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Discussion Starter #1
Hi Guys,

I have a HD street 750 for the past 6 years, and recently the engine paint has started to peel off in spots. The Spots seem to appear more and more over the days and its really looking ugly. Can you please suggest what could be the reason for the same and how to rectify the spots.
 

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2016 Harley-Davidson Street 750 in Sunglo Velocity Red
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601 Posts
The spots happen on many motorcycles. The engine heats and cools and expands and eventually the film finish cracks and eventually flakes off. This is especially true if the engine was not completely clean prior to painting.

I would do the following:
  1. Hit the effected area with a hand held wire brush so that any loose finish that is about to flake off does so now instead of after painting, thus taking new paint with it.
  2. Scuff the exposed surface with fine sand paper or steel wool to help the new paint adhere and also to feather the edges around exposed areas of metal and the layer of paint that stayed bonded.
  3. Clean the engine with a degreasing agent. A bucket of water and dish soap is good, but there are some very serious degreasing agents on the market if you choose to go that way. This is to get any chunks of dirt or old finish out of the way as well as to remove any grease or oil that will stop paint from bonding.
  4. Dry the engine with a blow gun connected to an air compressor, shop vacuum, or even a hair dryer. We want to make sure all of the water is gone as paint won't adhere to it.
  5. Spray paint the engine. I would just hit the bare spots, but you might want to do the whole thing. That is up to you.

You should be able to get black, high temperature engine paint at any auto supply store. Engine paint is much better than hardware store spray paint at standing up to high temperatures, which will crack and peal away after a few heat cycles. H-D sells engine paint, but any brand should do and most will cost less.

One tip is to cut a hole in a piece of cardboard, hold the cardboard between the spray can and the surface, and spray through that hole. Keep the spray can back at a normal distance from the surface being painted, usually a foot or so away. This will reduce paint spatter onto the parts of the engine that don't need paint while not making an obvious crisp line between the repainted and unpainted areas. It's also less tedious than trying to use tape to mask irregular surfaces such as cooling fins. Use a piece of cardboard with a smaller hole to touch up a small area rather than holding the can closer to the surface.
 

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"Loose Nut" from Houston, Texas
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365 Posts
Here's an engine I painted not to long ago. Pictures are before and after paint with added chrome. Basically did it like @PugslyCat explained.

27600


27599
 
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