Bitten by the misfire bug

[Mudhen]

Hey dudes...my Steamer has been bitten by the misfire bug and I'm in need of advice.

Background - was riding.  Started to run rough at idle/part throttle.  At about 4k RPM she smooths out and comes on strong, though.  It smoothed out the other day for a couple miles...then right back into the stumbling.

Have tried:

 - cleaning carbs
 - replacing coils (one at a time)
 - looked at spark plugs - #3 had deposits on it (cleaned them all but haven't replaced them yet)
 - plug wire #2 was completely loose on the plug - replaced wire with another one I had lying around (thanks Zahi)
 - cleaned carbs again - this time using Mustangs thread - little jet (that the pilot jet?) looked clogged so I cleaned it out - they all look good now - was soooooo sure that was it!!! ARGH
 - felt exhaust header pipes and they're all hot
 - put ice on fingers

My biggest clue right now is that if I pull the coil wire off the #3 coil the bike continues to run the same crappy way...but if I pull any of the other coil wires the bike dies.  Can I measure voltage at the coil wires - what should I get there?

Thoughts/suggestions greatly appreciated.  I'd like to keep 'er running until my new one arrives in March.  

Thanks

[BruKen]

What colour is No3 sparkplug?

[Mudhen]

What colour is No3 sparkplug?

Top is white...I think it says NGK on it.  Bottom is silvery..

 

It was grayish...definite deposits on it.  Wasn't black/sooty at all.  I rode the bike about 300 miles since it started acting this way.

[BruKen]

Well it doesn't sound like carbs then and if you changed the coils around and still had the problem I'd start checking the wiring loom for loose or poor connectivity, the valves for clearance and check for leaks around the rubber manifold boots.

[Mustang]

valve clearances if it's always #3 with the coils swapped around and have you ever synced the carbs ?..............

and you have mikunis don't you ? what do the tubes that the needle jet ride in look like ?

[Mudhen]

valve clearances if it's always #3 with the coils swapped around and have you ever synced the carbs ?..............

and you have mikunis don't you ? what do the tubes that the needle jet ride in look like ?

Have I ever synced the carbs...why I oughtta...

Of course!  Just did it in fact!  15k miles ago...I guess mileage flies when you're having fun.  They days all seem to run together...my kids are getting the best of me...

From memory I'd say I just did most of this stuff.  But in looking at the old spreadsheet...valves, emulsion tubes were done at 42k miles.  Synced the carbs at 39k.

Maybe I should actually do the 48k mile service...hey, there's a thought...

Edit:  the bike has a little over 51k on it now

[Mudhen]

You know what, though...I went up to York the other day to grab the tag...and it ran crappy for the first few miles, then cleared up for a couple miles (where I proceeded to REALLY enjoy it), then it ran like crap again.

So I'd think that may rule a bunch of stuff out...that it fluctuates some.

It does seem to be running a little better now I've cleaned the carbs...but I can make out a slight backfire.  I may run it some and see if it can clear its throat.

[Mustang]

It knows you been thinking about cheatin on her with one of them new fangled 800 adventures :D  :shock: seriously check your valve clearances on the intakes has it been starting hard ?

Want me to bring some nologys over to rule out coils and plug wires ?

[Mudhen]

It knows you been thinking about cheatin on her with one of them new fangled 800 adventures :D  :shock: seriously check your valve clearances on the intakes has it been starting hard ?

Want me to bring some nologys over to rule out coils and plug wires ?

No, starting fine.

I just put these nologys on 7k miles ago...tried swapping back one of my old ones in each place and it didn't help.  Maybe I'll try swapping them all back.  I'm lucky right now because I have the '95 parts bike...  :lol:

I was going to throw the tank on and take 'er for a spin.  Maybe I'll check the valves first while it's open...just to rule it out.

How about the coil wires - should I have intermittent 12v on one of them to each coil?  Although, I know I get some voltage to #3 as it sparked a little when I yanked it off...

[Mustang]

are absolutely positive you got the pilot jets clean especially on #3 ?

If so try riding with the gas cap cracked open and see if it starts to run rough or not  you could have a plugged vent or better yet try the tank off the 95 on it .
 Hell for that matter just keep stealing parts from one until you fix yours and then you'll eventually find the culprit to the rough running .

[Rocinante]

You may have tried this but if not, here´s how I pinpointed my recent poor running to the carbs:

Take it for a ride and when it runs poorly try accelerating starting at slow speed in all gears. Keep a close eye on the rpms and the throttle to see whether it smooths out above a certain level of rpm or at a certain position of the throttle.

In my case it was the throttle position that decided how it was running, independent of the rpms. Hence, the problem was most likely, and in fact, the carbs.

It was finally pinpointed to the pilot jet on the centre carb, and after blowing through it with carb cleaner and compressed air, it ran fine again.

Just my non-mechanic 2-cents...

Dag

[Mudhen]

Thanks guys.

Yes, absolutely sure I got the pilot jets clean...I chased them with a strand of wire.  I just checked the valves and they look good.

Dag - if you were standing in front of me saying that, you'd get to see my deer in the headlights look...but now I've read it a few times I think I understand what you said.  

Will probably button it up now so I can take it for a ride and will try it out!

Pat

(and if it's still running rough, watch out Zahi...because your bike is going to be my new parts bin!)

[Mustang]

(and if it's still running rough, watch out Zahi...because your bike is going to be my new parts bin!)

[Zizi]

:?
I need to check these forums more often!  Make sure Pat hasn't started selling off the parts to my 95.  
Anyway Pat, at least I don't go riding around on a baby blue scooter, like some people I know.   .

[Mudhen]

Finally got around to stealing the uh, 'extra' set of carbs in the garage and putting them on my bike...no difference in the running condition.  Backfires and sputters still.  And pulling one of the low voltage wires off the #3 coil still has no effect...but pulling one of the others kills the bike.

I swapped the #3 coil with #2...problem stayed the same.  I also pulled the plug out of #3 and verified that I have spark...

Maybe I'm too focused on #3?

Since it has spark, maybe it's just not firing at the right time?  Where's the distributor on this thing...I could replace the points/condenser  :lol:

Maybe the ignitor box?  That's only $1k...pop down to Great Bay and pick one up.  :roll: