect the early thinner pushrods more than the later SS kind.

Pinking Issue.......I fitted a Pazon and set it as instructed to 31? static and strobed. I had horrible kick-backs and pinking. Eventually is was fine at 28?. I also have a new premier 932 single carb. The fitting instructions included a 220 main jet which killed the acceleration. A 240 plus filter works fine.

However, my carb came with a 106 needle jet. You mention that your carb has a 107 which may be too large.