Well! Time for more show & tell.
I got all my bodywork out and ready for paint. Mike from Street Scene will be picking them up soon and giving them his magic touch. I was going to paint 'em myself, but I realize that I simply can't do everything as busy as I am. Mike's a good dude, and he's a hardcore scooter guy too. I'm looking forward to the end result! It's going to be all white. Leaves plenty of room for decals to stand out...
Doing a couple of tests with the new manifold. I like it! I'm going to try using the longer rubber section and a more rounded and shorter bellmouth. The bellmouth should be in next week.
So, I figured I had a small head gasket leak during the races. The first thing I thought when I pulled the head was "Oh no, detonation!" but on closer inspection, it didn't look to be detonation at all, but rather it was where coolant hit the piston. At least, this is the best I can make of it.
Here's the culprit. With my Airsal cylinder, I had to fill in all the o-ring grooves on the cylinder so that I could use the Stage 6 modular head. Here you can clearly see the failure where an air pocket was present. Nonetheless, the scooter ran well at the track, with no breakdowns and on one of the last runs of the day I managed to run 11.086 seconds in the 1/8 mile.
The cylinder still looks pretty good, though the ports could use a little more work.
Okay! So let's get to work on that head eh?
I was going to settle with this - a slightly narrower squish band. I had a hair up my tail I guess, and decided I wanted to try a toroidal combustion chamber.
This is not the best shot, but you can see the tool that I used to cut the combustion chamber.
It's hard to tell in the photos, but there's a 12 degree positive squish angle that compliments the piston nicely. I'm somewhat worried that I may have lowered my compression ratio more than I wanted, but I will have to measure this later. There wasn't time for this at the machine shop tonight. I hate to "wing it" but that's what we had to do. No matter - I'm more or less guaranteed to learn something from this experiment, and I have extra "blanks" for the head if the results are undesirable.
Since my old fixture didn't work too well, my very good friend Dan decided to sacrifice one of his expanding mandrels to adapt to my cylinder. He started with one that was slightly bigger than the bore, and then turned it down to 47.? mm.
Now the base is turned a bit more, and the squish clearance is where I want it. The port timing is (of course) lower, but I will run it like this and note the results before raising the ports any more.
Loosely bolted back together, and ready to be tightened up with new gaskets and re-installed. Let's get under 11 seconds now!
Of course, a lot of the 1/8 mile time is on me, so I need to get a lot of practice.
Stay tuned!
~Josh
