honda pc50 transmission query

I have a 1969 honda pc50 and it's almost a great little moped. I need to hear from anyone who has owned one of these because i have a whirring noise coming from the crankcase and it just occured to me (after 2 weeks of browsing and head scratching)that it could be normal! Are these bikes incredibley noisey??? The blurt of the engine is over ridden by a whirring sound that gets louder as i accelerate.

I can peddle it without the motor running(gears disengaged) and it sounds fine

i can rev the engine (gears disengaged) and it sounds fine

i had assumed it was the centrifugal clutch but ive opened the crankcase and it seems fine.

Are these bikes notorious for being noisey. or has some bearing fried?

I've looked all over for a manual( including links on this site) but no luck

Any comments would be greatly appreciated, i am sick of being a 30mph air raid siren.

Re: honda pc50 transmission query

Hello carl,

This is an UK site and i think they are able to help, better than me, my english is not that good to understand the sound have.

Good luck.


Re: honda pc50 transmission query

steve matichuk /

i too have PC50, however i'm told it's a '72.

yes. these are noisey little buggers. admittedly, my exhaust is not in mint condition (soon to be rectified), but it's definitely loud for a 4-stroke engine nonetheless. a couple of weeks ago, as i rounded a corner onto a relatively quieter street, a lady on the sidewalk actually spun around to face me with this look of horror as she covered her ears!

as for the whirring noise, i hear something similar to what you've described too, however it's not constant. i'm a bit of a novice so i'm not much help diagnostically, but i'd be curious to hear what explanation for the noise you come up with.

let me know,


ps. sweet ride otherwise, eh?

Re: honda pc50 transmission query

Steve Williams /

i built a minibike using a pc motor which made some very strange noises,i found the best way round the problem was to use a monograde oil,i used 50 weight and it shut up,the clutch was a little draggy until it was warm though

Re: honda pc50 transmission query

steve matichuk /

i read in an owners manual to vary the oil weight in accordance with the ambient temperature:

above 20 celsius (70 F) = 20W

below 20 celsius = 10W

cold weather riding = 5W

is 50W really an alternative?

Re: honda pc50 transmission query

I am using 10w/30 oil, the few specs i found on this bike so far say its the right one. I am going to go back and look at the clutch again, although it looked ok last time and the bike seems to run fine i cannot yet just accept it and move on with earmuffs, i dont like risking long hauls! with unidentified noises.

Re: honda pc50 transmission query

Steve Williams /

i must admit i didn't check because i didn't care!seemed to be fine on it though.

Re: honda pc50 transmission query

Steve Williams /

i had a friend who had a knackered yamaha xs650,he put 90 weight in it to quieten it down!it ran for another year before it shit itself.

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