Air cooled AF

[CR500R7]

OK so you modify the H peice, where does that put your engine in relationship to everything else on the bike.
Remember once you change something it means something else always needs to be change as well.
It is not really the H piece that is the problem anyway, it is the TOP REAR ENGINE MOUNT.

[90cr500guy]

Well I no longer have my '84 to look at.
I do however rember looking to see if it would fit in my '90 and it seemed to look fairly easy at the time as far as the mounting.
That H piece is your saviour on this transplant because it could be easily modded with out irreversible mods to the cases.

[CR500R7]

The H piece is in the same place as the rear engine mount on the later cases.
So if you redesign the H piece you will have to shift the engine to avoid hitting the top engine mount on the shock.
Once you shift the engine, the sprocket moves, the bottom engine mount moves, the inlet manifold moves and every GOD DAMN THING MOVES.
Hence the reason for the LATER MODEL CASES.
An 81-83 could still be used but you would need to cast some new cases to avoid some of the problems of the twin rear mount.
Cast new cases as a single rear mount like later model cases.
That is unless the 81-83 jug bolts onto the later cases, in which case you could modify it that way to get it into the frame cheaper.
If the jug does bolt onto the later cases you would have a right side kickstart for one.
Which brings us to our next problem the KICKSTART to be used.
Every single CR500 shares all 3 engine mounts except the 84 which has the front one closer to the rear by about 10mm.
The reason for the front mount on 85-01 being further forward was to make room for the water pump.
So all engines sit in the exact same position, so if you modify the H piece to shift the upper rear mount you effectively shift the entire engine, WHOLE NEW PROBLEM.
I supposed what I am getting at is there is no simple / cheap way around this conversion, not if you want it done properly.
Maybe better put this way, there is no way to use the 81-84 bottom end in standard form without modifying the CRAP OUT OF THE AF FRAME.

[Roostius_Maximus]

There are better things to do with that engine. Stick it in a 1980 CR250R frame with the 1981 swing arm and make a 1978 Honda RC400 works replica....

k, i also have a 450 engine, who's got the '80 250 chassis for sale?

[CR500R7]

That would be easier and a hell of a lot cheaper that is for sure.
Just my

[redrocket190]

Look in the swap meet here - http://www.alp-sys.com/honda-elsinore/ or eBay. You could get everything you need for about $500.

[yota]

There are better things to do with that engine. Stick it in a 1980 CR250R frame with the 1981 swing arm and make a 1978 Honda RC400 works replica....

now that is a cool bike.

[90cr500guy]

The 480 cylider will bolt on. Piston is the same size, not sure about conrod length.

If I had the money I would undertake the challenge.

I still like the '84 engine better than the h2o's

[honda02]

That could be my next project I been lalso been looking a Old Maico, Husky, CAN AM , I like old air cooled bike.
The sound of the fins.

There are better things to do with that engine. Stick it in a 1980 CR250R frame with the 1981 swing arm and make a 1978 Honda RC400 works replica....

now that is a cool bike.

[CR500R7]

Part number for the rods are different, indicating that they may not be the same length.
I would look at the height of the jug and compare the two, if both are the same height you could swap one from the other.
The only thing would be the port timing would be different so the power band would be like a 480.
If useing a 480 jug be sure to use the piston that goes with the jug.
I love the air cooled 84 CR500 an awesome bike for sure.
If I had someone bank rolling me I would undertake the challenge without a doubt, it would be an interesting creation for sure.
I have no doubt it could be done, who knows what it would cost all up.
From what I have been reading on here the best candidate for an air cooled AF would be the gen3 CRF450, supposedly there is more engine room.
If this is the case it would be a big help fitting the fins in as well as the exhaust and kickstart.
Every little bit helps.

[Wheelie-Gene]

I like old air cooled bike.
The sound of the fins.

Some sound really bad...like the engine is falling apart internally, but I love the sound also. Maybe Honda produces the best metalic ring ever.
My 480 is the best I've heard (maybe someone could post a vid of a 500 pinger).
I can run my fingers across the fins and they sound like a xylophone...not one out-of-tune.



Sad thing is I had a 79 and an 80 CR250 (one had Fox shocks) many years ago. Pretty much gave 'em away.
An RC400 project is something I wouldn't mind venturing into.

[Roostius_Maximus]

I'm stil up for this kinda project, i'd like to do a twinshock, have a 81 250chassis with the 450 engine sitting in it tho, if anyone has a line on a twin shock steed worth puting a wrech to let me know