ignition timing and a math question


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virgilmobile
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ignition timing and a math question

Postby virgilmobile » Tue Sep 27, 2011 3:58 pm



I know I have issues with both the 1100 and 1200 ignition vacuum advance timing.I'm trying to develop a "EASY TEST"method.
Here's the idea....I want to check static timing,mechanical advance function and vacuum advance function.
My thought is to steal a previous post idea using a strobe timing light against the cam sprocket.

The question..The timing for the 1100 calls for 10 degrees with full advance at 38 degrees.Thats at the flywheel.
I 'think' the cam is 1/4 the diameter of the crank so should I mark the timing spots 1/4 the degree marking? eg.2.5 and 9.5 degrees ???



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RoadRogue
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Re: ignition timing and a math question

Postby RoadRogue » Tue Sep 27, 2011 8:37 pm

That doesnt sound quite right to me.
The cams turn at 1/2 crank rpm. If you are using a strobe to check timing it is also running at half crank rpm. the cam will always be in the same place each time the plug fires. Use a degree wheel mounted to either the cam gear or the crank gear, either will give you the same result when the strobe fires. Once you know where TDC on is you can use the degree wheel to mark where the advance timing marks should be for the cylinder on the compression stroke ( usually done for #1 cyl).
Ride safe, Todd
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littlebeaver
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Re: ignition timing and a math question

Postby littlebeaver » Wed Sep 28, 2011 12:40 am

I believe it's 1 1/2 total rise on the stand Virgil, just mark it up that much and try it..

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virgilmobile
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Re: ignition timing and a math question

Postby virgilmobile » Wed Sep 28, 2011 7:51 am

Thanks RoadRogue .That's right,It's obvious that one can over think a problem and forget the KISS theory :D

My head decided to cheat.Here's what I did.

Clamped a piece of cardboard to the crash bar.
Pulled the access caps off,rolled the crank to TDC and marked the cardboard.
Rolled the crank and marked the timing mark,the same with mechanical and vacuum marks.
Each mark on the cardboard matches the factory marks BY THE BOOK.
Hook up the strobe and checked.Electronic timing works,ground the wire(to simulate 4th gear)and the vacuum kicked in.
YEA verified 100%.here's a pix of the setup.Cheap,easy and able to clearly test timing,mechanical advance and vacuum advance.Can be used on the 1000,1100,and 1200.

The whole point of this drill was to verify correct ignition timing variable functions.
It did help find that the vacuum portion on the 1100 did not work and it would not advance further than the mechanical,which was also sticking.
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littlebeaver
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Re: ignition timing and a math question

Postby littlebeaver » Wed Sep 28, 2011 8:55 am

So does it come out to an 1 1/2" on your thingy there?

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virgilmobile
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Re: ignition timing and a math question

Postby virgilmobile » Wed Sep 28, 2011 10:56 am

Dunno..I got distracted with my dog attacking the mosquitoes.It seemed like,no mater where you measure the mark at , it will always be at that specified angle.The distance between the marks get larger the further away you get from the center of the shaft.
That's why I marked the cardboard against the site glass marking.eg T ,F1 , etc. rather than using a protractor for angle marking.

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littlebeaver
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Re: ignition timing and a math question

Postby littlebeaver » Wed Sep 28, 2011 8:20 pm

Virgil, I tested mine tonight and the advance would rise to about once inch from the t-1 setting's on the pulley..I couldn't get it to the 1- 1/2 mark so I'm not sure if the mark is accurate, if someone else gets just 1 inch rise it's probably good there..After the belt change and belt proper tension adjustment, and a valve adjustment my bike is really for another trip to KC.. It runs and sound's really good... :D We really need other guys to test it this way and report their findings to come up with a common denominator....WingAdmin, have you tried this yet?

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virgilmobile
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Re: ignition timing and a math question

Postby virgilmobile » Thu Sep 29, 2011 7:39 am

littlebeaver,

I haven't done this on the 1100 like yours,but consider that the timing system is different than the 1200.

The 1100 uses a mechanical advance mechanism that advances the timing proportional to engine RPM.((The 1200 is electronic in 1-3 gears.4th and 5th are electronic and vacuum.))

Then to add to it.it uses a vacuum unit to further advance the timing.

So in testing,you should first disconnect the vacuum line and rev the engine to see the advancing change(from 10 to about 20 degrees).Then hook up the vacuum,rev it again , it should advance even further(up to 38 degrees).

I guess that the measurement is not as critical for a "look see" as that it is actually advancing the timing.

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littlebeaver
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Re: ignition timing and a math question

Postby littlebeaver » Thu Sep 29, 2011 1:32 pm

Ok, everything checks good then... thanks

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virgilmobile
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Re: ignition timing and a math question

Postby virgilmobile » Thu Sep 29, 2011 3:33 pm

Wonderful.Without proper timing throughout the throttle demand,peak horsepower will not match the factory power curve.

It may fall flat in one rpm range that requires a different timing mark than just broken and stuck at the default idle timing.
It's a anal thing that ensures a clean continuous power curve.Some just don't care as long as it runs.I just want mine to run at its best.

Does it really make a difference? Well its just one part in a lot of little things that make the difference between OK :) and I LIKE IT :D




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