Convert timing/ idle issue

[bigbikerrick]

Hi Folks, I am still struggling with my Convert, trying to get the timing sorted. I have gapped the points correctly, modified the mounting plate to the left cylinder points so the timing can be adjusted further, and have consulted Guzziology,and all the online manuals.
 when I set the right side timing perfectly for both idle, at one line above the "D", and also the advance setting, then I set the left, where the idle setting is correct,and also the advance mark at 4000 rpm, using a timing light.  When I set both cylinders timing where they should be, the bike wont idle. I have to advance the whole distributor a couple degrees to get it to idle halfway decent. The carbs have been gone through,and rebuilt, valves adjusted, cylinders balanced, etc.
When I set the distributor where it will idle, I cant see either the right or left timing marks in the window, as its too advanced, and they are down below the hole. When I rev it up, I can see the advance mark in the window, and it goes a bit past where it should be by a couple of teeth.

Guzziology states to only time the dual point to the full advance marks on both the right and left cylinder, that at idle rpms, the distributor will be into its advance curve. I tried that, but it still would not idle properly, and would stall out at stops.
Do you guys have any ideas on what else I can check? when I ride the bike, it runs good, except when I come to a stop, it wants to stall out, at idle.
Rick D.

[Vecchio Lupo]

I don't want to steer you wrong...there are way more knowledgeable people than me. I know you said you have been through the carbs, but unless you have stretched out advance springs, this sounds fuel related just a bit. What happens if you up the idle on the carbs? Does it still die off no matter what?  My Convert would stall at stops and act a fool, even after carb and timing checks...turned out my valves were way too tight..causing a bit of a compression squeak on exhaust. set them up correct and loud as they are it idles away chug chug chug

[bigbikerrick]

I will re check my valve adjustment, to make sure. I have rebuilt the carbs last week, even though they really didnt need it. since I had the rebuild kits I figgured I may as well. The plugs look good, perfect color.
Thanks
Rick.

[Bulldog9]

Hi Folks, I am still struggling with my Convert, trying to get the timing sorted. I have gapped the points correctly, modified the mounting plate to the left cylinder points so the timing can be adjusted further, and have consulted Guzziology,and all the online manuals.
 when I set the right side timing perfectly for both idle, at one line above the "D", and also the advance setting, then I set the left, where the idle setting is correct,and also the advance mark at 4000 rpm, using a timing light.  When I set both cylinders timing where they should be, the bike wont idle. I have to advance the whole distributor a couple degrees to get it to idle halfway decent. The carbs have been gone through,and rebuilt, valves adjusted, cylinders balanced, etc.
When I set the distributor where it will idle, I cant see either the right or left timing marks in the window, as its too advanced, and they are down below the hole. When I rev it up, I can see the advance mark in the window, and it goes a bit past where it should be by a couple of teeth.

Guzziology states to only time the dual point to the full advance marks on both the right and left cylinder, that at idle rpms, the distributor will be into its advance curve. I tried that, but it still would not idle properly, and would stall out at stops.
Do you guys have any ideas on what else I can check? when I ride the bike, it runs good, except when I come to a stop, it wants to stall out, at idle.
Rick D.

I'm sure that others will come along with far more helpful advice, but back in the old days we used to set the advance and idle mixture screws by ear.

Start with the timing at top dead center. Preferably on an already warmed up motor. With the motor running turn the distributor to get the most stable idle. Mark that then do your 3,000 to 4,000 RPM the same way and Mark that. If they are not the same, then split the difference between the two and call it good enough.

Of course this is just old school shade tree stuff I'm sure the experts will be along shortly.

Granted I have not attempted to do any timing on my convert, but I would think that set ting the timing on one side would carry over equally to the other?

My guess is that you may not have it at top dead center on the cylinder you're setting the timing. If you do it that way you should be good to go.

[bigbikerrick]

Thank you, Bulldog9. I tried leaving the distributor bolts a little loose,and rotating the distributor while the engine is running,and trying to find the "sweet spot" by ear. I still could not get a decent idle . when I turn it towards the retarded direction, its worse, as I turn it towards the advance direction, it will start to idle, but its WAY advanced, and still it does no idle "right". It just sounds weird. I am starting to think something else, that I have not discovered yet, is messing up my idle. I worked on this bike almost all day yesterday, and a good part of the day today.  I think I need to back up,and think about what I may be missing here. Something is just not "right".. ... I just have been unable to put my finger on the cause.

Back to the old drawing board.....

Rick Duarte

[bigbikerrick]

An update… today i re checked valve lash, adjusted thee timing via stroboscopic light , where the right cylinder, is timed exactly to the full advance mark, at idle speed it is about one tooth above the tdc mark. I adjusted the point plate on the left, to get it  correct , reaching full advance as it should. I buttoned everything back up, and my idle while is a little better, its still not  right, and gets worse, as the engine warms up. The only thing i have left to replace are the condensers. My bike still has the oem condensers as far as i know, and it is 47 years old, even though it only has 12K miles. I assume bad condensers can cause a bad idle?
Rick

[Vecchio Lupo]

I would change condensers just because. good call

[moto-uno]

  Once you have the condensers installed , and after the engine is warmed up ( 10 or so miles ) try adjusting the mixture screws in or out to see
what increases the idle speed . I tend to turn them out 1/4 turn (richer) after I find the highest consistent idle speed . I'm also assuming that while
you were setting the timing (with the light) that you didn't notice the timing mark wandering in and out of the inspection hole . Good Luck , Peter

[bigbikerrick]

Thank you ,Peter.will do. I have been tuning carbed Guzzis for over 20 years, and have never run into one that is so “finnicky”  about getting a good idle. I have found that they will run, decent,even if things are just in the ballpark, as far as settings are concerned.
  If replacing the condensers, does not solve the issue, i think i will put a Dyna ignition in, and probably will eventually, as this sweet convert is deffinitely a “keeper” bike for me.
Rick

[bigbikerrick]

An Update, Folks. Ive had it in my head that the condensers may be the culprit,and I have a new pair coming from MG cycles. Today,I was talking to a mechanic friend,and he gave me the idea to try an automotive condenser just as an experiment, I went down to auto zone and bought a pair of condensers for a 73 chevy 350 with points ignition. I had to lengthen the wire a couple inches, to get them to reach the terminals, but they mounted up fine and as soon as I fired the convert up, I could tell there was a big difference. The idle smoothed out like it should be.  Actually it was the condenser for the left cylinder that was causing my problems.
  before I mounted the condenser to the distributor, I hooked the wire up,and just held it to ground against the cylinder, while running, if I removed the condenser from the ground, it would immediately go back to the bad idlle,and stall out.....so I am pretty sure that is the problem.
I dont want to claim victory,until I bolt everything back together and take it for a good test ride, but so far ,it looks promising.
Rick D.

[glenm64]

Excellent news Rick. I love the 1950's Russian tractor technology on the old Guzzi's. Not too much that can really go wrong.