Yamaha Neos, 70cc build

[cavboy1980]

My 2004 Neos YN50, purchased last November, 9 owners, no history and untraceable mileage.what a good machine.



In fairness it's been a decent bike, getting to and from work, 30 odd miles a week plus other local journeys
'I,ve been looking on this forum for a while but until last week i've not had much worthy of inputs.
Well, not until this happened.





Last Friday it started making a very metallic noise on my way home. It's had a slight 'chatter' on idle for as long as i've had it and i thought it was a Minarelli thing. Clearly it wasn't happy that day and when i oened the CVT case and spotted 5 of the 6 fingers from the star washer laying in the case, alloy swarf and the variator pulley sitting at a jaunty angle i knew something had certainly gone south.
Once stripped i was still puzzled as the variator nut was good and tight but the crankshafts splines were half chewed by the pulley spinning freely.
Well, my hand was forced, i'd been toying with doing a mild 70cc build and now was the time to make it so.

Here we are pulling the engine

[aeroxbud]

That's different. The star washer is made of much harder metal than the fan.
What cylinder are you going for?

[cavboy1980]

I've been looking at doing a budget build of sorts.
I've gone for a RMS iron cylinder 70cc head, piston and barrel set up. RMS reinforced crank, seals and bearings, RMS reinforced variator pulley, Malossi variator, lightened RMS clutch and clutch bell. Dellorto 17.5mm carb, Technigas Next R with the restriction removed.
I'll update you all with the engine tear down,it came with more surprises.

[chehystpewpur]

you needed a shim somewhere on your variator. the nut goes on tight cause it bottoms out on the crank but its not clamping the variator pieces down and they still have play. hence why you heard a rattling.