SFM 125 Roadster-8A Spark Plug K157FMI CR8EIX with 10mm Halfords Spanner

**dscheoff** · 01-14-2016, 11:59 AM

Posting to save someone else hours of research on this.

The bike is a SFM 125 Roadster-8A 2013
Engine = K157FMI with flat piston

-Changed the spark plug for a NGK CR8EIX (Iridium) the manual states D8RTC (but this one fits) - what was on there was a CR7E which is a hotter plug - I went by the LEXMOTO spec for SFM Roadster 8A

- You can put a CR8E on here, I went for the Iridium (IX) as a try out
- Halfords 10mm Spark plug Spanner did the job - finding what size socket was near impossible other than going in the shop and testing it!

**dscheoff** · 01-14-2016, 05:32 PM

Found this on the NGK Website when researching whether what going up to CR8E from CR7E really meant:-

http://www.ngk.com.au/spark-plugs/te...ge-explanation

Heat Range Explanation

Typically the heat range for NGK Spark Plugs varies from 2-11. This number indicates the thermal characteristics of a spark plug, or how ‘hot’ or ‘cold’ a spark plug is. The term hot/cold is commonly used to describe whether a spark plug heats up easily (hot) or whether it provides resistance to heating up (cold).

Generally, low power engines such as lawn mowers don’t produce a large amount of heat, hence use a low heat range (or hot) spark plug such as a 4 heat range. This means the spark plug will heat up easily and reach its optimal operating temperature. High performance engines on the other hand produce a large amount of heat, hence a high heat range (or cold) spark plug such as a 10 heat range needs to be used to resist the heat developed by the engine.