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Honda rotavator; totally flummoxed!!!

RekusuRekusu Posts: 125
in Tools and techniques
What ho one and all,

I have a Honda FG110 rotavator with a GX25 engine that will not start.  I have tried everything and am totally flummoxed.

Replaced carb parts with a repair kit
Replaced complete carb (albeit with a Chinese one!!)
Replaced ignition coil
Replaced spark plug
Checked for spark at spark plug
Removed top cover to check that timing mark is at TDC
Checked that timing marks (crankshaft and valves) line up correctly
Checked the clutch key (it is moulded into the flywheel so not replaceable but it is not damaged)
Checked spark plug and ignition magnet gap and reset
Tried with both new fuel and Aspen fuel
Checked the exhaust is not blocked

It seems to be 'trying' to start which leads me to think the timing is not correct but all the timing marks line up.

Throw it away or take to a stealer for an expensive fix are not really on the cards.  What is next? 

Any suggestions will be gratefully taken on board.



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Posts

  • rachelQrtJHBjbrachelQrtJHBjb Posts: 819
    Have you checked to see if a stone or some other object is jamming the blades?
  • RekusuRekusu Posts: 125
    While I appreciate your suggestion, do you really think that having given a list of all the things I have done to attempt to make it start, I would not have found a stone.  A stone in the blades will stall it, but as the tines are clutch controlled, the engine will run with a stone jamming, but will not rotate.  That is not the problem, it will not start at all.
  • FireFire Posts: 19,096
    Check every video on Youtube for that model if you have not before. Then call a mechanic
  • raisingirlraisingirl Posts: 7,093
    Mine (not the same model though) had a slightly perished seal that was letting air into the fuel line so it would sput sput die. sput sput die. Is it getting that far?
    Gardening on the edge of Exmoor, in Devon

    “It's still magic even if you know how it's done.” 
  • steephillsteephill Posts: 2,841
    Have you tested compression?
  • DovefromaboveDovefromabove Posts: 88,147
    Oh dear ... is this the one you bought in 2016 .... 
    https://forum.gardenersworld.com/discussion/987334/honda-mini-tiller#latest  :'(


    Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.





  • KT53KT53 Posts: 9,016
    Rekusu said:
    While I appreciate your suggestion, do you really think that having given a list of all the things I have done to attempt to make it start, I would not have found a stone.  A stone in the blades will stall it, but as the tines are clutch controlled, the engine will run with a stone jamming, but will not rotate.  That is not the problem, it will not start at all.

    Rather an unfriendly response to somebody who was trying to be helpful and suggest possible issues you hadn't listed.  As you would appear to know you have checked everything why bother asking?
  • BobTheGardenerBobTheGardener Posts: 11,385
    All generic advice from running motorcycles as I'm not familiar with that model:  If not already done, it would be worth checking you actually have decent fuel flow through the pipe which feeds the carb., by physically disconnecting it.  If flow is strong, then check compression in case of damaged piston or valves.  If you have already tried those things and still think it is a timing issue, try advancing or retarding the timing by a few degrees as a test.  Do the coils come complete with spark plug cap and lead integrated?  If not, try replacing them - modern ones are carbon-cored to suppress interference and that carbon can (and does) break-down sometimes (a visible spark from an unplugged spark plug doesn't prove it will spark under compression.)
    A trowel in the hand is worth a thousand lost under a bush.
  • RekusuRekusu Posts: 125
    I have not done a compression test as I don't have that sort of equipment;  however, I have had my finger over both the spark plug and exhaust ports and there is certainly compression.  Is it the correct amount?

    Agreed regarding advancing and/or retarding the ignition but to the best of my knowledge and research, the GX25 does not have this facility.  If the timing marks on the camshaft and crankshaft are in the correct position, that all should be good.  And they are.

    Coil has been replaced and gap checked.

    There is don't think there is a split in either of the two fuel lines.  There is only one item that I have not changed as I have not been able to find one; namely the gasket that sits between the carb and engine.

    Fuel is a possible issue and a neighbour offered his can of Apsen (ethanol free fuel) to try. After priming the carb, and five mins of pulling, still nothing.  Of course, the Aspen fuel may not have been getting through as any residual regular fuel probably would have clogged the carb jets.

    No intention to causes any upset but a stone between the tines causes the blades to stop rotating  but the engine continues to run.  Basically, the clutch is doing its job.  My problem is that the machine will not start at all. 

    All I know is it is not rocket science but I don't know where to look next.
  • BobTheGardenerBobTheGardener Posts: 11,385
    "There is only one item that I have not changed as I have not been able to find one; namely the gasket that sits between the carb and engine."
    Any air getting in there will cause the symptoms you describe as it will bypass the carburettor and make the engine run very lean, so that is a good area to look at.  In the past, I have used the old gasket as a template to cut a new one out of cardboard and then soaked it in oil as a temporary replacement.  You could also try a tube of 'instant gasket' or similar instead/as well (use sparingly!)  However, if it's that, it should start when the choke is on, but will then cut-out as the choke is opened (this often happens automatically when the throttle is opened.)
    A trowel in the hand is worth a thousand lost under a bush.
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