exhaust gaskets

[kpke]

I tore my bike down a bit for a cleanup. I found too much exhaust goo blowing out around the lower manifolds. I think most is coming out through the slip fit of the pipe going into the manifold. I do use high temp RTV in that area.

Has anyone made their own paper exhaust gaskets to use between the manifold and the cylinder?

I am using JL stainless pipes. The doughnut gasket is also used. But I am wondering if a paper gasket might ensure that at least it will not leak there.

Thank you.

[RuZty]

Yamaha PN 29L-14643-10 is listed for the RZ350 but also for the TZR250. Possible it has the same bolt pitch? I have never had one of those silver composite gaskets leak on my 350.

[Speed Freak]

You can use graphit gasket material and cut it by your own.
But it shouldn`t be necessary in case of the RD500 because the standard seal is a different type ("spiral" grapite seal) which is usually quite good stuff.

Maybe the mounting method of the JL pipes (i guess by a spring) is not applying enough pressure to the seal, so it`s leaking.
If you put a gasket between cylinder and the pipe flange the force of the spring is reduced even more and it will still leak between flange and pipe.

Maybe you can take a picture from the pipe side?

[silverstrom]

Yamaha PN 29L-14643-10 is listed for the RZ350 but also for the TZR250. Possible it has the same bolt pitch? I have never had one of those silver composite gaskets leak on my 350.

I just checked. The RZ350/TZR250 gasket fits.

[kpke]

Thanks for the replies guys.

I may have some of the RZ350 exhaust gaskets here. Need to dig them out.

Speed freak, you are right that use of a gasket here will actually elevate the flange off of the cylinder a bit. I was concerned when I assembled the exhaust on to the cylinders about the donut gasket. It was barely elevated above the flange surface on the cylinder. It is nothing like the much larger donut used on the RZ350. Much smaller and not as much compression is taking place.

I am hoping using a flat gasket here and probably smearing high temp silicone on both sides will give a complete seal and the donut will not be used. Then I will pack a little extra (this time) high temp silicone into the flange for the slip fit of the pipe into the flange.

Where am I going wrong or is this worth a try?

For the pipe to flange joint, for us with old style non-O-ring pipes, ultimately I would like to find some silicone tubing that would go over the flange and the exhaust pipe and be clamped on. I have seen this used on Kawasaki triples expansion chambers.

[Speed Freak]

Ok, this design has to leak

How does it look like when you pull off the flange from the pipe (remove the spring)?

Can you tell me following diameters:
- Inner and outer diameter of the pipe without flange
- Inner diameter of the flange removed from the pipe (should be the same as the pipe outer diameter...)

Flange and seal dimensions I can take from my own cylinders.

I guess between pipe and flange there is no seal?
My NSR125 Jolly Moto had an O-ring inside the flange

I can check what`s possible to avoid leakage in this area if you want.
It should be possible without this high temp silicone...

[kpke]

Thanks Speed Freak.

Any help would be greatly appreciated.

Yes, this slip fit design between pipe and flange without O-rings is a faulty leaky design. I have been mostly successful on my RZ350 chambers. But even when successful eventually they begin to leak.

I am at work right now so I will measure things when I get home this afternoon.

[silverstrom]

When I used Lomas pipes on 350s I sealed the slip joint. That stopped all leaks. I put painters tape above and below the joint. Then I used high temp sealant to fill the joint. Remove the tape and you have a very clean application with no mess and no leaks. That was using both exhaust gaskets.

[kpke]

pipe OD 44.5 mm
pipe ID 40.2 mm

flange ID 45.2 mm
flange OD 40.0 mm
The pipe fits in between the gap made by these two dimensions. This is where the RTV goes.

thanks again

[Ron57]

Hi I had another groove cut in and second oring.
Then use original exhaust gasket no more leaks.
Cheers Ron.

[kpke]

That's really nice!

Unfortunately my pipes are not o-ring style. I wish they were.

[Speed Freak]

pipe OD 44.5 mm
pipe ID 40.2 mm

flange ID 45.2 mm
flange OD 40.0 mm
The pipe fits in between the gap made by these two dimensions. This is where the RTV goes.

Hi,

Now I found time to make a small CAD model - dimensions are not 100% ok at the moment, I didn`t measure the cylider side flange. But at least the gasket is the correct size.

"flange OD 40.0 mm" is this a mistake? Or did you measure the flange on the cylinder side?

This is how I understand the dimensions and how i think the flange looks like:


It`s only "pipe in pipe" held by a spring without O-ring (?)

[silverstrom]

It`s only "pipe in pipe" held by a spring without O-ring (?)

It is with Jim Lomas pipes.

[kpke]

Thanks Speed Freak! That is really cool.

No, the 40.0 mm is not a mistake. On your drawing there would be a second tube welded to the exhaust flange internal to the ID of the expansion chamber.

If you pulled the expansion chamber out (in your drawing), then draw another tube that is smaller than the ID of the chamber. This makes the cavity that gets filled up with RTV, then the expansion chamber slides into that cavity. In other words, there are 2 tubes welded onto the flange.

I hope this makes sense to you. I'll take another photograph of the flange one I get home.

[kpke]

Here you go