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Bike WAS running perfect till sunday :/ ...running cold

Posted: Wed Oct 12, 2011 8:52 pm
by rusty wing
My '76 has been running better than ever. I rebuilt the carbs and used the mercury sticks on 'em.
Idle has been perfect. ok, now for the bad....the bike will only get warm at all at idle, runs cold all the time. I went on a long ride Saturday w/ a friend and it performed great. Then....Sunday on the way back from work thru Atlanta, the bike starts loosing power....70mph tops.
Havent looked at it yet, but I think the bike is running too rich (runs cold) and maybe the plugs are starting to foul?
How am I supposed to set the air screws?

I am unsure where to start, just looking for some feedback.

Thanks,

Rusty

Re: Bike WAS running perfect till sunday :/ ...running cold

Posted: Wed Oct 12, 2011 8:59 pm
by Toehead
Thermostat stuck open could explain the cold running, but probably not the loss of power.

Is it running rough, like you are down a cylinder or two?

Re: Bike WAS running perfect till sunday :/ ...running cold

Posted: Wed Oct 12, 2011 9:25 pm
by rusty wing
after looking at some posts....
i have set my idle screws out 1 1/2 turns out....
is that rich or lean?

Re: Bike WAS running perfect till sunday :/ ...running cold

Posted: Wed Oct 12, 2011 9:35 pm
by Whiskerfish
That is probably a bit lean for a 76. Run it for a bit then check the plugs to be sure. If you can the idle drop procedure is a pretty fail safe way to set the screws.

Re: Bike WAS running perfect till sunday :/ ...running cold

Posted: Wed Oct 12, 2011 11:25 pm
by wilf
possily fuel supply problems or electric gremlin's. there are a ton of things that can cause your problem and you just have to work your way throw it.
I think on the radkin site there are some good writeups on where to start your systematic overhaul of your bikes systems. dirty fuel tank blocked fuel cap vent plugged fuel filter weak fuel pump sticking slides on carbs etc.
weak or cracked coils. problems with the points condensers . bad spark pug wires or boot's. There are 5000 ohm resistors in the sparkplug boots along with a spring. these can become brittle and coroded and cause loss of spark.

Re: Bike WAS running perfect till sunday :/ ...running cold

Posted: Thu Oct 13, 2011 6:38 am
by RB
Run the bike..while running spray some water on the header pipes..water should steam off instantly..if not there's your non firing cylinder(s). If 1/2 or 3/4 coil/point issues if just one then most likely carbs issues.

Re: Bike WAS running perfect till sunday :/ ...running cold

Posted: Thu Oct 13, 2011 8:54 am
by rusty wing
Thanks guys...i know where i am going to start.

Re: Bike WAS running perfect till sunday :/ ...running cold

Posted: Sun Feb 05, 2012 9:46 am
by rusty wing
Well, after sticking new plugs in, the bike is back to running like a charm. Also, I see that the temp guage sensor has come off (hence running cold all of a sudden).
Today, riding to work, I stalled it at a green light....then wont start, so I roll stated it to make it to work.
After I parked it, I tried to start it again...NOTHING.
So, I hope I make it back home.
Guess its time to start overhauling to ignition parts.....stators are uncommon to go out on these, right?

Thanks

Re: Bike WAS running perfect till sunday :/ ...running cold

Posted: Sun Feb 05, 2012 10:14 am
by Oldewing
yea, the 1200 have had some problems. Check the 3 yellow wire plug under the left side(battery) side cover for a good connection. Most cut that plug out and hard wire it, any yellow to any other yellow is good. Shoptalk has the complete run down on how to check your stator.

Re: Bike WAS running perfect till sunday :/ ...running cold

Posted: Sun Feb 05, 2012 10:51 am
by robin1731
You say it didn't start. Did it turn over and just not start or did it not even turn over? I'm a bit confused because you talk about ignition parts then ask about the stator.

Like Oldewing said check the plug at the stator. The plug is a kind of known problem from corrosion. And most of us have just wired them.

Re: Bike WAS running perfect till sunday :/ ...running cold

Posted: Sun Feb 05, 2012 11:01 am
by rusty wing
Well, the bike had no electrical juice, which is why it wouldnt start. These bikes are OK running with no battery? I will test it when I head home in a bit. I still have the kick start bar :)
I will most definately check that plug. I have never had a problem with the charging system before, but the bike does sit more than normal during the winter.

Re: Bike WAS running perfect till sunday :/ ...running cold

Posted: Wed Sep 22, 2021 7:33 am
by pidjones
It would be difficult if not impossible to start without a battery. You would at a minimum need to temporarily jumper the ballast resistor - tough to do if you haven't set up for that previously. And riding without the battery will be hard on the electrical system. Might just be a dead battery - they do die, you know. Then there is the "three yellow wires" connector that is marginally designed (although they did last 30-40 years), are not listed in the manual for service, and live in an area of moisture and battery acid fumes. If the problem is just the battery, NOW would be a good time to replace the connector. Many threads on doing this. I use high current RC helicopter connectors covered by shrink wrap. Some just solder the wires together (no polarity issues as it is AC) and shrink wrap.

Re: Bike WAS running perfect till sunday :/ ...running cold

Posted: Wed Sep 22, 2021 7:39 am
by gltriker
;) 9+years since last post
Good information, though! tumb2

Re: Bike WAS running perfect till sunday :/ ...running cold

Posted: Wed Sep 22, 2021 7:46 am
by pidjones
gltriker wrote: Wed Sep 22, 2021 7:39 am ;) 9+years since last post
Why did it show up in my unread feed?

Re: Bike WAS running perfect till sunday :/ ...running cold

Posted: Wed Sep 22, 2021 6:07 pm
by Figor
On a different forum I have been getting old replies in my new emails. When I questioned it I was told it was some form of phishing attempt. Maybe that’s what’s happening?