After got Trek pipe tested some, realized I was right back to running hot again, have to set carb too rich to run cool, etc. So, I went back to NextR pipe, retarded the timing a little more, and changed out 9oz Malossi rollers with 8oz Dr Pulley sliders in the Malossi variator I had already installed.
Initially, I tried to retard timing approx 2 to 3 degrees. This time I was trying to retard timing 5 degrees from OEM setting. This is how I did it.
1st pull the flywheel, you will need a flywheel puller, next remove the stator assembly just to get it out of the way and remove the magnetism that will make it hard to get an accurate result.
To retard timing, you will need to rotate the flywheel on the crankshaft counter clockwise. That will cause piston to travel up the bore a little closer to TDC when the sparkplug fires. The spark is always advanced to fire before the piston reaches TDC, to retard you are delaying the spark a littler longer so the piston is closer to TDC. Retarding ignition timing should help engine to run cooler, plus should over rev better, anyway that's what Gordon Jennings says, author "2 Stroke Tuner's Handbook".
I computed 5 degree by measuring the circumference of the flywheel, approx 13 3/8 inches, and divided 13 3/8 by 360 degrees and multiplied that result by 5 to get portion of flywheel circumference equal to 5 degrees, or approx 0.186 inches. 3/16 inch is equal to approx 0.188 inches, so I used 3/16 inch for my measurement on the outside of the flywheel.
Next, I installed a piston stop, installed the flywheel with the key, and rotated the crankshaft counter clockwise until it stopped at the piston stop. I also installed a pointer I made out of a large paper clip so I could accurately see the position of the flywheel relative to the engine case. You can tighten or loosen the piston stop a little to adjust the position of the flywheel so you can use something on the flywheel as a marker. Once I established my marker, I remove the flywheel, put it in a vice to hold it, and used a hacksaw to lightly mark the spot where the pointer lined up with the flywheel with the piston stop with the key installed. Then I measured 3/16 inch to the right of the 1st mark for the flywheel position to retard timing 5 degrees, and used the hacksaw to lightly mark this spot too.
The trick is to get it all back together without using the key to position the flywheel, because now in the 5 degrees retarded position the key will not fit. I am not sure you have too, but I lapped the crankshaft and flywheel with some valve grinding compound to mate the surfaces a little better. It should go without saying, but be sure to clean/ remove all the grinding compound, I used a rag, brake cleaner, and compressed air to clean.
So, with the crankshaft stopped against the piston stop as you turn the crankshaft counter clockwise, you install the flywheel onto the crankshaft lining up the pointer with the 5 degree mark, the one to the right of the OEM mark you made. I use an impact driver to quickly set it in position before I torque down. Note: the piston is against the piston stop and will not turn counter clockwise, you are tightening the flywheel nut clockwise, so you are not banging on the top of the piston. Be very careful using a piston stop and impact driver, or you can easily hammer top of the piston. I think piston stops are OK to torque on the flywheel nut, but just not with an impact driver. Also, do not take the CVT cover off the other side and use the variator nut to hold the crankshaft in position, you can easily twist the crankshaft, then you really have problems.
OK, after all that I took it for a long ride. I had already adjusted the carb some trying to get the Trek pipe to run better, so I figured it would be a little rich. Anyway, ran like a champ, probably the best it's ever run. High temp was 408F, but I hit that after running a couple of miles at approx 9500 revs, and went to WOT the last 1/4 mile or so before I stopped for red light. It never balked or acted up, didn't act hot or anything. Actually, was generally running so cool I am thinking of going back to OEM BR8HSA plug. Yesterday I was depressed about the Trek pipe, today I am pumped again. Cheers
