860GT ignition timing

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rjk40
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860GT ignition timing

Post by rjk40 » Mon Sep 17, 2018 8:38 am

Gentlemen,

Please forgive me if I am re-stating the obvious:

The original 860GT ignition is crankshaft-triggered to a stationary pickup, unlike a typical cam-triggered engine, where the camshaft drives the distributor, thus gets a trigger on every rotation of the crankshaft, whereas the cam-triggered engine only gets one trigger for every two rotation of the crankshaft.

Crank-triggered engines will get a spark pulse on the exhaust cycle in addition to the "working" pulse on the compression stroke, not that unusual an occurrence in motorcycle engines.

As I have installed a Sachse ignition to replace the defunct OEM unit, I am assuming that the Sachse will perform the same way, unless it has a "divide-by-two" counter in it, which would make it necessary to find the place where all the camshaft dots on both cylinders are aligned.

Am I mistaken in my understanding of the second spark on my 860GT engine?

Thanks in advance.

Regards,
Richard

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BevHevSteve
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Re: 860GT ignition timing

Post by BevHevSteve » Mon Sep 17, 2018 8:59 am

What does it say to do in the instructions from the manufacturer?
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rjk40
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Re: 860GT ignition timing

Post by rjk40 » Mon Sep 17, 2018 12:14 pm

Hi Steve,

The instructions make no distinction about any initial adjustment beyond the initial static placement, with no reference to what stroke (compression/exhaust) must be used, nor if all of the cam gear dots must be pointing at each other. No way to know if these instructions are, like a previous posting, showing the cylinder wiring reversed, or if they have been corrected. I shall know when I kick it for the first time.


My original question at the bottom of my post remains to be answered.

1funduc
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Re: 860GT ignition timing

Post by 1funduc » Tue Nov 27, 2018 7:27 pm

I am quite certain the Sachse ignition is also a "wasted spark" as it fires with every revolution of the crank. It is a very good unit but be sure to upgrade your voltage regulator as well. The Sachse does not like voltage spikes and a 40 year old regulator will probably fry the Sachse.

rjk40
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Joined: Thu Dec 05, 2013 10:54 am
Location: Malabar, Florida

Re: 860GT ignition timing

Post by rjk40 » Wed Nov 28, 2018 6:37 am

Thanks for the info.

And yes indeed, I have gotten a new regulator from Steve, a "Rick's Regulator", which should cover the caviat you mentioned.
And thanks for that piece of info.

Regards,
Richard

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