Honda GXH50 - engine cutting out on hills

Discussion in '4-Stroke Engines' started by Irish John, Jun 3, 2011.

  1. Irish John

    Irish John Guest

    Can anyone tell me why my Honda GXH50 with a HuaSheng carby might be cutting out when going up steep hills? I've had problems with this carby and have cleaned it just recently and it runs perfectly on the level but when going uphill it dies out altogether after about 250 metres on a slope. The Honda is one of the newer ones with the oil cut off thing under the motor but I've had several of those engines and it has never been a problem on any hills.
    Any help gratefully received. Pic of engine set-up attached.
     

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  2. darwin

    darwin Well-Known Member

    My 1st place to look is fuel not getting to the carb when the bike is angled and why that is. Pickup tube in the tank, make sure the float has free and full travel ie......is the gas level above the carb when going up the hill so gravity can do its job? OK saw your pic the tank is high so thats not it. Is there a restriction on fuel flow? Petcock, filter or hose kinking? Those are great lil carbs once you get it figured out. Did you run a wire thru ALL the openings in the carb to make sure any debris is removed..................just ideas.
     
    Last edited: Jun 3, 2011
  3. darwin

    darwin Well-Known Member

    Is your filter designed for gravity fed carbs? Some are only good for diaphram carbs.
     
  4. Irish John

    Irish John Guest

    Thanks Darwin. It's almost certainly not fuel blockage but the filter is a possibility although I can't see that being the case as it is a normal filter and tilting has no affect on it. I have wired out the carby but I'll take it apart tomorrow and blast air through the fuel line into the carb. It has to be the carb I reckon. I think it might the float bowl setting and the needle. The needle might be sticking so I'll polish that with Brasso metal polish.
    IT's a quandry alright. Added to that I had a dud spark plug which was new and was misfiring intermittently so it was like a carb malfunction but that is fixed now. I might put another carb on it if tomorrow is a failure and see how that affects it. If it still cuts out I reckon it might be the low oil cut-off switch being over sensitive. I suppose I could disconnect that or overfill the oil to stop it.
    Also that bike has blown 2 brand new thornproof tubes with slime in last 48 hours which has cost me $$18 in slime and about $40 in tubes. Must be a spoke sticking through although it could well be a bad batch of rubber tubes with low quality control. I'll buy another slimed tube and a roll of rim tape. It's expensive but the bike must be totally reliable.
     
  5. RdKryton

    RdKryton Active Member

    I agree with the float bowl setting!
    You may have to raise the fuel level in the carb a little bit. The level may be set too low now and when you get on a hill there is not enough fuel in the bowl to operate correctly. Don't go too high or you will create a whole new set of problems.
    Also if it is the low oil shutoff being overly sensitive do NOT over fill to compensate. Too much oil will cause the oil to foam up because it is being hit by other parts of the rotating assembly. Once it foams up it looses some of it's ability to draw heat out of the engine. This is very bad especially on an air cooled engine. You are better off just disconnecting the low oil sensor and just keep a close eye on the oil level. I had this explained to me by a small engine expert. I never would have believed that more oil could be bad but it is very bad for these engines. Go figure...
    Try the disconnecting low oil shut off first because it is the easiest to try.
    Good luck.

    Jim
     
  6. Irish John

    Irish John Guest

    Thanks Jim, I'll not try overfilling with oil. thanks for warning me.
    I'll put a good carby on the bike and see if that fixes it. If it works OK I'll know it's the needle & float almost certainly.
    I have never had any problem with slight tilting affecting the low-oil cut off switch. Going uphill is only a slight tilt really - not more than about 25 degrees on the steepest hill - it wasn't ever a problem on the ten or so Hondas I've built.
    Methinks it's the carby because I've had trouble with that carby over the years - ever since it got a dirty load of fuel through it but it has been cleaned twice since then. The engine cut out is instant though so that makes one think it could be electrical and hence the oil switch.
     
  7. Irish John

    Irish John Guest

    Just changed carbies and both work OK. The engine still cuts out on the problem bike even with the perfect carby installed so I have deduced, by elimination, that it must be the oil cut-off switch. Not sure how to disconnect that but I dear say I'll work it out. So I still haven't got that bike working properly yet!
     
  8. Irish John

    Irish John Guest

    I'm wondering how to disconnect the low-oil cut-offswitch. I've got a new Honda on the bench all set up to go just by itself and when I start it up and tilt it it is OK and doesn't cut-off even at 45 degrees tilt.
    Under the base of the motor is a huge plug thing that actually goes inside the motor and is what measures the oil level. It has to stay in place because otherwise all the oil would fall out. It has a green earth wire attached to the engine casing at the plug and another yellow wire that goes up to the on\off switch. I reckon to disconnect the oil sensor switch I would need to cut this wire but that would probably cause the motor to cut off altogether. Has anyone ever done this? I'll do a search and see but I think all the Hondas on this Forum came from Small Engine Warehouse and those are just the engine itself in the raw & don't have all the extra clutter on them.
     
  9. Irish John

    Irish John Guest

    I have solved the disconnection of the oil sensor - it is a really simple thing to do and I'll post a thread later with pics showing exactly how it's done. Meanwhile will my bike still cut out on hills. That remains to be seen. Just checked and the problem was indeed the oil sensor - problem now fixed. Case closed.
     
    Last edited by a moderator: Jun 6, 2011
  10. rustycase

    rustycase Banned

    Good!
    One less thing!
    rc
     
  11. RdKryton

    RdKryton Active Member

    Glad to hear it!
    Have fun now and enjoy the ride!

    Jim
     
  12. Irish John

    Irish John Guest

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