A long story....
I did not tighten the head hard enough a year ago, the MLS head gasket did not seal good enough.
This ended up in a huge oil leak inwards that needed an internal clean. Strange, it did not smoke despite drinking lots of oil.
When apart I got the chance to buy a set of JE 970cc pistons for a good price from a friend. Around 15 years old but never run. Only used in a build.
Too high compression stopped that.
At the same time sleeves from CycleX on sale.
I could not miss that!
A good looking stock cylinder from my friend too.
Billet block with its pistons as a reference when calculating deck height for OK compression.
The 970cc pistons outer flat area 0.5mm lower than the newer JE 71.25mm pistons the Billet block has.
So mill the cylinder another 0.5mm compared to the Billet block that is 84.5mm.
1mm off on that 85mm high stock cylinder which was done before fitting the sleeves.
Sleeve flanges needed to get their grooves milled deeper and the 2 o-ring holes milled too.
The 970cc got its own head, 392. The latest head ported a year ago 33.5/28.5 mm valves.
The billet block ran fine with a ported K2 head 34mm F2 in valves and 28mm ex.
The 970cc setup got a thinner base gasket to reach a better squish. The cylinder block could have been milled another 0.25mm.
But that is for the outer area only. The piston domes had to be cut too. Dome volumes measured compared with the other pistons before deciding how much to cut off.
Those 12.5:1 JE pistons have thick domes, over 7mm. No problems to cut 3mm.
The result is fine. 970cc setup reached 104whp on dyno late October last year.
The billet block setup 1005cc got 101whp on same dyno a year before. Use a thinner base gasket will probably add a litte, reach close to the 970cc compression.
I used the bike as a test rig when billet block was off. An 890cc setup.
Also 12.5:1 JE pistons that needed to be milled down for OK compression. Tests with 3 different cams.
Pinging even with DP315 running with smaller lash making a bigger overlap decreasing the compression. Fuel Shell V-Power.
Those 12.5:1 piston domes now cut 2mm off that I think can work fine.
That will avoid double spark plug washers to make plugs clear from pistons.
Chambers are rather roomy, over 24cc.
That kit get my old ported head that had 5mm valve kit with bronze guides with huge wear after around 21000 km. The upper part had a huge wear. New CycleX iron guides and their SS valves 34/28mm that fitted the seats.
That set will be used in another engine build I have. Engine case milled to use billet block just for sure.
That engine has got a frame with registration plate....... Most of the needed parts in my garage......
But I miss the billet block in the K6. It look really nice.
Having left over parts can end up in a new build, another bike to be born!!