Friday, July 30, 2010

Swamp Hobbit parts / KStar Thread Repair

My race bike is just about ready for next weekends race, I'm holding out for some new tires, hopefully they will arrive in time! Some photos from the last few days of repairing things. Here is Joel's cylinder that I stripped the exhaust stud. Drilling and a quick Heli-coil has fixed this Athena thing-a-ma-bob.
After ensuring there were no more flammable gasses in the tank ....

I cut it open to try and patch some holes.
It was beyond saving, but I gave it a good try. These little buggers were too leaky and the metal was too thin to weld without melting it completely.

I've got another variator to use now on my daily rider hobbit. This one, amazingly, cleaned up.

Monday, July 26, 2010

Post Races

After a brief trip and day at the track, I've discovered many things. It is impossible for the bus to leave on time or get somewhere without making a wrong turn. It is also terribly enjoyable to drive the bus, probably the best part. It was also quite fun to jump 4 train tracks in a row with the bus at 40 mph and watch a little dog fly up into the air. We also used the PA to harass other motorists. The track was hot as always, and it sure feels good to take the first lap in you wet-with-sweat leathers, and let those vents suck air in and cool you off. I trashed the ring on my race hobbit, which could be due to the seize it experienced at BD7 when it was in trike mode.
I ended up racing on the Wizards Loan-mos, a $40 Tomos A35 with a 70cc Treats Cylinder, Dialem Side draft 15mm intake and 15mm bing, and a circuit pipe. No real magic, other than assembled by the Wizard of Naz. It was probably faster than my race hobbit, or about the same, as Jesse and I still got to battle one another neck and neck most of the heat races. Sadly, Jesse was trapped behind a stock Aprilia Scarabello thing that was on the track with us, and couldn't get around to race me during the races, so I ended up trying to catch Travis, who never ever though I was so close to him. We would come out of the final twistys and into the straight and I would be about 10 feet or so behind, a few moped lengths, and a hard distance to close, and then he would walk away in the straight, and I would reel him back in during the corners.
Since I didn't have Jesse to try and stay ahead of, and was instead, trying to run someone down who outclasses me in skill, intelligence and moped speed, I ended up getting confused as to which way I was supposed to race on the track. Or I low sided.
This regrettable accident caused me to experience something that only Travis knows about, and that is coming in DEAD LAST.

Next race is in two weeks, and there will be camping and all sorts of fun in Oregon! Hopefully I will have a running bike of my own engineering by then! Thanks to all who came out to the track! Lets go have some fun!

And also thanks to Jihee for pictures!

Tuesday, July 13, 2010


After nearly two months, the curse is broken, and I completed a Moped Monday ride without any mechanical failure! OH JOY!!!!

Saturday, July 10, 2010

Piston flaws, intake restrictions and math

I got a wonderful package of goodies from 1977mopeds yesterday. Most notably, it included a new cylinder and piston for my wife's bike. 50cc TCCD 7 port "Racey" cylinder. I like these cylinders, even though I've had a (2)stroke of bad luck recently. They don't make loads of torque, but put a reasonable stock gearing and up the compression and you do just fine, and they really wind out. They love small carbs, and if you put a 6p on them or some other such high RPM pipe, you can really rev the heck out of these things. So I got home from work at about 5:30, opened the package, and began assembling my wife's engine so she could ride it last night. So I pressed the bearings on the new crank (the Stuffy Alu crank), new seals, yamahbond the engine cases, assemble clutch, make a new thick base gasket to generate proper port timing and head clearance (as the stock gasket doesn't fully reveal the exhaust port) chamfer the cylinder and ring, set the ring gap, file this casting leftover out of the piston window (which remind me of the bushes from Super Mario Brothers), bolt on the head, install on the bike, and get it ready to ride in less than 2 hours. A pretty good clip, at any rate. Hopefully it all continues to work well. I've got a 12mm bing on it at the moment because I forgot my nice 14 intake and carb down at the shop. Here is a 14mm intake that I discovered a wonderful restrictor in. 10mm. That thing is tiiiiiiiny. It was on a freespirit, with a 14mm carb no less.

I also was working on my Hobbit race motor yesterday and was doing math to try and calculate very exactly the exhaust duration of my Athena cylinder. I'm aiming for around 190 deg, stock is 180, and with Travis' nifty little Wizard spacer, the timing ends up just over 200. I think I'll just end up raising the ports a little and not running a spacer, rather than space it up and deck the cylinder, but who knows. If you are doing the math, don't forget than it isn't really cosine but inverted cosine to use the formula correctly.

Wednesday, July 7, 2010

Harbor Freight blast cabinet upgrade

Its been on my mind since DeLuxe opened up that I should have a small blast cabinet with glass bead for polishing. Aluminum oxide is great for paint removal and powder coating prep, but glass bead leaves such a nice finish on aluminum on things you don't really need or want coated, like engine cases and brake plates. Today, with super coupon in hand (20% off) I went to Harbor Freight and bought the $140 blast cabinet that was on sale for $119, and for some reason rang up $89, and then took 20% off that. It was quite a deal. Sadly, you get what you pay for. The cabinet needed quite a bit of adjustment to get it ready for work. The exhaust port was the correct size for a shop vac, but a little too small for my dust collector from the big rig, so I had to modify that just a bit. It doesn't come with any lighting in there, so I'll be putting in a nice flood lamp tomorrow. The worst part is the abrasive pickup tube. It's one tiny little metal tube with another little metal tube in side it. A terrible design, and then it is cheaply made, so you know its bad. This cabinet was hardly pulling any abrasive, so I built a new one modeled after the Skat Blast pickup. Night and day difference. The Skat Blast pickup tube allows fresh air to travel down the extra tube, instead of trying to suck nothing but abrasive, it allows abrasive to enter the air stream at a higher velocity. I then upjetted my gun (really, it has an air jet, I bored it out) since I have a big compressor, and now this thing polishes like mad. The cabinet is the perfect size for engine cases and other smaller items like brake plates. It would be kind of a pain to do a tank, but possible. You can see on the right half of this picture the case finished with Glass bead, and on the left half is the case finished with Aluminum oxide. GB makes a much nicer and more appealing finish. Hooray! Also of note, the Polini is back in operation after some honing, piston sanding and new ring installing. Free Spirit is back on the road too! Can't wait to blow these up shortly!

Tuesday, July 6, 2010

Today's Carnage: RIP POLINI

Exploded my ring today on the Viaduct. Back down to Zero running mopeds again. The curse isn't a joke, it's real.