YN100 repaired, but operating out of powerband :(

Paul /
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Hi Guys,

Been a while since I've been in here.

Got a problem with my Yamaha YN100, okay, so not technically a moped, but I know there are some kind folks around here that know a thing or two about V Belt transmission.

The problem started when the belt and rollers got worn. I got them replaced. The bilke was fine for about a week then it started sticking in what-would-be 1st... rev its head off, then suddenly shift all the way up to top gear.

I left it in to the mechanic yesterday to have to fixed. Got it back today, with new rollers (again).

It's running fine, but the revs are way too high. It's definatly out the top end of teh powerband, I can feel it has no power at all and while yesterday, even with the dodgy shifting problem it would do 55 reliably and 65 with a hill or wind behind me.

Today, although shifting perfectly smooth, it will do 45 relliably and 55 with a wind behind, down hill. It just has no power at all once it's over 30/40 mph.

(speeds are mph).

I opened up the case and found it all looks quite simple inside, I can see that the rear pulley opens up when i let the rear wheel spin up, but I can't seem to figure out how the front pulley works.

A page on another website said that to lower the running RPM of the engine I need to tighten the spring on the rear pulley.... but I can't get the clutch bolt to move, and gave up and put the case back on.

Does anyone have any tips or suggestions?

Thanks.

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