1985 Honda CBX 250

I bought this little bike with the intention of fixing and then selling and update to something a bit bigger, when I purchased it a couple of weeks ago I was told it need new rockers so I tracked down a second had rocker cover with rockers (tappets) for a fair price, little did I no at the time there was a lot more damage to the top end of the motor, which included chewed out threads, seized bolts 2 off which the previous owner had cut the heads off the bolts to remove the rocker cover and some how snapped 2 more. After having a good look I think the motor had got pretty hot and ended up chewing out the cam as well as the head and rocker cover.
I ended up buying a parts motor as it seemed I might be able to build 1 good motor out of the 2 of them and hopefully still can, I've got the barrels swapped over and also swapped the cylinder sleeve out for the 1 from the bikes original motor as that barrel and piston are in pretty good condition, the reason I swapped them was because the thread holes for the small 6 mm bolts that seal off the near the timing chain port had been stripped, anyhow I put the barrel back on and torqued it down without a problem, I started clean the old gasket off the side plates and engine block when I noticed something didn't look right with the bearings around the clutch basket shaft, so I compared them to the ones on the parts motor and then It hit me like a lead balloon, there was no bearing race only 8 ball bearings, now being a mechanically minded person I soon realized that to fix the problem properly I have to split the cases and remove most of if not all the gearbox just to replace the bearings, ok I can think I can do that no worries and then I started wondering how the motor would have run before, as when the bearings are evenly spaced there is no movement in that shaft but when the ball bearings all gather together it has to much movement. So I'm after peoples thoughts on what would be the best thing to do, should I just leave it the way it is or pull the motor down further to replace the bearings ?

 

Ordered a new bearing from Honda part no.91006-KK0-003 $24.80, should be here tomorrow then I can put the bottom end back together, my other worry is the head has a crack on each exhaust valve from the spark plug hole. not sure if it's a huge problem, very common with this motors and have been told by a couple of people not to worry about it as it's not cracked through to the valve seats, looks worse in the photo

 

I spoke to a couple of places that do heads and they don't won't to no about it, there is another place about 150 klm's away from me that I'm waiting to here back from with a quote as they do recondition them, short of that I would have to send off to Melbourne, it all comes down to cost as I still need to replace the clutch plates and funds are a bit short atm. heres a couple of photo's of the head that came off the original motor

you can see the wear on the cam shaft circled in red compared to the 1 circled in green and how it chewed out the race on top of the head

 

here's another photo of the cracks and after cleaning around the spark plug hole with some throttle body cleaner the crack extends about 3/4 of the way up the spark plug hole, anyone have a good head they want to sell me.

 

thanks fella's, I have sent some emails off tonight with pictures of both heads asking for prices, will post there replies up here

 

This week I took the head to Adelaide Cylinder Heads and there going to fix up the cracks and put a M8 helicoil thread in for the spark plug, the guy said it would be as good as if not better if they were to completely weld up the plug hole and re drill it , the guy also thought that putting a M8 in would be a great idea (thanks for that suggestion Murdo's) replace the valve seats, cut in the valves for $440, all other quote were above $500, I will need to find a plug of the same heat range to fit but think that should be quite simple.