coil question on my 80 gs850 gt

[Guest]

Got low spark on number one cylinder,looking to replace oe coil with aftermarket any suggestions?

[azr]

A lot of people buy the Dyna coils, I as well, a good product. But you should try and figure out why you have a 'low spark' first before you buy a new part. Likely your coils are just fine, it's one thing on these bikes that seems to last for ever. And if you don't figure out what the issue is you'll just have some nice new shinny dyna's with 'low spark'..

[Steve]

Before you go to the trouble and expense of new coils, check the resistance from #1 to #4 (plug cap to plug cap). Specs call for something near 30k ohms. If it is much more than that, just unscrew the caps from the wires, trim about 1/4" from the wires and screw the caps back on. There is a good chance your spark will return to 'normal'.

While you are at it, do the same thing to #2 and #3.

.

[mottacycle]

What i did yesterday was the old stick a screwdriver in there and get it close to ground. It produced spark but only a faint blue spark. Then reved it up to 2500 still faint blue no change.(tells me that it was either the wire or coil. when i get off work ill report back here round 6pm PT thanks again

[azr]

that'll tell you if you're getting spark but the volt metre will tell you a bit more. Are you actually having issue's with that cylinder though?

[60ratrod]

another issue could be old corroded plug cap resistors. but like azr just said, you need to meter the resistance on the coils with a multimeter. that's about the only way to see what condition your coil is in

[mottacycle]

Azr it seems like i have a dead clyinder i pulled the plug and no heat marks still brand new. The pipe dosent even get heat!!!! I unscrewed the contact inside the boot and buffed it off,also there was a little pin behind that(im guessing to bridge the gap between the contact and the wire ) was covered in carbon so i buffed that as well ill get back tonight with pics and reading from meter. Thanks guys

[hannibal]

Before you go to the trouble and expense of new coils, check the resistance from #1 to #4 (plug cap to plug cap). Specs call for something near 30k ohms. If it is much more than that, just unscrew the caps from the wires, trim about 1/4" from the wires and screw the caps back on. There is a good chance your spark will return to 'normal'.

While you are at it, do the same thing to #2 and #3.

.

You say to unscrew the plastic L shaped caps, trim, and screw back on. Is it that easy? This thread suggests the caps are crimped on.

http://www.thegsresources.com/_forum/showthread.php?236315-is-there-a-tool-for-spark-plug-wire-ends

Am I just misunderstanding something?

[fastbysuzuki]

You say to unscrew the plastic L shaped caps, trim, and screw back on. Is it that easy? This thread suggests the caps are crimped on.

http://www.thegsresources.com/_forum/showthread.php?236315-is-there-a-tool-for-spark-plug-wire-ends

Am I just misunderstanding something?

i believe that the thread is for a gs1100 pretty sure the gs850gt is screwed onto the cable.

[60ratrod]

turbojohn is also using the dyna coils, which requires custom cut to length and crimped wires. stock coils have caps that screw on the ends of the leads

[wymple]

Stock caps whether molded or screwed on are easily replaced with aftermarket screw ons for chump change.

[hannibal]

Thanks for the clarification. I have NGK caps on stock coils. I was afraid of ruining the caps or HT leads. When I tested cap to cap resistance by sticking the multimeter probes into the caps where the head of the spark plugs usually snap on, I found 25 times the recommended level (about 800K ohms!!). I will remove the caps and trim the HT leads as suggested.

[rustybronco]

Those plug caps should measure under 10K ohm's. I suspect you'll find it reads much higher than that. If it does then remove the other three plug caps and do the same thing.

Replace those that are bad.

[mottacycle]

Alright guys I am off for the year!!!! Finally got some time. To check those plug caps 1and 4 read .645 and 2and3 read 30.8 while I am at it I threw plug four on cylinder 1 and plug 1 on clyinder4 still ran... pulled plug it died so what's goin on there....? Plug has spark to run #4 cylinder but not one... compression no good in 1 let me know what's up thanks

[Dogma]

It looks like you definitely have something going on between the 1 and 4 caps. $10-12 for four new caps would be a good start. Replace all four, because the old caps are likely cracked or otherwise not watertight, resulting in you getting stranded in a rainstorm. I recommend one pair each of NGK XB05F and VB05F. I like to get these (and many other things) from Z1 Enterprises, but their web store is apparently still being overhauled. I think they're still taking orders by email and phone. Anyhow, the new caps literally screw into the end of the wire after you put the little rubber boot on the wire. No stripping, no crimping. If the end of the wire looks like it has some corrosion, trim it until you have clean copper.

Nobody mentioned making sure you have good voltage supplied to the coils. All the switches, connectors and wires feeding the coils getting dirty and corroded can lead to cold spark (but should be the same between pairs). While you're in there, it's not hard to pop the connector off and see how close you are to battery voltage. A bike will run at 9V, just not nearly as well as it could or should, and may be on the verge of failing.

After saying all that, I can't say why cylinder 1 has no compression. Most often, low compression is due to neglected valve adjustment resulting in burnt valves. How much compression did it have, and how did the other three do? Surely it didn't have zero...