I would not have asked, if I haven't seen this picture of a beemer's head:

http://www.ecmspy.com/download/gunter/i ... laster.jpg (3.6 MB!)

There the surface looks so different and much rougher after blasting than before.

But seemingly this is another question where the answer is depending on moon position, pattern of sun spots and rider's karma

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"It is often said that before you die your life passes before your eyes. It is in fact true. It's called living."
Terry Pratchett

I can see where you're coming from now Gunter... though I can confirm that the surface definitely isn't as marked as those beemer cylinders. The combustion chambers are smooth as a babies arse and though the gasket surfaces are a little 'rougher', its not as rough as if they had been blasted with some coarse material such as aluminium oxide. The finish looks a lot smoother. To be honest, I don't think there's going to be any issues.

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Illegitimi non carborundum

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Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR

By the way Mich...

Did I tell you yet how proud I am of you, that you dedicate yourself to the bike(s) so much? You're the best, no matter what people say

chockies time m8

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xxxx

Guys, important question.

I was a bit concerned about your comments about the roughness of the head gasket surface so I did a bit of research and also went through my photos. Luckily I'd taken a photo of the head when it came back from machining and the surface was indeed a lot smoother. So I have *NO* idea what the feck the blasters did (on their own accord) and I have *NO* idea how they managed to roughen up the gasket surface but leave the combustion chamber smoothe as a baby's arse... but hohum... I need to sort it out now.

How can I solve this WITHOUT sending the heads back to Powerglides to be 'decked' again? Can I tape a sheet of 240 grade wet a dry paper to a glass plate and then run the head over it 'lightly' until it is smooth?

I'm picking those figures of sand paper out of the air more or less, based on an article from here: http://www.aa1car.com/library/ar996.htm



Cometic advise that you need a surface finish of of 50RA for the MLS gaskets that I have. So should I go with 240 paper?? (http://www.cometic.com/faq.aspx#q4)

Lastly. The machined squish band. Can I smoothe that by hand VERY CAREFULLY and gently, or should I not bother? Will those little peaks and throughs become an issue in the combustion chamber and accumulate carbon and possible create points where self ignition due to glowing carbon deposits can occurr??


As usual, this shit only happens to me! As if I didn't have enough work to do to get this bike back together by the end of the month

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Illegitimi non carborundum

Sad garage talk..... my little lathe expired on Saturday. Turned it's last, just finished a spacer for the race bike when it cried 'enough'....... sad day for the race team.

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Spencer Racing... www.spencerracing.co.uk

Right........ Just spoken to Powerglides and the chap that did the machining of the heads. He said that it would not be an issue. As long as the surface was not distorted the finish would be fine. He also advised that there would be no issue with the squish band.

Then, just to re-assure myself, I also rang the blasters and spoke to the guy that did the work and he assured me that he did NOT bead blast the gasket surface. He said that they do this kind of work all the time (and I did see other motorcycle parts being worked on at the time...) and that they use Vapour blasting ONLY. No bead blasting.

So. Crisis over. Feck me... I'm gonna get a heart attack over this shit one of these days.

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Illegitimi non carborundum

That *is* a shame actually. Is it not something you can repair? Or would it be too expensive?

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Illegitimi non carborundum

A lot of Brit singles run without a head gasket (as my Ducati does ) and using grinding paste as Ian suggests on the head barrel spigot, is the best way to get a gas tight seal A dull matt finish is fine

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If your dreams don't scare you, they are not big enough.

Fear not, 'There are many here amongst us' who have lathes My time and Myford are at your disposal, although the others are far more skilled Engineers and Machinists. I am just a not very skilled bodger but if you need owt, you know where I am

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If your dreams don't scare you, they are not big enough.

Cheers Adam.... a pair of heads machined out to take 'top hat' inserts and then the inserts with centre plugs and a decent squish please......

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Spencer Racing... www.spencerracing.co.uk

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I started out with nothing and still got most of it left.