I actually started this last year. Had some time to play with it yesterday and thought I'd snap a few pictures. I spent last spring doing some testing on E85 2-stroke oil and satisfied myself technology as advanced enough to make something actually compatible. (that is a whole other thread)
But with fuel lined out, time to get the engine. The standard issue Grubee 66/80 is pretty cheap, so it doesn't make me feel too bad about taking it apart immediately and running some experiments.
Before I ever cranked it over, I milled the head, re-cut the squish band, ported it, matched the ports/pipes, ceramic coated the piston and head, put on a hopped up ignition and jetted the carb.
Went a little overboard on the head milling...piston came up and hit the spark plug! So I indexed the plug and ground a bit off the outer thread area. Runs good now!
I started with the standard carb 'jet drill' to give it 25% more area to be E85 compatible. But with all the hop-ups, it needs even more gas. I've now drilled out to twice the diameter, but still wants more fuel...runs pretty good with the choke partially on, but leans out too much with it off. I'm planning to drill in to the mid .040 inches diameter and see how it runs from there. The flip side is, E85 and crazy high compression mean a much more efficient motor, so I probably cruise with much less throttle which offsets much, if not all the increased jet size.
Needs a little work on the ignition, too. Running the Jaguar ignition coil and circuit, but already had a couple of solder joints crack loose from vibration. So a true circuit board with some type of potting is in order...one of these days.
Some pictures of the adventure so far.
Before and after carb porting / smoothing
Fine Chinese engineering...
Drilling a #[very dang small] bit through the jet... currently up to 0.040" and still needs more fuel.
Milled head and piston. Ceramic coating on the head/piston crown, thermal transfer coating on the head, and dry film lube on piston skirt.
Spark plug...tuning is getting pretty close as indicated by the nice gray color on the electrode. I gave my special 'taper cut' a quick sanding to highlight it. This is required so the corner of the spark plug threads don't hit the piston due to the milled head.
But with fuel lined out, time to get the engine. The standard issue Grubee 66/80 is pretty cheap, so it doesn't make me feel too bad about taking it apart immediately and running some experiments.
Before I ever cranked it over, I milled the head, re-cut the squish band, ported it, matched the ports/pipes, ceramic coated the piston and head, put on a hopped up ignition and jetted the carb.
Went a little overboard on the head milling...piston came up and hit the spark plug! So I indexed the plug and ground a bit off the outer thread area. Runs good now!
I started with the standard carb 'jet drill' to give it 25% more area to be E85 compatible. But with all the hop-ups, it needs even more gas. I've now drilled out to twice the diameter, but still wants more fuel...runs pretty good with the choke partially on, but leans out too much with it off. I'm planning to drill in to the mid .040 inches diameter and see how it runs from there. The flip side is, E85 and crazy high compression mean a much more efficient motor, so I probably cruise with much less throttle which offsets much, if not all the increased jet size.
Needs a little work on the ignition, too. Running the Jaguar ignition coil and circuit, but already had a couple of solder joints crack loose from vibration. So a true circuit board with some type of potting is in order...one of these days.
Some pictures of the adventure so far.
Before and after carb porting / smoothing
Fine Chinese engineering...
Drilling a #[very dang small] bit through the jet... currently up to 0.040" and still needs more fuel.
Milled head and piston. Ceramic coating on the head/piston crown, thermal transfer coating on the head, and dry film lube on piston skirt.
Spark plug...tuning is getting pretty close as indicated by the nice gray color on the electrode. I gave my special 'taper cut' a quick sanding to highlight it. This is required so the corner of the spark plug threads don't hit the piston due to the milled head.
