Pilot jets

[Taid]

What would be the effect of having a smaller than specified Pilot Jet .. ?

My m31 has a 20 pilot jet but the parts list and the Burlen Amal website says it should be a 30, but Burlen are currently out of stock

[Andy G]

Im guessing, but hard starting, hot, lean running at tickover then decreasing effect the more the throttle is open? Maybe some impressive banging on decelerating..

Might be able to correct by closing the air mix, or leaving the choke partly closed but I'd still aim to get the right jet when you can. And I wouldn't leave it ticking over for any longer than necessary...
A lean mix will cause more harm and quicker than a rich one, but every engine behaves slightly differently and it's a long time since its original set up, might even run better!

[Andy.S]

Hi
Club spares have jets in stock why not order from them ?

[Joker_Bones]

I have heard it said, though never tried it myself, the best way to tune the idle is to change the pilot jet to give the right mixture with the air screw 1 1/2 turns out which is supposedly its optimum position, rather than adjusting the air screw to suit the jet...

[Joker_Bones]

IMG_20220916_110916.jpg

What model year is your 31? What slide cutaway do you have?
1960 (or late '59?) is underlined on the chart above

[Joker_Bones]

Burlen are currently out of stock

Whenever I have looked at the Burlen site over the past year or more most of the carbs are 'out of stock'... Now they haven't got a pilot jet

???

[bitza]

Try Hitchcocks brum they stock carb spares.

[Taid]

Hi
Club spares have jets in stock why not order from them ?

Just didn't think .. but tended to believe club spares were bits not available anywhere else ..

Burlen expect stock in the next couple of weeks, and I have it on order .. there's no rush .. it'll be ages before I'm ready to fire it up ..

[Taid]

What model year is your 31? What slide cutaway do you have?

It is a 59 .. or, at least , it was registered 14 SEP 59 .. single tube, not cradle, frame ..

The carb is not original, it's stamped 389/10 which I think was set up for a Shadow .. all the other bits in it are correct for the 59 M31 .. just the pilot jet is wrong ..

[Joker_Bones]

The carb is not original, it's stamped 389/10 which I think was set up for a Shadow

Yes... you said that in another another thread, but I didn't put that and this together.