KR-1S.co.uk Forum

what are you machining in the 4th picture and why has it so much angle ?

and your O-ring seems to be very close to the cylinder bore. might be too close. as mentionned above, 3mm is ok. 99% of the seal should be done by alu against alu, O-ring is only there for whatever get's through. the less alu seal, the harder it will be for the O-ring.

I've just had to edit the post as the photo site I used was a waste of time (anyone know somewhere that hosts pics for forums but isn't full of pop-ups, adverts, click bait spam?) Anyway the pic of machining the angle... The dome on the pistons I'm using doesn't match the squish previously cut into the head, which was matched to the old pistons, and it left the squish tight towards the centre. The best solution I decide was to machine the inner edge of the squish off and picked 30 degrees as it looked nice Apart from that, having taken out the head gasket I needed to lose some cylinder volume so it killed 2 birds with one stone.

The O-ring did end up closer to the cyl than I'd hoped but they were off the shelf 60mm ID 1.5mm rings. I thought about machining the groove ID larger but that would have meant stretching the oring into it which I doubt would do it any good. Next time I do one I'll pick bigger orings and go as close to the water/kips as I can. Anyway as a test this one has surprised me by the fact that it's running at all!

Well it's still working so I'm calling it a success (till it blows). I've done about 130 miles now, the water drip from the front edge stopped after a re-torque at 60 or so miles. In hindsight I'm not sure the type of 3Bond is the best sealant for that joint, I'll probably use a slightly stronger setting silicone version next time. The bike is booked for a dyno in a week or so, if it all holds together I'll have some time to play with ignition curves