Author Topic: Plug chop for dummies?  (Read 9818 times)

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Offline flybox1

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Re: Plug chop for dummies?
« Reply #25 on: January 06, 2016, 07:21:27 AM »
I guess i'm lucky.
Highway 9 is in my backyard and I have a 10 mile stretch with only 3 stoplights...and only 2 miles of it is flat  ;D
As I mentioned above, most riding probably isnt done at WOT, so 'close' main jet is fine.  Plugs just shouldnt be lean/white here.
For the vacuum sync, what type of unit are you using, and has it been calibrated recently?
Vac sync should be done at the lowest possible, non-laborious idle your bike can handle. 
Mine is ~1100rpm, and yes, my gauges show different vacuum across the gauges if the throttle is held open.
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

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Offline flatlander

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Re: Plug chop for dummies?
« Reply #26 on: January 06, 2016, 07:32:57 AM »
Would also love some more input on how else I can determine proper jetting that doesn't require hauling ass at redline down windy, hilly roads for a few miles.  ;D

you can find out where, in your area, there's a shop with a dynamometer (dyno). best would be one that's familiar with our type of bikes and has a good reputation.

you can do runs on the dyno instead of the road and a sniffer in the exhaust measures air/fuel ratio instead of reading plugs. plug chops are cheaper (as long as you don't get a ticket or hit something) but the dyno can save you a lot of time and nerves.
as a side-benefit it can also measure power output on your rear wheel if you're interested.

i've done plug chops and got to fine settings with them, they work. but since i found a good dyno guy who doesn't charge too much, i just go there.

Offline Duanob

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Re: Plug chop for dummies?
« Reply #27 on: January 06, 2016, 09:05:53 AM »
Personally I would just ride it as much as possible for a couple of weeks and then see what your plugs look like. If they are still lean then maybe you have too much air coming into the system? Maybe a vac leak or you need to restrict the intake?
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Offline SamP

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Re: Plug chop for dummies?
« Reply #28 on: January 06, 2016, 12:09:24 PM »
This is my vacuum synch tool. Yes, restrictors are installed. Syncing at about 1000-1100.

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