Hi all

Just rebuilt a 1&1/2 inch SU carby with a new jet, but the piston is sticking.
If I loosen the jet lock nut and give the jet a bit of a wiggle piston moves freely, so i'm guessing the needle is sticking in the jet. What is the best way to line it up?

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Its no how ya make porridge

Screw the jet adjusting nut right up to raise jet.
Loosen the jet locking nut.
Undo the jet screw in the piston, drop the jet about 2mm so the shoulder is below the piston.
Refit piston.
Tighten the jet locking nut.
Push needle back into piston and tighten screw.
Adjust mixture as required.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

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Stop Licking the Dog...I Don't Care Who Started It

few extra bits in that H type!

i take the jet adjusting nut "spring" out,,, then slip it all back together , loosen the jet sleave lock nut & then with the top of the jet set level with the bridge of the carb, i lift & drop & lift & drop & lift & drop,,, gently trying to center & tighten the jet sleave

it often takes a few goes but once it`s done & you have the piston liting & falling sweet,,, then with the sleave lock nut tight you can slip the jet back out & re-fit the jet adjusting nut "spring"

yeah it`s a fiddly proceedure but "usually" has to be done after a jet change

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Thanks for that
played around with it today and piston now going up and down okay - so jet/needle must be centred okay.
What's a good start up position for the jet? I think I read somewhere on here to wind it right up then back it off 20 flats of the adjuster nut.

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Its no how ya make porridge

20 seems a lot, I think 12 is more like it...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

yeah 2 full turns down from flush with the bridge

that`s 12 flats down

_________________
No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.