Tuesday, September 8, 2015


Some Stelvio owners have suffered from faulty spark plug caps. The symptoms are one cylinder goes dead from lack of spark, but the fuel is still being supplied. The fuel then is burnt in the hot catalytic converter which makes it hotter and significantly shortens it's life. This is not a good situation to be in and is best shut down ASAP.

The solution and fix is cheap and easy. A pair of NGK spark plug caps will save the day. These should at least be carried around with any owner in case a plug cap gives you grief far from home. NGK #SB05E

 Replacing the caps is straightforward. Pop the Guzzi logo from the 8V cover-

Remove hex screw and spark plug wire cover-

The careful way to remove the spark plug wire if you don't intend on replacing-

The original cap cuts off very easy and could be done on the side of the road-

Original rubber boot pulled from the spark plug wire/insulator-

 Unscrew insulator from brass stud crimped on wire end-

Use a knife to cut through wire near the crimp end. Use wire cutters to finish-

Place NGK boot on wire, twist NGK cap as far into the wire as it will go-

Slide NGK boot over cap to seal-

 Firmly place over spark plug, replace cover and logo- DONE!


  1. Nice job.
    I did the same, but used the all-rubber NGK caps.
    They're a little longer than the plastic ones, and the tops stick out from the Valve Cover a little, but as they're rubber, they fold down OK under the Lead Cover.
    Means you can easily pull on the Caps themselves when removing.


  2. Hi John , would you still have the NGK part no for the rubber caps ?