Zuma 50 rattles and bogs down

[commanderky]

My setup is a Zuma 50, athena speed variator, Tecnigas Next R Expansion Pipe - Yamaha Zuma/E-ton, Malossi VL12 Reed Cage - Min H Malossi MHR Delta Clutch (white springs all around), Malossi Wing Clutch Bell - Ø 107, Malossi X Kevlar Belt, Minarelli - 746.5x16.5x30.

When it reaches 20 mph, it bogs down and there is a metallic clicking noise coming from the front of the scooter, guessing the engine? It will not go over 20mph and if I try to make it, it sounds like it is going to die so I ease off it and baby it home going 10mph and it doesn't die. On the stand, it performs great! No clicking or rattling or bogging.

I have never heard this kind of bogging before. It just sounds hollow... The metallic sound is like something clicking around inside the scoot's innards. It did this also right before I installed the new variator and clutch springs so i am guessing it is unrelated to the tranny which made me think of the piston. It is a brand new piston with less than 50 miles on it.

It just started one day out of the blue. It was working great and then WHAM, the bogging and metallic clicking..

Does anyone have any clues what this is?

[zeonsredcomet]

Did you adjust your carburetor when you performed these mods?
Metallic clicking coming from the front? only does this under load and NOT while you rev it out on the stand correct?

[commanderky]

I hve adjusted the carb to make it work with the changinh parts.and yes and yes.

[buguy]

Sounds like you soft seized it and rubbed the piston down and now you are getting piston slap? Can you check your squish? Maybe you have too much compression and it is pinging? If it were me though, id pull the bore and measure everything.

[zeonsredcomet]

This has nothing to do with squish. Squish adjusts your distance of piston clearance and spark plug. Squish also raises your power band when you adjust it up.

Do a compression test before you go through all the work of pulling your jug. Let us know what top end you have btw. When you do a compression test make sure your bike is warmed up and that when you are cranking away you have it WOT