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Refinishing GPz550 Side Cover with spotty paint

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12 Jul 2020 08:13 - 12 Jul 2020 08:20 #830454 by srsupertrap
Picked up this ratty side cover up on Ebay for $10 because it had an emblem . Going to refinish it. The top of the side cover has bare plastic with splotchy remains of paint. What is the best method to knock the cobbled surface down and get it ready for primer?

Thanks

1981 KZ550 D1
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Last edit: 12 Jul 2020 08:20 by srsupertrap.

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12 Jul 2020 11:00 #830465 by F64
Probably 400 grit sandpaper, but only after you wash it really well with soap and water. You don't want to embed any contaminants in the paint. Otherwise, you may have adhesion issues with your primer.
Make sure to remove any loose paint before you primer.
320-400 grit finish is usually used before primer to increase adhesion. Some will recommend 800 grit.
Read the data sheet on your paint system.

81-KZ440-D2.
Louis Dudzik's GM HEI ignitor conversion installed 2015 s3.amazonaws.com/gpzweb/Ignition/GPZgmHEImod.html
Motogadget m-unit blue installed 2017.
LIC, NY
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12 Jul 2020 13:29 - 12 Jul 2020 13:30 #830474 by Nessism
Hi Steve,

Sandpaper for sure but not 400 grit unless you got hours of time for sanding. I'd go with 220 or even 150 or thereabouts. Don't sand too deep into the plastic otherwise it will take more layers of primer to fill the scratches. I like to remove as much paint as possible before priming. It takes longer but lower film build is a good thing.
Last edit: 12 Jul 2020 13:30 by Nessism.
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14 Jul 2020 06:23 #830638 by srsupertrap
Replied by srsupertrap on topic Refinishing GPz550 Side Cover with spotty paint
Hey Ed & F64,

Thanks for the advice on sanding the side cover. I will get to work and start sanding and report back.

1981 KZ550 D1

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15 Jul 2020 08:31 #830725 by Deuce
In case you haven't started yet, try spraying Aircraft Remover on it and let it set. That stuff took off the factory paint on my 900F tank. If sanding, start with about 220 to 400 then go 1000 and 1500. If you don't you'll see all your sanding marks after you paint it.

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1982 GS1100G
1997 Yamaha Vmax
1979 Kawasaki 1000

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15 Jul 2020 17:49 #830766 by Nerdy
That doesn't look like sun damage - I think the bike it was on caught fire. :S

If that is the case, the heat may have made the plastic brittle. Be careful not to break it when you're sanding.

Speaking of, agreed that 400 grit would be a good start. Then apply a plastic-specific primer.

1979 KZ400 Gifted to a couple of nephews
1967 Yamaha YCS1 Bonanza
1980 KZ440B
1981 Yamaha XT250H
1981 KZ440 LTD project bike
1981 GPz550
2013 Yamaha FZ6R

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16 Jul 2020 21:38 #830850 by Highway Magician
Replied by Highway Magician on topic Refinishing GPz550 Side Cover with spotty paint
I would put my Optivisor on and carefully scrape the bulk of it off with a new single-edge razor blade. More than one blade will likely be needed. Then finish sand it.

Motorcycle builder since 1973. Master Tech. Current bike: 1982 GPZ1100B2.

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