u/Safe_Designer_2246

Hi all,

I'm restoring a 1986 Honda CBX750F (RC17) and I'm stuck on the fuel petcock. Hoping someone here has been through this.

What I've done:

- Rebuilt the vacuum petcock with a Tourmax FCK-1R kit (new vacuum diaphragm and O-rings)

- Replaced the tank-mounting O-ring (OEM 91305-MC7-000)

- Replaced the fuel hose from the petcock outlet to the fuel filter with a new one. The new hose has a slightly different diameter from the original.

The petcock has 3 outlets:

1. Vacuum line to the engine

2. Fuel line to the fuel filter

3. A third outlet that isn't connected to anything, which I've capped

The problem:

When I crank the engine, fuel leaks out through the capped third outlet and the bike won't start. Fuel only comes out while cranking, so the vacuum seems to be opening the valve, but the fuel goes out the wrong way instead of reaching the filter and carbs.

My questions:

- What is the third outlet for on the RC17? Should it be capped, or is it supposed to be connected to something (second feed, return line)?

- Could the small diameter difference of the new fuel hose cause a restriction that pushes fuel out of the third outlet?

- Is it possible I assembled the diaphragm or an internal gasket wrong during the rebuild? Anything specific to watch for with the Tourmax kit?

- Any tips on priming the carbs once the leak is fixed?

Photos of the petcock and hose routing below. Any help or a photo of the original routing would be really appreciated.

Thanks!

Hi everyone

I’m looking for recommendations for motorcycle workshops/custom builders in Germany that have experience modifying classic Hondas, especially the CBX 750F (RC17).

I have a 1986 Honda CBX 750F, and I’d like to modify/shorten the rear section (tail/subframe) to achieve a cleaner, sportier look similar to the CBXs in the attached pictures.

I’m specifically looking for a shop that could:

* Shorten/modify the rear subframe and tail

* Adapt or fabricate the rear bodywork/seat as needed

* Keep the modification professionally finished and, ideally, TÜV-compliant / road legal in Germany

I’m located in Bonn/Cologne, but I’m willing to travel within Germany for a good shop that knows these bikes and can do this kind of custom work properly.

Does anyone here know a workshop or custom builder you would recommend? Even better if you’ve had similar work done on a CBX 750F.

Pictures attached to show the kind of rear-end look I’m aiming for.