GPR Camp: Replica Racers

Howdy Folks!

I recently stumbled upon this forum while researching this bike I acquired a month or so ago. When I got it it was in pieces and the engine was seized.

So far I have freed up the motor and currently trying to track down and fix a leak in the gas tank.

Welcome!

Post some pics if you can.

Where are you located?

Those are fun bikes. It is likely that the leak is at the connector to the petcock if the tank is leaking. However, if there is just a gas leak then it is likely that the float valve in the carb, and the petcock are worn out.

There is information on petcocks which can be found at Treats, and if the bike has the stock carb it is probably a Delorto PHVA. Which is a fine carb, but it is worth considering an alternative like the Polini CP.

Located in Montana and I will try and get a few pics up.

Here is one I could snap real quick. Please excuse the dust, it is currently sharing space in my wood shop (read garage)



Found my tank leak, one of the o rings on the tank fitting had rotted out and fell apart after I removed it.

I believe it has the stock carb as the delorto sounds familiar, not sure on the model though.

Quick question: on the stock petcock, which is the fuel send and which is the vacuum line? I'm having trouble finding documentation on it and don't see any markings.

The fitting closest to the tank is the fuel line, and the one on the bottom of the petcock is the vacuum line.

Thank you! With any luck ill have it running tonight.

Well, no go. Gas is not flowing through the petcock. Is there anyway to repair it or will I need to replace it?

You can try applying a vacuum to the lower fitting by sucking on the tube. Fuel should then start to flow out the upper fitting.

What happens is the alcohol in the fuel rots out all the rubber bits, and the diaphragm in the petcock goes bad. But usually when they go bad fuel comes out both fittings.

The OMG petcock that you can get from Treats doesn’t have the fuel gage sender. I ended up going for a high flow petcock that doesn’t even feature a reserve. You have to check your gas by opening the tank, and taking a look.

That's what I was afraid of, I already tried sucking on the bottom one. No fluid out either hose

As for a replacement, the OMG one looks alright. If I choose to go for the screw operating version, what do I need to do to the vacuum barb on the carb? Take it out an replace with a screw I suppose? Or just save the hassle and stick with a vacuum petcock?

You can put a cap on it. Treats has them.

The big issue with using the non-vacuum petcock is that you don’t have access to it if you install the bike’s side fill panels. That’s the main reason I don’t have the side fills on my bike.

If you are running a larger carb (~24mm) then the higher flow petcocks are important (remember to get a high flow fuel filter too). If not the vacuum units are fine.