Significant power loss By kamil (Read 981 times)

[kamil]

Hello everyone,

I've just joined today for some hope to get info on how to fix my little 50cc moped.

It's a 50cc Jonway Madness 4 stroke. Registered this year 2014, chinese scoot. It's done 5900km

So, the problem is, is that there is at least 25%+ less power than usual. And the accelerating is really bad, slowly builds up speed and the main problem is that it feels like there is something trying to brake(slow) the engine down. So when I build up speed, and let go off the throttle, there is like automatic engine braking that is very violent. So it's not normal.

How it started:

One day whilst riding about, the bike violently lost power, which was noticeable immediately. I thought it will fix it self after time. It didn't. So a week or so later, when riding down the road, my drive belt snapped. The engine was still running with no problems but the belt was gone. So, I took the cover off to see what was up. The belt was shredded. I also noticed that the clutch assembly (back metal plate) was bent in one place. 

So I decided to take it to a mechanic to fit it. I've been told that even though the belt was put on, it lacked so much power that it was useless to me, and also told it needs the engine stripped. After a day of leaving it with them, the took the belt out and put it back on and apparently it was fixed. So, I got it delivered home, I went on a test ride. It had the same problem before the belt has snapped. So now I'm stuck with it like that. 

I've checked the carb, spark plug, coil wire, clutch assembly, variator assembly, and nothing. (I hope the terms are correct)

I'm really sorry for this long, boring story but my 50cc is my only means of transport, and haven't rode it in 2 months. I've exhausted every possibility (to my knowledge) and emptied my wallet. Bear in mind that I might got some of the terms incorrect.

I will appreciate any, any information or tips, as I don't want to blow my money on mechanics that will do nothing.

This is my scoot: 

Thanks guys

-Kamil

[Bashan]

You said your clutch was bent. Is that fixed now?

[kamil]

Hi,

No, the clutch is not fixed however, I thought that such a little bend will not make a difference so it's been left as it is.

[adamhoyer]

I think a bent carpenters level would be no good and throw things off? So why not just replace the clutch for $40-50? Wait for   Bashan or alley or cyborg to give you the 100% answer, but look into buying a clutch from your dealer.

[cyborg]

Anything bent that spins = no good,,,it's at least part of the problem for sure,,,oh i meant to say earlier,,,very nice looking scoot

[Bashan]

Replace the whole clutch assembly, you don't know what's going on inside it. Yes, buy the entire assembly and the old slides right off and the new right on.

[Alleyoop]

I think what he says is bent is the plate that covers the springs. To me that is not bent most clutches come that way the plate is not completely flat no biggie. Also that would not cause what he is experiencing loss of power.
With that many miles on it I would FIRST adjust both Valves to .003 inch's, then I would check the Weights in the Variator. The mechanic that did any work just actually put a new belt on and that was it.

So Kamil do you have any tools and are you willing to get your hands dirty. These scoots are easy to work on and not to much go wrong really unless you abuse the crap out of them and not do any maintenance.

[kamil]

Well, the second plate that holds the belt in between the first and second plate, is the plate that is bent towards the back wheel. If you know what I mean. I do have the tools and would like to get dirty with it, but don't have an impact gun.

[Alleyoop]

So are you saying the VARIATOR FAN PLATE is bent and not the CLUTCH pulley? OR is it not on right can you take a picture of this bent part. Because the picture above I do not see any bent pully on the clutch.
Alleyoop

[kamil]

The clutch pulley. In the picture, where the belt goes on the clutch pulley the very back plate of it touching the belt is bent. Sorry for confusion. I will later post pictures to make it clearer.

[Alleyoop]

Ok so this is the pulley that is bent if so you need a new clutch assembley.
Alleyoop

[kamil]

Sorry Alleyoop, the other plate is bent. So it sounds like I new a new assembly.

[rks]

Yes you do...Doesn't matter if it's the inner half of the clutch pulley, or the outer half.....if it's bent, it's shot

[kamil]

Ok thanks. Didn't know whether I leave it or not. Also, if that wouldn't be the cause, what else could be?

I'm going to post pictures and videos to give better insight.

Thanks everyone.

[richardv]

I would be checking rear wheel bearings.