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Unreliable Ignition

Printed From: guzziriders.org - moto guzzi forum
Category: Technical
Forum Name: Loop Frames
Forum Description: Anything about the original Guzzi V Twin.
URL: http://www.guzziriders.org/forum_posts.asp?TID=7993
Printed Date: 16 Dec 2018 at 18:11
Software Version: Web Wiz Forums 12.00 - http://www.webwizforums.com


Topic: Unreliable Ignition
Posted By: Rick B
Subject: Unreliable Ignition
Date Posted: 09 Oct 2017 at 01:45
I have a 1973 V7 Sport.  10k Miles (U.S., sorry).  It wasn't ridden for 15 years.  I've cleaned the carbs, changed fluids, etc.  Also put on new coils, condensers and points, plugs & wires.  Right side was only firing intermittently.  Thought I'd narrowed it to condensers.  So I switched condensers.  Sure enough, left side fired intermittently.  Installed a new left side condenser.  Ran great for about 25 miles, then left side started cutting out.  Now it barely fires at all. 

Questions:
1) Will timing affect ignition?  That is, can bad timing cause a cylinder to not fire?  Or will it fire regardless, just at the wrong time?  No other signs of timing problems.
2) Can wiring problems before the coils, condensers and points, cause such a problem?
3) Left side point sparks more than the right side.  Is that normal?

Any suggestions would be appreciated.  Also, happy to donate to server costs.  Tell me how.

Thanks,
Rick


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Rick Busselle



Replies:
Posted By: Brian UK
Date Posted: 09 Oct 2017 at 08:15
Yes, yes and no in that order.
 
It's not unknown for new condensers to be faulty especially if they are old stock.
 
Timing can cause a misfire, but it would have to be out by quite a bit.
 
Any wiring fault between the battery and coil could stop the spark.
 


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Brian.

Better 5 minutes late in this world than years early in the next.


Posted By: ranton_rambler
Date Posted: 09 Oct 2017 at 12:50
I had a condenser fail on my loop, and then replacement failed after about 300 miles. Currently got a condenser from a Mini fitted, as that's what I was able to buy to get me home.
There is only one set of points on a loop, and they tend to wear the heel and close up, eventually running really badly.
I would check all the wiring feeding the ignition system, including making sure you have good earths. Is the ignition system supplied through a fuse on these?


Posted By: Ken-Guzzibear
Date Posted: 09 Oct 2017 at 12:52
Bought 2 sets of new condensers 'till I got one that worked ok the end result is find either a marelli one or Bosch ...fiat used the same parts 22micro farad condenser ...easy to tell look at dizzy with top off huge sparks at points = Condenser buggered (That's a guzzisti technical term for "it don't work no more" )

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The Older i Get, The Better I Was


Posted By: Rick B
Date Posted: 09 Oct 2017 at 13:55
Thank you, Sirs.

Someone, probably one of you guys, said that the likelihood of getting a bad new condenser is about the same as a 30 year old one failing.

The fact that it runs really well for a few miles here and there makes me think I'm chasing wiring problem.  I'll trace the wiring back to the box.

I appreciate these forums and all the hard to find expertise that they can tap into. 

Will check regularly and read your thoughts.  But I won't pester with minutia until I've eliminated the wiring as a problem. 

Thanks,
RickBeer


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Rick Busselle


Posted By: Mike H
Date Posted: 09 Oct 2017 at 16:09
Originally posted by Brian UK Brian UK wrote:

It's not unknown for new condensers to be faulty especially if they are old stock.
 

This reminds me, by all accounts newly made ones tend to rubbish, i.e. are badly made.

can you possibly still use the original ones?




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"Chicken nuggets don't dance on a Tuesday."


Posted By: Ken-Guzzibear
Date Posted: 09 Oct 2017 at 19:03
if condenser proves to be ok check coil as you say it runs fine for a short while, No real experience of a loop BUT once had a cut out happen on the 76 Vthou ....drove me nuts ...it was a blocked breather on the tank flap ...... I had put a new seal on it and had not positioned it quite right ....just some ideas no clue if it helps, always go for the cheap, easy stuff first ....


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The Older i Get, The Better I Was


Posted By: Rick B
Date Posted: 09 Oct 2017 at 22:01
Good thoughts both.  I'll keep you all posted.
Best.


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Rick Busselle


Posted By: Brian UK
Date Posted: 09 Oct 2017 at 23:03
Sparks failing after a short time is certainly one symptom of a failing coil. When I had it happen, I could do about 2 miles before it stopped. Waited 5 minutes then another 2 miles. Took a long time to get home.

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Brian.

Better 5 minutes late in this world than years early in the next.


Posted By: Rick B
Date Posted: 23 Oct 2017 at 01:20
Hi All,

I had that 73-V7 with ignition problem - right cylinder firing intermittently.  After replacing the second bad condenser.  I've read that you're a likely buy a bad new condenser as have an old on go out.  Seems true in this case. Don't know if they will help anyone but the point associated with the bad condenser sparked a lot.  Now that the new one is in, the spark is barely visible, just like the other side.  So, maybe a sign of a bad condenser is a "sparky" point. 

Anyway, the bike is now sparking nicely and ran pretty well for a 20 mile ride (about mile 6 turned the odometer over the 10,000 mile mark).  But it seems like it should have a bit more acceleration at high rpms (5000-ish).  When I checked the timing with a light, the right cylinder mark is showing below the window at 2000rpms and the left cylinder mark is nowhere to be seen, although, I can hardly find the LC timing mark when the bike isn't running. 

Would you all recommend advancing the timing a bit and then messing with the carbs?  Or trying to fine tune the carbs and leave the timing for now?  I've read that it's ignition THEN carburetor.  But I'm not sure how much faith I have in those timing marks.   

Thanks for your thoughts, again. 

Rick.




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Rick Busselle


Posted By: Ken-Guzzibear
Date Posted: 23 Oct 2017 at 12:42
Yes sparky point is usually condenser if you look in the thread general electrical issues ...page 2 scroll down to Rita ignition help Brian has put in a link to Euro spares on there the info re timing the rita also gives very useful info for timing a big block Guzzi in their "Text for installing rita to T3 Guzzi it may help ie each tooth on the starter ring =3.75degrees therefore 33degrees BTDC = 9 teeth .....sure helped me ....

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The Older i Get, The Better I Was


Posted By: Brian UK
Date Posted: 23 Oct 2017 at 15:05
The condenser is there to stop the points arcing, so if you see sparking on the points, the probability is that the condenser has seen it's best days.

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Brian.

Better 5 minutes late in this world than years early in the next.


Posted By: johnno
Date Posted: 23 Oct 2017 at 15:49
Originally posted by Brian UK Brian UK wrote:


The condenser is there to stop the points arcing, so if you see sparking on the points, the probability is that the condenser has seen it's best days.


I never knew that

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GSXR1100 L ,Moto Guzzi .750xpa,.1100 sport,1100 sport corsa rider


Posted By: red leader one
Date Posted: 23 Oct 2017 at 15:54
You know everyfing Brian.


Posted By: Dave P.
Date Posted: 23 Oct 2017 at 16:06
http://www.dailymail.co.uk/news/article-2960913/Mechanic-fixes-Land-Rover-POTATO.html" rel="nofollow - http://www.dailymail.co.uk/news/article-2960913/Mechanic-fixes-Land-Rover-POTATO.html
You could always try this.

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TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.


Posted By: Ken-Guzzibear
Date Posted: 23 Oct 2017 at 18:58
The thing "condenser" is another description for Capacitor it stores charge .......BUT bad ign after 20 ish miles could be faulty coil touch it if very hot it is brokedid ..... the ign system as actually very reliable BUT condenser breaking down gives sparks and gives the coil a hard time coils are not that expensive, good connections and good earths are paramount all reasonably easy to check

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The Older i Get, The Better I Was


Posted By: Mike H
Date Posted: 23 Oct 2017 at 20:05
Originally posted by johnno johnno wrote:

Originally posted by Brian UK Brian UK wrote:


The condenser is there to stop the points arcing, so if you see sparking on the points, the probability is that the condenser has seen it's best days.


I never knew that


Yep.


.



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"Chicken nuggets don't dance on a Tuesday."


Posted By: Jerry atric
Date Posted: 23 Oct 2017 at 20:11
Brilliant. New potato or main crop, which is best?


Posted By: Brian UK
Date Posted: 23 Oct 2017 at 22:03
To take the theory a bit further, the induction (ignition) coil requires a sharp cut of the current through the primary to induce a large spike of voltage in the secondary.
If the condenser isn't there, or is in poor condition, you get arcing across the points as they open, thus the cut in current isn't as fast, so you get a weaker spark.


-------------
Brian.

Better 5 minutes late in this world than years early in the next.



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