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Just getting back to the 1981 1100. Rebuilt the carbs and fired it up. Running a little rough. Pulled the 1 plug wire and had a slight change in running. pulled # 2 and it died. Tried again with 3 and also died. # 4 reacted like #1. Decided to check coils and have between 2.4 and 2.7 on coil primaries. Tried checking secondaries and nothing on both coils checking plug to plug and plug to wire.. I do have some spark on both 1 and 4. Any idea what I am missing? first tiime checking coils.
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81 LH in process
09 vstar 1300
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With 40+ year old coils that may be the problem. The two things to try BEFORE going the new coil route are the plug caps and wire ends.
You can unscrew the wire caps off the end of the plug wires. Once off, you should have about 5K Ohms resistance between the wire side and the plug side. If it's higher or just open, replace all the caps. The new caps can be the non-resistor type, as you just put in resistor plugs.
On the coil wires, cut off about 1/4" of the end of the wire. There may be oxidation causing a resistance that will also cause problems.Ray Matteis
KE6NHG
XS1100 E '78 (winter project)
XS1100 SF Bob Jones worked on it! -
Appreciate the info. thankyou.81 LH in process
09 vstar 1300
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The coils could be good but look at your high tension wires. Your wires could be microscopically cracked (tough to see with your eyes). When this happens, your spark is getting sucked into the metal ground of a motor cover, ect. A quick diagnoses involves spraying the wires with WD40 (Wire Dry 40). It will temporarily seal the cracks. If the bike runs better you have found your problem.
Another quick way to tell if this is your issue without using WD40 is to spray plain water on the wires (lightly so it does not choke the carb) while the bike is idling. You will notice an immediate change in RPM if the wires are bad. If you spray good wires with water the bike still idles normal. Sometimes you will find this out too late when riding in the rain or trying to start your bike after a wash. Bad wires on an old bike is a very common problem but the coils either work or they don't (open coil). Yours seem to be working. Rays suggestion about wire end caps is also a very common problem
Last edited by DEEBS11; 12-09-2024, 08:48 AM.Comment
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So I pulled caps on plugs 1 and 4. plug 1 - 7.96 k ohms and plug 4 - 9.83 k ohms. Tried wire to wire again and still 0.81 LH in process
09 vstar 1300
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You might want to consider replacing your coils. Check this maintenance tip out. Dyna Coil Upgrade - XS11.club Forums
Be sure to note that the now recommended Dynatek coils are the DC1-1's. They are available on Ebay. Also, if you go this route make sure you include solid core wires. You can go with the non resistor plug caps and resistor plug combination.
One other note: if you go this route you will need to do away with your ballast resistor. The coils in the tech tip are 1.5 ohms, The DC1-1's are 3 ohm.
Re reading this post I noticed that you have an 81LH so you won't need to worry about a ballast resistor. Your bike has the 3 ohm coils originally.Last edited by cajun31; 12-18-2024, 04:10 PM.2 - 80 LGs bought one new
81 LH
02 FXSTB Nighttrain
22 FLTRK Road Glide Limited
JimComment
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The Dyna coils are nice. Don't buy the Chinese counterfeit units. I noticed a big difference in performance.Originally posted by cajun31 View Post
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Thanks for the input. Was looking at Yamaha oem coil replacements. Can anyone loan me a arm and leg? Lol81 LH in process
09 vstar 1300
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I'd go with NON-RESISTOR caps and resistor plugs first before deciding to start throwing money at the problem hoping it fixes it. Non-resisor plugs are getting harder to find so in this case it makes sense.
I'll never forget an old school mechanic telling me one time "I've only seen a bad coil ONCE in my entire career" On my bike I swapped my coils over to 3ohm Honda coils off a 88 750 Nighthawk in order to eliminate the ballast resistor and also change the wires and it works well. A lot of people like to spend big bucks on things thinking they're getting something better and if you've got $200 to spare for a set of coils then by all means go for it! Mine where $20 each.
1980 XS1100G
I identify as a man but according to the label on a package of Stauffers Baked Lasagne I'm actually a family of four!Comment
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Yes, I agree that a good used coil is better quality than most new coils these days (especially Chinese junk coils). Make sure its 3 Ohm like LAB3 mentioned. Another good feature to look for is wire nuts which make putting on new high tension wire easy. Non resistor ends are good also. You will get hotter spark.
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