Spark plugs

[FerretFing]

Just bought the wife a Yamaha Mt-03 (2006) & in the process of doing a service on it noticed there was a different spark plug in there - NGK CR8EIX - compared to the proper one (according to service manual) that I'd bought - CR7EIX....what would the difference between the two be & could it have caused any problems with prolonged use? Thanks.

[temeluchus]

the heatr range governs the self cleaning properties of the plug and the manufacturer matches it against the conditions in the motor to get the ideal properties.

It is not uncommon to have different heat ranges used in one model to match differing fuelling, local conditions and intended use.

One heat range difference may not make a big change and as you are installing the recommended plug I would think you would be ok. The old plug is unlikely to have caused any issues.
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[0l0dom0l0]

The cr8eix is a cooler plug than the cr7 you've bought.

If the manual says you should have the cr7.. you'll be fine.

It is slightly more important on 2 strokes but for that I wouldn't worry.
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CBT Passed: 30/08/2009, Theory Passed: 31/08/2010, Mod 1 Passed: 6/9/2010, Mod 2 Passed: 13/09/2010. Restriction ended 13/09/2012.

Bikes: 2007 Derbi GPR 50, 1998 Yamaha Fazer 600 (written off), 2002 Yamaha Fazer 600, 1994 CBR 600F, 2003 Triumph Daytona 600, Kawasaki ZX6R J1.....Current: 2006 Yamaha FZ6, 1998 Suzuki TL1000R and a Honda VFR 400 NC30.