Loss of power By bolts (Read 1,143 times)

[bolts]

So I have a scooter that I have been working on, the scooter is a 50cc 4stroke, and it has been running really well. Topping out between 35 - 40 mph. Pulled in, and from that time to the next, something has happened. It is now only getting up to 20mph, and is slow on acceleration. I cleaned out the carb, adjusted the valves (.08mm), thought about playing with the timing, checked the spark plug, even changed the belt (the old one was a bit thinner, and showing a few cracks). But there has been no change, weirdest thing, fine one day almost dead the next. Open to suggestions.

[jomama0867]

You might check your vacuum lines; mine had a hairline crack and it took me forever to think about checking those lines!

[bolts]

Sounds like as good a plan as any. Could it be something electrical, like the CDI or something like that? What about the variator. Planning ahead just in case

[jomama0867]

Not sure about anything electrical; and my experiences with variator trouble reminds me that usually you can "hear" and/or "feel" when the pulleys have troubles. Still, wouldn't hurt giving the CVT case a look-see!

[Bashan]

How about the clutch? A tensioner spring can spontaneously snap and so the bike acts different from one moment to the next. Rich

[Alleyoop]

How are the RPMS are they higher or lower when your doing 20mph or about the same. Is the MOTOR loosing power or is it still revving up good. It could be the weights are pretty flattened out and will not push the variator out for top end speed but you would still have good revs and power but no speed.
Alleyoop

[bolts]

So it feels like the revs are about consistent with the speed. I changed the CDI and it felt like it got a little better, but that may be psychological... I checked the fuel and vacuum lines, and they looked fine. I even tried changing out the plug wire. Still nothing. So I pulled off the left side cover and checked the roller weights, and they all seem to be fine, no flat spots or anything. And still no difference. As for the clutch, everything looks good, I don't see any loose springs, and it is tight getting the belt in. I am really getting frustrated with this scooter, the icing on the cake was when the center stand got hooked up on my garden hose and snapped the spigot off the wall, it was a pretty geyser, but I had to spend time fixing that.

[Alleyoop]

Can you get a Video with sound and start it up on the center stand and rev it up to hear the motor and see the rear wheel.
Alleyoop

[bolts]

Not sure the best way to upload, but I can do that

[Guitarman]

Did you film the water show also? That would be cool...

Sounds to me like something is restricted or leaking. Check yout fuel filter, petcock if you have one, any and all vacuum lines, especially to the carb...

[bolts]

here is the video as requested

[Guitarman]

Check your belt in the CVT. Might be slipping.

[bolts]

I thought of that, but the belt is brand new, and the clutch is tight on it, and the variator has no grooves or anything like that. Wouldn't it make a noise or something like a fan belt on a car if it was slipping as well?

[Alleyoop]

I don't understand what the problem is SOUNDED really good when it throttled down did you let go of the throttle or where you backing off slowly?
Alleyoop

[bolts]

I let go of the throttle. The problem is the fact that there is very little acceleration, and it won't go above 20-25 mph, where as before, it was going 35-40 mph. I checked the valves, changed out the spark plug and plug wire, vacuum line, fuel line and filter, changed the belt, and checked the variator and clutch. The strangest part of all of this is the fact that it was working fine one day, and then this the next.