revtothelimit - motorbike forum

Some time in the near future I need to decoke the zorsts on my 350LC prior to getting them ceramic coated. My Cunning Plan involves stringing the exhausts up from the washing line (approximately horizontal), hammering a rubber bung in one end and pouring a caustic soda solution in via the other end. Then I'm intending to agitate the Caustic Soda angry pixies by playing a blow torch on the exhaust to accelerate the degreasing action.

What could possibly go wrong?

<Disclaimer> I will be wearing a half mask, eye protection and industrial strength rubber gloves. I'm also aware that I need to add CS to water, and not the other way around.

When my KR1S went pop and Graham File was rebuilding it, he advised a rubber bung in one end of the spanny and filling with Jizer or equivalent and leaving to soak for a few days before pouring out through a sieve to catch the bits that went down the exhaust and got stuck in the goo ready to be sucked into the rebuilt engine if they weren’t released by solvent. That seemed to do a good job of cleaning them out.

Assuming your taking the baffles out, as well as the caustic treatment, I also degrease them, wire brush what I can/could. Blowtorch the baffles and wire bush again and stick the flame up the exhaust as well.

The caustic should work

MingtheMerciless wrote: Sat Mar 20, 2021 5:02 am When my KR1S went pop and Graham File was rebuilding it, he advised a rubber bung in one end of the spanny and filling with Jizer or equivalent and leaving to soak for a few days before pouring out through a sieve to catch the bits that went down the exhaust and got stuck in the goo ready to be sucked into the rebuilt engine if they weren’t released by solvent. That seemed to do a good job of cleaning them out.

Have you seen the price of Jizer these days?

Seriously, that's another option, but as I already have a tribal size bucket of caustic soda I'm going to try that first. But the baffles will get the blow torch treatment, as will the end of the pipes that don't get touched by the caustic soda. I have a suitably sized rubber bung...

GuzziPaul wrote: Sat Mar 20, 2021 8:20 am Assuming your taking the baffles out, as well as the caustic treatment, I also degrease them, wire brush what I can/could. Blowtorch the baffles and wire bush again and stick the flame up the exhaust as well.

Ideally I'd just set fire to the exhausts and burn off all the oily gunk, but as I'd like to stay on reasonable terms with my neighbours and not envelop the neighbourhood in a pall of two stroke smoke, I may have to pass on that option.

Le_Fromage_Grande wrote: Sat Mar 20, 2021 8:58 am The caustic should work

I reckon.

Have you done them yet, I need to decoke my YPVS pipes so I'm wondering how you get on.

Pencilled in for next week. Will keep you posted.

The caustic will work on steel pipes. Don't let it come into contact with anything aluminium though!

Doc wrote: Sun Mar 21, 2021 12:44 pm The caustic will work on steel pipes. Don't let it come into contact with anything aluminium though!

Yes, agreed. And it does very nasty things to exposed skin, as well. I'm planning to keep a bucket of citric acid solution close by to neutralise any spills.

Le_Fromage_Grande wrote: Sat Mar 20, 2021 10:44 pm Have you done them yet, I need to decoke my YPVS pipes so I'm wondering how you get on.

Details of my exploits here...

viewtopic.php?p=66122#p66122

I thought the caustic soda treatment would have removed the majority of the 2T gunk, but the guy who did the ceramic coating said not. To really get the innards clean he filled them with industrial strength degreaser and left them for a day or so, then emptied them out and used a steam cleaner with long lance to really shift the stubborn muck. He said that unbelievable amounts of foulness came out.

Burnt 2T oil is tenacious stuff...