Help diagnosing dodgy engine noises?

[Loops]

Having got the valves on the CG adjusted thanks to some fine WB help, I now seem to have new problems... ::)

He has always been pretty noisy compared to other 125s, I assumed due to age and design, but now it's getting rather noticeable and worrying as he has been doing his best thumpy-pitbike-steam-engine impression lately :-/


The most worrying noise is the 'thumping' from the engine
if I come to a sharpish halt, i.e. without pulling in the clutch and going down the gears slowly, there's an odd 'puffing' noise. (To my inexpert ears that sounded like a leak in the exhaust but I've looked and although it's rusty it appears to only have holes where it should have holes...)


Any ideas? Would welcome anyone who's local having a listen to help advise!

I'm not afraid to take things apart (with some help), but I'd just like to have a few ideas first as I use him for work, which means he can't be off the road for more than 2 days at a stretch (weekends) or I need to get another bike..!

[Nokesy]

Would love to help you out Loops but don't have the know-how :( Maybe us girls should club together and buy a cheap bike just to take apart and put back together so we can learn a bit more about bikes? I don't think I've ever contributed anything useful in this part of the forum!! ;D But would like to :)

[whizz]

Hi i can always have a listen for you ? pm me if you need help :)

[Jon_W]

The "puffing" sounds like over-run. Is perfectly normal. If you want I'm free monday evening to take a look.

TBH, is probably you nioticing noises now that the valves are quieter.....

[Loops]

Jon, whizz, I'd love one of you to take a listen and either look at me in horror and tell me to take the bike of the road NOW and fix it, or assure me nothing is wrong ;D

Where are you based? I don't want either of you to have to go miles out of your way just to listen to an old bike.


Would love to help you out Loops but don't have the know-how :( Maybe us girls should club together and buy a cheap bike just to take apart and put back together so we can learn a bit more about bikes? I don't think I've ever contributed anything useful in this part of the forum!! ;D But would like to :)

Well if I ever find out mine needs interesting work then I'll let people know and you can all come help/watch! :P

[whizz]

Hi Loops i sent you a pm with my number just give me a ring and il pop over ok ! :)

[Dilldog]

Loops you have pm

[Jacde]

I think Gemma's idea is a great one, I reeeeaaaaalllllllllyyyyyyyy want to take an engine apart and put it back together again, maybe we could find an old classic and restore it and it could become our mascot? :)

[Loops]

Well whizz has just been by and reckons the CG will need the engine rebuilding soon, although it's currently not terminal (but will become so!)

So once I've either got myself a second bike or a spare engine, I'll have an engine in need or a rebuild and I want to learn myself!

[470four]

Well whizz has just been by and reckons the CG will need the engine rebuilding soon, although it's currently not terminal (but will become so!)

So once I've either got myself a second bike or a spare engine, I'll have an engine in need or a rebuild and I want to learn myself!

Buy good engine (like £25 on ebay, or £40 a pair :D) swap with yours so the bike is straight back on the road - strip, service and rebuild your old mota.

Sorted. :)

[Loops]

If anyone can help me find a good one - I don't trust my own skills in selecting a good condition engine!

But you're quite right, that is the thing to do.

But also this is a good excuse to buy the second, bigger bike that my mum thinks I don't need ;)

[470four]

If anyone can help me find a good one - I don't trust my own skills in selecting a good condition engine!

But you're quite right, that is the thing to do.

But also this is a good excuse to buy the second, bigger bike that my mum thinks I don't need ;)

Pick the engine up and shake it, any rattles means its a bad 'un :D

[simongpz]

the cg125 engine is a very basic engine and very easy to fix i had a cuple of cg125s when i learnt to ride and thay are a very reliable engine even with high milage and thay are a very rattley engine due to the design of engine push rods rather than cam chain like on never bikes
but if the engine is beond repare thay made so many of them over the years it will be very easy to find a replacement second hand engine
it not unheard of for a cg 125 engine to go round the clock atleast once without brakeing down
thay may sound rattlely but thay keep going

[Jon_W]

The CG engine is a pretty simple unit and ideal as a first engine strip.

Ref a new engine, there should be plenty of old CG's around. Look for crash bikes as well. You can take what you want and flog the remainder.

[Loops]

Thanks guys making me feel better - even if Stanley is thumping like a good 'un. Hey, at least people can hear me coming, especially combined with the old school 'proper' exhaust, not one of these wimpy moped style ones ;)

[Cemorah]

Try Forest Breakers at lydney 07854432806 Chris seems a straight guy just bought an engine for an SRX on the basis he would take it back if it was no good. I am sure some kind soul on this forum could pick it up for you.