Here's a very effective cleaner for your badly stained engines & exhausts.

For example, this is the exhaust off my four-stroke engine.

BEFORE

Just spray on the cleaner and leave for about 20-minutes.

Clean off with water and a soft wire brush and, 'hey presto'

AFTER

That's not bad.  No trickery.  Give the piece a second go (as I did here) to remove really heavy staining.

Price of Fairy Power Spray.  Less than £4 !!

IT APPEARS THAT THIS PRODUCT HAS BEEN WITHDRAWN FROM SALE.   SAD 'COS IT WAS REALLY GOOD!

'Taildragger43'