My First 4hp

Hi all,

I'm new to owning 4hps, but have read that they have a smaller stroke, and higher compression than 5hps.

I have brought this 4hp for 40 bucks NZD ($28 USD).

I was wondering if these were rare? It looks to be a silver motor which I read were good. I'll have model numbers when I pick it up today or tomorrow. I would say it is 60s because of: The metal kill switch on top, The aluminium ring by the pull cord and the fuel cap. :thumbsup:

I will most likely do a restoration on this motor.

What are your thoughts?

Got it home today. It's a 1965 silver motor. Very dirty, but fires up. I will be restoring this motor in its original colour (silver). I just need to repair the recoil. Can anyone give me info on the 4hps? What were they used for?



Well-Known Member
fox used them on some bikes, My 1967 came stock with one and you can see in brochures where it was offered. I can tell you that the bore is smaller than the 5 as I had the head off to see what I needed for rebuild. Also according to a mini bike service manual I have (printed inthe early 70's both bore and stroke show smaller on the 4 compared to the 5.

Dunno what the typical application was for. May have been better on apps where the engine had to run all day just to keep something moving, as it may run cooler due to more block to dissipate heat. And the Fox did use the same sidecover without the holes as the clutch guard mount used the rear engine mount bolts.