is it true you can't stroke the trailmaster motor?

[wildbob]

This is something I've heard. Can any GY6 experts chime in on this and why this is so?

[mb1134]

No strokie for you!

[SYCARMS]

The GY6 is originally a scooter engine. The external rev was added for the buggies. Every year EPA mandates more stringent emission specs. Scooters are having no problems passing since they are much lighter, use less power thereby emitting less emissions. The internal reverse also allows for different gearing which is why the older buggies out of the box done 32mph tops. The difference in the gearing with the new design engines gets up to 40mph out of the box. This is how they got the emissions down to pass EPA.
The crank in all new buggies with internal reverse is different in 2 ways. If you ever changed out a drive belt on both older and newer gy6 engines you will have noticed the older engines you would pull the variator outer pulley to remove the belt since the belt rode to the outside of the case. The newer engines along with pulling the variator outer pulley you also have to remove the clutch nut and pull the clutch outward so that the belt will clear the case for removal. Since the clutch sets further back into the case the same had to be done with the variator. To accomplish this the old tapered boss which the kick start gear was pressed on, the taper has been removed thus no longer using the gear, but also requires a longer spline on the crank. Also for some reason different size bearings are used on the crank. The bearings are not a problem if you have the special crank tools to pull the sprockets. The spline remain the stumbling block. The spline used are metric so the basic machine shops cannot cut them. Of the few I have found who will do it want $300.00 - $400.00 to cut longer spline claiming the extreme cost for the broaches they would have to special order. I have inquired about having a stroked crank made but the minimum order is 100 with promise to order 50 each year.
One more note, new stock cranks are no longer available for these engines from any of the manufacturers ASW, HH, Trail Master or Kandi. They tell me they can no longer special order them. I have yet to find a supplier of them since they are designed solely for the buggy.

[wildbob]

Awesome info. I couldn't ask for a better explanation than that!