New Member
I just changed my plugs, around 15.5k miles (5 years). Was having no problems but wanted to do a tune-up before taking it to the track next month. The plugs looked good, but you could definitely tell there was wear on the electrodes; if you looked square on the tip of the electrode, it was actually oval shaped and not round where the two arc paths from the sides had worn away some material. I don't know if it was really enough to make much of a difference on the gap; I didn't have any problems before and didn't notice any improvement after.


I just replaced my plugs on my 2012 at 20K miles and the OEM plugs were worn. The gap was .034" and the electrode was definitely rounded. I replaced them with the iridium equivalent, CR9EIX.


New Member
Evening All. I realise this is a fairly old thread, but I'm new to the FZ-1, and only just entered the wonderful world of the owning one...

Basically I am trying to replace the plugs (bike is running lumpy so air filter, plugs, oil filter etc all getting done) but my bike didn't come with the Yamaha tool kit, so I'm sort of stuck. I have purchased the NGK CR9E plugs, and they have a 16mm hex head, but that is the one size spark plug socket I don't own. Happy to buy one, but I am not too sure which one will fit into the plug wells, and I don't want to purchase the wrong one. Can anyone recommend the thin wall socket that will fit into the engine head??? I have spent the last 2 hours trying to find out which socket to get, or trying to purchase the correct tool (kit or by itself) but no-one seems to have one for sale anywhere online (all the forums state is 'the correct 3/8" socket, which isn't much help tbh)

Following other threads about the spark plugs on the FZ-1, I have lowered the rad to gain access etc, haven't removed the AIS as others have said (don't think I am that qualified right now to try that one), so am so close, but right now, there's no cigar....