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allankelly1:

--- Quote from: Oddjob on August 26, 2021, 04:58:10 PM ---Correct me if I'm wrong but there is some abrasive in the vapour blasting?

--- End quote ---
Yes it does but the process is so gentle on the case that it only remove dirt and surface oxide

If you look carefully you can still see the “shadow” left by the base gasket

It so gentle that it will not remove any paint or powder coat present hence the need to get them chemically dipped first to expose the original surface

I have in the past cleaned wood parts with this process




But still the cases will be thoroughly cleaned again by myself before paint and rebuild


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4wDaz:

--- Quote from: Oddjob on August 26, 2021, 04:58:10 PM ---Correct me if I'm wrong but there is some abrasive in the vapour blasting?

--- End quote ---
Glass is mainly used for vapour blasting although most media types can be used, fine spherical beads are used for finishing which has a peening affect, not a cutting action. Trouble is some operators add aluminium oxide in with the glass to cut and clean then the glass polishes, it does the job faster but much more abrasive. It’s advisable to tape all bearing surfaces and the glass beads just bounces off. It’s also done at a lot lower pressure compared to dry blasting, normally 30 to 50 psi. The biggest problem is getting rid of all the glass before rebuilding the engine, I pressure wash them, oven dry, blow down then repeat the process again, oilways can be plugged but it still gets in. The safest option is acid clean and soda blast

allankelly1:
Hi Daz

Like you said you need to ensure the cases are spotless and clean after the process and clean and check all orifices and stud holes then clean again

The company I used was Broomie Racing in Swindon as like you said there are some cowboys out there

Dave’s  main work is vapour cleaning bike engines and he was originally recommended by another bike mate when I was doing the RD350LC as they really specialise in bike engines so know their stuff

Best wishes Al


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McCabe-Thiele (Ted):
Whilst I like the look of an engine casing that is nice and clean inside I asked myself a simple question - how long will it stay clean before normal useage stains the inside again?
Polishing or painting the outside now that's worthwhile as we can see it and maintain the shine.

Back in the 1960's I had Mini 1275 S that had been peviously tuned for stage rallying - it had fully polished gas flowed inlet ports that were a mirror smooth finish - the cylinder head was  also  mirror finish. At that time I was regularly stripping the engine down to fit a better camshaft (Mini Special Tuning 731 was my favourite) change the final drive units etc. In a single year the engine was removed, rebuilt & refitted about every 3 months - it never stayed clean internally!

Every time the engine insides seemed full of brown deposits with carbon in the inlet ports probably due to a ridiculous 649 full race cam having daft valve overlap. When Russian NAFTA petrol was sold in the UK I had to decoke it after 3k miles it was so gummed up due to the crap 5 star leaded petrol they sold over here. The best petrol back then was ICI Petrol it was semi-synthetic made as a by-product from the chemical industry.

The above experience is what  put me off vapour blasting - that said it does look nice if the cost is not an issue - you are starting  from new in terms of the inside cleanliness.

Probably the best way today to keep the inside of an engine clean today is to use fully synthetic engine oil but motorcycle wet clutches and synthetic oils are not a great match so one sticks with mineral oils and hope the modern additatives work.

McCabe-Thiele (Ted):

--- Quote from: Oddjob on August 26, 2021, 10:35:26 PM ---I used to swear by BPVF7 Ted, there were so many detergents in it that you could eat your dinner off the inside of the engine, that’s if you didn’t mind the taste of oil that is.

--- End quote ---

That reminds me of the early days of Shell Rotella for Diesels - when a customer collected his vehicle they often dipped the oil level and were horified to find it had turned black on the drive home!

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