View Full Version : CX500

hovercad - n/a
26-Mar-06, 11:03 PM
Hello all,

Anyone got any surgestion if a honda cx 500 engines are worth looking at for a craft??

I know these are a bit old but occasionally seen some cheap.

are they a lot heavier than the cb500 twin??

Think racing will be out of the question as not recomended engine.Would just like to get one of the 2 hulls i have off the ground.

Unless some one has a very very cheap engine ready for a fenland flyer with 900mm duct to drop in.

Now ex wife and kids restrict funds.oops not ex kids.

All input much appreciated.

about engine and craft not ex wife etc.he he he



Ian Brooks - n/a
28-Mar-06, 07:11 PM
I considered this a little while ago - I asked my friend, who's a bit of a CX bloke (or was, came to his senses aventually!) and here's what he told me:


Hmmm... Interesting idea.

My first thought was that there must be easier engines to get a drive from the crankshaft.

The CX engine is arranged like this...

At the front of the engine, the crank drives the clutch drum beneath it, directly via a spur gear. There is no access to the crank-end. A hole through the engine block casting there may be possible, but I've no idea how thick the casting is, or where oilways run. You never see that bit. It is a wet clutch behind a small round casing which just exposes the clutch front. I doubt if a larger gear on the crank (to give you 1:1 could be accommodated. The clutch drives the gearbox behind it (two shaft). The gearbox drives the drive-shaft in-line through a splined connection. The fan is run from the cam-shaft . At the back of the engine, the alternator is mounted on the crank internally to the large back casing. It would be unaffected by disconnecting or removing the clutch/gearbox. The shaft protrudes through an oil seal and waterseal, as it drives the waterpump impeller directly. However it is small diameter at that point - 12mm?. Maybe a larger diameter shaft could be attached outboard to the alternator, inside the casing. It would then certainly need an oilseal arranging. There is plenty of width to achieve this as it is

a kind of chamber where the shaft goes thro the casing. i.e. there

are two walls.One has the oilseal, one has the ceramic/graphite disc waterseal. The water pump (which is normally just a casing sitting over the impeller, sitting on the outside of the back casing), would need to work in some other way (i.e. a separate pump.) Coolant could be fed through pipes attached into the casting.i.e. into the two holes in the casting through which the feed and return coolant is usually fed to/from the pump-housing.

All things are possible, but it may be easier to select an engine

which has the shaft sticking straight out of one side-casing!


Hope thats helpful...

You might consider the 3 cyl Suzuki Swift engine, at about 130lb it is lighter than the CX (150lb), 45 hp and easy to hoverise.


hovercad - n/a
28-Mar-06, 08:59 PM

Thanks for your reply.

Had wondered wether the power take off could be using the final drive.AS per the original bike would have been.(limited knowledge of the bike thought it was shaft driven.so would connect to flexi coupling etc etc.)

Like most of my ideas there usually flawed.

Would like the cb500 route but they still command alot of money

even in an unroadworthy state that my prescent budget can extend to.Rotax totally out of the question.Hopefully next year out racing.Been collecting lots of elastic bands so may get of the ground this year.lol


jon_curtis - n/a
28-Mar-06, 09:31 PM
you can run off the sprocket on pretty much any bike

cant you?

the bike shop around hear, sells sprockets with no teehso you can machine the mating of a flex coupling onto it.

its just the weight penaty of the gear box etc.

Ian Brooks - n/a
28-Mar-06, 09:52 PM
Yes - you could do that, the only problem is the weight - the CX always as an overweight lump, at 150lb it comes in more than some car engines.


srn4 - n/a
29-Mar-06, 09:47 AM
That is heavy!

My subaru engine (ea81) weighs about 180lbs (82Kg)and can kick out around 90hp all day long..(hopefully)

Thats about 1.1 hp/Kg compared to the 0.9hp/kg for the bike engine