worn su?

[mattyguk11]

hi again, stripped the carb off today to see if its causing the "rough running" im experiencing! the piston was a bit black n stickey so ive cleaned that. what are the tell tell signs of a worn carb? thanks matt

[les]

Scoring where the butterfly shuts and play in the spindle(the most usual wear) the aluminium piston can show signs of fretting if that is worn. If all is ok just renew the jet and needle, maybe the spring, I think it should be a red spring as standard. Good luck.
ps; the main jet at the bottom sometimes gets bent which can stop the choke fully releasing

[brixtonmorris]

piviot points for butterly shaft, wears out and allows air through it. also miss aligns the butterfly valve, causing damage to the ali body at points of contact.

[bmcecosse]

Aye - but all that just gives slightly difficult idle - the actaul running will be fine.

[brixtonmorris]

but its still worn out

[samheath100]

You can buy are carb overall kit from thge morris minor centre in oldbury (J2 or J3 off the M5) I have ordered one for mine but have not got it yet.

[bmcecosse]

SU carbs can go on for ages - even with a little bit of wear in the spindles. Don't worry about it !!

[Alec]

Hello Matt,

as BMCE says, spindle wear is not significant. However, what they do not like is the piston\damper assembly (internally) being cleaned using an abrasive of any sort (even metal polish).


Alec

[bmcecosse]

A wee bit of brasso will no harm if used sensibly - but if the piston rises easily and falls back with a clunk, then all is well !

[Alec]

Hello BMCE,

that is contrary to what I have been advised and especially if done long term as maintenance the piston clearance will be affected and adversely affect the performance.

Alec