Yamaha Neos 50 A/C URGENT HELP NEEDED!

Hi, hopefully this forum will give me some answers!

My YN50 is due for an M.O.T very soon, so I had to do some work, one of which was changing the piston and barrel.

So I bought this: http://www.ebay.co.uk/itm/220914217...X:IT&_trksid=p3984.m1439.l2649#ht_1528wt_1163

It went together fine. But it took ages to start, and when it did, it died on low revs below 3/4 throttle, and bogged almost everywhere. The need for constant high revs caused me to crash my bike on the ice, so I now have a week off to fix this problem. I removed the barrel to find I had installed the piston upside-down (I had the arrow facing up)

The rings looked fine, there was one very light scratch on the piston, (couldn't feel with finger) and there was no scoring on the barrel, so I reinstalled it. A compression test tells me I have between 70-75 psi of compression, which was the same as when I had the piston the wrong way round, except now its not starting at all. I did notice that my head gasket was wet, but I can't see any leaks around there.

- I bought this: http://www.ebay.co.uk/itm/380399878610?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649 And i'm just going to start over.

I'd really appreciate any help now, I've got until Tuesday to fix this, otherwise i'm probably going to lose my job.

Thanks,
Harrison.

 

70-75 psi is very low.

On my bike i get 140+.

Sound like your rings are buggered.

That kit should get you going if nothing else has been damaged.

 

I actually ordered genuine yamaha rings, and they were twice as thick as these ones, also the piston went in very easily the first time, never a good sign..