Author Topic: Convert Timing Marks  (Read 1199 times)

Offline Kiwi_Roy

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Convert Timing Marks
« on: October 17, 2021, 04:42:28 AM »
I have conflicting information on the flywheel markings, several manuals show me I should see (RH cylinder) 4 - 2 - D (LH cylinder) 5 - 3 - S
Instead of this i have what looks like a chisel mark highlighted with white paint then ~ 1-1/2" further clockwise D
I checked through the plughole the D obviously is at TDC on the RH cylinder
Other information tells me when retarded 2 degrees BTDC to 33 degrees fully advanced
The white chisel mark I assume is fully advanced highlighted for a strobe light.
I am trying to do a static timing using a lamp on the points, my gut tells me I should just set it to open with the D just rising in the view hole and call it 2 degrees, does that make sense?

Later on I can borrow a strobe light but since a convert doesn't have a tach how do others check the advance?
72 Eldorado
17 V7iii Special
76 Convert
Half a V9 Roamer

Moto Guzzi - making electricians out of riders since March 15 1921

Offline chuck peterson

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Re: Convert Timing Marks
« Reply #1 on: October 17, 2021, 04:59:42 AM »
Low range full accel

Nudge the advance forward until it begins to preignite

Back off a 1/2 ndge…

I just makedbsure it’s getting there to max advance. I used centerstand, wheel off the ground ( maybe a 2x4 underneath..and spin it up. I never strapped the clutch disengaged as some have

Or not bother chasing performance on a vert  :tongue:

Guzziology/dr dave does a great explanation and shows how to distinguish the correct springs…

Some find closing the gap on the 2nd points works better than moving the plate. Some have filed out the plate allowing it to rotate enough

I had to stop being too picky about it..



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Offline Stevex

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Re: Convert Timing Marks
« Reply #2 on: October 17, 2021, 05:03:44 AM »
I would say your painted line is as you say, dynamic timing mark for a strobe.
If you want to be super accurate, use a piston stop and timing disc to mark them spot on, as the oem timing marks do seem on average to be a couple of degrees out; I don't think Luigi ever worried about being too accurate.
I had to do this on my LM2 when I fitted a lightened flywheel with no timing marks on it.
Full advance is usually arrived at by 4k revs, without a rev counter advance your revs until you see the full advance marker come into the timing window with your strobe on; when it stops in one position, you're there.
If your static timing is 2° btdc it'll be close to the the tdc marker anyway. It'll not need to be super accurate as you'll be adjusting your distributor and points back plate again at full advance anyway.
I fitted new points and a Gammatronix amp before setting my gaps etc. Also worth replacing your possibly worn advance springs in the distributor.
« Last Edit: October 17, 2021, 05:05:51 AM by Stevex »

Offline Kiwi_Roy

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Re: Convert Timing Marks
« Reply #3 on: October 17, 2021, 10:19:24 AM »
Thankyou for all the words of wisdom  :thumb:
I still haven't nailed down the actual mileage of this bike, the oddo and paint condition tell me its 13,000 but the mess previous owners made of the wiring tell me it might be more.
The date code on the front tire was from the late 1980s, similar on the rear.
A degree wheel of course if I can figure out how to mount it on the alternator leaving the allen key for turning the motor.
Thanks again.
72 Eldorado
17 V7iii Special
76 Convert
Half a V9 Roamer

Moto Guzzi - making electricians out of riders since March 15 1921

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Re: Convert Timing Marks
« Reply #3 on: October 17, 2021, 10:19:24 AM »

Offline moto-uno

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Re: Convert Timing Marks
« Reply #4 on: October 17, 2021, 10:45:18 AM »
 I believe that the flywheel gear teeth are about 3.75 degrees each . If you get to TDC on compression ,
 turn the flywheel back 8 or 9 teeth ( after you've verified ign. point gap) and twist the advance cam
 until the points just crack open ( use your meter ) and you will be quite close to correct timing . As you
 mention , check with light for full advance . I have a light you can borrow :) . Good Luck , Peter

Offline Kiwi_Roy

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Re: Convert Timing Marks
« Reply #5 on: October 17, 2021, 03:17:13 PM »
I believe that the flywheel gear teeth are about 3.75 degrees each .CONFIRMED there are 96 teeth 360/96=3.75 degrees
 If you get to TDC on compression ,
There's an idea, I can count the teeth to verify that
 turn the flywheel back 8 or 9 teeth ( after you've verified ign. point gap) and twist the advance cam
 until the points just crack open
I tried that already. yes that seems to correspond to the highlighted mark
( use your meter ) and you will be quite close to correct timing . As you
 mention , check with light for full advance . I have a light you can borrow :) . Good Luck , Peter
There are 9 teeth between the TDC mark and the highlighted one or almost 33 degrees of advance as per the manual. The manual is very misleading because it shows all 3 marks in the window together, the fully advanced mark is 9 teeth away.
I set the Left Hand cylinder to TDC, it has a double mark in the window just under one tooth in gap, that must be the static mark for fully retarded. (2 degrees)
BTW I just have an old tail-light bulb with a couple of wires soldered to it, makes a great static timing light.
« Last Edit: October 17, 2021, 11:13:00 PM by Kiwi_Roy »
72 Eldorado
17 V7iii Special
76 Convert
Half a V9 Roamer

Moto Guzzi - making electricians out of riders since March 15 1921

Offline Kiwi_Roy

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Re: Convert Timing Marks
« Reply #6 on: October 18, 2021, 10:24:35 PM »
I set the Left Hand cylinder to just open the points at 2 degrees, the bike started up and idled at the first jab.
The fully retarded setting marks are on the Left Hand side but the fully advanced marks are on the right, it kind of makes sense when you think about it.
I won't bother with a timing light, I dont think I can get it any closer
In the past couple of weeks I changed the rubber and exorcised most of the electrical Gremlins, I can tell its going to be a sweet ride.
I had a devil of a job getting the points off, one of the large hydraulic hoses snakes through beside the points getting tangled in the condenser so I mounted the condensers onto on a bracket near the coils.
« Last Edit: October 18, 2021, 10:36:21 PM by Kiwi_Roy »
72 Eldorado
17 V7iii Special
76 Convert
Half a V9 Roamer

Moto Guzzi - making electricians out of riders since March 15 1921

Offline mtiberio

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Re: Convert Timing Marks
« Reply #7 on: October 19, 2021, 04:28:12 AM »
Don't trust what you see, put a wheel on it and make your own marks.
Land Speed Records w/Guzzzi:
SCTA M-PG 1000 141.6 MPH
LTA M-PF 1000 137.3 MPH
ECTA M-PG 1000 118.6 MPH
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Offline Kiwi_Roy

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Re: Convert Timing Marks
« Reply #8 on: October 20, 2021, 04:44:09 AM »
One thing that really stands out with the Convert is how gentle you can apply the power, I found myself riding right next to another bike at low speed in high ratio, you couldn't do that without slipping the clutch on an ordinary Guzzi..
I guess that's what you guys mean by "The Magic Carpet Ride"
72 Eldorado
17 V7iii Special
76 Convert
Half a V9 Roamer

Moto Guzzi - making electricians out of riders since March 15 1921

Offline Kiwi_Roy

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Re: Convert Timing Marks
« Reply #9 on: October 20, 2021, 05:40:28 AM »
Don't trust what you see, put a wheel on it and make your own marks.
360 degrees divided by 96 is pretty accurate don't you think?
I checked the TDC marks with a probe in both plug holes.
I must be missing your point.
72 Eldorado
17 V7iii Special
76 Convert
Half a V9 Roamer

Moto Guzzi - making electricians out of riders since March 15 1921

Offline Stevex

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Re: Convert Timing Marks
« Reply #10 on: October 20, 2021, 10:08:15 AM »
360 degrees divided by 96 is pretty accurate don't you think?
I checked the TDC marks with a probe in both plug holes.
I must be missing your point.

I think the point is, if you want total accuracy, go with the piston stop and timing disc.
Here is a pic of my original LM2 flywheel, prior to replacement with a lighter item.
The 'D' mark is factory applied TDC, the twin spot is mine using a piston stop to be dead accurate.
The timing marks were also a bit hit and miss.




Offline Kiwi_Roy

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Re: Convert Timing Marks
« Reply #11 on: October 20, 2021, 12:44:47 PM »
Please tell us how a piston stop is used, at TDC there must be a huge mechanical advantage against a mechanical stop that could do some serious damage or does the stop work away from TDC?
72 Eldorado
17 V7iii Special
76 Convert
Half a V9 Roamer

Moto Guzzi - making electricians out of riders since March 15 1921

Offline Scout63

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Re: Convert Timing Marks
« Reply #12 on: October 20, 2021, 02:50:35 PM »
You don’t push against the piston stop, just use it so that the piston stops gently against it.  Note the degree wheel reading and then roll the piston back down and through until it hits the stop again.  Note the degrees.  The midpoint between the two readings is tdc.  Remove the piston stop, rotate the engine to that midpoint and you are at tdc. Set the degree wheel at zero and then start setting your marks. (if I’ve got that wrong please someone correct as it is from memory).

I like to find tdc with a dial gauge on the piston.  When I rebuilt my G5 I found the tdc flywheel marks off by a degree or two if I remember correctly.  I made new marks with a small square file and some white paint.
Ben Zehnder - Orleans, MA USA

Offline Kiwi_Roy

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Re: Convert Timing Marks
« Reply #13 on: October 20, 2021, 08:52:25 PM »
 That makes sense e.g. set the stop several mm down the bore so it stops well before TDC (not too much mechanical advantage), I was missing the reason for the degree wheel. :thumb: :thumb:
72 Eldorado
17 V7iii Special
76 Convert
Half a V9 Roamer

Moto Guzzi - making electricians out of riders since March 15 1921

Online Tom H

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Re: Convert Timing Marks
« Reply #14 on: October 20, 2021, 10:54:19 PM »
Since we are messing with TDC.

How many degrees does the crank turn while the piston is stationary at the top of the bore?

Don't know if it would make a difference if it was a Loop 750/850, Tonti 1000/1100??

Enquiring mind wants to know!!
Tom
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Offline moto-uno

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Re: Convert Timing Marks
« Reply #15 on: October 21, 2021, 12:36:52 AM »
  Has anyone really noticed on a street Tonti that a 1 degree change makes a noticeable difference ? Peter

Offline Scout63

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Re: Convert Timing Marks
« Reply #16 on: October 21, 2021, 01:38:55 AM »
  Has anyone really noticed on a street Tonti that a 1 degree change makes a noticeable difference ? Peter

I can’t imagine it does but I’m Swiss by descent and I was in there. It surprised
me that it would be off in the first place. I got to exercise that much more control over the bike and I feel more connected to it when I ride. Maybe some therapy is in order.
Ben Zehnder - Orleans, MA USA

Offline mtiberio

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Re: Convert Timing Marks
« Reply #17 on: October 21, 2021, 05:14:37 AM »
I have seen guzzis start and idle with the timing out 45 degrees on one cylinder. If you think you can feel 1 degree off, rent your your self out as a Dynometer.
Land Speed Records w/Guzzzi:
SCTA M-PG 1000 141.6 MPH
LTA M-PF 1000 137.3 MPH
ECTA M-PG 1000 118.6 MPH
http://gjm.site90.com/mtiberio

Offline Stevex

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Re: Convert Timing Marks
« Reply #18 on: October 21, 2021, 05:41:53 AM »
  Has anyone really noticed on a street Tonti that a 1 degree change makes a noticeable difference ? Peter

Very doubtful, however in respect to myself, that's not the point.
To my way of thinking, if you can, why not be as accurate as possible, which means spot on.
I guess you don't work for NASA...the moon, it's that way, give or take a degree  :grin: (Saturn next stop).
« Last Edit: October 21, 2021, 05:43:02 AM by Stevex »

Offline moto-uno

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Re: Convert Timing Marks
« Reply #19 on: October 21, 2021, 03:51:59 PM »
  I didn't realize Moto-guzzi had a space program  :grin:
Peter

Offline Kiwi_Roy

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Re: Convert Timing Marks
« Reply #20 on: October 21, 2021, 04:58:10 PM »
  I didn't realize Moto-guzzi had a space program  :grin:
Peter
You didn't think the wind tunnel was for testing motorbikes did you?
72 Eldorado
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76 Convert
Half a V9 Roamer

Moto Guzzi - making electricians out of riders since March 15 1921

Offline guzzisteve

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Re: Convert Timing Marks
« Reply #21 on: October 22, 2021, 04:50:10 PM »
  Has anyone really noticed on a street Tonti that a 1 degree change makes a noticeable difference ? Peter
If you are doing dual points then .001" on gap = 2* on flywheel.  Has anyone noticed it??? I doubt it.
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Offline moto-uno

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Re: Convert Timing Marks
« Reply #22 on: October 22, 2021, 05:07:14 PM »
 ^ :thumb: , Peter

Offline guzzisteve

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Re: Convert Timing Marks
« Reply #23 on: October 22, 2021, 05:16:33 PM »
Been doing too many lately. Nice to know how much, goes much quicker when you have to cheat.
"Pray through Carlo & your bike shall be healed"
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