Coils

[Love Eagle]

Hi I am new here and to the XS ball game . I just picked up a 1979 XS 11 s with no spark . I found a separated wire on the pick up coil and got it running on 2 holes ! Question Would one separated on the pickup coil negate spark to all four cylinders ? I now have spark in all four but 1 and 4 pipes are warm but cooler than 2&3 ? The spark looks the same almost on all 4 and compression is 165-170 psi across all cylinders . Fuel is good and new fully charged battery . I do not have any history of this bike ! It shows 68000 Km on the odometer and was last registered in Manitoba in 05 with 66000 km ? Fuel is clean and flowing good after new lines and a clean up ! I suspect a bad primary coil is that my next step ? I am north of Edmonton at Clyde Alberta ! Any Alberta Members here that need a good parts bike LOL ! Any of your input shall be greatly appreciated Thank You for Your Great Site and all You invaluable information ! How do I get into My Profile here to updated it ?

Thanks in Advance Dwight

[natemoen]

Welcome!

One broken wire will not kill spark to all 4 plugs. There are 2 different pairs of wires that come from the pickup coils and each pair is a separate circuit.

with that said if it 1 and 4 that are not warming up it points to an electrical problem because those 2 are paired together electronically. Try swapping the small wires going into the coils (I think they are orange and grey, but it is NOT the red with white stripe wires) between coils and see if the problem switches to the #2 and #3 cylinders.

[Love Eagle]

Coils

Thanks Nathan

The wires to the primary 2 coils not the pickup coils is that correct ?

We should be out riding on a nice day here ! I ride an 03 Yamaha Classic all piped and chromed up with 16000 km on it that I do not need to work on LOL ! But the oldies are fun and a challenge at times ! I remember getting waxed by a XS 11 back in the day in a Drag race on my KZ 1300 Dressed in line Six so when I saw this XS that a Harley buddy had given to him I had to rescue it LOL ! He would not take less than $ 300 for it though so when I got it home and had no spark I got a bit tense ! Have a Perfect Weekend ! And Thanks Again !

Dwight

[natemoen]

Correct, the wires to the primary ignition coils not the pickup coils.

[DGXSER]

Whoaaa, if you switch the grey and orang, you also switch the timing and the bike will not run. You will also need to swith the plug wires from 1-4 to the 2-3 cylinders and vice versa. Now, if the problem moves it is in the coil, or its plug wires. If it stays the same, it is probably the pick-up coil wires.

[natemoen]

There I go typing faster than I think. Good catch DG.

[CaptonZap]

And to compound the problem, the stock high tension leads are not quite long enough to do the switch.
If you ohm the high tension leads on both coils, from lead to ground, and they are all close, you can probably assume that both coils are OK. If there is a marked difference between the two, then you might look into the R&R routine.
Fouled plugs can contribute to that sort of situation, so you might try new ones, or at least blast clean the one you have.
One test that can be done is to rig up a spark gap that can be varied in distance. Try the good coil, opening up the gap till it wants to quit if you go any wider. Don't do it for more than a second or two, as you can damage the insulation in the coil.
Then try the other coil and see if it will push a spark across the same size gap. I take the plugs out of all cylinders when doing this, making sure that the coil not under test has a plug on the both wires, and the plugs laying on the engine head.
The coil under test has one lead away from everything, and the other one to the spark gap. It doesn't matter which lead you use, the only difference is which way the spark jumps, and you can't tell by looking. I've found that if you can get a spark across a 1/4 inch gap in open air, you have all the spark you need.
YMMV, CZ

[DGXSER]

Not sure who cut your leads back CZ but I have done that swap several times with stock coils.

[TopCatGr58]

Hey there Eagle,

Others have already answered your bike tech question. Not sure what you were trying to do with the POLL, there's NO QUESTION in the POLL, so folks don't know what to VOTE FOR.

As to the Profile.....if you'll look at this page...the blue menu bar across the top with the topics like User CP, FAQ, Members List, etc..... you need to CLICK on the UserCP(control Panel), and there you can then edit your PROFILE info.

I'll be CLOSING YOUR POLL since it doesn't really have a PURPOSE in this thread.

T.C.

[Love Eagle]

Thanks Guys ! Your Awesome ! Just unfamiliar with the site TC is all sorry ! I will go test the coils !

L Eagle

[Yard Dogg]

These bikes operate on a wasted spark system. If you're sitting on the bike, the left side coil fires 1 & 4. It fires each cylinder on the compression and exhaust stroke, "wasted spark". The coil on the right fires the 2 & 3 cylinders in the same fashion. The two coils behave like a 2 cylinder engine even though this is a 4 cylinder. Be sure your sparkplug wires are in the correct order.

[Love Eagle]

Thanks Dogg

Well now I know my coils are good so now on to the carbs . It fires on all 4 on full choke ? I took it for a spin around the country block and it smoked everyone out on the Hy-way ? What should the compression be on these bikes ? It ran not too bad but the clutch seemed weak ? I did not try to adjust the cable yet . It still won't idle without the choke on ? It does start good however . Thanks again You All !
Dwight

[Yard Dogg]

You can adjust your clutch cable to see if that solves it, but if it still slips, don't go out and buy a new clutch just yet. The clutch springs on these bikes are weak causing clutch slippage. A lot of people buy barnett clutch springs and it solves the problem. What color is the smoke? If your bike will not idle without the choke on, then you may have some plugged jets. You should read the tech tips for carb building to get a feel for these before you do it.

[DGXSER]

Thanks Dogg

Well now I know my coils are good so now on to the carbs . It fires on all 4 on full choke ? I took it for a spin around the country block and it smoked everyone out on the Hy-way ? What should the compression be on these bikes ? It ran not too bad but the clutch seemed weak ? I did not try to adjust the cable yet . It still won't idle without the choke on ? It does start good however . Thanks again You All !
Dwight

Hey Dwight,

If it fires on all four with full choke, but even after warming up will not run well without the choke, then you most likely need to clean the pilot circuit in the carbs. The pilot circuit is small and needs to be pretty clean for the bike to run well.

Compression should be 142 + -10%. I have an SH that has about 100-110 PSI across all four, not as much power as it could have, but it runs decent. The + - 10% is more important than the actual numbers.

As for the clutch, do go through the cable adjustment first. Then if it still is slipping, you can start by replacing the springs. While the springs are not bad form the factory, they are 30 years old, and it is not uncommon for them to be weak and out of spec if they are the originals.