New Project - Electrical Problem

Hi,

I have just taken on an XJ550 (yes another one) and trying to get it going....

The carbs were completely jammed but are now well on their way to being ready for testing.

I charged the flat battery and decided to do a compression test while the carbs parts were soaking. Part way through testing the pressed the starter and it stayed on - I couldn't get it to shut off. I traced that to a fused starter relay and swapped the battery as I read if the condition of the battery was poor, the voltage can drop causing the ampage to increase thus fusing components like relays.

New starter relay in and managed to continue compression testing. The main fuse however got VERY hot (now struggling to type this as my finger is burnt!).

So my question is, what might be causing the main circuit to get so hot? Whilst compression testing I noted that there was no spark on any plug. (They were grounded to the case, the side stand was up but the bike was on the central stand - don't this this activates a saftey circuit does it?).

Any ideas guys?

 

Work stand hasn't got a cut out, but the side stand relay could still be at fault, disconnect it. With a new bike you will have to start testing the whole circuit, starting with the pick up coils.

 

And you shouldn't run the starter motor for long periods.

 

Definitely agree on not running that starter too long during a compression test, give it at least a couple of minutes between cylinders.

Does it still have the original fuse box? They are notorious for developing resistance, which then adds to heating.

It's easiest to just disconnect the TCI during compression testing. That way there is no risk of damaging the coils during the testing from spark plug wires that are not properly grounded.

Normal main current when the ignition switch is turned on is around 7 amps, and after 3 seconds will drop to around 4 amps as the TCI shuts down. The stock starter solenoid coil draws about 3 amps of current, so during compression testing the main current should be relatively low at around 7 amps.

Yamaha recommends removing the headlight fuse during compression testing to reduce the load on the battery - approx. 3.5 amps of load on low beam.

Safety circuit, like Wizard said, side stand relay could be an issue if no spark as it disables the TCI if the safety circuit is deployed or if it is defective. However, the safety circuit is two parts, and since the starter circuit is functioning, then the safety circuit is not deployed as a result of neutral or side stand switch failures. Therefore, if the safety circuit was causing no spark, then either the side stand relay or it associated wiring would have to be defective. Since the side stand relay applies ground to the TCI to disable it, simply unplugging it is the easiest way to test it for a no spark issue.

Good luck with you new project. I wish I could find a cheap 550. Thanks to this forum and the knowledge gained, the 550 would now be my XJ of choice.

 

I agree. You need to test the entire starting system, however, imo you should follow the manual and start with testing the battery. Record all data for spec comparison and future reference.

Gary H.

P.S. - a good visual inspection, electronics cleaner and dielectric + making sure all connections are solid prior to testing goes a long way when trouble shooting electrical issues.

Gary H.

 

Thanks guys. The fuse box is very suspect with non standard fuses in too so I have now chopped it out and put some mini blade fuses in. I also found the cable from the battey to the starter relay was about half severed when I check under the insulation tape so have replaced that. Run out of light to do more testing but you have each given some great tips to get on with tomorrow.

Electrics is not my strong point..... How do I use the multimeter to show the current being drawn at any one time? Do I just set it to the currect rang of amps and put it across the main fuse?

Bit of history with this bike. I got it off ebay a couple of days ago as a donor bike for my XJ550 bobber project ( which has been a 2 year long saga!). I thought I would swap the block and hopefully shortcut getting my bobber on the road. The funny thing is, the donor bike arrived and it is beautiful, better than I could have hoped. It was imported from Colorado... guessing the weather must be amazing there cos this bike hasn't any rust at all.

I want to get her running and may keep this one instead!

For a bike that looks mint, I would love to know how those carbs got so completely stuck. Reckon it must have been off the road a long time!

 

you can't check the current draw of the starter with any normal meters, if you had one that could, you would know it. your meter probably goes to 10A, the starter might go double that. then you put a fuse in the meter.
while your testing, it's a good idea to unplug the headlight and keep a trickle charger on the battery. your battery will thank you

 

OK, thanks for that Polock.

 

Some progress made..... the fuse box WAS causing an issue. I have replaced now with blade fuses.

Now the stater motor works without making anything hot! I am a bit puzzled with what I now face..... Number four plug sparks sometimes, none of the others spark at all. I have used a car battery to boost the bike battery just incase as the voltage on the TCI dropped a bit below the 10V spec when cranking. It didnt make any difference. I swapped out the coil feeding plugs 1 & 4 (with one I know works) and got the same result only sparking on 4.

When looking at the timing rotor arm, I couldn't see any sparks as it passed either point.

I swapped the TCI over and that made no difference either.

Any ideas anyone?

 

So how are you testing for spark?

Are you using new plugs?

Do you have a manual to check the continuity on the ignition coils, wires, caps, and pick-up coils?

You need a complete electrical path for proper testing with the wasted spark system, which means plug 1 must be installed or electrically connected to the head when testing plug 4, and plug 4 must be installed or electrically connected to the head when testing plug 1. Same is true when testing 2 and 3.

Current path for spark is from one side of the coil, through the plug wire and cap, through the plug, through the head, through the other plug, through the other cap and plug wire, and back to the other side of the coil.

 

I too found this important bit out eventually.. after I bought some new coils.