Get that head re-chambered, and you won't have to worry about ANY aviation fuel. With a high compression re-chambered head you will be able to run pump gas with zero detonation. This I know.
Your port work is a great start. Thanks for the photos. It is however, not very close to the porting templates. You have a way to go to get to a "aggressive trail" port. The beauty is that you have plenty of room to step it up. This is how you learn, and your doing great! Remember that its only a few nuts and bolts to yank that cylinder off, and try the next step. That's the fun part. Just be sure to take notes.
I realize that my port time area at %50 open by degrees will be a little lower than others because I retained a close to stock curve at the top of the exhaist port and due to the limitations of my tool I was only able to widen so far , anyhow I might have went a bit wider at top to give it a better shape, but it was my intention to limit the initial hit of the power band somewhat, as well as preserve ring life, as my youngins will be learning on it.
Purely based on timing alone (I forget the numbers) it falls between the porting styles i mentioned, might call it a muted mx port or maybe a tame xc port.
I guess it would be similar to throwing a cam in a 4 stroke without using high ratio rockers, or bigger valves.
I will really never know unless, I dyno it and compare it to other dyno graphs, because I really don't have any other blasters to ride and compare it to.
I am getting my bore, chamfering and head rechambering done by Ken O'Connor, which reports and experience tell me that, he is a really good dude, who takes pride in his work and really puts his best into jobs large snd small.
My imagination say it will run similar to one of the more sedate 250 bikes from just before the power valve era, with a little lower power to weight ratio of course. That is my hopes anyhow, a strong fat midrange, with a good wide powerband that comes on predictably and some what smoothly. Of course they say "wish in one hand, shat in the other", in this case meaning I wish it would run this way or that ,but absolutley don't have the experience, knowledge or skill to produce such an effect at will. Unless I am really lucky or my hand was somehow blessed with divine guidance while cutting, I wouldn't be surprised to have at least one hitch or funny spot in the band where it gets out of wack due to poor scavenging, excessive boost port blow thru at a certain rpm, transfer port aim that no longer matches the proper rpm range, etc ,,etc etc.
By the time i put it the box to ship,
the exhaust was brought up by 1.5mm and widened by around 2.5mm total
transfers were raised by: primary .8mm, secondary .2mm and widened a negligible amount, (sleeve was cut with flame tip which gouged a small groove in the aluminum, and aluminum was hand matched as well as possible)
boost port was raised .5mm + a degree or so (really hard to measure in that small of an incriment with such a steep angle)
intake windows ended up a about .5mm taller and slightly ( <.25mm)wider than in the %90 pictures.
I also made the area below the boost port into a flat underoo (maybe tight whittie or bikini brief) shaped area with an angle nearly as steep as the boost port itself.
I am super stoked to get it back together and running, and can't wait to see how it runs, I won't be dissapointed if it only picks up a couple horse, but from what I have heard just cleaning up the casting flaws, and going 1mm on the exhaust port, combined with a rechambered head is worth at least 5-8 horse over stock which with an open airbox and a toomey is said to be 20.3 horse which puts it at 26 to 28 horse at the wheels,which is really plenty. Only time will tell but if all goes well I am figuring to be on the high side of that.
If there are any really funny spots I should be able to figure out (with the forums help) what went wrong what to cut or what to put back if I can.
