Mountfield hp414 problems
- Thread starter zutman
- Start date
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This will be the Chinese 100cc OHV motor I think.....
The problem, so long as you haven't adjusted the governor, will still be in the carburettor, more than likely.
Its only really possible to clean the carb with compressed air and a carb cleaning solvent - the slow running jets on these can't be taken out as they are simply drillings in the carburettor body.
Try running the engine without the air cleaner......does it run slightly better if the choke is half on?
John
The problem, so long as you haven't adjusted the governor, will still be in the carburettor, more than likely.
Its only really possible to clean the carb with compressed air and a carb cleaning solvent - the slow running jets on these can't be taken out as they are simply drillings in the carburettor body.
Try running the engine without the air cleaner......does it run slightly better if the choke is half on?
John
Dont have a choke on this one thing i did do when it was runnin i took the cover off removed the foam filter and put my thumb over the air intake and the engine ran smooth soon as i removed my thumb the engine started hunting again very strange i checked the gaskets all seem ok
By doing that, you are restricting the air going into the engine, which is drawing more fuel through the (partially) blocked jets.....a call for a compressed air supply, methinks to clear them out.
John
John
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The single jet is called the main jet, and all the fuel passes through this when the engine is running fast.
The other jet above it is called the emulsion tube, and allows the engine to run well between half and full throttle.
There may be a pilot jet in there somewhere.....if you can see a small drilling to the side of the main venturi (air cleaner off) make sure its clear.
Also, drop the float needle out (usually attached to the float) and clear in there too.
John
The other jet above it is called the emulsion tube, and allows the engine to run well between half and full throttle.
There may be a pilot jet in there somewhere.....if you can see a small drilling to the side of the main venturi (air cleaner off) make sure its clear.
Also, drop the float needle out (usually attached to the float) and clear in there too.
John
Thanks john after work i spent anothe 2 hours on it but still the same all is clean as before if i restrict the air intake a bit it runs great one thing i did not say when its hunting or revving the silver bar that connects to the engine block then to a spring then to the carb does move when its hunting if i hold the bar to stop it moving it does run better but you can feel it wanting to keep revving the other end of the silver bar connects to the engine block and there is a black round bar that goes into the engine this moves when you move the silver bar hope you understand that and thanks for trying to help me
Ps i had a reply from mountfield and he told me the petrol cap was too tight but its only loose
Cheers
Ps i had a reply from mountfield and he told me the petrol cap was too tight but its only loose
Cheers
To my simple mind, the fact that when you restrict the air intake the engine improves, still points to a fuelling problem.....
I'm supposing that fuel runs happily from the tank to the carb?
Is the gasket between the carburettor and cylinder head in good condition?
When you hold those rods you mention, you are effectively restricting the governor.....when the engine is starting to conk out the governor opens the throttle - when the engine is at speed the governor closes it again, so that seems to be in order.
Tell me - is the float bowl completely round? Some machines have a sort of step in the bowl, and if this isn't aligned with the float, the float can't drop fully. I'm starting to suspect the fuel level is too low in the float bowl, but this isn't adjustable.
Do you have compressed air to blast the jets out? Notice the main jet should have one horizontal drilling to let fuel into it from the float chamber, and there should be a fibre washer between it and the out side of the float bowl.
Scratching head now!
John
I'm supposing that fuel runs happily from the tank to the carb?
Is the gasket between the carburettor and cylinder head in good condition?
When you hold those rods you mention, you are effectively restricting the governor.....when the engine is starting to conk out the governor opens the throttle - when the engine is at speed the governor closes it again, so that seems to be in order.
Tell me - is the float bowl completely round? Some machines have a sort of step in the bowl, and if this isn't aligned with the float, the float can't drop fully. I'm starting to suspect the fuel level is too low in the float bowl, but this isn't adjustable.
Do you have compressed air to blast the jets out? Notice the main jet should have one horizontal drilling to let fuel into it from the float chamber, and there should be a fibre washer between it and the out side of the float bowl.
Scratching head now!
John
The bowl is not totaly round it steps down and ther are two bolts one i think is to empty the carb and the other removes the bowl i have blown out with compresed air from a can which i use at work to blow out gas jets petrol flows great from the tank i know what you are saying aboutnthe float i will check in mornin but it must have been ok when the problem ive never had it off before
I unscrewed the main jet and the other jet falls out i have blown these out i just cant get my head round it all the gaskets are fine can the governor go faulty ? Only other thing i can do is take to mountfield service dept trouble is i can buy a new one for 140 quid, i feel it must be something simple
Pain in the ass
I unscrewed the main jet and the other jet falls out i have blown these out i just cant get my head round it all the gaskets are fine can the governor go faulty ? Only other thing i can do is take to mountfield service dept trouble is i can buy a new one for 140 quid, i feel it must be something simple
Pain in the ass
You are correct regarding the 2 bolts on the float bowl - one secures it, the other is a drain.
Check something for me? The bolt that holds the float bowl on, screws into an alloy stalk - if you like - that also holds the two jets.
Is there a hole at the bottom of this stalk, that could possibly be blocked by the float bowl bolt as it screws in?
Mind you, if this wasn't tampered with before this event, there's no reason to suspect that.
I don't suspect the governor - its simply a centrifugal thing inside the engine driven by the camshaft and if it fails, the engine revs out on full bore.
John
Check something for me? The bolt that holds the float bowl on, screws into an alloy stalk - if you like - that also holds the two jets.
Is there a hole at the bottom of this stalk, that could possibly be blocked by the float bowl bolt as it screws in?
Mind you, if this wasn't tampered with before this event, there's no reason to suspect that.
I don't suspect the governor - its simply a centrifugal thing inside the engine driven by the camshaft and if it fails, the engine revs out on full bore.
John
Yes, the symptoms are of a partial blockage somewhere.
I use a proper carb cleaner aerosol, toluene based, which has a thin polythene nozzle - great for getting into passages unseen. I flood the passages from both directions, and then blow them out....mind you, my compressor can deliver 120 psi @ 14 cfm so its a wee bit better than an aerosol can!
Good luck with it - but at the end of the day a visit to a garden machine repair shop could be a good move if you don't get anywhere.
John
I use a proper carb cleaner aerosol, toluene based, which has a thin polythene nozzle - great for getting into passages unseen. I flood the passages from both directions, and then blow them out....mind you, my compressor can deliver 120 psi @ 14 cfm so its a wee bit better than an aerosol can!
Good luck with it - but at the end of the day a visit to a garden machine repair shop could be a good move if you don't get anywhere.
John
He he he i went to our local mower man in the town he said i have never seen that model before sorry cant help you cant tell you what i said, anyhow have just taken all apart again and while it was runin i adjusted the black screw on the carb and it does seem better, i have also changed the oil as well for good luck it is still hunting but only a bit because the black screw stops the throttle going all thenway back, you should open a mower repair place
Thanks pete
Thanks pete
hi sorry to jump in but i got a mountfirld with a lc40 engine hunting, it keeps running so i can cut the grass but sounds terrible,strangely when its running out of fuel and the engines just using whats in the carb it runs fine for about the last 30secs before it stops.any help please?
I'm not sure what you mean when you say that the engine sounds terrible? Does it chuff black smoke?
No matter.....does this sound like your engine - a Briggs and Stratton Classic?
This means it has a foam air cleaner on the top of the carburettor, and the fuel tank is below the carb - and it has a red primer bulb?
If so, try pressing the primer button slowly when the engine wants to stop...does this help?
If so, the rubber diaphragm / gasket between the carb and the tank is notorious for failure...its part number is 795083.
There are, of course other things that may be wrong!
John
No matter.....does this sound like your engine - a Briggs and Stratton Classic?
This means it has a foam air cleaner on the top of the carburettor, and the fuel tank is below the carb - and it has a red primer bulb?
If so, try pressing the primer button slowly when the engine wants to stop...does this help?
If so, the rubber diaphragm / gasket between the carb and the tank is notorious for failure...its part number is 795083.
There are, of course other things that may be wrong!
John
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