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Lawn mower engine + Honda VFR750 carb??
unixguy - 22/5/08 at 10:22 PM

Hey guys.. I found allot of technically competent/friendly people on here when I had questions about my 'blade engine, so I thought I would ask this here..

My question is: I have a spare set of carbs from a Honda VFR750.. is it going to be a workable idea to try and install these on two 2-stroke 98cc (or 120cc, can't remember) old Victa branded mower engines? They are high quality, strong little things, which I think are made by Honda - not the usual lawn mower junk engines. The carbs are, however, cheap plastic crap, and are designed for a fixed high RPM - you can't really rev.

I can probably make a little converting flange thingie so that the carb will fit on the engine, but what I am not sure about is how the engine will run.. the VFR750 has 4 cylinders, each almost twice the size of the single cylinder of the mower engines. Is it going to be possible to tune these carbs so that they would deliver a usuable mix to the engine?

Oh yea, why do I want to do this? Well.. if I can make these engines revvable, I could use them for some cool project, couldn't I :]


caber - 22/5/08 at 10:35 PM

I think the carb would be way too big for the lawnmower engine. I think you will probably blow the engine up if you try and rev it higher than it is designed for!

Caaber


Mr Whippy - 22/5/08 at 10:42 PM

over carbing it so much will make it very difficult or imposable to start (due to the very slow air speed in the venturi failing to draw out the fuel to start) and give it no torque. It will also most likely fly apart.

[Edited on 22/5/08 by Mr Whippy]


unixguy - 22/5/08 at 11:20 PM

Mr Whippy,

Thanks for the reply, and thanks for giving the REASON, that's great!

I see your point about the slow air speed.. If I supercharged it, might it draw ok (and help it explode better!)?


MikeRJ - 23/5/08 at 07:58 AM

Get a carb from a 2 stroke bike engine of similar power. Realistically I suspect the lawnmower engine is making about the same power (or quite possibly less) than a typical 50cc moped (~3-4bhp).

As said the VFR carb will be massively too large, you'll never get it calibrated correctly.