Two part muffler

Jeffrey Lunger /

I recently bought a new muffler for my Jawa 207. It came in two pieces - one part was the pipe (https://www.jawashop.com/exhaust-pipe-babetta-207_z1097/) and the other the muffler assembly (https://www.jawashop.com/exhaust-silencer-complete-babetta-207-210_z1289/). So, ok, two parts and two questions.

1. The pipe is too long. I assume it's meant to be cut to length, but I want to make sure before I go hacking things apart.

2. How is the pipe meant to seal to the muffler body? There is a screw on cap that one might take for a pressure fit nut, but the pipe isn't flared or anything. How is that meant to work?

Any info would be helpful

Re: Two part muffler

Looks like the nut gets tightened after the header pipe is slid into the muffler .

Compression fit .

Re: Two part muffler

And I would add that typically mopeds from the factory have a head pipe that extends several inches into the muffler. Cutting that pipe down will change the way it sounds and runs.

Re: Two part muffler

Jeffrey Lunger /

Neither of those things are the case. The pipe does not fit into the muffler body nor does the nut have anything to compress onto. I’m really at a loss here as to how it’s supposed to work

Re: Two part muffler

Pics would be helpful. When you unscrew the nut bolt compression fitting thing on the back what does it look like? Does the pipe even slide into the hole?

Re: Two part muffler

Jeffrey Lunger /

The interior part of the muffler has a small shoulder. I was assuming the pipe would be flared and would be held tight to this shoulder by the nut, but this isn't the case. The pipe's diameter is the same as the nut's. It's possible to kind of get a friction fit with a tiny length of the pipe when you push it firmly into the muffle. I'm talking 1 maybe 2mm at most. The nut doesn't seem to do anything except perhaps center the pipe a bit. I have my doubts as to how effective this would be towards sealing exhaust gases. Maybe some sort of high temperature putty is meant to be used to seal it up? I just don't know. At any rate the pipe is way too long as is. Unless it's meant to go further into the muffler it's about 6 inches too long.

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Re: Two part muffler

Almost seems like the pipe is missing a part. Mabye try an get a small maby 1/4 piece of copper pipe that fits over the header and sandwich the coupler and pipe like a compression fitting? Worth a shot

Re: Two part muffler

Sealing the header to the muffler , I'd measure the header outside diameter and find a fiber crush washer or even some high temp rope or other material to put on the header after the nut , so the washer or other material gets crushed snugging the pipe in the muffler .

Re: Two part muffler

I would just slide it on the pipe and bolt it to the two threaded exhaust support holes below. start it up and see how it rires. At this point don't worry about having a super crushed seal where the two meet.

Re: Two part muffler

What is the diameter of the header?

Re: Two part muffler

> cheetahchrome . wrote:

> -------------------------------------------------------

> I would just slide it on the pipe and bolt it to the two threaded

> exhaust support holes below. start it up and see how it rires. At this

> point don't worry about having a super crushed seal where the two meet.

Because that will be your very next step . ;)

You won't like the farting and leakage that happens if you don't seal that joint .

Re: Two part muffler

Is this the first two stroke moped youve ever worked on? Stock pipes extend several inches into the muffler on two stroke mopeds. Theres nothing wrong with it extending 6 inches into the muffler. Put it on and fire it up already! If it sounds and runs good, worry about the fiber crush washer thats missing later. You will need a new exhaust gasket for the head pipe to cylinder also. (edited)

Re: Two part muffler

Jeffrey Lunger /

It is, but regardless without using a lot of force I don't think I can get the pipe into the muffler body. It's very, very tight and short of somehow using a hammer I'm not sure it would go in.

I measured the pipe and it came to about 20mm. The inlet to the muffler is about 25mm.

Re: Two part muffler

It looks like all that goes in there is a fiber rope seal. I imagine some ceramic fiber rope for a stove seal would be an appropriate replacment.

Re: Two part muffler

Weld her up. And spray with some clear coat (edited)

Re: Two part muffler

Put down the hammer and pick up a dremel. Lightly sand or grind the hole (below the threads) until the pipe slides in. Chrome plating is probably a touch too thick or hole has a burr around the edge. I see enough rust around that area to cause problems too. Its not rocket science its mopeds. (edited)

Re: Two part muffler

If you choose to grind or sand the offending opening be damn sure you blow out all the abrasive dust and chips left behind with compressed air before running it.

Re: Two part muffler

Jeffrey Lunger /

You were correct, and I didn't even have to grind anything, I little attention from a piece of 80 grit sand pipe and I was able to get the pipe in. Thanks for your help! I have some gasketing rope on the way that should serve to seal it up. After that I should be good.

Re: Two part muffler

You are more than welcome. That looks like a nice oem pipe and it didn't need cut, welded or beat on. Tune the ped stock then modify it one step at a time and retune for more performance, if you choose to. (edited)

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