Pa50-II, poor top end

Hi !

today i checked my pa50 to see why it doesnt do the regular 30mph it should do... I must have checked for 2 hours or so.... and i cannot find what can be wrong with it.

Plug chop is beautiful, it starts right up, and the low end is really good... at least... i think so...(i've never drove this pa50 fully working)

now i'm wondering what can be the problem for not having enough top end



Re: Pa50-II, poor top end

mmm, take your side cover off on the belt drive side and look to see if the clutchs are moving in and out on the front and back pulleys. you change the belt latly? what belt are you running?

Re: Pa50-II, poor top end

take your air filter out( the whole thing) I did this and i gained 7mph on a pa50 I

Re: Pa50-II, poor top end

so many things could be the problem.. dragging brakes.. choke thats partly closed.. dirty carb .. variator / belt problems.. bad rings/compression.. head gasket leak.. vacuum leak .. carbon-clogged exhaust or port or.. the list is too long.

A healthy, stock PA50II should accelerate quickly right up to 30 mph on level ground. Anything else means there's a problem.

Since it never ran right, what else is going on with that bike? Is it 100% stock? Are there any other symptoms? List the things you already checked.. How fast does it now go? etc, etc, etc .. More information would be helpful.

Re: Pa50-II, poor top end

thanks all.

I think i missed some infos on the frst post... sorry...

i know my engine is okay, the rings and the compression are great. The engine has been rebuilt by my uncle(he's a mechanic) and he checked everything. Now i'll be able to do the next engines alone.

The choke moves freely, the brakes are nto dragging, i do not really have brakes, i need some brakes pads,(do you have some joew?)

My exhaust has been cooked in a fire, and it should be clean.

The bike is 100%stock, yeah, except for an aftermarket air filter element which fits perfectly in the compartment, and i think it's ok, if i read the plug after a plug chop.

the carb has been cleaned toroughly.

I'm pretty sure that the problem is the variator.

The belt is climbing up as my engine revs up, but not a lot, it climbs around 1/4 inch only.

and the belt is going down on the read variator, but not a lot, it's proportionnal with the front variator, let's say somewhere around 1/8 inch.

is the problem there?

I know i have a little too much oil in my gaz, because the engine has been rebuilt, so i wanted to make sure everything was allright, so i added a little oil. But i dont think that this makes the diff, because i added very little, and the plug chop is beautiful.

So, what do you think?

thanks a lot.


p.s. Joew, is it just me or have you been out of mopedarmy for a long time? I missed your advises.

Re: Pa50-II, poor top end

g.b. Like you, I am glad to see joew back.

It sounds like your variator is not moving fully. Take it off and make sure it will slide fully up to its limit on the shaft.

Take the air filter element out. Although it looks good it might be overly restrictive.

Joew thinks that the main problem with a PA50II is the muffler. Honda makes it quiet to keep people happy but it chokes the unit up.

Let us know what you find out.

Re: Pa50-II, poor top end

thanks silver. i'll try to open the variator soon.

I already read some joew's post , and you are right about the exhaust, it's VERY restrictive, but it's DAMN quiet, i dont know if you already heard one, but it's 1/4 as louad as my other mopeds.

And at least, the moped can do 30mph, like a puch maxi or any other.

I'm pretty sure it's the variator...

best thing is that i bought some variator weights(nos), from ebay, like 2-3 weeks ago, i couldn't pass, they were like 2$

so i have some spare ones now...

but i'm afraid that the REAL problem is the rear variator, it's really hard to open, i'll see what i can do.

and about the air element, i think my nes one is a little too restrictive, but what about the plug chop, it's nice... a little on the dark side, but the excess oil in the gaz must cause this.

can it still be bad?



Re: Pa50-II, poor top end

Hey guys.. Work and other projects have kept me away... it's nice to be missed and nice to back for a while. :)

_The belt is climbing up as my engine revs up, but not a lot, it climbs around 1/4 inch only_

If you mean the belt rises only 1/4 inch, I have no doubt the variator is part of (or all of) of the problem .. the front pulley sides should close and the belt should rise to within 5 -7 mm of the outer edge of the pulley (nearly to the bottom of the little square cut-outs around the pulley's rim).

If the front pulley is not closing all the way, chances are it is worn inside. The centrifugal roller-weights ride on ramps. The ramps can wear down and/or the rollers can wear down. Because of the angles, even slight wear in these areas translates to a huge difference in top gear ratio. I'd disassemble the (front) variator and give it a close inspection.

If things look OK internally, the main shaft could be corroded and preventing the pulley side from moving inward. A badly adjusted belt might also be part of it.. So could slippery/oily pulley faces or belt surfaces .. Everything involved with the variator needs to be perfect to get top speed.

Re: Pa50-II, poor top end

thanks joew!

now i'm pretty sure that the only problem is the pulleys.

i have NOS roller weights for pa50, i'll try them out soon.

thanks a lot


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