Honda - 78 CG 125cc running problem

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Sun 13 Dec 2009 21:17
78 CG 125cc running problem - stevecg
Hi i have a problem with a honda cg125 1978 and i wandered if anyone could help me once it has warmed up it misses and back fires, so i have changed the plug it made no difference so i changed the points and set but now when it starts it ticks over really fast i have tried turning the idling screw which makes no difference and i checked the accelerater cable and it is not sticking any ideas would be greatly appreciated

Edited by Pugugly on 13/12/2009 at 22:35

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Mon 14 Dec 2009 00:24
78 CG 125cc running problem - Dynamic Dave
Have you checked for air leaks around the carburettor or exhaust leaks?

Also, have you checked the air/fuel mixture is correct?
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Mon 14 Dec 2009 08:12
78 CG 125cc running problem - craig-pd130
I'd agree, sounds like an air leak in the inlet side ... either a hole / split in the hose from air filter box to carb, or in the carb mounting stub (or a leak at the mounting stub gasket).

Check also the exhaust gasket isn't blown where it mounts on the cylinder head, and that there are no holes in the exhaust. A backfire implies that air is getting in on the exhaust side.

Edited by craig-pd130 on 14/12/2009 at 08:13

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Mon 14 Dec 2009 09:59
78 CG 125cc running problem - mark
Can only agree with what has been said above.

The thick rubber gasket on the inlet mounting stub does harden with age and let air in, this is a typical fault on older Hondas. The alloy studs holding the carb to the inlet can also "loosen off".

Also as I recall the down pipe is seperate from the exhaust so has a joint each end, again check these have the correct intact gaskets in place and that all connections are tight.

Again check the exhaust over for for holes or splits, as the silencer usually rots from the inside out.

Parts for these bikes are plentiful in the breakers as it had a long production run.

As always

Mark
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Mon 14 Dec 2009 19:47
78 CG 125cc running problem - stevecg
I will try these next thank you
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