1980 xs11 special dies with throttle

[darylcaribou69]

With the key on 12.5 volts at the battery. 11.5 volts at the power wire to the coils.Resistance through primary side of both coils is between 1.9 and 2.1 ohms. And 13.8k ohms through the secondary side of both. When I went out to test them I started the bike just for a good time and it fired up without a problem.

[motoman]

With the key on 12.5 volts at the battery. 11.5 volts at the power wire to the coils.Resistance through primary side of both coils is between 1.9 and 2.1 ohms. And 13.8k ohms through the secondary side of both. When I went out to test them I started the bike just for a good time and it fired up without a problem.

That voltage drop to the coils IS the issue. That sorta drop in primary voltage is from poor grounding of system. Check and clean all ground locations. Also, the Run/Stop switch COMPLETES the running circuit. Those switch contacts ARE a common location for a voltage drop. The Run/Stop switch COMPLETES the bikes running circuit. Remove switch from bars, take apart carefully, watching for that teeny internal spring. Drop all pieces including switch itself into a shot glass full of Evapor-Rust and leave overnite. Remove and rinse pieces with water and dry them Those pieces WILL look like new including the switch itself. Re-assemble and intall. Again, check the voltage going TO coils for any improvement. That plug-in for the Run/Stop switch is located at top frame rail under tank on right side of bike. That plug-in also needs unplugged, contacts cleaned and plugged back in. Other than that, your headed in correct direction for diagnosis and corrections. Again, low voltage to coils IS bikes ignition issues, leaving plugs black.

[TopCatGr58]

With the key on 12.5 volts at the battery. 11.5 volts at the power wire to the coils.Resistance through primary side of both coils is between 1.9 and 2.1 ohms. And 13.8k ohms through the secondary side of both. When I went out to test them I started the bike just for a good time and it fired up without a problem.

Hey,

The primary resistance is a bit beyond spec, but could be due to corrosion of connectors. I would first try cleaning them, and then retesting. You could also expose a little bit of fresh wire beyond the connector under the wire insulation to get clean copper and retest again. If still high values, then the OEM coils are suspect, should be 1.5 ohms. And the secondary is supposed to be 15Kohms +/- 10%, so 13.5K to 16.5K range. With those high primary resistances, they would tend to get HIGHER as they heat up reducing the amount of power output, poor/weak sparks.

I would really highly suggest just getting new/newer used 3.0 ohm/12V coils, and bypass the ballast resistor so they get 12V all the time for stronger spark ALL of the time.

T.C.

[motoman]

Daryl, since coils are the likely issue, if you have a motorcycle used parts distributor nearby, take your ohm meter with you and look for a pair of Honda VFR1100 coils that check out to be at least 2.9 to 3.1 ohms for a 3ohm coil replacement. Those are the next best option and way less cost than new aftermarket coils. The VFR coils are also a simple bolt-on frame replacement and use separate screw on retainers for plug wire to coil attaching. That is what I have had on my Venturer for some 5yrs. with never a weak spark issue and bike runs smooth as silk at any rpm. Like T.C. stated, in your bikes case, bypass the ballast resister when using 3ohm coils. Not an issue with the 81 Venturer, as it comes stock when new using 3ohm coils. Having two sets of stock coils that over a few decades of use have gone from 3ohm originally to 2.4ohms was reason for change.

[jetmechmarty]

Decrud all of your electrical connections while you're at it. That one volt drop to the coils is excessive. If you have 12.5 at the battery, you should have no less than 12.2 at the coils.

[darylcaribou69]

Did some testing. I get 12.5 to the ignition switch and only 11.8 ish volts out. So there's one issue. The rest of the system shows 11.5-11.7 including the wire to the right thumb switch. Can I take apart and clean the key switch? Or is that something that will just need to be replaced? I hate wires.

[MaximPhil]

Did some testing. I get 12.5 to the ignition switch and only 11.8 ish volts out. So there's one issue. The rest of the system shows 11.5-11.7 including the wire to the right thumb switch. Can I take apart and clean the key switch? Or is that something that will just need to be replaced? I hate wires.

Hi Daryl,
Yes you can clean the ignition switch. Make note of the connections and remove the assembly. Be careful when disassembling the switch on the bench or bed as there are two tiny springs in there. Soaking in EvapoRust overnight will clean the parts up nicely.
May as well do the Kill switch at the same time. Use a jar and save the EvapoRust for the next job.

Phil

[darylcaribou69]

Sounds good! Looks like I have a little work to do. Is the general consensus that the voltage drop and higher resistance in the coils is giving me my issue? It makes sense but only Mr. Yamaha knows for sure. I appreciate the advice. If there are any veteran's following this forum I thank you for your service.

Semper fi,
Daryl

[jetmechmarty]

After this many years, wires and connections have corrosion at every junction. It must be dealt with.

I had a chat with the Metal Rescue folks at Barber. They told me that their product is designed to attack ferrous metal oxides. I won't work on other metals any better than plain water. Members of this forum say their results say otherwise. I just thought I'd put that out there. One way or another that corrosion has to go.

Embrace the wires!

[darylcaribou69]

Had some time to mess with the electrics today. Cold the pickup coils were at 700 ohms. Hot 70000 ohms. Well there's yer problem. The first time I checked them a while ago I didn't know anything about electronics and resistance and other stuff. I am going to fix the wires and try it out. Hopefully this will solve the majority of the problems with the bike. Those damn wires. When I first checked them out I was a little worried I would mess something up if I poked around too much so I just tooled and thought everything looked good. Today I took the cover off and dug in and tugged at the wires a bit. They were like rubber bands. Learning a lot with this bike. If I don't make it in finance I'll open a bike shop.

If I replace the wires and the coils and it still doesn't go I'm going to go insane.

[darylcaribou69]

Replaced two wires on the pickup coils. Now the resistance doesn't change when I pull on them. But it is at almost 800 ohms. Is this in spec or is this an issue? Also the spark coils are at 2 ohms. When it's cold it fires up and runs awesome. When it gets warm it does the same thing it did before, it with the slightest amount of throttle. It starts hard and won't rev up evenly. If you punch it, it'll go to the moon. I noticed when I was revving it that the advance doesn't move when it revs up high. And it'll do that. At idle and top end the advance is in the same spot and it goes. When I rev it slowly vacuum builds and pulls the advance and it dies. I'll post a video on YouTube of this.

[darylcaribou69]

https://youtu.be/-U9yZdPW1zo

[skids]

Replaced two wires on the pickup coils. Now the resistance doesn't change when I pull on them. But it is at almost 800 ohms. Is this in spec or is this an issue? Also the spark coils are at 2 ohms. When it's cold it fires up and runs awesome. When it gets warm it does the same thing it did before, it with the slightest amount of throttle. It starts hard and won't rev up evenly. If you punch it, it'll go to the moon. I noticed when I was revving it that the advance doesn't move when it revs up high. And it'll do that. At idle and top end the advance is in the same spot and it goes. When I rev it slowly vacuum builds and pulls the advance and it dies. I'll post a video on YouTube of this.

I saw the video. I am no carb expert, but i'll say that when you goose it, the diaphragm assemblies immediately rise to pull up the main jet needles. Alternatively, when you slowly roll-on the throttle, there is less vacuum to raise the main needles and the carbs should be using more of the idle circuits (I think). I think the vacuum advance is working normally. There is something else wrong - like the idle circuit.

Tell me (again?), it this a set of morphodite carbs that were used during the development of the later carbs, or not?

[darylcaribou69]

I believe the later carbs. There is no crossover passage between the main and pilot jet tower.

[darylcaribou69]

Unhooked the vacuum advance just for the sake of a good time. It will stumble through the Rom range but won't stall.