12 January, 2014

Car and Driver Mags

Sent from my iPhone

Engine Assembly

I got the engine assembled for the project bike.  It is a Yamaha GT80 base, which is a 80cc two-stroke with 7-ports and reed valves.  Very solid runner used in a previous bike for a short time, I had aleady fit a new piston and ring, and honed the cylinder lightly.  

For this bike, i milled a bit off the cylinder head to give a tighter squish area.  I also followed some info I found in an old Yamaha tuning manual by filing a small "notch" into the top of the piston where it covers/uncovers the exhaust port, for a slightly longer exhaust duration.  I also cleaned up the intake ports and transfer ports a bit, getting rid of some flash, and putting a radius on the edges.

Lastly, I built a new intake manifold that mounts the rebuilt 20mm carb.  I still need to get some proper case bolts, and cut a few gaskets, but it is assembled and turns over with lots of compression.

04 January, 2014


I fabbed up some footpegs for the project bike. These were on a spare crash damaged Yamaha GT80 frame, so I cut off the mounts and welded them to the footpegs I had previously made.

01 January, 2014

Headlight and fender

Here is the headlight glass lens with a few coats of Krylon yellow stained-glass paint.  It gives it a nice amber look.

The taillight assembly, made from a scrap piece of 2.5" exhaust tubing, cut and ground to fit the contour of the seat cowl: 

I also made a rear fender, out of some scrap aluminum sheet.  Hand bent and hammered.  It bolts underneath to the seat itself, with the bolt heads fitting perfectly inside the frame tubes at the back:

First time I've had all the little accessory bits on the bike, like the headlight, heat shields, tailight, fender etc.

Honda Air Box

My neighbors Camry got hit and run last night.  It appears the culprit is a silver Honda product, thanks to some silver colored front bumper pieces, and this air box that was laying in the gutter.