Admittedly im pretty new to bikes and biking and bought a 1983 Honda CM 125
just before christmas. Its a nice bike but seems to be showing its age, as its being very temperamental
and not running smoothly.
Basically I keep getting a problem where the bike just isnt accelerating and once i have changed out of
1st…2nd gear there just isnt any pull in the bike and really have to open the throttle on full in 3rd
just to drag it up to 20mph(!)
This is the 2nd time this has happened. The first time I had a friend
look at it who opened up the air filter and sprayed carb spray into the carbs. We also checked the spark plugs,
cables and topped up the battery fluid as well as oil . This sorted it for a month or so , but now the problem
is back and just want to sort it once and for all! (The friend lives in Cornwall, so isnt available to take a look again
and also their knowledge is reasonably basic too)
It is a simple bike, but im not a mechanic and know the basics but anything else is beyond my knowledge but am assuming its
something to do with the air mixture or fuel / carbs? Maybe needs the carbs taking apart and cleaning out.
Does anyone have any tips on this or ideally im looking for someone who can come take a look
and give me a hand to get it sorted? Pic of the bike is attached.
I will add that I can pay, but dont have alot of cash. Im based near Old Street, so please
let me know if you can help me out! Itching to get out on it while the sun is still out!
Did it ever do more than 20 MPH from new? Sorry couldn’t resist.
Seriously though there is a mechanic on here who will come to you - he is highly praised on this forum and reasonably priced so worth a call. He is Rob 07912 991 715.
By the way, he works weekends, so give him a call see if he can sort you out asap.
and while your at thatcheck the compressionscheck/adjust the valve clearancesrenew the engine oil and filter
renew the spark plugs and check HT leadsclean out the air box and renew the air filterrenew the fuel filter, although if it’s like the CG’s it’ll be a wire gauze thing, thoroughly clean it with paraffincheck/adjust and lube the throttle cablescheck/adjust and lube the clutch cablecheck/adjust and lube the brake cablescheck brake shoe friction materialclean check/adjust and lube the drive chaincheck/adjust and lube the headstock bearing and swinging arm
It’s an old machine so it’s probably well worth having the tank, seat and side panels off to check all the wiring for any chaffing, re-insulate and adjust the routing as necessary. Someone will no doubt chip in with something I’ve forgot to mention add that to the list of ‘thing to do’ too.
You’ll love your pride and joy all the more from sharing it’s bodily fluids, blood sweat tears and oil you can’t beat it
It is my first bike and I know its old and was quite cheap, but frustrating me I cant use it properly as its so temperamental
and annoying after my friend sorted it before. Just wont accelerate properly, just has no real drive or pull and engine sounds
a bit deeper and more chokey than normal.
I did change the spark plugs previously as well as top up the oil, sprayed carb cleaner and changed the throttle cable too
but do have the feeling its probably a block or something up in the carbs. I know its a simple bike but Not being very knowledgable about it
id probably rather get someone to take a look at it rather than me taking it apart.
I ll certaintly give that mechanic a call. Cheers!
UPDATE - so got a mechanic to come round couple of days ago to take a look and try sort it.
he thought it was a problem in the carbs so took them out and gave them a good clean.
After that all seemed good again and was accelerating and pulling like new again…
however 2 days later (today) have tried it again and same problem again!
Sluggish acceleration, no pull or drive and then engine cuts out.
So bloody annoying and throwing money down the drain(…or carbs!) Another friend said to me
that it does indeed seem to be a problem in the carbs and perhaps dirt is getting in
some how. Going to try get a fuel filter for it as I dont know if there is one
as someone suggested… but any other ideas?? Sorry know im a newbie to this,
Just want to get it working and solve the problem and stop pissing my money into the wind!
Cheers.
That has a small wire gauze fuel filter within the fuel cock, take a look see if CM is the same. I’d guess your ‘mechanic’ didn’t go far enough with the cleaning. My guess is the gauze fuel filter is either broken or missing altogether and there is some foreign matter slurring around in the fuel tank with nothing to stop it entering the carburettor and fouling the fuel ways/jets.
DO IT YOURSELF - it’s fairly simple and you have to start somewhere.
Inspect clean/replace fuel cock gauze filter
Inspect and clean out fuel tank
Inspect and clean carburettor
Then get yourself a Haynes and give it a proper step by step full service. Take photographs and keep a note of what you did, when you did it and the mileage for future reference/service history.
Yes my friend (who doesnt live in london unfortunately) said it might be the fuel filter that is broken
or missing and just instantly letting dirt in again. The mechanic i got to do it was young and perhaps a bit inexperienced
in hind sight but did get it running again (as short as it was!) and seems like it pin points that it is a problem with the carbs.
I will check the filter and get one for it if its missing. As you said i need to start somewhere so may
just have a go doing it myself, just need to remember how to put it back together, but the photo idea is
good. Appreciate the advice.
Back in the day when troglodytes roamed the planet and I was an apprentice oil rag we were taught to make line drawings and notes, in our paper note books, of assemblies as we dismantled them.
Now the troglodytes have become extinct and mobile phones with built in digital wotsits roam the planet a simple click click, as Jimmy would have said, saves the day when it comes to reassembly. Save them to your non-paper notebook to review later too.
It’s a different world, I remember when a Big Mac kept the rain off your back :Whistling:
if theres that much crap in the fuelk tank then it will only clog the carb or filter again shortly after cleaning, if car clean works then at same time clean out the tank and petrol tap.
check if inside of tank is rusty too, if so give a good rinse through.
