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Need someone with a good ear for pilot tuning

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by Kernel, Aug 5, 2011.

  1. Hi guys,
    I want to get the pilot circuit on my DR650's carburetor tuned after adding an aftermarket extended tool-less adjuster screw. I think can sort of hear a slight difference in the engine as I turn it in but I just don't have a very good ear for it (yes the bike is at full operating temperature when I do this).
    Is anyone with a good ear and touch for doing this willing to do it for me? It's a 2 minute job and I'd like my bike to be dialed in close as possible to the optimum settings.


     
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  2. Set it to standard, raise your idle around 500 rpm (more if need be) or so above standard & turn the needle in until the revs rise, then turn it the other way past standard until the revs rise again, & set exactly halfway between the two.

    You will where this is because you counted the turns both ways.

    Hope that helps.
     
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  3. MV I started to say this last night. Then didn't because somewhere in the back of my mind I think I recall most carbs being more sensitive going one way than the other (sorry - can't remember which) which means it won't be the half way mark.

    I seem to recall leaning it down till it stumbles then backing off a fracton but so long since I have had a single carbied motor I am struggling to recall.

    However I suspect that doing it as you suggest won't be too far out and it won't make a lot of difference.
     
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  4. It does make a difference, bike often stumbles at closed - 1/4 open throttle and even stalls, probably because I've got it tuned WAY wrong...
    I might just take it to the dyno tuners, get it tuned with everything spot on by the professionals. But I might wait until I get the pumper carb on before I do that, else I'll just be throwing money down the sink.
     
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  5. I meant probably wouldn't make a lot of difference between doing it as MV suggested and having it persactly spot on.

    On Sat I suggested pulling a plug and checking whether it looked rich or lean. Did you do that? That will give a hint as to what it needs. I am guessing it is rich
     
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  6. No not yet, but from the way the bike behaves I think it is running rich. I might blip the throttle a bit in neutral and it'll take its time getting back down to idle. Like it'll sit above it for a bit then go back down.
    I will pull the screw out, set it at 2 turns out, go for a ride, and see if I can find the sweet spot. And I might check my plugs just to see if they're fouled. I need a can of compressed air though to blast the crap out of around my plugs.
     
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  7. You don't need air, In fact I suspect air wouldn't do all that much although I have never tried. If your plugs are fouled you can clean them with a magneto file or even a bit of emery paper. Then flush off with metho.

    Or I can lend you the special tool I carry on the BM for just this purpose - a sharpened bobby pin :LOL:

    But try doing as MV said. Just take note of where the screw is first so if all else fails you can put it back to that setting. That is screw it all the way in and count the turns till it bottoms out.
     
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  8. You've got a single. Put your hand loosely over the end of the exhaust as you turn the adjuster.
     
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  9. I hadn't thought of that.
     
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  10. Used to do it on a twin without a cross-over pipe. You can get a pretty good feel for how sweet it is firing.
     
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  11. Not familiar with this technique, what exactly are you feeling for ibast? Not that I can do it on my bikes.
     
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  12. Maybe he means cup my hand over my exhaust to alter the sound to hear the tuning better?
     
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  13. You can feel how well it is firing. You want a nice solid pulse without hint of backfire. It adds an extra dimension to your ear.

    So you get it nice, then bring your idle down, then get it nice again. Repeat until it won't idle any lower, then maybe bring it back up a bit.
     
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  14. Thanks I'll try it on Sat
     
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