Topic: Leaky Petcock

[martini]

For some reason the petcock on my 750k0 has started to leak. I'm going to take the opportunity to rebuld it. My question is, is the k0 petcock to same as subsequent k models or am I looking at forking out big bucks for a "sandcast" rebuild kit (its not a snadcast but I'm sure someone will try and advertise it as such)?

Thanks in advance for the help.

[736cc]

Welcome to the "club"; they always leak. If you bought all the rubber gaskets and packing, it'd cost more than an entire new petcock.

[martini]

So its seems. Looks like I'm ordering a new petcock.

[merc2dogs]

 My observation, on the 74 model anyway, has been that the gasket -should- be thicker

 What I did with mine after getting a new rubber seal for it and having it start leaking a month later, without seeing anything wrong with the petcock itself, was to polish the sealing face on the lever to ensure smoothness, then file the housing itself down a slight bit, effect was to reduce the stack height so there was more pressure on the gasket.
 possibly doubling or trippling the wavy washer/spring would do the same thing.

 Slightly stiffer to shut off, I used a dab of oil on it when I first assembled it, gas has kept it lubed, But it hasn't leaked since.
 And if you let the tank sit for a while with no gas in it, loosen up the screws and shoot some wd40 or tranny juice on it before moving it.

  Last new petcock I bought leaked within a year, so I wanted to improve the thing instead of simply replacing it.

 Don't know if yours is the same set up as mine, if so this will work.

Ken
 

 

 

[sandcastcb750]

As best as I can tell, all the petcocks are the same from K0 to K4, meaning the petcock is on the right side of the bike and two hoses are supplied to 1,2 and 3,4 carbs respectively. The K5 is on the left and runs one hose with a splitter before thw carbs.

Having said that, calling a petcock good for a K4, sandcast, commands more interest and hopefully more money for them.

Sometimes you can fix the old petcock. Behind the lever on the petcock, the spring needs to be re-bent in order to put more pressure on the rubber gasket. It leaks out there at the lever once in a while. When you can't turn of the gas, keeps going to the carbs but does not show a leak, that can be the fiber washers holding the two 6mm phillips screws holding the petcock to the tank. A quick sanding the red fibers flat stops the leak as many years of compressing the fiber washer causes an indent. This always happens after you remove the petcock from the tank after many years. It is hard to find the same position, hence you flatten the fiber or get another. Finally, the rubber ring that fits with the bowl becomes distorted or hard. I have even sucessfully used tape to seal the bowl.That was a bike that had marginal use and I didn't feal like spending money on a new part or parts.

If you have $50, a new petcock makes life simple. Just tell them you're not buying the sandcast story.

[martini]

Thanks for the replies!

[bryanj]

All the same, cheapest place www.davidsilverspares.co.uk BUT you need to replace the fibre washers under the heads of the screws that hold it to the tank or gas will flow through to the carbs all the time and those washers are a special size (both diameter outside AND thickness) and as such cost a relative fortune

[martini]

I wonder if they would come with a new petcock?

[bryanj]

Nope, always been a seperate part!

[martini]

figures