Stelvio spark problem?

[HarveyMushman]

I adjusted the valves this morning, buttoned everything back up, and connected my TwinMax and GuzziDiag in preparation for a TB balance.  Except now the engine runs like shit.  Rough, almost (but not quite?) on one cylinder, rich, trying to stall.  I pulled the clutch side spark plug cap off and reseated it, and without the plastic cover installed started the engine again--same symptoms--but this time I saw and heard orange sparks from inside the plug tunnel.  Killed the engine, sat down to type here.  Did I damage the plug cap in removing it? 

[guzzisteve]

Possibly. Do you have the newer wires w/flattened top profile? How did you remove the caps? 

[MLR]

Sure sounds like it to me. Try wrapping them up in electrical tape for a short term fix.

[HarveyMushman]

Possibly. Do you have the newer wires w/flattened top profile? How did you remove the caps?

Flat top, yes.  The clutch side was a bugger to get off the plug, so I admit to using some grips to pull on it.  Very stupid, probably.  Th other side I was able to remove with just my fingers.

I started the engine again after another reseat of the cap.  It ran better, maybe even normally, but I'm still seeing intermittent sparks from the tunnel. 

[HarveyMushman]

Sure sounds like it to me. Try wrapping them up in electrical tape for a short term fix.

This is ok to do?  I don't see any tears so any damage is inside the rubber boot.  Not sure how long it'll take to get a new cap delivered. 

[Lannis]

This is ok to do?  I don't see any tears so any damage is inside the rubber boot.  Not sure how long it'll take to get a new cap delivered.

If it's an earlier Stelvio, you don't want the new cap anyway.   They look tough and competent, but they fail almost immediately.

They need to be replaced with NGK parts.   You need to buy two $4.00 caps for each side.   One NGK cap has the right size fitting for the cable connection to the spark plug electrical connection, and one has the right size rubber grommet, so you need two pairs of NGK caps to do the bike.

Here's the history and procedure: http://wildguzzi.com/forum/index.php?topic=61267.30

Lannis

[MLR]

I used rescue tape on mine until I got new caps. It is heat resistant.

[HarveyMushman]

I used rescue tape on mine until I got new caps. It is heat resistant.

I wrapped the cap in some high temp insulating tape and the arcing seems to be fixed.  I couldn't find the replacement NGK caps locally so I ordered them from Amazon. 

Thanks, all!

[Wayne Orwig]

You are supposed to stick a screwdriver in the vent hole by the exhaust pipe and pry the cap off from below. If you pulled it from above, it is likely damaged.

I have had good luck painting them with 'liquid tape' to seal the cracks. Also cut off all of the worthless sealing 'fins'.

[Xlratr]

Just slide a cable tie underneath and pull.

[ChuckH]

Just slide a cable tie underneath and pull.....

Right!! That's how Jim B. at Rose Farms showed me when I bought the bike in '12.  He even installed a pair of cable ties, and I'm still using them.  Put your finger in the loop, wiggle it back and forth, then lift it straight up.  Works every time.  If you use a pair of pliers, vise grips, etc on the sides of the cap, you'll short it out every time.  Guaranteed.