Accuspark fitting

Discussion in 'Mech Tech' started by Geraint Thomas, May 4, 2019.

  1. .. when the engine is cold...

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    77 Westy likes this.
  2. All I have done is take off the carbs they have been refurbished and I have put them back on and fit new dizzy . Why should I need to adjust the valves ?
     
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  3. First step on service / tune.. unless you're happy there still ok from last time..

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  4. 77 Westy

    77 Westy Supporter

    This^ You’re tuning the engine after changing the distributor and carbs – the first step in a tune-up is the valves, then timing and finally the carbs. If you try to do the carbs first you’ll be doing them again after you’ve adjusted the valves and timing.
     
  5. Sorry to be a pain but I’m well confused now ! How do I adjust the timing when it’s Rev so high after start up ? The valves where set right last year and I have barely been anywhere.
     
  6. 77 Westy

    77 Westy Supporter

    Set the timing to 28 to 30deg BTDC at maximum advance – that will be around 3000 revs.
    EDIT That’s maximum mechanical advance with the vacuum pipe off the carb and blocked (at the carb).
     
  7. Normally you would adjust the carbs last, but as the engine is running fast the carbs need adjusting to slow revs down. Dizzy probably not far off as it starts and runs and your valves were set not long ago.

    You need to get help on how to adjust your carbs.
     
  8. Nope the engine could be doing 5000rpm and you can still set the timing.
    Your just doing it at max mechanical advance instead of idle.
     
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  9. 77 Westy

    77 Westy Supporter

    It is potentially damaging to guess that the timing is not far off, an engine will start and run (and run fast) with far too much ignition advance. Adjust the timing before the carbs.
     
    snotty likes this.
  10. ^this, again. Wrong timing can have a significant effect on RPM.
     
  11. Could the engine be rev high through some other factor ? Like the linkage bar between carbs not sitting properly ! The accelerator pedal seems a lot stiffer know then before

    I have blocked vac at the carb and in the pipe but it still revs fast and won’t idle. Could it be choke problem?
     
    mgbman likes this.
  12. Chokes come back on once left to cool a bit and take 3 mins or so to come off each time.. assume you know chokes need you to rev it once they're warmed up to let the springs take them off the steps inside the choke to let it slow down again... or if you need to slow it down temporarily pull the idle solenoid power supply and it'll drop to 5-600 revs if all else is ok

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  13. Are the accelerator stops going back to touch the carb once chokes are warm? If not something is holding them open... try disconnecting the linkages

    Ours after a rebuild happily went off at 2000rpm with chokes off u till tuned down a bit.... idle volume screw right in maybe half to one turn out to slow it down..



    also the dampener can unscrew and hold the connecting bar open ...



    Sometimes those ICT's look very tempting.... or maybe drla's...

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    mgbman likes this.
  14. same fast running happened on my 1600tp engine after I installed a newly refurbed solex carb and pertronix distributor. I had a throttle linkage problem at the carb and jets out of adjustment. once I slowed it down to more or less correct rpm at idle, I went back and did the valves, timing and final carb adjustment, run great ever since.
     
    Lasty likes this.
  15. 77 Westy

    77 Westy Supporter

    Have you adjusted the timing? Worry about the carbs when that’s done – I hope the engine has a timing scale and you have a strobe timing light?

    The throttle linkage shouldn’t have that clip where the return spring attaches and it could be there isn’t enough free play in the cable. But you need to find out why the throttle is stiffer than before, it obviously shouldn’t be. Do you have the cup and spring in the end of the cross bar, RH side? You’ll never get the carbs right if it’s missing.
     
    snotty likes this.
  16. What was the throttle linkage problem?
     
  17. I don’t want to touch the carbs I’m struggling to sort this out first. I have a strobe light and the timing scale . There is a problem with the accelerator linkage but I don’t know what
     
  18. 77 Westy

    77 Westy Supporter

    I can’t see enough of the throttle cable to see what is wrong but I can see enough to know it’s not right; the spring is correct, the clip isn’t. It might work fine as it is but you should check it - compare what you have with the pic in your manual.

    Disconnect the throttle cable and remove the linkage – don’t lose the spring and cup from the cross bar. If they’re missing you must replace them. Check that each carb opens and closes smoothly; they should if they’ve just been overhauled. Replace the linkage, but not the throttle cable – check that the carbs still open and close properly and at the same time. Make sure the throttle pedal and cable operate smoothly then reconnect the linkage with some slack in the cable. The pedal should open the carbs with little effort and the carbs should spring closed.

    Find the TDC mark on the pulley, you can feel it on the engine side of the V-belt groove with a finger nail – it’s difficult to see. Mark it with a blob of white paint and mark 30deg BTDC on the timing scale. Start the engine and aim the timing gun at the marks, slowly increase the revs and watch what happens. When the ignition stops advancing that’s maximum mechanical advance, don’t worry about the revs but don’t let the engine slow. Keep watching the marks and move the distributor until the marks on the pulley and on the scale line up. Tighten the distributor clamp bolt and rev the engine again to check that maximum advance is still 30deg or slightly less. Reconnect the vacuum hose and you’re done.

    It’s taken me longer to type this than it will take you to do it. But you’ll need three hands or an assistant.

    Then find someone to adjust the carbs if you don’t want to.
     
    Last edited: May 5, 2019
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  19. Hey thanks for that, I understand everything you have mentioned and I will have another go tomorrow to sort it all out . Much appreciated
     
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  20. 77 Westy

    77 Westy Supporter

    Good luck – leave the hammer in the tool box.:)
     
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