Relay mod to get full volts to the coils

[KA1J]

I've read some posts regarding this and one of the links explaining how is this one http://www.wgcarbs.com//index.php?op...d=12&Itemid=26 and I'm wondering if I can just remove the red/white wires from the coils, join them together to connect to terminal 86 and use that as a voltage source?

I'm not sure where to find the proper location to tap off the wire coming from the kill switch on the XJ11 but the r/w wires going to the dynacoils are easy to get to.

My battery with the ignition on reads 12.2V but to the coil it reads 10.01V so it's markedly reduced. I don't trust the wiring on the bike as there are some wires that are unconnected and wrapped in tape. But Just today I started getting familiar with the electrical system & removed the cover to the fuse panel & the PO did me again: two fuses were replaced with glass in-line buss fuses. One had the original wires & connectors left attached to the original fuse but it was no longer attached to the fuse box & was "floating & was wrapped with aluminum foil so as to never blow. The last fuse was left on the fuse box but it too was wrapped in aluminum foil so as to never blow. I am so lucky nothing bad happened electrically because of that stupid botch job.

So my first thing is to convert all the fuses to the flat terminal fuses and the second immediate goal is to get full power to the coils.

[bikerphil]

Yes, the red/wht that powered the coils (+) now goes to 86. I have this mod on both my bikes, I am sold hotter spark = runs better/better mileage. I hooked my main power feed (fused) diredtly to the battery instead of the solenoid.

[XJOK2PLAY]

Hey Bikerphil...

First time for me to hear of this mod. Question: Is it for an XS11 only, or would it work for an XJ? (Wondered, due to the electronic timing control of an XJ TCI...)

Does it seem to help an 11 start faster? I've seen many 11's that seem to be in top shape, yet crank forever when they get hot. I often wondered if coils & weak spark, after they get hot, were the cause? Those same bikes run great, once they start...that is...

[bikerphil]

It will work on the XJ, anything with 3 ohm coils. Don't know about bikes with a ballast resistor and the 1.5 ohm coils though. I always thought the hot start problem was leaky float valves slightly flooding the carbs. Pair this mod with side gap spark plugs and your golden. I know there are a few members that might disagree with this mod, preferring to clean/replace every wire/connector to increase coil voltage.

[XJOK2PLAY]

Thanks, Phil.

[KA1J]

Thanks for the info, that's what I needed to know. I guess I really only need to connect one of those R/W wires to the relay 86 as it's the trigger saying voltage needs to be applied & then I can shrink wrap the other terminal.

For that matter, I suppose one could leave the R/W attached to the coils, run a jumper from that attachment to terminal 86 and then run the pigtail from 87 to the R/W connection on the dynacoils. ( just to keep the original wiring in place but still get the benefit of the full voltage ). Maybe that's just extra work...

I went to Autozone to get the replacement fuse terminals & looked for a relay & the only one they had was $15. Advance had one for less than $5 and another for $7. I chose the $7 one because the terminals looked to be brass which might hold up better than the steel looking ones on the cheaper relay. Here on the coast, corrosion is always a concern.

[KA1J]

Another thing I noticed was if I touch bike ground and then touch the plug caps, I can get a pretty good jolt & that's with 10.1V to the coils. It happens on each plug cap so it's not one defective cap. Don't feel a thing on the plug wires, I guess the original caps aren't great insulators.

There used to be some spray you could lay on your distributor to prevent arcing to the outside, it was a high voltage spray. Nowadays you don't see those things on the market. Wondering if this is a job for liquid tape or if it even matters...

[DAVINCI]

This is voodoo electronics. Let me not repair the problem but install a bypass and three more failure points (relay feed, relay ground, coil connection). Huh?

Sure, this connection will work, but it's not good practice. Does it give you any higher voltage there? If it does, you have a problem in your wiring harness and connectors and that's probably not the only issue in your wiring.

Have you tested your voltage on the red/white at the coils with the red/white unplugged from the coils? I'd bet if you do, you'll see a higher voltage cause with it plugged into the coils you're seeing a drop through the coils to the TCI. This condition is normal.

Adding points of failure is not normal.

[bikerphil]

If the setup failed (knock) I would just have to connect the trigger wire back up to the coils and away we go.

[cywelchjr]

What Randy is saying is this is trying to shortcut around actually fixing the real problem, which is a wiring problem of some sort as you should NOT have a voltage drop to the coils. If you do, it's because you have problems with connectors or something similar. Now, I might be inclined to to some current checks and wire size comparisons to see if wire size and length might be an issue, as that could make the relay a more reasonable modification.

[crazy steve]

What Randy is saying is this is trying to shortcut around actually fixing the real problem, which is a wiring problem of some sort as you should NOT have a voltage drop to the coils....

In a perfect world... I'll semi-agree with Randy, as adding another set of contacts and the additional connections is a bit of a band-aid over the underlying problem. But, given the OEM harness wire sizes (barely adequate IMO if everything is perfect) and 30+ year old switches and plugs, it can be tough sometimes to get the wiring and all those contacts/connections back to 'like new' performance. Depending on what you're working with, a relay can be more 'cost effective' rather than tearing the harness apart and/or replacing switches.

With that said, I probably wouldn't install a relay, but it is a solution....

[KA1J]

All things considered, I decided to do the mod. I tried finding where in the wiring harness the volts were encountering resistance enough to drop them 2+ volts but it didn't become apparent & since all else works cept the L side emergency flashers (which I'll get to this winter), I went the quick route and did the mod.

I really can't tell much of a difference in that I was using the dynacoils already but there is definitely close to 3 more input volts to the coils and I know that makes a functional difference n output. It is a comfortable feeling knowing I'm getting full KV to the spark plugs.

This winter I'll go over all the connections on the bike & make sure they're clean and the connections are solid. I was going to use a fuseblock to replace the original but decided instead to use separate in-line spade lug fuses with a protective cap on top. I got them soldered in a couple days ago and they're fine but that didn't increase the voltage to the coils.