PA50II Spark plug

so I finally have my PA50II running on and off the choke and idling like it should... it currently doesnt seem to do much more than 20mph even though it should do 30.

There are no airleaks and the carb is really clean.

Which leaves me 2 questions...

1.Currently it has a NKG number 4 plug instead of a 6 would this have any effect on overall top speed?

2.The filter foam that is in it currently is just a generic peice from a chainsaw, would it have any effect on top speed over an original foam?

Open to any other ideas too.

Many thanks,


Re: PA50II Spark plug

if it is the PA50-II and it has the II ramp and the II carb and reeds and intake and II pipe but is still hitting a wall at 20mph ish.... check your rear variator cheecks and contra spring to see if the fully separate under pressure.... the wiki will explain in detail but essentially the moveable pulley cheeks and the contra spring body of that rear variator can get "stuck" at about the halfway open mark because of the tabs inside the assembly jamming against the moveable face.... this locks you down at partial variation and limits you to about 20mph

similarly, check your front variator assembly and make sure it opens and closes fully.... if the rollers inside the front variator have broken end caps or are mashed sideways inside the retaining clips etc, they can jam up at about halfway variated also meaning the moveable face cannot completely close to push the belt all the way to fully variated, again locking you down at partial variation and about 20mphs

also, if you are running stock exhaust II pipe, make sure that thing is compleeeeetely decarbonized inside and flushed out cause a clogged stock pipe will never hit 30mph.... or just get a better pipe :) i like stock pipes and derestricted stock pipes for silence but they are nnnnnot fast (edited)

Re: PA50II Spark plug

Also to add, if your stock belt is worn heavily you will get high rpm and no speed.

But to your original questions:

1. speed, no, other things when you are making FAR more power than stock, yes.

2. Depending on the density of the foam and whether it is oiled or not, yes absolutely. Your filter is in the proper plastic sliding drawer/tray right? If you suspect the bike may be lean you can cover one, or even two of the three little holes in the "snorkel" that protrudes from the air box and see if the problem becomes better or worse.

Re: PA50II Spark plug

I believe my var is felt moving at both ends, I think the issue stems from the engine as at full sore the engine doesn't seem to be screening like a 2 stroke should. I'll try a different foam.

Would the plug make any difference?

And what about the idle scree is out about 3 to 4 turns... Die it need to be out this far?

Plug is Brown on the tip and all the way down the ceramic.

Re: PA50II Spark plug


Re: PA50II Spark plug

I answered your plug question already. Read. And no your idle screw should not be that far out. Search for proper idle air screw tuning procedure.

Re: PA50II Spark plug

also check the rear variator like they said above. seeing youre not hearing any "screeming" rpm's its most likely the problem.

Re: PA50II Spark plug

If the rear pulley were sticking you would pretty much only be seeing screaming rpm. You would not have speed due to lack of gearing change but the rpms would climb just fine as though the bike were single speed.

Re: PA50II Spark plug

depends on where/when its sticking i guess.

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