Spark Plugs can be one of the many issues of why your Lambretta won’t start, or why it has issue while it is running. It’s always a great idea to carry at least one or two spares in your scooter or in your jacket. Leaving them in the box is ok – but the box seems to crumble up so maybe a smaller sturdy container is ideal.
So seems that most of us use NGK spark plugs. NGK is the plug that this piece will be on.
So a spark plug is identified with numbers & letters. What do they mean? The various numbers and letters in a spark plug code or identification numbe, basically identify the features and functions of a particular plug. Included would be information such as plug type, heat rating, construction, thread diameter, thread reach and firing end construction. What we Lambretta riders need to know when we get our plugs: a standard plug for standard riding is 7 or 8. If you ride WOT or seem to be out in the straighaways/ roadtrips/ interstates/ keeping the r.p.m.s up a 9 may be your number. So that’s a B7ES or B8ES or a B9ES. Every scooter is different deepening on where you live, desert vs. mountains, tuning, and modifications. Starting at 8 is safe and plug checks are a recommended necessity at first to know what your scooter likes. The range can be 6 in some cases or 10…if this is you, then you probably won’t be reading this anyway.
Once a plug is in it’s good till it’s fouled….Of course the best thing to do is gap it accordingly If you’d like to get the most out of your plug: suggestions are- 0.020-0.024in for 4 pole systems & electronic ignitions & 0.018-0.020in for 6 pole systems (as suggested in the Sticky's Spanners guide). Experiment a bit to see is you can see a life span. Some folks re-use plugs but for the most part it can work in a pinch – but for an item under $4.00 – why go cheap?
While we are at it, make sure your spark plug cap is a resistor model- as these seem to be better then what originally came on a Lambretta. Any clunky metal caps, chipped up, or brittle caps should be upgraded. Ask for NGK LB05F –These 90 degree plug caps feature tight fitting rubber waterproof covers and positive attachment mechanisms on both ends for shake-proof grip.
If you know of another brand or have experience please add it.
Edited by k-dog