Harley does sell small touch up bottles that are pretty cheap and in all colors.Black and solid colors can be touched up rather easily. Silver,gold or 3 stage paints {red hot sunglow} are not going to be so simple.Metallic flake is polished on one side so when sprayed from a gun you are trying to get the flake to lay down giving it that brilliant sparkle. A brush tends to stand flake up leaving it streaky and exposing the darker unpolished side of the flake.
Using a fine brush apply a couple of coats inside the scratch. Be patient and allow each coat to dry,try keeping it only inside the scratch.The idea is to build up some layers to fill up the scratch.If your hand is not that steady you can use a rubber block and 2000 grit wet paper to remove any paint outside the scratch. Once good coverage is achieved apply a coat of urethane based clearcoat again using a fine brush.It is not as important to keep the clear inside the scratch as it will blend in with the clear already on the bike.
When finished you want the clearcoat layer to be raised slightly. Allow the clear to dry overnight at at least 65 degrees. Once dry take a NEW razor blade and apply masking tape to the last 1/2 inch on the outer edges of the blade.This will prevent the corners of the blade from contacting the undamaged area. Keeping the blade flat, smoothly drag it in one direction across the raised clearcoat straight up in a flat position to the panel.You will notice white material being removed, thats excess clearcoat. Trust me this is OK.You should see the raised clearcoat {only the raised clearcoat} as a white line.Continue with the blade until the the clear you applied starts to become level with the existing clear on the bike. If you start to remove clear from outside the touched up area its time to stop with the blade.
Now that you've gone as far as recommended with the blade its time to wet sand.Using 2000 grit wet paper and a rubber block sand the area smooth. Once smooth use a buffer and some medium grade compound and buff.It generally takes 3 to 4 applications of compound before all the scratches are gone and you realize that crazy razor blade idea actually worked. Follow this by polishing and you're done. If you end up with low areas in the scratch simply apply more clear and repeat.
Clearcoat will hide any scratch 1000 grit or finer so if you start sanding with 2000 and realize you need more clear stop sanding. Before applying additional clear make sure to throughly clean the affected area as trapped wet sand residue will remain white. You wont see the scratches you just made so don't worry. The idea is to remove as little of the bikes original clearcoat as possible.
Hope this helps.
When I originally wrote this I wanted to clarify a couple of things after reading it but the elapsed time for editing had expired. Then the wife stepped in. Oh well cant argue with her wanting to go for a ride.
1. When I said keep the blade flat what I mean is straight up in a flat position to the panel.
2. Before applying additional clear make sure to throughly clean the affected area as trapped wetsand residue will remain white.
