Lawn Mower Carbs....Better Performance

Matt Wilson /

Ok Guys as my winter project this year I'm trying to hop up my old 1977 peugeot 105. I'm trying to avoid spending lots of money like buying performance exhaust systems, overbore/big bore kits, racing carbs ect... however if possible I still want a fast ped. Now I've had a couple of ideas and I wanted to talk them over with some other knowledgeable people.

1. It seems that car air filters have much less restriction on airflow than my moped air filter. Does anyone think that replacing my foam filter with a cut out of a car's airfilter for a performance filter.

2. Would it be a good idea to buff out the cylinder with steel wool to reduce friction

3. I tried removing the head gasket and the ped ran about the same as before perhaps is some pressure leaking out where the seal used to be? Would it be load or noticeable?

4. Has anyone tried configuring a lawn mower carburator that is built for a larger engine to a moped? How about an entire lawn mower (or any 2 stroke engine) engine to a moped? Does the transmission line up ect?

5. Where can you buy carb jets and are they expensive?

6. Is less restriction on the exhaust system better, or do mopeds need some air pressure to push the piston back into the cylinder?

7. I have also read on some scooter websites that to increase performance you can drill out the ports on the piston and cylinder so that the carb will inject a little more of the gas fuel mixture. Does this make sense to you guys? My logic is that all of the air/gas mixture is push into the cylinder regardless of how big the ports are...?

Well thats it... I didnt really mean for this to be such a long post nor do I expect one person to help answer each point but if you can help out great! Also any other performance enhancements would be apprectiated.

Thanks and have a good bbq

Re: Lawn Mower Carbs....Better Performance

Ok about your air filter, use computer foam. That shit rocks.

Re: Lawn Mower Carbs....Better Performance

ok, carb jets aren't too expensive (you can get them from moped parts stores online or by phone order). and they do make a difference. not sure about attaching a lawnmower engine, it might work, but mounting it would be tough. also, a lawnmover engines doesn't pull weight (it gets pushed). the carb of a lawnmower might be a different story ... but it's best to use a larger carb designed for your engine.

i've been told removing the head gasket actually helps. but the best thing is to clean your head and all that. i think porting might be good, but i'm not into that yet. so someone else will have to comment on that.

making your own custom exhaust will be tricky, since the exhaust is an important part of a two-stroke engine. custom performance exhausts are designed to give more pressure.

that's all i got. wait for ron, ree, or fred to comment. other gurus will too, i hope and tell you everything you need to know.

Re: Lawn Mower Carbs....Better Performance

I've got a Sachs westlake that has a carb from a sthil weed eater. I was forced to use it, because the ped had no carb when I got it. I silver-soldered an adapter together, using elecrtical conduit and a small chunk of steel. The advantage is a built in diaphram pump, good choke, easy adjustment, and a very simple design, compared to the stock carb. I use a filter off of a craftsman lawn mower. When it runs it is really reliable and easy to start. The only problems I have had were caused by me. Annother sugestion-replace all phillips screws with something you can torque down, like an allen head bolt.

Re: Lawn Mower Carbs....Better Performance

I was assuming tht what he meant by "lawnmower carb' was a carb off a 4 stroke .

one of a 2 stroke lawnmower (or other 2 stroke 'power tools' ) is not a bad idea if you can find one.

Re: Lawn Mower Carbs....Better Performance

Matt Wilson /


Do you think that you would get more performance out of a 2 stroke carb designed for a 75cc motor as opposed to a 50cc one?

Can ayone help out with the other questions?


Re: Lawn Mower Carbs....Better Performance

Maybe... but I just thought of something else... I don't think those carbs (lawnmower, weedwacker, etc.) have replaceable jets.

So if it didn't run right... you couldn't 'jet it in' to run better.

But if you get one for free, and it isn't hard to install.... heck... try it.

Re: Lawn Mower Carbs....Better Performance

Oh... and... 'buff out the cylinder' with steel wool to reduce friction ?

It probably won't hurt, but I don't see any benefit either. (don't use sandpaper)

A 'performance pipe' is probably the easiest way to get more HP and rpm.

Porting the cylinder is also important, but it should be done by someone who knows what they are doing... or by following instructions carefully.

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