working on float valves up side down?

[marp68]

On the 80 Special petcock I just had apart there is also a seal (not an o-ring) on the perimeter of the tap, the part with the handle, I removed it, lubed it with silicone and reassembled everything. Don't know how it worked though because someone bought the bike before I could put gas in it.

No more seal on mine. Was yours mounted on the front side of the wave washer? And the strange thing is that it was okej before. The only leak was down the tube. I thought the wave washer served both as a seal and to make the tap movement a bit harder, staying in posittion.

M

 

[xjwmx]

You need to take it apart and examine it and play with it until you understand fully how it works. Then you'll know what it needs. That's the right approach to mechanics.

I've had mine apart at least twice, but I can't be of any specific help because I remember what's there just long enough to do the job, like a phone number....

But I can tell you the wave washer isn't a seal - but it probably puts pressure on something that does seal to make it seal. Also, the wave washer isn't going to wear out, so you don't need a new one.

 

[marp68]

I've do had it apart and examnied it. The only thinig that's seem broken was the wall of one of the holes of the rubber seal. But when I put it together again, it now also started to leak through the tap on the outside, and not as before only a little through the tube (even on Off). That's why it's so strange that it seems to leak through the wave washer now.

Anyone knows if the waves on the wave washer should be positioned in any specific way to seal properly?

M

 

[xjwmx]

You need to take it apart and examine it and play with it until you understand fully how it works.

 

[marp68]

I tried to put it back twice with different positions, but maybe I will have to try it more, like you say.

 

[xjwmx]

I didn't mean to sound hard. I think you haven't learned the right approach to it yet. When you understand how it works, you'll understand why yours doesn't work. Grasshoppah

 

[weekendrider]

mar68
The position up, down, this side, that side doesn't matter for the wave washer.
What does matter is it is centered. It is easy to get it pinched between the face plate and the body of petcock. It's purpose is to hold the selecter against the valve washer with enough tension to seal it, but not so much that you bend the tab/handle on the selecter.

Find a bike shop with a parts man that knows or at least has an idea of what he is seeing and ask him if he can match it.
Try not to say what bike it is. You say XS650 they go into automatic "discontinued" mode.

 

[5twins]

You've already flipped the rubber disc, try rotating it as well. You'll notice on the 4 holes, 2 sit on locating pegs and 2 sit over holes. The 2 over the holes flow the fuel and do most of the sealing. Try to position the better condition holes there if possible.

 

[marp68]

Halfway there... i hope

I managed to buy one rubber washer from a local shop on one side of town and two wave washer from another local store on the other side of town. What a luck they had them.

I mounted the parts and it seems to hold tight, even if the other old rubber washer couldn't be replaced. We'll see tomorrow.

Thanks all you guys for moral support and information. After the petcocks I don't know if I start with the leaking float valves immediately or wait until the winter. It would, however, be nice to fix then also now. But it seems a more delicate job... Or?

/Martin

 

[xjwmx]

The float valves should just be a matter of replacing parts, where the petcock turned out to be a lot of head scratching. The petcock could have been just a matter of replacing parts too, but that's the coward's way out Do one at a time so you have the other to go by.

 

[marp68]

I saw this in the XS650 carburettor guide:

"Member "stevesemti" has identified another potential float system defect. In pre-'78
carbs, the float chamber is vented at the bottom of the float bowl through a brass pipe
seated in the float bowl, which opens above the correct fuel level. It prevents vacuum
from forming as fuel level drops and drains off excess fuel in the event of overflow.
Steve traced a fuel leak through the vent (usually caused by float level or float valve
problems) to the seat of the vent pipe (below fuel level in the float bowl). He reports that attempted repair with JB Weld slowed the leak but didn't stop it. Any fuel leak is a
dangerous condition. It might be possible to use a micro torch to sweat the pipe to the
seat with solder. Failing that, the float bowl should be replaced."

Beside the draining plug on my carb there is a rubber tube through which the overflowing gas goes. Not immediately, but after a minutes or so it starts to fill up slowly during the night. Is this tube the same as he calls "brass pipe" for venting?

I think I will try to inspect the floats tonight, but up side down witk the carbs still mounted.

/M

 

[5twins]

Yes, the hose you speak of connects to the bottom of that brass tube. You could try swapping the bowls from side to side and see if the leak follows the bowl. Or you could remove the bowl, fill it with gas and let it sit. If it starts leaking out the hose then you would know the overflow tube was leaking at it's base.

 

[marp68]

Good tip!

Unfortunately they both leak.

M

 

[marp68]

And, good news. The pecocks hadn't leaked during the night, so I guess I did a good job.

 

[marp68]

I now dismantled the float bowl, valve seat and needle. They seem okej. No dirt. When I press the needle into the valve seat, it shuts completely.

A mecanic at a local store that deals with yamaha gave me a tip to check the needle and seat function. To check if it seals properly, I could try to blow air through the gas tube (the tube from tank to carb). If I then shut the float needle manually, I would not be able to blow air, since this is the only way for the air (petrol) to go. If it's shut and I still can blow air, the problem can be dirt between the seat and the needle or that the needle has been worn.

When I blow air, it come out through the seat, and when I shut the seat with the needle, it stops some air, but I can still blow. It seems to come out somewhere else.

What do you guys say, can fuel only pass from gas tube through the carb down into the float bowl? Is it a sealed path, that is, the only two open ways are in the beginning (the gas tube from the tank) and the end (the float needle and seat opening)?

Or can fuel still reach the float bowl, even though the needle shut the seat hole completely?


M

 

[marp68]

I anyhow was going to adjust the height. Do I press the needel to close completely and then measure? Or should the tounge of the floats only touch the needle and then measure?

M

 

[gggGary]

just touching do not press or compress the spring.

 

[gggGary]

I am not sure which carbs you have? BS38s or BS34s?

 

[marp68]

Damn, I pressed it and adjusted it accordingly. Have to readjust. Can the needel be damaged by pressing it to the bottom?

I think bs38, since it's a xs650 B 1975. Standard carb, right? If previous owner have changed, how do I check?

What do you say about the tip I got, to blow air and press the needle to check that it close properly? Did you understand my difficult explanation...

 

[gggGary]

That's why I wanted to know which carbs. You probably have the Bs38s easiest way to tell is BS38s have a choke lever you pull up, BS34s have a choke knob you pull out.