Troubleshooting help - sudden loss of power

[Roostabunny]

not to ba a PITA but have you assured that you plug cap and wire are OK

I dont recall seing that in this thread

but then its a long thread

There's been a little electrical talk, but not that specific question. I got a good spark from a fresh plug, but is there something else I can do to test the wire/cap?

[Calvin Blackmore]

well my best test is a cheap one
trade cap A for Cap B and if the problem moves then you have found a culprit.

I find spark hard to gauge by eye especially in daylight

[Calvin Blackmore]

oh also when you checked your diapraghm spring ddi you doa visual inspection for tearing or any tiny pinholes in the rubber

if one is leaking the machine would run rich i believethis could be fouling the plug as well

[Roostabunny]

OK, oil leak solved. \\/

My cam cover gasket had worked its way out in an inner corner. Loosened up the cover bolts and was able to squish it back into place with a gentle nudge from a screwdriver. Let's hear it for Real gaskets. Fiddly but forgiving.

After doing that job with the horns still attached, a nice 10mm ratcheting box wrench (like those slick Gear Wrenches) sure sounds nice.

Now back on the road and see what's up with #1.

[Roostabunny]

well my best test is a cheap one
trade cap A for Cap B and if the problem moves then you have found a culprit.

I find spark hard to gauge by eye especially in daylight

Am I doing this wrong? I swapped #1 and #2 wires on the plugs, and it wouldn't start. Swapped 'em back, and it started up.

[TheCafeKid]

Yeah. Cant swap the wires. Only the caps. 1 and 2 are different coils.
1 and 4 are the same coil, 2 and 3 are the same coil. You may be able to get 1s wire to reach 4. Try that, if you dont want to pull the caps off the wires.

[KEITH KRAUSE]

You also can't just swap leads 1 and 4 with 2 and 3. You also have to swap the ground terminals at the coils. Won't start until you do that. But you may get a big backfire if it tries to start.
Roost...I did mention checking the plug cap and lead connections. I always do if there's any possible spark issue.

[Roostabunny]

You also can't just swap leads 1 and 4 with 2 and 3. You also have to swap the ground terminals at the coils. Won't start until you do that. But you may get a big backfire if it tries to start.
Roost...I did mention checking the plug cap and lead connections. I always do if there's any possible spark issue.

Sorry Kieth - you did say that.

The coils scare me. Pardon my ignorance, but it looks like a big capacitor waiting to knock me on my ashtabeula. Do I need to do anything (e.g. disconnect the battery) before fiddling with the coil leads?

[KEITH KRAUSE]

Usually it's good enough to check for spark at the plug by removing the plug and snapping it into its plug cap. Be sure the plug is new or very clean so you know any weak spark/non spark issues are not plug related.
Place the plugs ground electrode firmly against the head and rotate the crank (in a dark area is best). You should see a decent bluish spark. In your case, compare the spark to one of the others that hasn't any issues. If the spark looks similar, then you have spark and I'm assuming the spark is healthy.
Now if the spark at #1 is orange/weak and not like the others, then you obviously have a spark issue and hopefully nothing more. Of course, I think you're burning oil but this is an easy to do check and is a basic maintenance item that needs checking regardless. First place you would check/clean would be the plug cap where it meets the lead. It must be free of corrosion and fit tightly when you snap it over the plug.

[Roostabunny]

OK, here's that #1 plug. Installed new then ridden for about 100 miles. Not quite what I expected - any thoughts?

Also, I compared the spark on a new plug between #1 and #4, and they looked the same to me. Wait - did I just check two plugs on the same coil?

[KEITH KRAUSE]

Yes, 1 and 4 are on the same coil. Comparing them is the right thing to do.
If they look similar now, I'm not sure what's going on that would cause #1 to lighten up.
Is the problem still there?
Do you now have the correct brand and heat range of plugs, NGK B8ES? Pics comparing 7 and 8 plugs don't help.
Unless you've made a change we don't know about, only things that come to mind to change the plug color are different test conditions/throttle positions used, or, removing the plug cap to change the plug has helped improve a poor/dirty connection simply by movement. Also, did you actually check/adjust gap with a feeler gauge or proper tool? Gap should be approx' .027" unless your manual states otherwise. Don't guess about the gap, too important.
Another thought is if this bike hasn't been used much up until the problem appeared, it's possible that regular running has helped minimize any oil leaking into the combustion chamber. I've seen and heard of leaking oil and water/coolant seals improving somewhat simply by being in service vs not being in service. Now if the bike has been running regularly the whole time before the problem appeared, then disregard this last thought.
Again, I know plug pics are difficult to judge, but that plug looks a little odd still. Much better than before but there's still a sheen to the brown near the top of the insulator. Kind of shiny or glazed over and a little blotchy/uneven.

[Roostabunny]

Yes, 1 and 4 are on the same coil. Comparing them is the right thing to do.
If they look similar now, I'm not sure what's going on that would cause #1 to lighten up.
Is the problem still there?
Do you now have the correct brand and heat range of plugs, NGK B8ES? Pics comparing 7 and 8 plugs don't help.
Unless you've made a change we don't know about, only things that come to mind to change the plug color are different test conditions/throttle positions used, or, removing the plug cap to change the plug has helped improve a poor/dirty connection simply by movement. Also, did you actually check/adjust gap with a feeler gauge or proper tool? Gap should be approx' .027" unless your manual states otherwise. Don't guess about the gap, too important.
Another thought is if this bike hasn't been used much up until the problem appeared, it's possible that regular running has helped minimize any oil leaking into the combustion chamber. I've seen and heard of leaking oil and water/coolant seals improving somewhat simply by being in service vs not being in service. Now if the bike has been running regularly the whole time before the problem appeared, then disregard this last thought.
Again, I know plug pics are difficult to judge, but that plug looks a little odd still. Much better than before but there's still a sheen to the brown near the top of the insulator. Kind of shiny or glazed over and a little blotchy/uneven.

Yeah, I don't get it. I'm still not at full power. Runs the same even with a brand new plug.

Yes, that plug is a B8ES and I did check the gap - it was within spec according to my manual (.024-.031"). And I've been commuting about 50 miles per day since August.

Your description of the plug is right on - that's exactly what it looks like in person.

I'm going to turn my attention to the carbs - see if that slide's sticking, check my mixtures, and re-sync and so forth. If it makes any difference, I'll rebuild the carbs. Had that on the list anyhow, and already have my O-ring set. Meanwhile, I'll continue to watch that plug.

[KEITH KRAUSE]

Hmmm. Sure would like to know what the spark looks like. Plug does look much better at the moment. You have good compression you say. Valves adjusted. Fuel is entering the cylinder. But a sudden lack of power, still happening.
Go ahead with your plan on checking things. Add to that checking/verifying the ignition advance is operating correctly. I believe yours isn't adjustable but I'd still verify the timing marks are lined up as they need to be.
I still don't know how the plug color could change so much without any changes. Because combustion has been so obviously different at cylinder 1, I've focused on the problem being at #1. Now if your fidding with the plug cap could improve spark by helping a poor connection make a better spark, then I can see the possibility. You still never said if you checked or cleaned any connections. However, I still think the plug looked oily and oil would have nothing to do with other tuning/maintenance issues.
I'd check the timing too because if for no other reason, it's a "basic" tuning item that should always be verified anyway. Quick and easy to do.