Petcock Problems.

pcloudy · Posted: Fri Jul 18, 2008 1:36 pm Post subject: Petcock Problems.

So I finally get fuel line and hook up my inline filters and go to test everything (draining gas into a can) and this is what happens
1. I cant put the switch fully vertical as it bumps into my tank so I cant turn my reserve all the way on.
2. The fuel didnt seem to flow when the switch was in the on position
3. In the reserve position fuel flowed from one side then stopped then flowed from the other side.
4. The on position then proceeded to work about the same as the reserve position did, sparatically.
5. I think my petcock was leaking slightly from behind the on/off/reserve switch.

Some things to note. I only put a small amount of fuel in there so there wouldnt be much pressure on the fuel. My petcock gasket seems fine but Im not sure if there is a proper way that it installs, it just looks like a gasket with four holes in it. Im going to try and spray some carb cleaner through it to see if that helps but any suggestions would be nice. Its a 73 cb350 if that makes any difference. Thanks

Johnny5 · Posted: Sat Jul 19, 2008 8:24 pm Post subject:

When I got my bike, the petcock was completely plugged with rust. I had to dissemble the petcock and clean it out. A small amount of fuel should still come out of the tank with the switch turned to the Res position. Also, make sure with your inline filters that the flow is going in the right direction.

Cleaning the tank, petcock, carbs should be the first approach to getting an old bike road worthy.

jayel · Posted: Sat Jul 19, 2008 9:20 pm Post subject:

don't have the plate that holds the lever on upside down do you? you may be trying to get it to work bass ackwards, lever straight down should be normal ON posistion then level forward and rearward for OFF and RESERVE

pcloudy · Posted: Sun Jul 20, 2008 4:05 pm Post subject: ...

It should be all assembled correctly. Im just thinking that I put such a small amount of fuel in there that there wasnt enough to push it through both lines at once. Does that make sense? And can you start a bike with no battery with just the kick starter? thanks

jayel · Posted: Sun Jul 20, 2008 4:21 pm Post subject:

it may fill one carb sooner than the other but both sides should flow, as for starting without a battery no, your bike as a alternator type system that needs battery voltage to excite the coil to generate electricity if it had a magneto then it would start without a battery

650BILL · Posted: Sun Jul 20, 2008 8:28 pm Post subject: Petcock

Never trust a petcock on a used bike, I've got a '79 CB650 and only thru trial & error I've discovered mine is off at 9 o'clock, on 12 & reserve at 6 650bill PEACE

gaj55 · Posted: Sun Jul 20, 2008 10:29 pm Post subject:

Petcocks require patience. The last one I fixed, for my cafe 360, I doubled up the tension spring. Worked like new.

I will tell you quick about my leaky carbs. I have had two sets of carbs where the overflow tube has been cracked. What a pain! Getting the petcock to work is essential.

Usually if the direction doesn't make sense it is because of combining parts of different petcocks. We have at least two different formats with different CL360 machines.

Good luck - check out my cafe bike... Third try at getting the motor right... fingers crossed.

Johnny5 · Posted: Mon Jul 21, 2008 5:45 am Post subject:

pcloudy · Posted: Mon Jul 21, 2008 12:01 pm Post subject: ...

The long tube going up from the petcock to the gas tank has a crack in it. Would this cause a problem? I will try adjusting the tension spring, by doubling it up do you mean you added another one or added bends to the existing ones? Thanks

Johnny5 · Posted: Mon Jul 21, 2008 2:06 pm Post subject:

It really doesnt cause a problem, the long tube is your "on" position and the bottom of the petcock is your "reserve". So really, you'll just be getting gas from the whole tank. If you run out of gas, then that's when you'll have your problem.

Know what Im saying?

hanly2 · Posted: Mon Jul 21, 2008 7:47 pm Post subject:

Just some insight I might add. Tonite I took my bike for a ride and it was running good then it would bog at 3/4 throttle. I thought the float was stuck so I pulled over and shook the bike back and forth. Well I was then able to make it home the rest of the way. When I got home I decided to check and see if the bowls were filling well the passenger side wasn't. So since this is the second time I've ever ridden the bike I thought that maybe the petcock got clogged. So I pulled the fuel line to the second carb. I wasn't able to get any fuel from the petcock in the on position but plenty in the reserve so I know the petcock wasn't clogged. Guess what I didn't have enough fuel in the tank. I filled it up with my handy dandy gas can and now I get plenty of fuel and it runs good again. So I would put more fuel in that tank when you do your testing.
Good luck

And nice bike gaj55 looks real good.

Johnny5 · Posted: Tue Jul 22, 2008 5:39 am Post subject:

The "on" tube for the petcock might be cracked. Mine was.

gaj55 · Posted: Wed Jul 23, 2008 10:47 am Post subject:

very common fro the overflow tube in the carb to be cracked - petcock also.

No mechanic I know has had an idea on how to fix it except to replace the carb bowl or petcock. I'll be at mid-Ohio in three days and ask the 'guys of VJMC'. Someone has to have fixed those tubes.

Good Luck