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Suzuki GS 650 Katana: Best spark plugs to use?
Posted: Sat Mar 14, 2026 9:28 am
by craik
I once owned a Suzuki GS 125 back in the 1980s, where the spark plug seemed to last forever and rarely needed replacing.
However, with the 650 Katana, they don't seem to last nearly as long. At the moment am using NGK D8EAs, as recommended in the manual.
What are other people's recommendations for this bike? Thanks in advance.
Re: Suzuki GS 650 Katana: Best spark plugs to use?
Posted: Sat Mar 14, 2026 8:54 pm
by fossie
DR8 ES-L more wildly available and used in other Kats too. In what way are they not lasting ?
Re: Suzuki GS 650 Katana: Best spark plugs to use?
Posted: Mon Mar 16, 2026 8:27 am
by craik
They just stop sparking. Cleaning them up with a wire brush doesn't really help.
Maybe the bike's getting old or the cheap ones I'm getting off eBay (£10 for 4) aren't genuine?
Re: Suzuki GS 650 Katana: Best spark plugs to use?
Posted: Mon Mar 16, 2026 11:06 pm
by fossie
That is an odd diagnosis.. usually 1 of the 4 will fail after a awhile .. I get 6-8000 miles before they lose motivation...
apart from better supplier , the only other options are over fuelling..or coils /cdi.. but again not 4 together..
Do youhave the shim kit?
Re: Suzuki GS 650 Katana: Best spark plugs to use?
Posted: Tue Mar 17, 2026 9:31 pm
by craik
Thanks. I don't have the engine shim kit but the shims were checked out at a repair shop a while back with the advice they didn't need adustment and were still within spec.
Anyway, it's no biggie, I'll just live with it. Should be grateful it's still running at all at this age!
Re: Suzuki GS 650 Katana: Best spark plugs to use?
Posted: Mon Mar 23, 2026 11:23 am
by Uncle Bob
I'd go for the Ebay ones being fake. I wouldn't buy NGK spark plugs from Ebay, I have heard about people having issues with fake ones in other clubs.
If buying online I get from
https://www.sparkplugs.co.uk/, they are £4 each and never had an issue with the ones I got from them.
UB