Just a gentle clean and polish, didn't remove much material, but I smoothed out the gasflow from one of the exhaust ports.
The actual outlet from the head casting is offset; (unlike the inlet, where it's roughly central between the two valves ports, so straight runs) therefore one gas stream is nearly straight, and the other has to do two near 90 degree bends to get into the outlet, where the header joins the head.
So I smoothed the port inside radiuses, and hope to get more efficient exhaust gas flow out of the head. not mirror polish, as TBH that's wasted as soon as a little carbon builds up, but a small grindstone on a flexi drive, then hand finished with wet'n'dry. If I'd been a perfectionist I would have removed the valve guides before I started, but they're good, so I just worked round them.
So whatever I get, it's possible to improve on it slightly with a bit more time, effort and money.
It's all based on nothing more than my own observations, so I've no idea if this will work, or help, but it seems logical.
What I initially wanted to do was to each thing one at a time, with a dyno run in between, so that I could see which modifications made a difference, (if they did at all, and it wasn't to make things worse!) but in this case I will have fitted high comp pistons and gasflowed the heads at the same time. I suppose I could swap the gasflowed heads with standard ones and do another set of dyno runs, if I get odd results, such as fitting high-comps and gasflowing produces less power.
Here's hoping that a gain on one isn't cancelled out by the other
I'll still be able to do runs between each of three cam configurations, though, so hopefully will be able to see and feel a difference between those. The three options are:
1. Standard cams
2. reground cams- from Newman Cams in Kent- both approx 1mm more lift and 5-10 degrees more dwell (haven't measured them in situ yet) and
3. Can't remember without looking it up again, but the Superhawk forum techies reckon that one of the cams is actually ok, either exhaust or inlet, but the other one is a little......quiet, and that's what holds the engine power back. But the cams are interchangeable, and as I have at least two sets I want to try running the "good" ones on both front and rear (i.e. exhaust or inlet cams in both positions in both heads) to see what difference that makes.
(*EDIT- two exhaust cams in each head with suitably revised timing for the exhaust cam used as an inlet is what I'll be trying- thanks for the info, Mikstr
)With the third option, it'll be a cheap upgrade option (assuming it works) until the E-Blag price for those particular cams goes through the roof when word gets out
I may have to buy in a few sets before posting, as an investment
I'll degree in each set, so that standard cam timing is used in each case, and use a control rear wheel and tyre (Thanks, Mac!) just on the bike for the dyno runs , so even if they're a week or two apart the conditions will be as equal as I can make them.
I love a little play, me.
Today (Saturday) is all about checking that there's enough clearance between valves and piston crown with each cam set, and making sure that the springs don't get coil-bound. (yes, Benny, I'll let you know
)Hopefully, all being well, I'll get the heads on tomorrow and turn the engine over on a spare starter to get oil round it thoroughly, then pick a weekend to swap engines.
More piccies to follow, and of course video of the start-up when that happens.....
I've got quite a few, but having changed some over doing clearances for some of you lot, I ended up with several spares, and gaps in the set.
