Plastic Media Blasting of Engine

Not sure if this should be in the "Paint" section, but it is definitely relevant to the engine.

I spent approximately 30 hours getting close to my GPz's engine. Still a lot of dirt and paint left to try and get off. The motor was running perfectly before getting the bike apart, so I don't want to strip the entire engine down just because I wanted to re paint it (call me lazy?). My dad who works in the aeronautics industry said he can have the completely assembled engine blasted with plastic media, since they use plastic media to clean their more "sensitive" aircraft components. My view is that if I do use plastic media to blast clean/strip the paint and dirt of the motor, any plastic that might find its way into the engine will not be that big of an issue. If I spend enough time by making sure all holes etc. into the engine is properly sealed off, then surely this should work?

Any opinions on whether I should go ahead with this? Or any opinions and/or guidance from someone that has used plastic media to do blasting before?

Thanks

Or let me put it this way. Cleaning in between the fins is going to take a while. What if I completely seal of the case from the rest of the engine, and just have the head sticking out? Surely then blasting would be okay?

Man "aeronautics industry" just sounds real good! High tech stuff! That media is probaly very costly! which means it will work nice on aluminum. They must have a huge bin tank or even a whole room to blast their stuff!
I would go for it myself. Just ask the Guys that work with your Dad. They should know!
Were you at? I'll bring an engine too :laugh: :laugh:

I glass bead Kaw engines apart. Trick is to hot tank, soak, agitate, totally get all oils and grease off 1st. before you do any blasting. I love glass bead. I have been doing it for 30 years on my own stuff and parts I sell on ebay.
I just did this old Z1 cylinder head.
Good Luck, let us see when you do this!

z1kzonly, you will definitely see some photos if I do do it. For some reason I am just a bit "worried" that the plastic beads might get in where it is not supposed too. And if it does, I probably will have to strip the engine anyway. Guess I should just jump into it and see what happens. It does help to keep the costs down when you "know a guy who knows a guy who needs to do you a favour". Instead of spending another 20+ hours sanding and cleaning I might as well spend a few good hours sealing off all ports and tapped holes. A good wash afterwards wouldnt hurt either. Your cylinder head looks good! Hopefully I will get there too.

Have you looked into dry ice blasting and / or baking soda blasting. Both of these processes help minimise the chance of clogging an oil passage and causing damage.

80b4 - The only guy I could find that does soda does it only on industrial scale. The same went for the guy that does dry ice blasting. So I am sort of stuck. I will never consider glass or sand since the chances of buggering the engine up with that is just too high for me.

I believe all GPz's had black engines. Are you planning to repaint it black? If so, blasting would be overkill. You're not after a gleaming natural finish. You just need a clean grease free surface. You'd be better off with a spray on chemical paint stripper followed by a degreaser with a good soap and water wash after each.
For me, the contrasting silver bolt heads are what part of the appeal to a black engine. It easy to spot an engine that was painted assembled. It's an all black blob. I guess you could tape each bolt, but that's going to be difficult and time consuming. Plus, any blasting process is going to strip the protective plating from the steel bolts. They will rust/corrode very quickly if you don't paint them.
There has been all kinds of "engine safe" media used for blasting. The compromise is that the softer media like walnut shells, soda and plastic also don't clean as well, or at least as quickly. I don't care how careful you are, some media is going to get inside the engine. Plastic may not scratch your bearings, but it can still clog oil pump, filters and passages.
The bottom line is I would not consider any type of blasting for an assembled engine. Take it apart and do it right, or stick to strippers/degreasers.

I have seen on different bike websites where professional shops have soda blasted whole engines. I was planning on doing it on a KZ750 twin (whenever i get to it) It is not hard to seal an engine properly, get some expanding rubber pucks for the intake and exhaust, and tape the couple remaining holes up real good with 2-3 layers of duct tape. IF some soda creeps past its no big deal as it will dissolve. The plastic media will likely be fine, its not like your going to blasting through gaskets, so as long as you stay away from oil seals I think you will be good. If you engine is whole you should be close to those anyway. when you are finished, hit it with a 100 PSI air hose to blow all the crap off if it, then blow out the intake and exhaust, then you're probably good to go.

MDZ1 - You definitely hit the nail solidly on the head. I don't know why I spent the last day and a half searching the interwebs to try and convince myself to go ahead with the blasting, it convinced me otherwise...and for the better. You are right, the GPz engines did come out of the factory with a black paint job. The problem I was sitting with is that the previous owner sprayed some (and by some I mean a lot!) of enamel over the OEM paint, causing thick paint runs. Most of that I got sanded off though. Got some paint stripper earlier today and tried it on a section of the fins. Came out pretty good. So from now on its some elbow grease, degreaser and various brushes and sandpaper for me. Don't want to mess up a good engine. And I have actually started polishing up bolt heads on the engine which will be taped off from overspray. I know it will take time, but being slightly OCD makes it worth it in the end.

Doc - I decided to not risk it.

I can relate to the damage a Previous Owner can do with a spray can, Below are pictures of the 75 Z1B I'm finishing up. The PO had painted the engine all black (a blob). This engine was disassembled. I glass beaded the head and cylinder. The cases took numerous rounds of stripper and final cleaning with Nyloc wheel brushes. I'm OCD as well.

She is looking good! Hopefully I can have the engine fully prep'd for paint by the end of this weekend, since I will be getting my frame and all the associated bits that were blasted and painted back tomorrow.