Dancing Timing

[Tonerjockey]

Has anybody seen this or am I getting too persnickity?

73 750.

Timing mark on flywheel jumps around at relatively high RPM... say 5000+. Partialy retard, partially advance. Looks like 5 degrees each way. 10 degree swing! Starts out dead calm then at the higher RPM the mark jumps around.

Reground B10 cam. I seem to recall this on the stock cam as well (too much happening to chase it down at that time).

With Dyna III module, distributor pick ups & dual plug coils, I think the right cyl jumps more than the left.
In a seperate stock distributor, with stock dual points and stock Guzzi coils (Packard wire and NGK plug caps) both cylinders dance around beginning at about the same 5000+ RPM. Maybe right more than left... maybe left dances in a tighter RPM band.

Using a different disributor gives me similar symptoms. The distributor springs etc MAY be bad on both though.
I am not sold on the cam moving against the stop (under the cam gear) thus changing the relative position of the distributor drive against its gear. Could be though... maybe a thrust bearing might help ... or at least shim closer.

Could be my Sears Best timing light. I'll try a different one tomorrow. Maybe two timing lights simultainiously might shed more light on the problem (ugh). One on each plug lead? Two lights triggered on same plug wire? hmmmm

Whatcha think? I race this thing WOT and I'm certain that an inconsistant ignition timing is not the way to best HP.

Alex

 

[john zibell]

The two prime suspects I'm aware of for the timing dancing around are worn springs in the distributor, and a timing chain slapping around.

 

[Tonerjockey]

Yo John,

Makes sense.

Using gears narrows it down to springs.

Currently looking for a retard system so I can lock out centrif advance.

Thanks for the note,

Alex

 

[john zibell]

Currently looking for a retard system so I can lock out centrif advance.

Alex

Can you say safety wire? Just pop out the springs and use a couple loops of fine safety wire over the spring mounting posts to prevent the advance from swinging out.

 

[Tonerjockey]

I'll do that today. If the dancing stops I'll see what HP the dyno shows... if the bike starts.

Should be interesting to see how the bike starts with max advance... that and high compression might stress the Valeo starter quite a bit.

Acceleration from idle should be impacted by a set advance. Fortunately I only idle for a very short time, and only accelerate from that low an RPM once per run. After 1st each gear starts after red lining the previous gear.

If its the springs I'll also see what I can do to them to stop the dance and still use some springs.

More later.

Alex

 

[Tonerjockey]

Improvement made!

These are BEFORE pics:

Lube weight pivots (kinda funky).
Tighten spring loops on pins a bit and lube easily.

Now just minor variations in timing at high RPM. I know this isn't perfect but I don't think I can make it better before this weekend.

This weekend is the final SCTA races at El Mirage. If I can come up with a final final fix I'll do it but this is where I am now.

Next configuration:
New CP Pistons
Balance crank, pistons etc
Reinstall dual plug Wyatt heads
Reinstall Norris 382 cam
Reinstall Dyna III system
Look for elect retard so I can remove spring advance in distributor
Install super groovy custom cut 5th gear set.

Next year baby!

Alex

 

[jr1967]

You could replace the bolt and washer in the distributor shaft(where there used to be a little felt pad) for a longer bolt with a large washer and lock it at maximum advance. I believe it is M5.
Then (with the ignition on) crank the engine by hand until it sparks. (Dyna's do this). Make sure this coincides with whatever the maximum advance should be. Once this is set, re-install the original bolt and washer and just forget what the timing does at less than full advance. Does this all make sense?
Let us know how you go!
Cheers, JR

 

[Tonerjockey]

Hey JR,

That would be a good way to set max advance if I could figure out how to determine exactly what the advance is while static.

I like it for locking out the shaft after removing the springs. I'll try that when I get an electronic retarder (isn't that a TV set?).

For now I need to get the spark consistant thoughout the range. Currently the bike won't get past 6000 or so in top gear (4th today). This is where the dancing happens. I am about 10 MPH from the record and the dancing ignition isn't helping me get to top RPM. I think.

I realize there are other factors at work here but best ignition is a must.

No matter, Terry just called and my billet pistons are ready from CP! Man that took a long time and they are expensive but I should get the absolute maximum compression from these. Untill the heads come off.

I'll post results...

Alex

 

[jr1967]

Your bike should reach maximum advance at 3500 rpm or so; I just assumed that below that engine speed it won't matter much for you except for starting the bike. I always wondered if my ignition(I have a DynaIII too with the exact problem as yours) would still wander under load, ie on a dyno. I never tried to use a strobe while on the dyno, maybe you could give it a try sometime and post the results.
The only solution I came up with, is as described before; turn the ignition rotor to full advance, block it, adjust ignition tower to match full advance mark, release ignition rotor and forget about the idle timing and ignition advance curve..... I ride the bike always above 3500 rpm anyway. And yes, it seems that electronic advance ignitions like DMC or ZDG give a very steady image with the strobe. I'll be looking into an ignition from these guys: http://www.ignitech.cz/english/aindex.htm
Fairly cheap compared to others and I read good feedback on several forums.
Good luck, JR

 

[Tonerjockey]

JR

I sent them a note. We'll see what they say.

I think a road trip is in order. Late Spring in Prague.... whhhhhooooeeeeeee!!!!

Alex

 

[Tonerjockey]

Spoke with Jan at Ignitec. Seems either I am not expressing my self in a meaningful way or they are not familiar with Moto Guzzi.

We don't know system on your bike. We are not able to say if it can work with our ignition.
We can offer you all system.
Rotor
Pickup S01T
ignition TCIP4 standard
You can use original coils.
We need to know exact angle of cylinders on rotor to be able offer you rotor.

I might be able to reverse engineer their system enough to make it work for me but I would prefer not to hafta rely on a kludged setup in racing environments if you know what I mean.

Their pick up sensors seem not to be using Hall Effect. Most likely counting passing metal (dunno the right techy talk) and making pulses. Hall Effect closes a circuit I believe.... It creates a circuit when magnet is sensed.

http://www.ignitech.cz/english/aindex.htm

I ask them if I can use my Dyna III sensors (HE style) with their controller.

Thanks for the idea JR!

Alex

 

[Tonerjockey]

An addition to previous post:


Ignitec seems to not know an old V7 Sport ignition and Dyna III ignition. They seem to be focused on modern systems with ECU's etc.

Alex

 

[Tonerjockey]

Letter to Ignitech:

Hi Jan,

Looks like your company is focused on inductive type sensing.

My old Guzzi (1973) used a distributor and dual points sets. I added the Dyna III ignition module. The Dyna III replaces the 2 sets of points with 2 Hall Effect sensors. A collar with a magnet is mounted on the shaft of the distributor. The magnet triggers the Hall Effect sensors and sends a signal (I don’t know if it is +12V or Ground) to the controller. The controller interrupts the current to the coils to collapse the field and fire the plug.

On your systems, you are using modern technology compared to my old Guzzi. Modern Guzzi’s use your type of inductive proximity sensing with rotors on flywheel etc. My old Guzzi doesn’t. Your type of sensing, and the electronic control it allows, is superior to the older points type of ignition, of course.

I am seeking the ability to programmatically control timing advance on an old race bike. I want to map the advance curve based upon engine RPM.

In the class that I race, I need to have the old distributor on the bike. I wonder if we can develop a system that allows the use of a distributor housing with either your rotor and inductive sensor, or, my Dyna III Hall Effect sensors triggering your Ignitech controller?

What voltage level and phase (+/-) do your inductive sensors generate? If I can match the signal you use with your sensors, with the signal generated by my Dyna III Hall Effect sensors, I may be able to replace just the Dyna III controller in my bike with a TCIP4.

BTW the engine is a 90 degree V Twin.

Thank you for your time,

Alex

Let's see what happens.

Alex

 

[Tonerjockey]

Here's another way... I dunno if the bike will start with so much advance...

Alex

 

[motoguzznix]

Alex

forget alll the distributor stuff.

Put in a new Valtech/Stucchi chain tensioner and the ignition will be stable.
If the chain has high mileage, replace it too. The early timing chain tensioner was not spring loaded and thus the chain looses the tension very soon. In the late eightys came a spring loaded tensioner that is way too soft. When using a camshaft with reasonable accelerations the spring can not cope with this and the ignition dances again. This is why I recommend a Stucchi tensioner especially in a race engine.

An other reason for ignition dancing can be big axial play of the camshaft. This can be adjusted by the brass metal flange below the cam timing gear. When replaced by a new one the ply should be like new again.

If your bike has the timing gears, replace them. If the play is that big they will soon go havoc.

 

[Tonerjockey]

I'm using gears ... Gunna swap in "Super Duper" cam. I'll check the lash at that time.

Good idea!

Alex