classic motorcycle forum

Motorcycle Discussions => Japanese Bikes => Topic started by: bob99 on July 08, 2007, 12:05:55 AM

Title: 1974 honda cb125s won't run...help!
Post by: bob99 on July 08, 2007, 12:05:55 AM

can any one please help with my non starting cb125s, she's getting a liitle long in the tooth and has stood for severall months...she did run but refused to rev out fully or tickover at slow speed...good spark at plug, and good petrol...
carb problems? have very basic workshop manual with no real help in it!

please help, my right leg is getting very tired from unwanted exercise!
thanks
bob ???

Title: Re: 1974 honda cb125s won't run...help!
Post by: L.A.B. on July 08, 2007, 12:44:21 AM

A bit difficult to say really. If it isn't a coil problem then I would suspect engine wear, probably piston rings, bore or valves? Or worn carb?
The camshaft runs directly in the aluminium head and it wears out the bearing surfaces fairly quickly especially if the engine oil changes are neglected, the cam chain also wears and stretches until there's no more adjustment available. So the engine could be in need of a rebuild?  

Title: Re: 1974 honda cb125s won't run...help!
Post by: bob99 on July 08, 2007, 01:04:40 AM

Thanks for the reply LAB,

the engine was running quite well last summer, not noisy or smokey, the oil has been changed on a fairly regular basis...

looking for a simple solution! ;D

Title: Re: 1974 honda cb125s won't run...help!
Post by: hmmmnz on July 09, 2007, 06:39:08 AM

check that the diaphragm in the carb is ok and not torn (im assuming its a cv type carb)
check the valve clearances (tappet gap)
heres a manual for your bike
http://www.mediafire.com/?20yydledzyw
hope that helps ya :D

Title: Re: 1974 honda cb125s won't run...help!
Post by: L.A.B. on July 10, 2007, 02:33:21 AM

Quote

check that the diaphragm in the carb is ok and not torn (im assuming its a cv type carb)

It should not be a diaphragm carb.

The manual link only goes to a log in page.

Title: Re: 1974 honda cb125s won't run...help!
Post by: Bruce on July 10, 2007, 03:53:50 AM

If it has been stood for some time I would suggest that you change the petrol you may need to clean the carb as well. "Modern" petrol tends to go off

Title: Re: 1974 honda cb125s won't run...help!
Post by: bob99 on July 13, 2007, 02:50:39 PM

Cleaned the carb very thoroughly, changed petrol...she now starts  and ticks over nicely, she splutters a bit when fully opened up on acceleration...any ideas please?



thanks for your help so far dudes!

bob

Title: Re: 1974 honda cb125s won't run...help!
Post by: hmmmnz on July 17, 2007, 03:14:28 PM

Quote

check that the diaphragm in the carb is ok and not torn (im assuming its a cv type carb)
check the valve clearances (tappet gap)
heres a manual for your bike
http://www.mediafire.com/?20yydledzyw
hope that helps ya :D

it works fine for me there is a botton on the left hand side that you have to press after a couple of seconds, also have to have your adblock turned off

Title: Re: 1974 honda cb125s won't run...help!
Post by: L.A.B. on July 17, 2007, 04:48:14 PM

It works fine for me now-without touching anything, but that wasn't the page I was getting before.

Title: Re: 1974 honda cb125s won't run...help!
Post by: bob99 on July 23, 2007, 02:21:00 AM

Thanks for the manual, this will be very helpful :D

will work through the service points and see what happens...

Does any one know where I can get some rubber fork gaiters and a ste of rear shocks for this bike please  ;)

Title: Re: 1974 honda cb125s won't run...help!
Post by: Grizzly on July 23, 2007, 02:46:54 AM

A local bike shop might stock fork gaiters for your bike. If not try M&P Accessories, their catalogue is huge. Sorry havn't got a contact number but they do advertise in CMM, or try an internet search.
Hagon Shocks
www.hagon-shocks.co.uk
Tel 0209 502 6222
Cheers
Grizzly

Title: Re: 1974 honda cb125s won't run...help!
Post by: sprocket on February 17, 2008, 12:03:05 AM

Quote

Thanks for the manual, this will be very helpful :D

will work through the service points and see what happens...

Does any one know where I can get some rubber fork gaiters and a ste of rear shocks for this bike please  ;)

Good place for honda spares.  http://www.davidsilverspares.co.uk/