Piston Rings

[OldGuy]

2001 Vino with about 11,500 miles.

A compression check (engine warm, WOT) gives me about 45 psi on the first stroke and a high reading of 75 psi after five strokes with the kick starter and the electric. From what I was able to find on the forum this is low.

My top speed is down to about 30mph (down from 37mph) on a flat but it still pulls hills at the same speed it always did.

Do I need to replace the rings? Can I buy just the rings? The service manual says I have to replace the piston and rings as a set.

Also any hints on how to do this would be helpful. I've read all the HowTo's but most seem to be related to upgrading etc.

Thanks,
OldGuy

[VINOGT]

The piston and rings come seperately, but for the small added cost, around $25 I think, you might as well get the piston too. It all depends on its condition. A rebuild is just the same procedure as an upgrade, it all comes apart the same. The big question is the condition of the cylinder. It may need replaced also to regain total compression. You just have to take it apart and see for your self.

[Zuma-Zuma]

Yes, take it apart first. It may just be a carbon-stuck ring. You may just need to clean it up. Be careful not to break the ring removeing it, if its stuck, that is. Wonder what the rollers and belt look like.

Sounds like a good time to .........UPGRADE!!

[OldGuy]

The belt (kevlar) was new about 300 miles ago. Don't know how to inspect the rollers. Can't afford to upgrade and don't really want to.

OldGuy

[Randy]

I would suspect a stuck ring as Zuma-Zuma mentioned. If the piston and or cylinder are that worn, you may be real lean and for a long time. One other thought-someone who upgraded to stage two may have a really good low mileage piston and cylinder lying around.

[scootertrash]

11,500 miles at 30 mph is about 23,000 minutes of running time.

23,000 minutes times 4,000 rpm means that little piston has gone up and down 92 million times.
Maybe it's just worn out.

[Randy]

I'm sure Scootertrash is absolutely correct. I missed the part of the original post where there is a gazillion miles on the thing. Pretty cool though that a little engine like that will go that many miles.

[REGMAR]

It's the little engine that could! My 2004 just turned over 10,600 miles, and almost all of it was wide open. I mean when your top speed is 40mph, you tend to go wide open a lot just to keep up with traffic. I'm only just starting to notice the top speed has dropped to 35mph, so I ordered new engine parts. I'll be replacing my rings soon too.

[calico-uk]

The belt (kevlar) was new about 300 miles ago. Don't know how to inspect the rollers. Can't afford to upgrade and don't really want to.

OldGuy

then just get rid of the scooter and buy something new, like the rest of the sheep., its sounds like to me that your belt it not opening up to the last position of the rear pulley, i doubt its a power issue, maybe the weight in the variator are not traveling out far enough? due to old belt shavings all over them and last but not least, could be a simple lack of power, either way, for about 300 bucks and a weekend in the garage, you can upgarde, but it sounds like to me the kevlar belt is the issue. that was the only thing u changed, piston and barrel kit that would suit your needs is less than 200 bucks, like 160-170 i think, thats whith a head as well if ita 2 stroke.

its as simple as that. a 70 cc kit will turn that belt a bit better and some slightly lighter roller weights would compliment that. its really easy, even if its valves and timing chain, easy, easy easy.

[calico-uk]

i used to own a yamaha passola 50 cc, that ran 38 miles and hour with the piston rings in 3 pieces for about 3 months, it just didnt pick up as well as it did when the rings where whole, it also had about 37,000 miles on it so....i doubt it.