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Hi Dave,

My YY250T had 24 gram rollers stock from the factory. I switched to 19 gram sliders. Acceleration was greatly improved with no loss of top end. 5000 rpm yields about at an actual 55 mph. The engine is turning between 5000 and 6000 rpm at full throttle from a dead stop.

The individual springs on the clutch shoes determine the speed (in rpms) that the clutch will engage. A 1500 rpm clutch will engage when the clutch assembly reaches 1500 rpm which is not necessarily the rpms of the engine.

The weights in the variator more or less change the timing when the clutch activation will occur. Lighter weights will allow the engine to spin higher before engaging the clutch while heavier weights will cause the engagement to occur at a lower engine speed. Scoots generate most of their power near the maximum engine rpm (redline). Because of this, it's best to tailor the weights to keep the engine near (maybe 1000 rpm below) redline at maximum acceleration from a dead stop. This usually means going to lighter weights from stock. However, this can be a balancing act as going too light can cause a lose of top speed because the weights do not have enough mass to allow the variator pulley to close fully before reaching the engine redline.

Slider weights work well because they allow you to use a lighter weight than rollers (better acceleration) while not losing top end because of their design. They also do not require lubrication like some roller weights.

Here's a set of clips and connectors which should do the job. Also from Harbor Freight:

www.harborfreight.com/28-piece-electrical-clip-set-67589.html

There is some sideways play in this bearing. Here's the spec's:

mpsracing.net/helix-manual/11-01.html

Side play service limit is .6mm and radial limit is .05mm. Page 11-3 shows how to measure.

There are no extra fasteners or hardware between the cylinder and head so they should be able to come out as one unit if desired.

Yea, now that summer is winding down, I guess we will all be getting a performance boost on our scoots.

Another thing to remember when mounting your fuel pump is that the feed to the pump has to be gravity fed so the pump has to be mounted near the bottom of the tank. The pump pushes fuel to the carb but does not suck fuel from the tank.

The sensor for the fan is on the bottom of the radiator and is always in the coolant unless you are completely out of coolant. Apparently, when there is air in the system the coolant will not flow properly and the coolant at the fan sensor never gets hot enough to turn on the fan even when the engine temperature is high. Since the temp sensor for the engine is located on the head or the cylinder, it will not always correlate with the radiator temp unless there is good coolant flow.