I have a Mountfield lawnmower with a Honda GCV135 engine. I tried to use it
the other day and although it started immediately it wouldn't run at a
constant speed. It slowed to a stutter and then speeded up then slowed down
and so on.
There is a linkage between the carburettor and a spindle projecting out of
the engine casing. This is oscillating backwards and forwards. I know what
it's connected to at the carburettor end but have no idea what the spindle
is connected to inside the engine.
Please can anyone suggest what might be going on?
I've done the obvious things like renewing the spark plug, cleaning the air
filter, checking for fuel line blockages. Next on the list is to strip down
the carb. but I thought I'd post here first.
TIA, Nick.

Nick no_bother@all wrote:
I have a Mountfield lawnmower with a Honda GCV135 engine. I tried to use it
the other day and although it started immediately it wouldn't run at a
constant speed. It slowed to a stutter and then speeded up then slowed down
and so on.
There is a linkage between the carburettor and a spindle projecting out of
the engine casing. This is oscillating backwards and forwards. I know what
it's connected to at the carburettor end but have no idea what the spindle
is connected to inside the engine.

That's the speed regulator, there's a flap inside the cowling which
gets pushed by the flow of air as the engine speeds up, this closes
the throttle and (if it's all working correctly) should prevent the
engine from over-revving.


Please can anyone suggest what might be going on?
I've done the obvious things like renewing the spark plug, cleaning the air
filter, checking for fuel line blockages. Next on the list is to strip down
the carb. but I thought I'd post here first.

It sounds like fuel starvation, so double check the fuel lines first,
then I think your next move is probably what you said, there may be a
blocked jet in the carburretor.

It may also be worth cleaning out all the accumulated grass and gunk
that's in with the regulator flap too.

--
Chris Green

wrote in message ...
Nick no_bother@all wrote:
I have a Mountfield lawnmower with a Honda GCV135 engine. I tried to use
it
the other day and although it started immediately it wouldn't run at a
constant speed. It slowed to a stutter and then speeded up then slowed
down
and so on.
There is a linkage between the carburettor and a spindle projecting out
of
the engine casing. This is oscillating backwards and forwards. I know
what
it's connected to at the carburettor end but have no idea what the
spindle
is connected to inside the engine.

That's the speed regulator, there's a flap inside the cowling which
gets pushed by the flow of air as the engine speeds up, this closes
the throttle and (if it's all working correctly) should prevent the
engine from over-revving.


Please can anyone suggest what might be going on?
I've done the obvious things like renewing the spark plug, cleaning the
air
filter, checking for fuel line blockages. Next on the list is to strip
down
the carb. but I thought I'd post here first.

It sounds like fuel starvation, so double check the fuel lines first,
then I think your next move is probably what you said, there may be a
blocked jet in the carburretor.

It may also be worth cleaning out all the accumulated grass and gunk
that's in with the regulator flap too.

--
Chris Green

Thanks for that. Please can you give me a clue as to where the regulator
flap is?
I heve removed the petrol tank which exposes the magneto and a 'fan'. Is it
somewhere in this area?
Nick.

wrote:
Nick no_bother@all wrote:

I have a Mountfield lawnmower with a Honda GCV135 engine. I tried to use it
the other day and although it started immediately it wouldn't run at a
constant speed. It slowed to a stutter and then speeded up then slowed down
and so on.
There is a linkage between the carburettor and a spindle projecting out of
the engine casing. This is oscillating backwards and forwards. I know what
it's connected to at the carburettor end but have no idea what the spindle
is connected to inside the engine.


That's the speed regulator, there's a flap inside the cowling which
gets pushed by the flow of air as the engine speeds up, this closes
the throttle and (if it's all working correctly) should prevent the
engine from over-revving.



Please can anyone suggest what might be going on?
I've done the obvious things like renewing the spark plug, cleaning the air
filter, checking for fuel line blockages. Next on the list is to strip down
the carb. but I thought I'd post here first.


It sounds like fuel starvation, so double check the fuel lines first,
then I think your next move is probably what you said, there may be a
blocked jet in the carburretor.

It may also be worth cleaning out all the accumulated grass and gunk
that's in with the regulator flap too.

I agree entirely with usenet's statement.

Also, the fuel pick up in the petrol tank has a mesh filter which tends
to block.

In message , Nick
writes
I have a Mountfield lawnmower with a Honda GCV135 engine. I tried to use it
the other day and although it started immediately it wouldn't run at a
constant speed. It slowed to a stutter and then speeded up then slowed down
and so on.

Mine (with a Briggs a Stratton) will do this after it's been running a
couple of minutes, if the fuel tank has been filled right up; if I
unscrew the petrol cap it's all OK again, so I guess it's due to a
vacuum in the tank.


--
bof at bof dot me dot uk

bof wrote:

In message , Nick
writes

I have a Mountfield lawnmower with a Honda GCV135 engine. I tried to
use it
the other day and although it started immediately it wouldn't run at a
constant speed. It slowed to a stutter and then speeded up then
slowed down
and so on.


Mine (with a Briggs a Stratton) will do this after it's been running a
couple of minutes, if the fuel tank has been filled right up; if I
unscrew the petrol cap it's all OK again, so I guess it's due to a
vacuum in the tank.


Supposed to be a pinhole in it..

Nick no_bother@all wrote:

wrote in message ...
Nick no_bother@all wrote:
I have a Mountfield lawnmower with a Honda GCV135 engine. I tried to use
it
the other day and although it started immediately it wouldn't run at a
constant speed. It slowed to a stutter and then speeded up then slowed
down
and so on.
There is a linkage between the carburettor and a spindle projecting out
of
the engine casing. This is oscillating backwards and forwards. I know
what
it's connected to at the carburettor end but have no idea what the
spindle
is connected to inside the engine.

This is it (the speed regulator that is).


That's the speed regulator, there's a flap inside the cowling which
gets pushed by the flow of air as the engine speeds up, this closes
the throttle and (if it's all working correctly) should prevent the
engine from over-revving.


Please can anyone suggest what might be going on?
I've done the obvious things like renewing the spark plug, cleaning the
air
filter, checking for fuel line blockages. Next on the list is to strip
down
the carb. but I thought I'd post here first.

It sounds like fuel starvation, so double check the fuel lines first,
then I think your next move is probably what you said, there may be a
blocked jet in the carburretor.

It may also be worth cleaning out all the accumulated grass and gunk
that's in with the regulator flap too.

--
Chris Green

Thanks for that. Please can you give me a clue as to where the regulator
flap is?
I heve removed the petrol tank which exposes the magneto and a 'fan'. Is it
somewhere in this area?

See above, it's whatever is on the other end of the "linkage between
the carburettor and a spindle projecting out of the engine casing.",
the engine end of it will almost certainly have a flap or something
which is 'blown' by the wind from the magneto fins.

--
Chris Green

On Sat, 30 Jul 2005 20:03:42 +0100, The Natural Philosopher wrote:

It slowed to a stutter and then speeded up then slowed down
and so on.

Mine (with a Briggs a Stratton) will do this after it's been
running a couple of minutes, if the fuel tank has been filled right
up; if I unscrew the petrol cap it's all OK again, so I guess it's
due to a vacuum in the tank.

My B&S developed a similar fault last year, took the tank/carb off to
look for gunge, nothing significant found and it worked fine after
assembly. This year it started doing it again, dismantled again,
noticed that one of the flap valves formed by the thin "rubber" gasket
between the carb and the tank was tucked into the hole it was supposed
to cover and was a little frayed on the edge. On assembly I made sure
that the gasket was positioned so that this flap covered the hole as
much as it could. Works fine now, might be better than it was as well.

These small engines are simple but very cunningly engineered. That
simple gasket together with channels and cavities on both sides and
one spring form the fuel pump, "float" chamber and required valves.
Drive for the pump comes from the vacum in the carb acting against the
spring.

--
Cheers
Dave. pam is missing e-mail