r/bikebuilders

With the paint removed from the tank and the bad welds fixed. You can just see how well it fits the bike.

The subframe is getting close to being done. The rear brake master cylinder is mounted. And a front fender has been modified to fit.

Carbs have been cleaned and made to look nice but aren't installed yet. Same thing with the rear brake caliper.

Give my brother a follow if you want to see more of the build. IG greyslopegarage

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!