Zeel Static Angle Change and Findings - PCDIS-02T/A02T

[Jcary85]

Hey All,
I've been doing some testing on static angle changes and wanted to share my findings. The hypothetical concern after discussions with various people is that with a 56 degree static angle, there is a good bit of crank rotation between the trigger and ignition event during which time crank speed could theoretically change and cause fluctuations in actual timing. To counteract this, I wanted to change the static angle to something closer to max timing (in my case, 32). I originally intended to do this by moving the pickup location in the front cover, but with a 760 flywheel, it would end up almost hitting the bendix. So here's what i did instead...

The "lumps" on a 760 flywheel are quite big. There is a + and - signal read with these lumps. The + signal happens when the lump first passes the pickup and this is what defines the static angle. The - signal is what happens when the end of the lump passes the pickup. In +/- trigger mode, the zeel uses the + signal over 500-ish RPM. At starting/low speed, it will use the - signal to trigger timing. I calculated this at around 14 degreed. So, in +/- mode you end up with about 14 degrees timing when starting. In addition to reducing static angle, I also wanted to run lower timing during starting. So, I ground exactly 20 degrees out of each lobe and then ran + only trigger mode. I set my static angle to 36 degrees and set my startup timing in the map to around 10 degrees. I confirmed the timing is spot on with a timing light.

I've only run this setup once so far, but it seems to start a little easier and the power feels very smooth. Unfortunately, it wasn't a pure back-to-back test, but anecdotally it feels better and I can't see how it would be any worse.

I'll be doing more testing but thought this info could be valuable to someone....

P.S. - this testing was done on an XS1200 with a GP800 front cover (chopped up).

-Jordan

 

[Jcary85]

Flywheel

 

[Jcary85]

Also, Borut confirmed that you only need a 1 degree difference between static angle and max timing. e.g., you can run 32 max timing with a 33 static angle.

 

[joeschuit]

Although I didn't change the static timing, I also changed to + only mode and lowered the 0-500 cranking to 10 degrees. I would like to put an amp meter on the starting system and see how much easier it is to crank. By sound/feel alone it seems better.

 

[Storbeck]

My understanding is that in +/- mode it uses the - signal for timing at rpm below your lowest rpm point programed in, or at least that was how it worked with the pcdis-1 when I was asking Borut about this.

Interesting stuff though.

Now stick a sensor on the gear teath of the starter ring gear and watch it with an oscilliscope so you can see how much variation in speed there is throughout the stroke.

Probably more of a factor in motors that have big compression, power, and reciprocating mass (a 1200) and or relatively lightweight flywheel/crankshafts.

 

[joeschuit]

I believe you're right. I could accomplish the same thing by just setting the first point to an rpm below cranking speed. Reading the manual again states:

When "[+] and [-] signal" is checked, then both signals are detected. Revs of first ignition point define switching point between, programmed ignition map and idle running timing position. - Ignition timing is defined with trailing edge of trigger bar, at revs lower then first ignition point (idle advance...se drawing above). - Ignition timing is defined with programmed map, at revs higher then first ignition point. Example: if first ignition point is programmed at 1500rpm, then below 1500rpm, ignition timing is defined with trailing edge of trigger bar (idle advance...se drawing above) and above 1500rmp, ignition timing is defined by programmed ignition map.

 

[Jcary85]

Yup you are both correct. Sorry I misrepresented the Manual a bit. The low speed timing thing was just a little “while I was in there” adjustment.

 

[Storbeck]

For sure the thing about reducing static angle to reduce error due to variation in crank speed is interesting. Especially because the error probably changes with load.

 

[waxhead]

If you really want to be tricky you could put in an extra pickup and run a 2 channel ignition system

 

[beerdart]

Spread sheet for static angle.

Dropbox

www.dropbox.com

 

[Jcary85]

If you really want to be tricky you could put in an extra pickup and run a 2 channel ignition system

I was planning to. I have that box sitting around. I’m not convinced it will make any difference. Also, I’d have to change to a different trigger lobe setup. I was going to make a dual pickup front cover then realized it’s not really possible with the 760 flywheel. The second pickup would be in the sealing area of front cover and case up near the wiring exit. I played with rear mount setup but the pickup size is an issue. I’d prefer a hall trigger and i know borut can make one but if I’m going through all that I’ve got better ideas for a totally different ignition utilizing “smart” TTL level triggered coils.

 

[waxhead]

The issue of high static angle is a problem when you have one lump per flywheel. I have spoken to Borut a lot about this. It’s not an issue with a two lump. As it’s picking up a speed reference every 180 degrees not every 360:

 

[Jcary85]

The issue of high static angle is a problem when you have one lump per flywheel. I have spoken to Borut a lot about this. It’s not an issue with a two lump. As it’s picking up a speed reference every 180 degrees not every 360:

Ya I honestly am not sold this static angle change was necessary at all. It definitely can’t hurt and was an easy change though.

 

[Storbeck]

I still think it would be cool if somebody made an aluminum lightweight total loss flywheel that uses a 760 pickup and fits under a 62t mag cover.