Strobe timing, cant get the LH/Starter side aligned

[tobydmv]

1989 Mille Gt with dual points plate and Marelli Distro
S=starter side, LH while seated
D=distributor side, RH while seated

Guys, I am trying like hell to get this bike timed with a strobe light for static marks.  I can get the D side spot on but that makes the S side way too early.  I actually had the D side on the static mark and the S side on the advanced mark the other day.  I've rotated the S side points adjustment to full retarted but seems odd that these 2 are so far off.  I just found this article on this old tractor that describes the problem and makes me feel a little better.

http://www.thisoldtractor.com/moto_guzzi_tonti_distributor_dual_points_plate_modification_so_you_can_time_both_cylinders_properly.html

So is this a known issue and completely normal?  I've found other threads by searching this forum that say its normal when timing to be unable to time the L/S side.  I thought i'd ask the group before taking a dremel tool to the points plate.  This is a sanity check.  The bike seems to run ok but is a little low on power.  I was thinking i'd have to compromise the D side to allow the S to get closer to the static mark.  But slotting the lower points plate to allow more rotation seems logical.
Thanks,
Toby

[redrider90]

My 90 Mille came motoplat electronic ignition which I used for the first 15K-20K miles. I never had any issues timing. I then put a points dizzy in it and installed a Dyna III and have never had an issues timing the Dyna. I always have kept the points set up around just in case but never installed it with points. I always have perfect timing at 5K rpms on both sides.  Never bothered to static time it. I took out the dizzy 2 years ago (marked it with a felt tip pen) and replaced the leaking gasket. I reinstalled it using the felt tip mark and put the strobe on it. It was perfect on both sides.
 I would be interested in Triple Jim's view on this issue as he makes electronics (CDIs) for bikes and has installed his brand of a custom CDI on his points Mille.

[Stevex]

I've got points in my LM2 distributor, setting the gaps and static timing was achieved without problem.
Checked the dynamic timing and it needed no further adjustment.
Before I removed the dizzy, I centre popped it and the crankcase to ensure I got it lined up correctly on refit.
I also renewed my timing chain and tensioner at the same time and used a piston stop and timing disc to ensure my flywheel timing marks were spot on...the original markings were 2-3 degrees out!

[Kiwi_Roy]

Guys, I am trying like hell to get this bike timed with a strobe light for static marks.  I can get the D side spot on but that makes the S side way too early.  I actually had the D side on the static mark and the S side on the advanced mark the other day.  I've rotated the S side points adjustment to full retarted but seems odd that these 2 are so far off.  I just found this article on this old tractor that describes the problem and makes me feel a little better.
 

We had another guy just recently had the same problem.
Make sure you are using the correct set of points for the cylinder
I'm not sure which is D & S but the LH side sitting on the bike fires 450° after the RH side then 270° later the RH fires again.
So looking at the points you have a large gap and a small gap, it's just a matter of getting the right set.

It's easy to get confused as the distributor turns at half crank speed so the gaps there are 225° and 135°

I checked my old Eldorado with a straw watching the points for opening just before TDC both valves closed, first one cylinder then the other. With everyone watching, after 20 years, much to my relief it fired in less than a revolution of the crank.

Update:
So that's what the D & S refers to Distributor and Starter
So it should be D, large gap S small gap D etc

[tobydmv]

Update:
So that's what the D & S refers to Distributor and Starter
So it should be D, large gap S small gap D etc

Hey Roy, I dont follow you with large and small gaps.  I have a Haynes manual that specs the gap is 14-18 thou for both.  No mention of one is bigger than the other.  But if the S side is smaller it will open later right?  Is that what you mean?  Have a look at the link I posted, it mentions
"...Manufacturing tolerances on points plates for dual-point timers often mean you have to choose one of the following: Equal points gaps OR the same timing on both cylinders. Usually, the left cylinder adjustments hits its stops before you can retard it enough to match the timing and gap of the right cylinder, unless you make the changes shown here"

I dont want to assume you mean the D side point gap is say 16thou and the S side is 12thou.  Can you clarify?


Thanks,
Toby

[Kiwi_Roy]

No, sorry I meant large segment of the circle before the next action
I think the distributor turns CCW
If you look at the picture of the points plate the black cam followers are at 6 and 11 oclock
so the large arc is on the RH side
If the distributor is rotating CCW then the points at the bottom are for RH cylinder

If the distributor is rotating CW then of course the points at the top are for the RH cylinder.

I assume you have had the distributor out and may have got the teeth of the cog in a different spot.

[Triple Jim]

My dual point turns clockwise.  I assume they all do.

[Kiwi_Roy]

Unless you are in the Sothern hemisphere.

Ok, I have it backwards then
The top cam follower at 11 0'clock is for RH cylinder then 225° later at 6 0'clock the cam follower is for LH (starter side) cylinder so the wires sort of cross, that makes sense the spark wires on the Eldo cross.
(I am referring to the last page of the Greg Bender link)

Thanks Jim

While we are there rotating the distributor CCW advances the spark CW retards it.

[rodekyll]

The points gap is not critical on a guzzi as long as there is some -- say between 0.010 and 0.030, just for folks who need numbers.  The time that the points open is important though.  So set the gaps such that they aren't wildly different from each other, and so they open within your adjustment range.