GSman Posted October 31, 2005 Share Posted October 31, 2005 96' 1100RT...42k.. bike starts acting weird this weekend.It is running at a lower idle and now has a miss through out rev-range. Get home, pull both plugs, right side is richer than left. Swap both plugs around . Leftside is clearing up, right side is worse so now we know it is the right side with issues. Take a spare plug (just changed to new plugs 1k ago), pull one lead at a time and look at spark while the bike is turning over/sorta running. Right side has weaker spark, so now we've narrowed it down to either coil or wire I think. Tonight I'm going to pull the right wire and check for resistance. Am I on the right path here ?? . I don't even know where the coil is on this thing but will look it up in the manual tonight. Has anyone ever tried to measure the resistance on a wire with acceptable results for troublshooting ?? I'm trying to do the right and not shotgun it with 300$ worth of parts because I'm intimidated by trying to find the true answer. Thanks for all the help ahead of time Link to comment
ShovelStrokeEd Posted October 31, 2005 Share Posted October 31, 2005 Yeah, your on the right track. Yes you can measure the primay and secondary resistance of the coil and the spark plug wire. Careful to get good contact with the conductor on the wire. I don't have the specs at hand right now but it might look something like coil primary 4 ohms, coil secondary 2K ohms, plug wire 3 to 4K ohms. These are just WAG as to actual numbers you'll have to wait for someone with the information closer to hand. Other places to look are ground at the coil bracket. The secondary circuit grounds through the coil body to the chassis. If things are corroded there you could wind up with a weak spark. The actual path is through the plug wire, to the center electrode, across the plug gap to the side electrode(s) to the cylinder head and through the engine block to the chassis and then to the coil bracket but that's too long to type. Link to comment
GSman Posted October 31, 2005 Author Share Posted October 31, 2005 Thanks Ed !!! I have the manual at the house, so I hope to find the specs in that ...I'll keep you tuned in.. Link to comment
Joe Frickin' Friday Posted October 31, 2005 Share Posted October 31, 2005 Strange that the right side would have a weaker spark; it's a single coil that fires both spark plugs. Or at least this is how it is on a '99 RT. Was it this way on the '96 bikes? Link to comment
ShovelStrokeEd Posted October 31, 2005 Share Posted October 31, 2005 I'm pretty sure it is. My '94 has only one coil. I think they are single primary dual secondary though so it may still only show a problem on one side. Wouldn't hurt to measure from secondary to secondary. Should show twice the resistance. Link to comment
Ken H. Posted October 31, 2005 Share Posted October 31, 2005 Was it this way on the '96 bikes?Yes, all 1100 & 1150 series up to the dual-plugers have the 'wasted spark' single coil cycle. Link to comment
GSman Posted November 2, 2005 Author Share Posted November 2, 2005 Well...it gets weirder...I just double checked my self..Had bike running, albeit rough, and pulled each boot from the plug. Left side, I can hear the spark snapping as it's jumping to ground. Pull the right side (the one with the dark plug)...no snap, ( it is sparking, just weakly compared to the left)so I swapped plug wires after measuring the resistance (6k ohms ..same on each one) and the right side still has a weak spark. So with the dual spark coil, is this possible? It seems as much as the coil fires both sides at once (like a Harley my dad says), is it possible that the right side of the coil is weak ? I did some resistance checks across the 2 plug wire terminals coming out of the coil and got 7.23K ohms. The manual mentions measuring primary and secondary and gives pin#'s for this measurement, but I don't know how they correspond to the coil...am I at the point where I just buy a coil or should I dig in deeper ? Link to comment
Ken H. Posted November 2, 2005 Share Posted November 2, 2005 If you have both plugs pulled at the same time, do they spark equally at the same time? Unless anyone else has any brilliant thoughts, I'd say try a different coil. Any buddies around with a 1100 series R bike you could do a quick coil swap as a test? Link to comment
GSman Posted November 2, 2005 Author Share Posted November 2, 2005 I don't know about the spark when both pulled, but I don't have a spare to try,it's all or nothing. I think that by swapping around plugs and wires that the coil HAS to be the issue. If it was up stream of that (the trigger itself), then it would affect both sides eqyual. Am I asking for trouble by getting a used one ? beemer boneyard has one for 30$ on sale... Link to comment
bmwmick Posted November 2, 2005 Share Posted November 2, 2005 If Mike has one at the Beemerboneyard.com , buy it. Never hurts to have that spare around. Primary coil circuit should measure about 0.5 Ohms and the secondary should be either 7.5K Ohms or 13K Ohms. My 9/1995 R1100RT measures at 13K Ohms on the secondary, some folks have reported 7.5K Ohms on later bikes. Mick Link to comment
SWB Posted November 3, 2005 Share Posted November 3, 2005 Don't forget that operating temperature can change resistance readings on any electronic part. In fact, "intermittant" failure is common with electronic parts. They may work fine while cold, but as they warm up, elect. contacts, shorts in wires, and etc. can open up a bit with normal expansion. After running 15 minutes, the electrical part suddenly doesn't work quite as well. Eventually, the part will completely fail, but it can be quite a pain in the b*tt while its slowly dying. Link to comment
GSman Posted November 8, 2005 Author Share Posted November 8, 2005 Well, I got a used coil in from the Beemer boneyard and the right side was snapping just like the left after i installed it. Fired the bike up and the bike was still running weird. I sat and tried to run through the basics. The bike ran fine at idle, but was rough when giving it throttle. I hooked up my vaccum guage and it was pulling way early on the right. Re did the synch and she runs like a top. I had replaced the throttle cable a week before, but had ran fine for 150 miles before this started. All I can think is it was a combination of a weakening coil and some mis-adjustment on my part of the cable after installation. She runs like a top now and thanks to all you for the suggestions !! Link to comment
ShovelStrokeEd Posted November 8, 2005 Share Posted November 8, 2005 Prolly adjusted the cable to compensate for the weak spark. Remember - valves, compression, spark, sync. Link to comment
GSman Posted November 8, 2005 Author Share Posted November 8, 2005 You are so right grasshopper. I forget about spark as part of synch equation .... Link to comment
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