SOHC.co.uk Forums > CB500/550

Pan screw

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Davelu88:
Anyone  know the best place to buy the carb bowl pan screws as on the usual sites they seem very expensive.  TIA

Nurse Julie:
Do you mean the original carb bowl JIS screws Dave? If yes, I do a bowl and top kit.

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Davelu88:
Cheers Julie , I will order them on your site

Nurse Julie:

--- Quote from: Davelu88 on October 01, 2022, 10:42:20 PM ---Cheers Julie , I will order them on your site

--- End quote ---
OK Dave. Thank you.

Oddjob:
Aren't the bowl screws supposed to have spring washers as well Julie?

I also don't use the original Honda sizes when replacing these, they are too short and leave threads unused, over time these threads corrode until IF you try and use a longer screw it won't allow you to, I always retap the thread and in the case of the upper 8 screws I recommend using a 5 x 20mm screw instead of a 5 x 16mm, those extra 4mm of threads may not sound like much but they pull in better and stop the threads stripping out as there are more threads engaged.

Same with the bowl screws, they are too short, 4 x 12mm IIRC, I would recommend going longer, use a flat washer under the spring washer ( I'd advise these for the upper 8 as well) to stop it digging into the alloy of the bowl, a couple of the bowl screws will hit the body of the carb if you use too long a screw. Best advice would be to use a longer screw, measure and cut the screw when it would just be flat to the body, you don't want threads exposed to air as they corrode and when being removed will start to damage the threads as they pass through. The problem with cutting screws like these is that you can damage the threads as you cut, you don't always get the cut straight either. To avoid that use a flanged nut, thread it onto the screw and position it where you need to cut, use the side of the nut as a guide for the hacksaw, when cut the nut will clean the threads off and straighten them of any burring caused by the hacksaw. A run over with a file is also a good idea to get the surface flat.

Because I tend to cut them to suit and JIS are not normally stainless but BZP plated this means the part cut isn't now BZP, this can cause corrosion and rust, which is why unless I can source JIS stainless I prefer to use just stainless instead. Even the cut is corrosion resistant.

Just my experiences and thoughts, feel free to ignore. However look at how many members complain of stripped threads in carb bodies and you can see how they happen.

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