Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: Grewth on March 11, 2026, 12:22:17 AM
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Can anyone tell me exactly what plastic the original Honda side panels were made from, and what will stick to them properly ?
I've managed to find a pair with paintwork to match my K4 tank .
The trouble is that both have hairline cracks here and there.
I'm thinking that if I don't reinforce them on the inside somehow, they're going to disintegrate if I start using them on the road.
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I repaired both side panels for my 550 that was imported from the states just to keep originality. But I should never have wasted my time as I dropped one and it shattered. Seemed to be very brittle, maybe depends what exposure it’s had. Replacements are of strong material, seem to be good. Good luck!
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Fiberglass woven mat and epoxy resin but it will make them heavy, LPM do excellant repos but not sure if they sell direct any more
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What about Aluminium foil tape, the stuff I have has very strong waterproof adhesive on it and is quite strong. I think the roll I have was from RS but screwfix etc stock it. I see there is also some insulated types designed for wrapping exhaust headers.
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As Bryan says,and what I have done was woven fiberglass, you dont need much to do a good repair, and they are not much heavier.
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Tape will allow either side of the crank to flex independantly so it will propogate.
First answer was very true in that by the time they crank the "plastic" has already gotten very brittle and shatters easily
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Very thin woven cloth (glass fibre weave) are available for this repair type application.
Unsure what the original plastic is though.
You can carefully test a tiny patch on rear with different solvent to see what makes it sticky to help research.
I've repaired some things like this with cotton scrim (well wash T-shirt) and epoxy resin to adhere it. Dont get caught by the owner of T-shirt though! Cut a patch only out of the back so they don't notice when wearing ;D
Repaired a car front valance recently with proprietary resin and their supplied patch. Surprisingly secure and workable (the black apron down underneath the bumper) against my initially cautious expectation.
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On my 750F1 I used a fibre Glass repair kit in the inside of the panel and on the outside I used CA to fill the crack and sanded it smooth.
The trick with the latter is not to leave the CA too long as it gets really hard, use an accelerator and leave it for about 20 minutes before sanding.
Cheers
Dennis
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Thanks for the advice everyone !
Woven glassfibre matting and epoxy resin it is then.
I'm only doing it to preserve the original paint on the panels, they'll last as long as they last, and when they finally fall apart, they'll be binned.
I've already got a set of the LPM panels, and very well made they are, although polypropylene is supposed to be a pig to get paint to stick to.
They still sell on ebay
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I had no problem painting my LPM panels, I used Halfords rattle cans for mine, undercoated with Halfords plastic primer, 2 coats of Ford Graphite Grey, one coat of clear. The Ford colour matched the original Honda colour.
(https://imagizer.imageshack.com/img923/1012/WTSsQ5.jpg)
While I was at it I did some spares just in case.
(https://imagizer.imageshack.com/img923/3461/TGGvKp.jpg)
Cheers
Dennis
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Thanks for the advice everyone !
Woven glassfibre matting and epoxy resin it is then.
I'm only doing it to preserve the original paint on the panels, they'll last as long as they last, and when they finally fall apart, they'll be binned.
I've already got a set of the LPM panels, and very well made they are, although polypropylene is supposed to be a pig to get paint to stick to.
They still sell on ebay
Its this type of GF im referring too for clarification https://www.fslplymouth.co.uk/glass-fibre-fabrics/200g-twill-weave-fibreglass-cloth/#price+per+square+metre:5+Square+Metres it "drapes" really well without much effort, adds very high strength when cured, but easy to work with.
It makes for pretty light structure, especially when single layer. Not too much resin but well rolled out through structure to prevent voids, makes quite a neat job of it.
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I use plastic epoxy.... JB Weld is thin and runny, works good as a glue, takes some time to harden. Can file/sand, prime and paint. Permatex is thicker, cures faster, and is very tough. Again can file/sand, prime and paint. I use it to smear a coating on the back side, wider on each side of the crack. and if you're good, can get it reasonably smooth. Then I'll put on an extra coat to build that up a bit.... it won't crack again in that location, lol. I prefer this over fiberglass personally.
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I use RS Components 2-Part Industrial Epoxy (same as used in my coil fix)
It too goes really runny when warm and finds its way into tiny cracks.
Takes 24 hours to cure though at room temperature.
https://uk.rs-online.com/web/p/potting-compounds/1991468