'82 PA-50 II "ping" sound from engine?

I'm new to mopeds, as of yesterday, and have run into a problem. I know nothing about small engines (yet), so any help will be appreciated.

I notice a 'ping' sound comging from the front of the engine - almost as if you hit a piece of metal with a screwdriver or something. This sound seems now to be associated with the moped not running even as well as it was yesterday. Stalls when at a complete stop, engine not running smoothly, etc...

Does this ring any bells for anyone? (pardon the pun)

thanks

Re: '82 PA-50 II "ping" sound from engin

i found a 78 pa50 hobbit at a salvage yard.. no spark plug.. it's a good thing i examined it before firing it up.. there was a bunch of gravel in the cylinder..

take the head off.. examine the decompression valve and everything else in there for indications that something's hitting something.. maybe the spark plug is the wrong type.. too long.. who knows.. Maybe you're hearing something unrelated to the engine..

go get the PA50 / Hobbit manuals on THIS page .. read them cover to cover .. since the bike is new to you, check everything before riding that thing again.. brakes, engine, etc .. search this forum for lots of PA50 threads.. ask if you got a question.. Read Fred's Guide (top of that page) for more tune up stuff..

spend a few bucks on any needed tools if you have none.. It's a very nice bike when it's in good operating condition and a few days of tweaking and tuning and dirty hands is well worth the effort.

Re: '82 PA-50 II "ping" sound from engin

Listen to what joew says. He is very knowledgeable on the Hobbits.

Re: '82 PA-50 II "ping" sound from engin

Are you using the proper spark plug?

The piston could be hitting the tip of plug if the plug is too long.

Re: '82 PA-50 II "ping" sound from engin

I get the same type of sound, unless you're refering to something else. Mine starts happening once I'm running at top speed for like 5 minutes, then a pinging or clicking noise starts coming from the engine, soon after the engine dies and seems to have over heated (small amount of white smoke comes out) Is this probably just me pushing the engine too hard?

Re: '82 PA-50 II "ping" sound from engin

that sounds more like preignition.. something in the combustion chamber is getting red hot and igniting fuel the mixture before the plug.... Then the plug fires.. so you have two flame fronts..

This causes very fast mixture burn.. closer to an explosion than a burn.. and that shocks the parts and causes a "ping"..

take off the head and clean out any carbon deposits.. These deposits can do a couple things.. a piece of carbon can be the thing that gets red hot and pre-ignites the mix...

Or lots of carbon takes up space and raises the compression ratio.. and that causes very high heat.. and that could get the spark plug's electrode or something else red hot..

aside from these things, there are other causes for preignition and or too high heat problems.... too advanced ignition timing, very low octane fuel (old fuel).. A too-hot heat range plug can do it.. lots of other stuff

to keep it simple, i recommend a thorough tuneup..

Re: '82 PA-50 II "ping" sound from engin

Thanks!

One more question, how much oil should be in the scooter? I was thinking that might've been part of the problem too, but no dip stick came with my scooter when I got it so I wasn't really sure how much I should be keeping in it..any ideas? Thanks again.

Re: '82 PA-50 II "ping" sound from engin

scooter? The pa50 uses no oil other than what's mixed in with the fuel.

Low oil , clutch slippage or gear friction can contribute in general to a hot engine, but i don't see it as a cause for what's ailing your bike.. but ya never know..

so.. what kinda bike do you have? might be a manual around here someplace.. or "search" the forum.. "my bike" oil level..

make a dipstick.

empty and then refill your gear box with the correct amount.. make marks on your dipstick for checking oil level.

oops.. gear box

tell me you meant the PA50's rear wheel gear box.. i forgot about that..

lets see.. 80W90 gear oil.. fill it till it comes out of the filler bolt with the bike vertical.

Re: oops.. gear box

Well unfortunately I'm not very auto/moped savy, I'm pretty sure I have the express II pa50? or the nc50? not sure hte difference, I do know theres something that says oil next to the gas tank, so maybe thats the oil gear box? heh Oh, and can 80w90 gear oil be found at most places like autozone? Thanks again for the help.

Re: oops.. gear box

the two bikes are very different.. there's a NC50 manual on this page break>

take a few hours out and read it while examining the bike.. Any questions not answered in the manual or a forum search or whatever just start a new thread with "NC50 Express" in the header so it'll catch someone's eye. Quite a few people have them..

Re: '82 PA-50 II "ping" sound from engin

Thanks everyone for your responses.

Over the next couple days I'll be able to take the time to look at things more closely and then respond with marginally more knowledge.... very marginal.

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