Bead blasting a complete engine ! My cranky method (UPDATED)

[AshimotoK0]

This is for one of my Honda Twin engines but relevant on here too.

http://www.hondatwins.net/forums/1-project-logs/34374-969-cb350k1-4.html

This is the relevant part:

Here are pictures of another engine I have for my JDM CB250 Dream replica. Ignore all of the fasteners (they are scrap) as is the camshaft . The camshaft is scrap because of the broken off points advance mechanism shaft (that cam was posted to me in a polythene bag only by DK Spares and hence broken in transit !). The cam bearing covers too are scrap ones. Engine is assembled with no engine internals (except broken cam) but with all gaskets (greased) and fibre washers on the fasteners. All oil seal holes blanked off with plates and rubber sheet. Exhaust and inlet ports blocked off with rubber faced seals. The starter motor aperture is blanked off temporarily with the end cover of a scrap starter motor, with its oil seal hole blocked with rubber. There a brass rivets pushed into the the holes of the alternator wiring rubber seal.

Tomorrow I will pressurize with air into the breather cover, and then if no leaks, I am going to dry blast with /100 glass beads. (VIXEN blast cabinet, Vixosheen beads). The idea is to blast without glass getting into the internals of the engine. I have two more engines to do like this, if successful, which includes the K1 CB350 engine of this rebuild thread. Will report back tomorrow.

I also investigated the crankcase finish on the K1 cases and also on the covers etc. I also had a NOS 286 crankcase top to test for original finish. I put a bit of 'proper' paint stripper on all surfaces to see if silver paint or clear coat applied. The NOS crankcase upper definitely had silver paint on it (please see the last photo).

So, to my reckoning, the factory finish was as follows:-  (UPDATED)

Crankcase ... Silver paint,
Clutch & starter covers ... Silver paint
Alternator cover ... Clear coat
Oil Filter Inspection cover ... Clear coat
Cam bearing covers ... Clear coat
Cylinders and cylinder head .. Bare alloy
Head Cover ... need to check !
Breather cover ... Silver paint
Drive chain cover .... Silver paint
Starter motor ... Silver paint

Here are the photos, last one is a NOS crankcase upper with paint removal.

Debating whether to the same with the 750K0 engine  ..lets see how it goes.  COMMENTS PLEASE !!

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NOS Crankcase showing original factory paint removal.


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Here is my best reference to original engine ( 1968 PP Prototype of CB350K0)


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[AshimotoK0]

Pressurized to 3 PSI and no air leaks so into the blast cabinet with 50/100 beads.

Alternator cover scrap (scored A NOS one today correct for K0 model    ) and cam covers plus all fasteners are all scrap, so didn't bother too much with those.

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[AshimotoK0]

Under Pressure ! Prior to blasting to check for air tightness == no ingreas of blast media.

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[Rozabikes Tim]

Impressed! When are you taking the patent out?

Tim

[AshimotoK0]

Impressed! When are you taking the patent out?

Tim

Just don't want any grit in the engine and don't trust someone else doing it. Not sure about cost of soda blasting it but with 4 engines to do could get costly. Problem is I couldn't use soda in the cabinet now and be safe, as the glass will be in every nook and cranny.

[mike the bike]

Did you maintain a constant pressure in the crankcases to discourage any grit from entering?

[AshimotoK0]

Just locked in the pressure as I didn't have a feed in the blast cabinet. Still had pressure when I finished though (took a long time in the blast cabinet)

Whilst doing it I got loads of adverse comments from boring f'king neighbours that pi** me off  (never owned a bike, never fix their own cars, look down on me as a pauper 'cos  my car is 20 years old (cars (except classics) are a waste of money IMHO)) then the same from guys where I work,  thinking I am some sort of cranky, geeky, obsessive nutter. I never seem to see any classic Jap bikes  around here any more just scooters. A bleeding swarm of Lambrettas went blasting past my garage earlier this year ... was like a scene from Quadrophenia  .

[tom400f]

Ash I would love it having a neighbour like you. Beats boring car washers and hedge trimmers any day. Rather hear the sound of random explosions than Dire Straits around the barbecue... 

[MCTID]

'Nils carborundum Bas*ardum' Ash..........you sound like my kind of fella..........keep the faith.

[Chris400F]

Ash I would love it having a neighbour like you. Beats boring car washers and hedge trimmers any day. Rather hear the sound of random explosions than Dire Straits around the barbecue... 

+1 from me too. I get on fine with my neighbours but would be quite happy to have Ash living nearby, with all his various schemes and projects.
As it is I'll have to settle for reading about what he comes up with next.

[mike the bike]

+2 with Tom.  My neighbours have got the shiniest cars and the straigtest lawns in the town but don't know which end of a screwdriver to hold.   one of then asked me to repair his double oven ; it was cleaner than the ones in Currys.  Talk about OCD.  At least they don't grizzle about the noises coming from my shed.

[AshimotoK0]

Doesn't stop em trying to get me to fix iPhones etc. though. My knowledge is OK when it suits them ! It's just mucky engines / motorcycles that they can't relate to. Oh and fixing one of those buzzy rabbit thingy's but we won't go there.

Wondering what to do about the 750 K0 engine. I may come up with a way of just sealing off the barrel/head/rocker cover/breather assembly, clamp together , pressurize and just beadblast that as a 'top end' assembly. I polished the covers etc yonks ago. The original Honda coating finish  is pretty good on the crankcases,  so I may just bung them in the ultrasonic cleaner and get them squeaky clean and then recoat. BTW the Ultrasonic cleaner was another work 'skip' find that just needed the heater rocker switch repairing. I even managed to find the S/S lid and the 'chip style' basket for it. We do have several at work but it's nice to have one at home as well.

[mike the bike]

It's amazing what people chuck away, I can't resist looking in a skip.

[royhall]

One of my neighbours at the last house we lived in complained about my compressor running once a day (never early morning or evening). It has a fairly large tank so runs for a while but as I say only once a day at the very most. Didn't stop him cutting his bloody grass with a power mower and strimmer at 8.30 on a Sunday morning, or washing his "beat the Jones's traveling salesman's car" with the jet washer. We stopped speaking as I may, allegedly and totally accidentally, threatened to beat him to death with his strimmer. It went strangely quite on a Sunday morning after that.

[AshimotoK0]

Engine number two .. one more twin engine to go ! Held pressure OK so into the bead blaster !

Same scrap fasteners and scrap generator cover and cam covers as used on 1st engine. NOS upper crankcase half on this one Cb350K1 twin engine next ... nicest condition !


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