Saturday, August 24, 2013

What's inside those heavy Tomos A55 pipes?

So I've been noticing a decent amount of newer Tomos coming into shop with the same problem. The bike will start and will run very intermittently when you rev it out.  It almost seems electrical or possibly like there is bad gas or water in the carb. The solution to all these bikes has been to replace the pipe with a new one, which 90% of the time it gets replaced with and performance pipe. So I know that due to Tomos being the only true moped still produced, they are going to have to keep up with standards and emissions. I've heard these pipes were catalyzed but have never looked inside one. The strange thing is this is happening to bikes from just a year or two ago. So I took a clogged pipe home to do some hacking and research. I've researched ways to clean the catalyzed parts and it seems like if this happens your only option is to cut it up or upgrade to a new pipe.

Looks like a good place to start.
Restriction cone.

Cutting more!
Catalytic converter.

Cut the welds all the way around the sleeve.
Converter comes right out.

Who knows, you could clean this and it could work out. Or you could just remove it and maybe even gain a couple miles an hour. 

Removing the cone.
Such a restricted pipe. If I owned a stock Tomos A55, I would probably just make a couple cuts and remove all of the restriction. If you have access to a welder it would be worth a shot.
So restricted.

So in theory, you could do the first cut I did and then also a cut 3-4 (?) inches or so in from there and the whole restriction setup would slide right out. If you look up a couple photos, you can see that youll have to cut close to the furthest heat guard mounting spot. I would try it out but I dont have a Tomos A55, maybe I'll try it out on thom's tomos sometime. 


  1. That looks exactly like the cats that Ural was putting on their BMW clones. At least there you could pull the short pipe and punch the converter out with a piece of rebar. I can't imagine how on earth a cat works with a 2 smoke. Wouldn't the burnt oil clog it up almost instantly?

  2. Motul makes a two stroke oil specifically designed to work with catalytic converters, I recommend it to all my new Tomos customers.

  3. im searching for it phil thanks! is it the Motul 710 synthetic smokeless?

  4. i cut right in front of the first weld at the big end of the cone, take out the whole middle section and leave the 'silencer' end section and weld it back on.

    you loose about 3 lbs and it isn't much louder, significant performance increase. doing that, the gear change, and cutting off the intake snorkle 90 degree thingy gets you damn near 40 on a stock A55. Plus even people who know what to look for cant tell you did anything to it.