honda pc-50 from canada

I recently came across a pc50 but can't seem to get it to fire. I'm very much an amateur so if anyone has a suggestion i would really appreciate it. Also, what kind of oil should i put back in the crankcase? 5W-30?

General Troubleshooting and Tune-Up

Dave.... Follow the troubleshooting steps to get it to run.

Don't be intimidated by the whole page... just read the parts that apply to you as you need them.




BASIC TROUBLESHOOTING (follow these steps to get it to run)

The 3 most common reasons why mopeds don't run are....

1...dirty carb (inside)

2...dirty, worn, or mis-adjusted ignition points.

3...fouled spark plug.

The first thing to check on a moped that won't run is to see if you have spark at the spark plug.

Pull the spark plug out and hold the metal part of the plug firmly against the cylinder head while you kick or pedal the moped rapidly with the key and switch on.... it might help to do this at night or in a dark garage to make it easier to see the spark.... it might also help if you have 2 people... 1 to pedal/kick, and 1 to hold the plug firmly against the cyl. head... you are looking for a blue spark to jump the gap on the plug.

Make sure you have a good spark plug to start with, a black or gunky or wet one will not spark.

It is smart to just buy a new plug to start with.. you can always save it for later if the old one turns out to be good.

(working for hours only to find out it was a bad plug is frustrating)

If there is no spark.... clean the ignition points (like it says below)

If there is spark... squirt a little bit of gas (like a spoonful) into the spark plug hole and try to start it.....if it starts and runs for 5 seconds and then dies, then check for fuel flow (like it says below)

If you have fuel flow to the carb and it still won't run.. then clean the carburetor (like it says below)





Remove the fuel line going into the carb.. turn the gas on.. does fuel flow freely out the gas line?.. No?.. You may have a vacuum operated petcock (if you do there will be another rubber line going from the engine to the petcock).. take this second line off the engine or carb and suck on it and watch for fuel flow.. If no flow, you must take the petcock off and disassemble and clean it..


Clogged or dirty carburetors are the most common reason for poor performance.

The parts of the carb that are dirty or clogged are the small holes inside the carb (air and fuel passages).. not the outside.

The carburetor must be removed... then you take off the float bowl (on the bottom)... then you remove the brass "main jet" in the middle of the carb... hold it up to the light and look thru it... it must be clean and clear.... if it is not clear you must poke a piece of fine wire thru it.... a wire plucked from a wire brush works good.... or some soft multistrand copper wire like from speaker wire or lampcord wire... don't use a drill bit !!.

Next you should screw the idle mixture screw in.... (( Make sure you count how many turns out it was set at !))..... then remove it and all other careful.. don't forget where everything goes.. and don't lose anything!

Now you must clean out all passages in the carb with aerosol carb cleaner and compressed air... (like 100 psi)... with a blow nozzle... squirt the cleaner in ALL orifices one by one followed by a blast of compressed air.... while you are blowing air thru the holes feel with your fingers to feel where the air is coming out of and blow the other way too.... take your time.... then reassemble all the parts.

Remember to turn the idle mixture screw out to its original setting... usually between 1 and 2 full turns out from all the way in) and reinstall the carb.


Older engines have "breaker points" ignition.. which can get dirty, wear, and need adjusting occasionally.

You will find them by looking through holes in the flywheel.. (usually on the left side of the motor)

Newer motors don't have points.. they use an electronic ignition called a CDI.. and there is nothing to clean and set.. but you can still check the timing with a strobe light.


You can clean them through the holes in the flywheel..(you don't need to remove the flywheel)

To clean them you need some sand paper (use 400 grit wet and dry sandpaper), a piece of clean paper, some scissors, and some aerosol brake cleaner or carb cleaner and some compressed air with a blow nozzle.

Remove the ignition cover and look for the points in one of the holes in the flywheel.... lay the bike over on its side and sit on a milk crate or something to get comfortable.

Then cut some thin strips of sandpaper (like 1/4" wide, 3" long).... pry the points open with a small screwdriver and stick the piece of sandpaper in between the points and let them close.... then pull the sandpaper out.... do this several times to each side.... now pry the points open and blow them off with compressed air... then spray them with the cleaner.... then cut a strip of the clean paper and pry the points open again and drag the paper thru a few times (the paper should be clean and should drag through smoothly).... blow them off again with air while open.... now they should be good.


You set the timing with the flywheel ON

Correct ignition timing means the spark plug is firing at the correct moment in the engines rotation.. a little before TDC (top dead center.. when the piston is closest to the spark plug).

The spark plug fires the instant the points "break" open.

You want the points to open when the "F" mark on the flywheel lines up with the mark on the engine case.

Clean the points like it says above FIRST.

Then look on the outside of the flywheel for some lines and letters.. there should be a T mark next to a line... and an F mark next to a line... There should also be a mark on the engine case .. the T mark will line up with the mark on the engine case when the piston is at TDC.. you can remove the spark plug and stick a screwdriver in the hole against the piston and turn the flywheel.. when the piston pushes the screwdriver all the way out, the T mark will be lining up with the mark on the engine case.. the points will have already opened BEFORE that.. they should just START to open when the F (Fire) mark lines up with the mark on the engine case.

To check this accurately you would need to have special tools.

But you can get close with the "paper test"

For this you need a very thin piece of paper (like cigarette rolling paper..or a cigarette pack piece of cellophane)

All you do here is put the thin strip of paper between the points... and keep light tension on the paper (like as if you are gently trying to pull it out) while watching the F mark and the case mark as you slowly rotate the flywheel with your other hand.

Remember you are rotating the engine in the direction it normally travels (CCW as viewed from the left side of the bike..CW as viewed from the right)..the paper should slip out as the points start to open when the F mark lines up with the case mark.

So it' hand on the flywheel.. other hand on the paper...eyes on the F mark.

If the paper pulls out too late.. you will have to move the points set for a larger gap.

Too early.. move the points for a smaller gap.


Most mopeds have 2 stroke engines.... 2 strokes consume oil for lubrication.

Newer mopeds might have an auto-lube oil pump.. so that you don't have to pre-mix the gas and oil.... For older mopeds you will need to "pre-mix" the oil with the gas.


With modern 2-stroke oils you should probably pre-mix between 3 oz.(43 to 1) or 4 oz.(32 to 1) of oil per gallon of gas.

Make sure you buy 2-stroke oil.

Some people say synthetic works better... But I have found regular 2 stroke oil to be just as good as the much more expensive synthetic oil..


Mopeds are low performance engines designed to run on the lowest octane of gas you can buy (87 oct.) because they are afraid that somebody who doesn't know better will put the cheap stuff in..... and higher octane will not make it run better or faster or make more power.

But higher octane will not hurt your engine either.


I also like to put a little gas treatment in the gas every once in a while.. because moped carb jets are so tiny that they get clogged easily...the gas treatment helps dissolve stuff in the gas that might clog these jets.

I use one capfull of gas treatment per moped tankful (you buy the gas treatment at a gas station or Auto parts store)

Re: General Troubleshooting and Tune-Up

Fred, thanks for the info.

I'll give that a shot and see what happens.

Is 10w oil alright?

Re: General Troubleshooting and Tune-Up

In my opinion almost any oil will work good in there

(but i don't own one)





The needs of a tranny like that are simple.

If anybody knows better... Don't hesitate to speak up.

It wouldn't hurt to call or stop by a Honda dealer and ask in the service dept.

Re: General Troubleshooting and Tune-Up

thanks fred. I got er to turn over last night after closing the spark plug gap a little.

It still won't idle (i'm afraid that's because i used a drill bit before i was warned not to on the carb!). These little engines are tricky! thanks again

Re: honda pc-50 from canada


Put 10W40 in a Honda 4-stroke!

DON'T put ordinary 10W40 for a car in it. Ordinary 10W40 will be as thin as water withing 500 miles, you need a 10W40 for a MOTORCYCLE. A car has a dry clutch and car-oil isn't suitable for a wet-clutch type engine. Motorcycles have wet clutches, motorcycle-oil is much better for your PC50, or any Honda 4-stroke for that matter.

David... Is that a 4 stroke ?

Hey.. Dave.....I assumed it was a 2 stroke.... like the majority of peds and scooters.

Is it a 4 stroke?.... And how old is it ?

If so... then I gave a bit of incorrect advice.... mostly on the ATF.

You can use ordinary car oil if you want... You don't have to use special "motorcycle oil"

And 10w40 car oil will not.... "be as thin as water within 500 miles"... it won't be any thinner than any "10w40 motorcycle oil".

Car oils HAVE changed within the last 5 years... they have gotten "slipperier" and a motorcycle clutch can POSSIBLY slip.... But I have an 1100cc putting out a lot of HP and it doesn't slip with car oil.

Your little 50cc monster won't slip its clutch.

... And I know ALL about the car oil/ motorcycle oil debate.

On the other hand the motorcycle oil is only about twice as expensive and you don't use much.

Re: honda pc-50 from canada

Ron Brown /

I use Castrol 20-50 in my bikes, as do many other people I know. If you change your oil at the recomended intervals you should have no problems.


Yeah... But..

I actually don't want to bring this up... but it's too late.


Yeah... But is it 20w50 car oil (SJ rating)... or 20w50 BIKE oil.??

This topic has been beat to death a lot.

But the truth is that car oil has changed in the last 5 years... For 2 reasons... Both government related.

The US gov specified "oxygenated" fuel for some parts of the country..

Oxygenated fuels get worse gas mileage.

So car manufacturers specified slipperier oils to get back some of that lost mileage.

Slipperier oils CAN cause motorcycle wet clutches to slip.

The US gov also has demanded that car manufacturers make their pollution control catalytic converters last to 100,000 miles.

And the main thing that killed catcons were "high pressure" anti-wear additives in oil... (which protect your engine under high temp hard useage times)

So they removed them from car oils.

And bikes typically run 50 to 100 degree F higher oil temperatures.

So....I have run "car oils" for years.... But.... They are not the same as they used to be.

The oil manufacturers have recommended using "bike specific oils" that don't have these changes.

Even new bike owners manuals do not specify the "SJ" oils (car oils with the press add's removed and slipperier base).

So... Those of us that have run car oils now have to make a decision of whether to believe the "Oil manu's"... and pay two or three times as much... Or?

So far I am using the "SJ" rated car oils.... My clutch now makes a funny "graauuunch" sound under hard engagement conditions (drag type starts)

But I'm not sure that's because of the oil or not.

And I CAN"T find the old oils my engines manuals call for ..."SE", "SF", and "SG".

Unless I go to a bike oil.

That is the state of the state of the oil situation.

Re: Yeah... But..

Ron Brown /


Good point(I think). I have read all of that too. My best recollection is that some metallic additive was removed to help the converter and that this metallic additive, or lack of it, caused pitting of gear teeth, under some circumstances, in engines which have the transmission and engine in the same oil. This includes almost all Japanese and most late model bikes of other ethnicities. I have the significant advantage of owning only old, relatively underpowered bikes so I do not suffer much from high pressures on the gear teeth. On the Moto-Guzzi and BMW the transmission is separate anyway.

Many people run Mobil 1 in bikes with wet clutches and do not suffer clutch slip. I don't think oil gets more slippery than that. I suspect your clutch has been slightly glazed from "drag strip" starts and is just letting you know.

As an aside, I have heard that Diesel oils still have the old additives, but as they are not as commonly on sale at the local auto parts or K-Mart, I have not bothered to investigate this. A couple of years ago, I saw a 55 gallon drum of SG in a farmer's barn/workshop and he said it was readily available at the local oil distributer, but I never followed this up either.

I have not personally seen any problems with car oil, nor have any of my friends, however, some of them do choose Mobil 1 or Motorcycle specific oil.

The bottom line here is that I could not see a moped developing enough power for this to be an issue. I would think the increase in hp from slicker oil would be more important.


Re: David... Is that a 4 stroke ?

Well Mobil1 10W40 sucks, I use Expulsa 10W40 and that really is the best 4-stroke oil I ever tried.

Re: update

Alright, so, i've gone through the steps here and the little banger runs!

Fred, as far as i know, it's a 1978 Honda pc-50 four stroke (1977 on the registration, '78 on insurance, i don't know why) . I am an amateur, but i counted four strokes and it doesn't look at all like other two strokes i've played with.

I tried fixing my mistake on the main jet by bending some copper wire and stuffing it in to close that cavernous hole a little. It did work. After cleaning the spark plug and closing the gap a bit it fires and runs, not with much power mind you and it still doesn't like to get going without a lot of coxing with the choke.

Here's some new questions:

Where can i get a new main jet? Is 10w-40 (car or bike) vital or can i stick with the 5w-30? And now that i've got the engine running I can't get the steeing column off!

Holding onto the handle bars i can just kick the wheel out of place, the bolt is in and won't tighten or loosen. Any advice for this one? Thanks

Re: update

If it is a Honda... Then almost any Honda dealer should have parts for it.

Call them on the phone and ask them.

Then go there, and look on the microfiche machine (fish) and look for the exploded view of the carb, so that you and they both are talking about the same part.

Then they might have to order it (you pay first).

In my opinion almost any oil car or bike 5w30 or 10w40 or 20w50 oil is fine.

Especially in a low HP motor like that.

But in general you should use the lower number in cold weather, and the higher number in hot.

So 5w30 is fine.

Maybe change it in June to 10 or 20w.

There is one good thing about Honda's... they are usually very well engineered...(even the stuff 35 years old) .. there are very few bad things about Honda's in general.

Re: update

You're right there!

Especially the Honda 4-strokes are just about immortal. I own a 1974 Honda Supersport SS50, runs like new, a 1972 Honda PF50, runs almost like new (it needs some tuning), a 1963 Honda C310a wich I'm restoring, a Honda Benley CD50 wich I'm building up from scratch and tomorrow I'm picking up my 5th Honda ... another C310a with an extra engine.

The pushrod type engines (PF50, C310 and also your PC50) are literally indestructable, but their poweroutput is low, don't expect them to go faster than 65 Km/h (41 Mph).

The SOHC type engine are a tiny little bit less indestructable but they still live forever and the poweroutput of these things is enormous, I tuned my 49cc Supersport to go 83 Km/h (52 Mph) and still with an awesome acceleration and the sound ... oh man, I love that sound!! And there are still some upgrades I haven't tried yet, like the racing camshaft and a nice Motorsport exhaust wich will add a lot of power my wheeled monster.

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