Sachs Westlake Exhaust

Ty Griswold /

May 27, 2020 07:04PM

Bought an unknown year Sachs Westlake moped recently, runs pretty good but can use some TLC. In particular the exhaust is pretty loud. There was a decent sized weld line at the transition from the header, so I figured the PO removed the baffles.

Taking off the silencer section of and looking closer I found that the muffler is actually a Harley dynaglide muffler that was welded up. I believe it's a stock header (which seems pretty loose to the cylinder. There is quite a bit of spooge there so I still have to clean that up and check the gasket and see if I can tighten things up).

My main question is there any problem with continuing to run with this 4 stroke Harley exhaust that the previous owner welded up? Other than the noise.

Re: Sachs Westlake Exhaust

P D /

pdcomm

May 27, 2020 07:17PM

You can run a straight pipe if you like . The old 2 strokes ran a pipe with an empty can for a 'muffler' .

Just don't make the straight pipe too short and don't expect any performance gain .

Re: Sachs Westlake Exhaust

Graham Motzing /

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grahammotzing

May 27, 2020 10:46PM

Damn, where is it still snowing!

Pipe ain't gonna hurt but if it's leaky you might be lean, which is gonna kill performance. You can buy some decent slip on chambers from treats that will help a lot and should be quieter.

The leaks is the big thing, can't have it leaking. Whatever you do that isn't stock you might have to adjust the carb jetting.

Re: Sachs Westlake Exhaust

Ty Griswold /

daerauko OP

May 28, 2020 10:52AM

I didn't think an exhaust leak could be causing an idle condition. It seems to be in pretty good shape, visually.

I took off the header pipe and was surprised that it wasn't a flange at all. There was a stubby pipe fitted somehow (couldn't actually determine how it was fitted) to the exhaust port, but it did have a slight wobble to it. The head pipe was a slip fit to the stubby pipe.

Besides doing a plug chop, is there a best practice for finding if there are any leaks? Is it an issue with the exhaust sucking air between the exhaist pulses, where the the reflection wave would be scavenging unburnt gases, it would be sucking extra air back into the chamber.

Re: Sachs Westlake Exhaust

Graham Motzing /

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grahammotzing

May 28, 2020 04:55PM

Ahhh man that stubby pipe is cast in to the cylinder. When they are wobbly like that it's broke. Might be able to hose it up with orange rtv and limp it along, but it would take major surgery to fix it any kind of 'right way'

Re: Sachs Westlake Exhaust

Ty Griswold /

daerauko OP

May 29, 2020 11:30AM

Well that is terrible news. Doesn't seem like the most robust design... sigh.

To be clear, there shouldn't be any movement in that stubby pipe? I have to take a closer look at the area around where it connects, maybe some muffler putty around the exterior would keep things sealed. I didn't look too close for leaks up that far, once I found that small hole. If I can feel any exhaust pulses from that area, it shouldn't be big enough to worry about, right?

Just disassembling and reassembling things seem to have helped the noise somewhat, I think. Maybe the crud buildup at the exhaust port was contributing to an extra leak, or things were fully seated. I did find a small hole in the weld job that is definitely leaking exhaust gas. I'll have to try and either use muffler putty or get my brother-in-law help me attempt to add some extra weld there.

I don't have much moped experience so I don't have a good baseline to compare against. I have not actually measured my top speed, since the Speedo is broken, but it seems to run decently well. I also have a 77 Puch Newport 2HP fully stock and while it isnt exactly fine tuned. They seem somewhat close in power (though I'm working through some idling issues with Puch).

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