1981 XS400 Special, no spark

[Scary]

Hey gang, I purchased a 1981 XS400 special from a buddy in my classic car club, This bike only has 15k miles on it. The bike was running back in November but it was parked and the gas tank drained.

I got it, replaced the battery, put some gas in it and have been trying to get it running again. The front brake caliper was stuck, so I got a c-clamp and compressed it a few times, and that seems to work now.

I changed the fuse to the electric starter so now it turns over but I can't get spark to the plugs. Should I suspect the coil under the tank or should I keep trying to open the points cover and is there anything I can do in side it once I do get it open? I can get the plillips screw off on the left but the right is stripped out and before I drill on it I want to know if it's even worth it to open it?

Cosmeticially the bike looks almost new (I posted an album but not sure how to link it here).

Thanks
Greg

 

[xschris]

The bike has a TCI ignition so there are no points. Make sure all the other fuses are good and all the connections are right. Also the bike is set to "run". I only say this because some people have done it

 

[Scary]

Thanks Chris, I shall resist drilling that brass cap then.

ill see if I can locate all the fuses and check the coil pack as well.

I did notice the Electric starter won't kick off unless it's set to Run so got that covered. LOL

 

[xschris]

There is an ohm test for the pickup that is under that cover. It is in the manual. It would be one more thing to test if other things are good.

 

[Scorpio1963]

Check the connections to the kick stand relay,if they are not making good contact your bike wont start.They are little bronze boxes attached near the bottom of the frame on the right side.Your bike should have 2 of them but maybe only 1.Either way if they are bad also your bike wont run.Make sure your bike is getting spark and fuel.

 

[Scary]

Thanks, it is getting gas just fine, but no spark. The kickstand should be down to start is what you're saying? Ill look for the relays tonight.

 

[user11206]

The Seca has a cutoff relay under the seat, not sure if the 81 is the same but mine had an issue where is was grounding out through that relay. Unplugged the relay and it now functions so I am wondering if you might have the same thing which is grounding your ignition.

 

[Scorpio1963]

the secas have the same relays as the 81 I believe.I know the xs doesn't have any under the seat just the battery and brain box.Hopefuly that's not the issue.If you need to find the kick stand relay relay there was a ton of them on ebay.I would but more than 1 of them.Good luck

 

[sproutroot]

Not sure about your SOHCs, but my '82 DOHC won't run when the kickstand is down. If I'm starting it in the garage it has to be on the center stand. Such a silly design. Took me 2 years to figure it out.

 

[Scorpio1963]

My 81 will run with the kick stand down or up.So did you find the source of your problem?You can always do a continuity test by turning on the key and checking the plug ins where the relays are.

 

[Scary]

I've changed out the coil packs under the gas tank. Still no spark. I also looked for a kickstand switch but there doesn't seem to be anything around the kickstand that is electrical. I'm still at a loss here.

 

[Scary]

So i've found under the seat, a suspicious level of inline fuses that has been installed at some point over the years. I'm wondering if any of these are my culprit.

 

[arfstrom]

Guessing the PO was not a member of our site.

 

[Scary]

Guessing the PO was not a member of our site.

he'd never heard of the site, no.

 

[BBS360]

"Fuse box? We don't need no stinking fuse box!"
Are they at least labelled somehow?

Just out of curiosity, are the extra leads on the batteries for a battery tender connection?

 

[Scary]

"Fuse box? We don't need no stinking fuse box!"
Are they at least labelled somehow?

Just out of curiosity, are the extra leads on the batteries for a battery tender connection?

Yes, there was a battery tender installed with the new battery.

 

[Scary]

So i wired in a brand new fuse box but still no spark. At least it looks a lot cleaner.

 

[Jtoroli]

Do you have DC showing up at the primary side of the coils? Just want to ensure there is no current there which will eliminate things downstream, coils, wires, resistor plug caps.

The resistor caps can disintegrate internally so as to cause spark issues.

Keep eliminating variables with your multimeter and your culprit will appear

Joe

 

[Scorpio1963]

Go through your wiring harness and near the front of the seat area is a tiny little resistor.Check and make sure its good.Its difficult to find so make sure you unwrapped the portion of the harness thoroughly.
Om my bike I check every connector to all the relays and such finding many that had bad connections.I cut them off bought a connector replacement kit and redid all them.