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Thread: 912 stops while doing a spiral d sent

  1. #11

    912 stops while doing a spiral d sent

    Is the higher pressure fuel pump flooding the carb?

    The highest pressure is just above tickover I find

  2. #12
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    912 stops while doing a spiral d sent

    Henry Long wrote: Is the higher pressure fuel pump flooding the carb?
    +1 for Henry, have the same carbs and pump, will try it if I can...

  3. #13

    912 stops while doing a spiral d sent

    G should still act vertically in relation to the trike unit in a steady spiral descent. Only time there is a 'lean' felt is during a sideslip - which a trike can only do momentarily, or when holding in sideways bar pressure which puts the trike slightly out of of plane to the G.

    But the increase in G may be bringing two somethings into contact with each other and shorting the ignition circuits? Maybe something silly like the ignition wires trapped between the seat moulding and the seat frame?

    Paul

  4. #14
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    912 stops while doing a spiral d sent

    How much fuel have you onboard? With around 15Liters your quite likely to uncover the fuel pickup in a spiral dive. Unless your diving for an extended time then you would probably get away with it I would have thought.

  5. #15
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    912 stops while doing a spiral d sent

    Does the Quantum have the anti-icing gubbins fitted? Kev Mallin had cutting out because in a long descent the temps dropped enough to reduce the heat going into the carbs, he cured that by adding two thermostats, both oil (shorter warmup) and one in the radiator for the carbs.

    On the ground the ide melts, only way to detect it is to see if the carb bodies are wet

    Cheers

    Kev

  6. #16

    912 stops while doing a spiral d sent

    Kev Armstrong wrote: Does the Quantum have the anti-icing gubbins fitted? Kev Mallin had cutting out because in a long descent the temps dropped enough to reduce the heat going into the carbs, he cured that by adding two thermostats, both oil (shorter warmup) and one in the radiator for the carbs.

    On the ground the ide melts, only way to detect it is to see if the carb bodies are wet

    Cheers

    Kev
    Hi.
    have de ice on both carbs ( hot water type) and have flown without no problem so far.

  7. #17
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    912 stops while doing a spiral d sent

    Worth also checking if the carbs can be displaced to the point where they kink any of the supply tubes or if there is a small tear in the carb rubber that appears only if the carb is very much displaced?

    If your Quantum has the anti icing gubbins but you keep above the minimum temperatures for oil and water (P&M neoprene rad shroud) you should not see the carb cooling to icing point, IMV.

  8. #18
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    912 stops while doing a spiral d sent

    Rethink......
    Consider that if you cut fuel to a 912 on tickover provided that the carbs are full it takes at least 10-15 seconds often longer for it to stop. It also tells you its going to stop by running increasingly rough until it stops.
    I dont think its fuel if it just stops when you spiral dive unless your very brave and performing the maneuver for a long time..

    Only thing that can stop a 912 dead is loss of power to CDI boxes both at same time - not likely as they are dual live feed
    Grounding cut out (mag) circuit activated both at same time ... possible chafed wires somewhere
    Ground to engine -battery failure which will kill both CDI and stop the coils charging. My guess.... One of the common grounds is poor and you maybe making ground accidentally in non stress and fails under load. Resistance test coil grounds on manifold to trike keel if its any more than a few ohms you have a problem.

    Start with the last one check all grounds especially keel to engine frame
    Check mag switches (not sure on quantum) make sure the teminals havent punctured the rubber cover and grounding to seat frame under stress

    Good luck....

  9. #19

    912 stops while doing a spiral d sent

    Frank Thorne wrote: Rethink......
    Consider that if you cut fuel to a 912 on tickover provided that the carbs are full it takes at least 10-15 seconds often longer for it to stop. It also tells you its going to stop by running increasingly rough until it stops.
    I dont think its fuel if it just stops when you spiral dive unless your very brave and performing the maneuver for a long time..

    Only thing that can stop a 912 dead is loss of power to CDI boxes both at same time - not likely as they are dual live feed
    Grounding cut out (mag) circuit activated both at same time ... possible chafed wires somewhere
    Ground to engine -battery failure which will kill both CDI and stop the coils charging. My guess.... One of the common grounds is poor and you maybe making ground accidentally in non stress and fails under load. Resistance test coil grounds on manifold to trike keel if its any more than a few ohms you have a problem.

    Start with the last one check all grounds especially keel to engine frame
    Check mag switches (not sure on quantum) make sure the teminals havent punctured the rubber cover and grounding to seat frame under stress

    Good luck....
    Hi Frank.
    thanks for the tips, and thanks to all that have given there time.
    i have taken apart all the charging wires to the modules checking for breaks and earthing to something found no faults.
    But i have not checked the earth wires, so next check. Had both mag switches apart and check to see if there earthing out when there should not be ( in the on positions ) no faults. Checked the fuel tank for dirt and changed the fuel filter, the old one looked ok and was only 5 months old.
    carb rubbers removed and checked.
    both top diaphragms removed and checked, no fault
    while on the ground the engine runs well, can start the engine on just one module each at a time,
    so any other ideas, please post.

    Thanks to all..

  10. #20
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    912 stops while doing a spiral d sent

    The likely earth wire is the one from the keel to the engine frame its bolted to the suspension leg support. PM never seem to strip back the powder coat to make a good earth (and others) so its often making the earth via the thread contact of the bolt with the frame. Bolts corrode

    If your trike has the waterproof electrical multi connector make sure its clean and not worked loose its often a cause of problems.

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