ABC 400cc pistons crankshaft

After 35 years or more restoration has started of the ABC sopworth parts that have been stored in various sheds garages and barns, I have a couple of quiries
I have been told that early Douglas crankshafts which are similar to ABC can take a single grind with larger roller bearings has anybody achieved this an ABC ? If so could you point me in the right direction
Also I know cylinders can not be bored but would like to know the piston clearance in the bore any help would be appreciated Dell

i had a shaft reground and larger rollers made but have never used the crank, the problems are how deep is the case hardening assuming it is case hardened and also the 1/4 inch rollers only just go into the conrod with very little clearance, with the larger diameter rollers you will need to grind the crank to allow more clearance for the rollers to slip into the rod, then because the rollers are larger you then have one less roller fitted and a larger gap or gaps between the rollers losing contact area.

You may wish to contact Alan Barker, EMP Tooling in Havant. They can laser weld a hard material onto the surface, which could then be ground back to the standard size. Laser welding has an intense ultra-fine contact point, so doesn't distort the material. Not sure of the cost of this option versus acquiring a better crank. I have used Alan, he also does fine work for Brooklands and Shuttleworth
best wishes
Ian

Hi
Sorry for coming late to this conversation.
Back in 2015 I discovered that some clown had hard chromed my crankshaft on one big end only. Fortunately I found out whilst resolving other problems.
The then had to grind off all the chrome plating, the end result was one big end was ground to 19.5 mm dia. and the other 20.65 mm dia. The larger dia. meant that I could use 8 mm dia. rollers in place of the 5/16 or 7.95 mm and I used the original quantity of 11 rollers. However the smaller big end meant making larger rollers. I used D2 tool steel and turned them in a stick of 5 rollers, then hardened them to 58 - 62 Rc and then cylindrically ground to 8.6 mm dia. Cut the stick into individual rollers and ground them to 8 mm long. I also needed spacers to fit into the 'horseshoe' big end clamps to control the rollers. I then honed the con rod big ends to match the new rollers.
So all assembled 11 rollers of 8mm dia on one side and 10 rollers of 8.6 mm dia. on the other .
All fitted and works AOK. I have now done over 3000 kms on my bike with no problems.

I hope that helps.
Andrew Cox

Hi Andrew a very interesting description of your solution to this problem,
Although beyond my personal capabilities I will retain for future references, also very encouraging to know that you ride your bike regularly,as I realise that a large number of restored ABC's are for display only

Dell