Gets up to operating temp and dies

hey guys so far I found the alt brushes are about 1/2" long, don't know if that is long enough or not, and there is no spark, battery cranking strong, but a littlle low so I added distiled water it shows 11.73 on my meter Thanks for the help

 

looks like I will be buying new coils the factory manual says the primary ohm reading should be 2.5 + or - 10% mine are 2.6 each secondaries are suppose to be 11k + or - 20% mine 29.76 & 22.32 the alt brushes are approximately 1/2 Thanks for all the help

 

if you take the caps off. the coils through the wires should show 11k. the caps are 5k each making an addition 10k. so if you measure at the caps. you've got 21k. within specs.

i'd be more concerned with the battery measuring 11.73. (if i read your post right) you might have enough to crank but not very fast and it's probably not enough to produce spark along with that crank. you could probably push start the bike. but not crank start.

with the plugs pulled out. you might get a spark.

a fully charged battery is considered 12.6.
3/4 charged is considered 12.45
1/2 charged is considered 12.30
1/4 charge is considered 12.15
12.0 volts and your considered dead. you might be able to crank. but odds are slim for a spark.

anyone been able to crank and still have spark under 12v????

 

Nope...

 

You definitely want to fully charge the battery and have it load tested at the auto parts store.

Alternator brushes have a "wear limit" line cut into their sides; if the line is gone they are past the limit.

These bikes can exhibit the phenomenon of spinning the motor quite vigorously but not producing spark-- this is the sign of a soggy battery.

Might also want to check the valves if you haven't yet...

 

The US models used 5k caps on the outboard wires (1-4) and 10k caps on the inboard wires (2-3). This assumes the original caps are in place. Most folks get the 5k caps to replace any that fail so measure your caps to be sure. I just measured a set of inboard wires this evening with another forum member and read 11k across the secondary high tension leads. I understand that the explaination provided in the book is rather confusing but you should see, through the caps, 21k for coil 1-4 and 31k through 2-3.

Amen brother, testify!

[quote="snowwy66]"anyone been able to crank and still have spark under 12v????[/quote]
Nope!

 

i was just thinking about that. that 2 and 3 measured higher. totally forgot about those 2 caps being 10k. shorter distance to travel then 1 and 4.

 

Nope![/quote]

Ahem.

BATTERY.

Either it's time for a new one or it's not being fully recharged by the bike or both. 11.73 volts ain't gonna fire an XJ, pure and simple.
You're gonna spend a whole lot of time (and money) chasing after all these relatively obscure deviations from specification when the obvious answer is right there. Further, if you don't deal with the battery, all the fussing over plug wire resistance and other minutiae, while being all well and good to attend to, will not fix your problem.



also...

I haven't seen a response yet as to when the valves were last checked...

 

Good Morning just got home from Church I have not been out to the bike yet answer to when valves last checked I have not checked them. I put a triclke charge on the battery over night will check that first as soon as I get out there. I do not remember seeing a limit mark so I will check that again, proably should just get new ones they are not that much save having to do it later
Thanks for the wealth of knowledge and willingness to share it
I will get back in a bit with the findings

 

I found thw battery after 11 hour trickle charge the multimeter reads 11.78 so I will get a new battery and start again

 

you can buy them at any auto parts stores. walmart too. autozone sold me one for suzi for $42.

 

Alright Thanks for that info I will go to Wally World (WalMart) & get a new battery

 

Turns out the battery was the problem. the battery reads 12.5vnot running it reads 13.53v running I will still order the brushes. tomorrow I will take it out for a test ride Thanks for all the help this site is the best

 

13.53 is good volts. it should go up to at least 14v when the throttle is revved a little. but your charging. that's the main thing.

 

I took it out today put on about 30 miles, no problems I shut it off check the meter reading the battery was at 12.95 so Thanks again for all the help and all the things to check I appericate it

 

That's good news. Watch the water level and monitor your state of charge after the next few rides.

Did you say the alternator brushes had no "wear out limit" line left?

Might want to go ahead and get them changed, based on your miles. Book says 10K, I think they just want to make you look at them. Mine on my '81 (550) still had lots of meat left past the lines at 18K, I'll be checking them again soon since I'm at 27K now. I'm betting I'll be replacing them around 30K miles...

Now about those valves... http://xjbikes.com/Forums/viewtopic/t=14827.html

 

Thanks bigfitz52 i did not notice any lines on the brushes so they are on the list to replace, and so are the new gaskets and doughnuts and the tool for adjusting the valves, I think I have mm feeler gauges, I have a 63 VW bug that forced me to start picking up mm tools shortly after getting the VW. This winter lots will be done, for now short rides till next time Thanks for everything