spark

(82 750 maxim) I seem to have a few more issues than I thought with my new purchase, cured most of the backfire problems(carb) but still have some miss, and slight backfire, today was warm enough to work a bit on it, and found that when I pulled the plug wire for cylinder 4 the motor made no change and had no spark, after playing around with wire a bit I managed to get a slight spark (to my hand LOL) thru the boot. After reading a few other posts, I have learned that the 1 & 4 plug get spark from same coil, removed #1 and bike died. So I have to assume the coil is good, but have also learned that you can not change wires (atleast easily) another not is that plug for #4 is very blackened and was replaced a few days ago. Is a replacement coil needed?? if so, does anyone recommend where to get (except e-bay) any suggestions or help is very very welcome starting to get warmer here in Minnesota and excited to get this bike running well.

 

regulator,
You might try unscrewing the plug boots, and check the wire and inside boot for corrosion. The boot has a small brass screw inside that screws into the wires core. If the wire is corroded you can cut 1/4 to 1/2 inch off (go easy as you don't have much wire to work with)
While you have the boot in hand, check it with an ohm meter. I think it should be .5 ohms (correct me if I'm wrong).
Also check the wires for cracks and brittleness.
I think you can get replacement coils from Z1enterprises.com
Someone help me with the part# please.
You might look at some older posts also. I think this is discussed somewhere in more depth.

 

Thanks that is good start, did not relize the boots could be replaced seperatly, also have another question along that line, when I bought new plugs had to remove the top (screw on) to fit the boot is that common on these bikes? (sorry to sound ignorant but first time ive had to do that)

 

Yes you can't put the wire on the plug without removing the small sort of nut.

 

Here's a link from that might be of help.
You could also try swapping the coils and see if the problem moves with it.

http://xjbikes.com/Web_Links/l_op=visit/lid=29.html

 

Another thing I found on my 750 (and I'm guessing all XJs). They have an "ignitor box" which works basically like the old spark box on late 70's- mid 80's Fords. Mine would run good for a while and then just like a switch was flipped, start running (what seemed) like on half the cylinders. As I recall, this box on my 82 750 Max was behinde the RH (?) side cover (could have been the LH, Its been @ 8 years). It's about the size of a cigarette pack (regular) and has a cluster of wires coming out of it. It is an aluminum box all around except for the back side which is sealed with that epoxy stuff that likes to melt and make a BIG mess when things get hot. Mine showed a little sign of heat but I found that when it started run crappy, I could move the wires at the epoxy and make a change (it would hit on all 4). The nw one was gonna hurt at $400 + so I took it of the bike and dug down til I could get an ohm meter to all the wires on both sides of all the wires (where they go into the epoxy) and found (I think) the yellow wired had an open in it. 1 and 4 was what was quitting on mine too. Hope this helps and you can make sense out of this rambling.

Kelly

81 XJ 550 Maxim

 

You had the epoxy encapusulant melting on you Kelly???!!!!! That aint right in any way!!! Something is very wrong with that. I would pull that unit from service or at least make sure you have a spare with you at all times. I would also check the output from your alternator! Epoxy has to get to very high temperatures to do that (300 degrees or better). Big warning here. Don't let this continue, you could have an electrical fire! Be careful friend, don't want to hear that happen! Have you fixed the discontinuity? Good luck!

 

No No Robert. This was on a bike from @ 8 years ago. Alt output was good I just had a wire with a break in it. I gutted the epoxy down to where I could get to the wires on both sides of the epoxy and found the bad wire. Replaced it with a new wire, filled the box with silicone (its all I had at the time) and it ran like a watch the last time I saw it.

Thanks for the concern though.

Kelly

81 XJ 550 Maxim (which hits on all of um)

 

thanks guys again for the help, ended up changeing the "boots" per a friend at a local dealer and got the spark back, only thing is that they did not have the longer boots for the 2 and 3 cylinder (replaced all 4) and the wires are a bit cramped in reach the plugs. One problem ends and another began however, took out for a ride today, and with throttle full open in 5th gear only got a top speed of about 63mph?? now im at a loss sounds and runs good under 40mph but have really lost top end not only speed but torque as well

 

Have you done a complete tune up?

 

so far just a carb clean new plugs, plug boots, but have not checked valve clearance or anything really in depth