The 650 engine has a longer stroke than the 500. This means the top hanger bolt is a bit further up and a bit further out.

This in turn means a standard hanger off a 500 frame will not fit. The bottom bolts are in the same place as the 500 so just the top ones to deal with.
The solution favoured by some, and me, is to modify the 500 hanger.
I had two spools machined up to take the top stud off the 650 Engine.
This involves cutting the upper hanger tubes to a point where the new sleeves will fit ove the 650’s bolts.

Out with the angle grinder and after a bit of fettling and grinding the spools were in the right spot and ready for welding.

When I got them in line I put the studs back in and tightened the nuts down on the sleeves.

I tacked them in position and had a friend weld the whole thing up for me.

Engine is now ready to fit into a 500 frame.

The frame I am going to use is already a running bike I call “The Rat”. I built this bike from bits and pieces and a 500 engine which originated in a bike that had been in a hedge !.

The 500 engine needs some work so is coming out and will be replaced with the 650 unit.

Engine went in without a hitch.

We managed to get the carbs to fit !. I was delighted. Didnt take too much pulling and dragging.

Put the 500 balance box back on. The down pipes fitted as well. Not sure about internal diameters and have to sort jetting for the carb yet.

Just tidying up and sorting things with the engine installation now.

Got the generator wired up and the pickups wired into the Ignitech.

Filled the engine with oil and coolant. Did not have spark plugs, they on order will be in today. I spun the engine over on the starter and eventualy the red light went out and no bangs or clatters.
Then I notice the leak.

The seal to the water pump on the rhs of the engine. Ah well, it was an original seal so that has to come out gefore we go at it again.
I will be happy if thats the only leak.

Got at the beast after we got back today.
Replaced the waterpump casing seal (thanks pat).
Wasnt much more to do after that, coolant, plugs, reassemble exhaust and away we went.

It Lives !!!!!!!

The hole in the rear casing was blocked with some gasket cement and has not leaked since.

I had to re-jet the carbs and it wasnt that easy to find an online shop, and when I did all their stock was at zero.

Ended up getting them on ebay from ABV racing who specialise in motocross stuff.

Main jet will be 125
Slow jet 78

As recomended by a chap in the UK.

The BEAST is on the road !.
When I got home last Sunday I braved the cold and ventured to the shed to put these jets in.

It was then I realised I had one type of jet completely wrong so I popped over to our life time member and we found a couple of 95 jets in an old set of carbs.

I popped them in and put it all back together. Fired up the bike and she is running well.
I couldnt resist taking her out so put the seat/side panels on and went for a run out the Summerhill road about 2 mile or so. (Was feckin freezin)

First thing I noticed was that the engine is turning over 1000rpm less than the 500 for the same speed. Plenty of power available although I didnt push it.
I hit 90 on way back for a few seconds then called to me mammy for some hot stew :).

Pics of bike at my uncles place. No leaks anywhere. The carbs work well, the bike does run a bit rich. The bike rides very well and pulls very well.