Well I run my race 50 at 0.5mm & at 14000 it almost grazes the head. If I reuse the double base gaskets too many time it just makes a noise.

But clearly the stroke is much larger on the 300. The other consideration is the MSV, which can be alleviated by taking some squish area out, but it isn't that big so I don't think its a problem & revs low so another lack of concern.

The closer you can run the head & piston the better (obviously without bumping the two together). Any mixture trapped there is lost to the cause, & the further away the less the piston gets the cooling effect of the head.

But lets not get too worried about it. The 300 has stacks of power, just closing the gap up should aid better combustion & thus fuel economy.

that sucks, i was under the impression the volume changed on them. would have been the main reason i was thinking about getting a set...

Thanks for the info F5. Good stuff indeed. I'll discuss it with a few others but I'd say I'll probably aim around 1.2 to keep some clearance and stay on the safe side of things. It seems to be whats accepted around the place from those in the know. It sure sounds like you have some experience yourself in building race bikes! You blokes on the other side of the lake are well smart!

Stainless, the volumes on the S3 actually measure the same as the stock head (or at least it did on the 300 that I cc'd).

Rings and Piston
 

Crunching some numbers now to determine correct ring end gap. Mostly for reference for myself. Working off the 66.4mm bore and using wiseco's calc bore x .004" top, and x .005" bottom.

Top ring: 0.27mm
Bottom: 0.33mm

As delivered the stock S3 rings measured in with gaps as follows (measured about an inch in the cylinder top, pushed down with the piston)
0.25mm and 0.28mm

The S3 piston is stamped A 66.33 S3 Vertex. Piston to bore clearance will not be measured as I don't have the tools to do so accurately, however dropping the piston into the cylinder it will slide in easily under its own weight. There is no notable play side to side.

Reminder to self, rings are installed with the marked side facing up.

I'll wait for a few opinions before making any adjustments. At this point planning on keeping the 0.28mm ring as the top, and opening the other to 0.33m for the bottom. Does anyone feel these are too tight and should be opened up a bit more?

Piston
http://i575.photobucket.com/albums/s...e/P1000417.jpg

Clearance
http://i575.photobucket.com/albums/s...e/P1000418.jpg

Bump for those with engine building experience. How's the ring gaps I've specified sound? Looking for some feedback. Thanks

I'm not a rocket scientist but your math is correct and I've never had an issue using the Wiseco specs. Unless you're going to be pushing the maximum on your RPM all the time then I go with those #s. I have (in the pits between motos) installed a new piston & rings and just eyeballed the end gap to be sure there was some with no problems. While the numbers are there for a reason, I've discovered through the years (55 of them) that they are very forgiving in most cases.

Thanks Fred :) Was pretty sure they were ok. One of those measure twice, cut once things. I don't have the experience to fall back on. This last year has been a steep learning curve, so I feel its better to ask and be sure!

I wish I could ride this thing at max RPM more often!

Yeah & the piston goes the other way up as well, but hey, that's only a suggestion;)

;) GOLD!

..too lazy to flip the jug for the pic and nothing to hold onto the otherway! Hah!

Ordered myself a C-Clipper today! I feel somewhat sad that the challenge of installing the clips will be no more, yet a little relieved that the stresses of worrying about a clip flying across the room, or worse into the crank cases, has been minimised.

Or poking it into your finger! Do you really not want that experience?