Flywheel Mark

[ScooterWes]

A little input please. I just bought a TaoTao Zummer scooter (GY6 50cc) and after receiving and assembling it I put about 300 miles on it and I was happy with its performance on the flats (30-35 mpg @ speedometer) but living in Forest Hill (Yes hilly) the performance on hills with my 270# on it was lacking and decided to go ahead with the 72cc BBK. (Thanks for the nice videos 90GTVert) I purchased all the parts and went ahead with the project but when I went to align the cam holes I noticed the flywheel mark was 1/4” beyond the mark. I went back and rotated the crank and saw that the piston was at the very top of the stroke when the cam holes were positioned properly but the flywheel was still 1/4” beyond the mark. I checked 3 or 4 times. I scratched my head and decided that it had been running good so I left the flywheel where it was and finished the project. I ran into 3 minor problems along the way. 1st the lower portion of the fan shroud gasket was melted away but I think that was due to the donut gasket not being properly centered at the factory when the muffler was installed (just ordered a new one). 2nd One of the alignment sleeves was stuck in the old jug. I was able to remove and reuse it after heating the aluminum casting around the sleeve with a torch. 3rd When I first started it oil was pouring out of a hole in the top of the jug. There was a tapped hole in the jug that was not in the original jug so I plugged it with a short screw and rubber washer. After finishing the work I went for a test ride and it performed very well. According to the speedometer the flats are about 40 mph but the hills have drastically improved (30% faster). It idles at 1800 rpm. and will go as high as 8000 rpm. Anyway, my question is about the flywheel mark location discrepancy. I believe the valve and piston locations are correct but the spark maybe wrong because of the flywheel being off location? (I just bought a flywheel puller to see if the key is there or sheared) Will this flywheel location discrepancy cause performance or overheating problems.



Your input please



Thanks,

Scooter Wes

[90GTVert]

It's tough to know what the flywheel issue could cause, because we don't know what the issue really is.

From the way it ran stock and runs now, it sounds like the markings could just be wrong on the flywheel. Perhaps it's alright, but only the marks are wrong.

It could be that the whole flywheel isn't clocked as it should be from improper woodruff key location or a sheared key. In that case ignition and valve timing would both be wrong if you installed the cam according to the marks on the flywheel rather than going by top dead center. If you installed the cam when the piston was at TDC, then just the ignition timing should be off.

Could be that the reluctor is in the wrong spot and that would just throw off ignition timing.

Most likely a new flywheel would fix the issue... but it sounds like it may not even be a real issue as long as you're lining up the cam to TDC and not the flywheel marks. A degree wheel and a timing light would tell you exactly what's up. The degree wheel would let you know where true TDC is and if the key is not sheared, you could mark that on the flywheel (scribe it carefully with a razor or other sharp tool). You could also use a dial indicator to find TDC. The timing light would let you know where ignition timing is. Unfortunately, I don't know an exact number to tell you as a standard timing. It varies a little, but most will be around 10-15 degrees before top dead center at idle-2,000RPM if it's a stock CDI. If it's far from that, it could be because of the flywheel. A little more advanced may not be a bad thing, depending exactly how much and where it maxes out. If it's more retarded, then it could be detrimental to performance. Again though, it sounds like it runs pretty well on par with other scoots so I'm not sure that you have any serious problem.

As long as nothing is sheared, a new flywheel should make it all align (assuming that flywheel is good). You may not want to bother with it since it runs fine though.

[pinkscoot]

I had a Linhai 257 that no matter what I did the flywheel mark was off just a little bit. Everything else lined up just not it. The scoot ran fine so I ignored it and figured it was a flaw.