Best muffler/silencer for exhaust

[woodman-46]

Hello,
I have been working on an old ride on lawnmower and " converting" it into a small tractor for my son.
All is done but I am wanting to buy a muffler or silencer for it as it is fairly loud. The engine is a Briggs and Stratton 11.5hp and I have set up a 1 1/2" pipe system from it that I then want to attach said silencer to. I bought one, which is shown attached, but although this has reduced the sound by a reasonable amount from having no exhaust at all it has a bore that goes right through of about 2 " with no deviations or dampning inside. There is obviously though, as can be seen, a thickish wall, I'm not convinced it is that effective.
Can someone please give me advice on the best sort of muffle/silencer for this set up that would reduce the noise by as much as it can do.

Thanks James

 

[Burnerman]

I think your best bet would be to use a small motorbike silencer as fitted to a Honda 125cc or similar.
These are remarkably quiet, unlike the straight through megaphone exhaust ( beloved by all youngsters)
that you have there. The exhaust diameter is pretty large for a small engine and therefore you’ll always get some boom.
It’s difficult to baffle that one but if the end cap comes off maybe you could insert a perforated tube, open at the incoming end but closed at the other that would collect the exhaust gas and slow it down. The exhaust gas goes through the tube perforations and hits the wall of the silencer, collecting and then expelling through the silencer end.
By the looks of it, that’s actually an expansion exhaust you have there, designed for two strokes originally.
It sounds like a great project!
John

 

[woodman-46]

Thank you John, does a silencer like the one you mention ( Honda 125 cc) have a muffler system inside it that "quietens" the exhaust as it goes through. I remember my dad had an old Yamaha c90 that as you say was realy quiet. I guess the fact that there is nothing inside the one I have, but purely an open bore, means that there is very little noise deadening.

 

[Burnerman]

Yes, the small Jap bikes had tubing baffles and the inside was lagged with a glass wool.....whisper quiet they were but obviously sapped a little power.
Pattern parts are available from M&P Accessories cheaply enough.
Unfortunately I don’t think you’ll find any Briggs silencer that will fit the bill - they all seem to make a din.
Of course if you have the cutter deck removed the machine will be quieter than usual.
John
As a P.S I made a trailer for one of these machines.....great for the owner to learn to reverse, etc. As it turns out, he’s much more competent than me at doing so.
He’s 9
J.

 

[woodman-46]

Thanks John

 

[Burnerman]

Most welcome!
A photo or two would be great to see if you have the time.
John