Hello Does anyone know what sparkplug fits the Bonneville 750 Harris from 1986? In the internet I find several ideas: some say NGK B6 others B8. The motor seems to be original. Thank you. Romeo
A search gave me the info below. When I changed the plugs on my 25 year old Ducati I went for NGK iridium versions on the basis that I don’t do many miles on the machine and will probably never change them again so go for the best. The standard spark plug for a Harris 750cc Bonneville (based on the Triumph T140V) is the NGK B8ES. However, depending on the specific model year and usage, other options like the NGK BR8EIX (Iridium) or NGK B9ES (for hard use) may be suitable. The key specifications for the standard B8ES plug are a 14mm thread diameter, 19mm thread length, 20.8mm (or 21mm) spanner size, and a 1.0mm spark position. Standard specification (NGK B8ES) Spark Plug Type: NGK B8ES Thread Diameter: 14 mm Thread Length: 19 mm Spanner Size: 20.8 mm (21 mm) Spark Position: 1 mm Spark Gap: 0.5 mm Alternative/Upgrade options NGK BR8EIX: An iridium-tipped plug for improved performance. It's often a long reach type. NGK B9ES: A "colder" plug often recommended for hard-use conditions. Champion: Some models may also use Champion alternatives, such as the Champion N5C for the T140V.
Many thanks Baza. I foun in between also the information for champion N3. As I always use NGK an my bikes I will choose the B8ES. Kind regards Romeo
@Romeo Keller Welcome to the family. Yes i think NGK B8ES Or Champion N3 OR N5. Would like a look at the bike if you tap the upload a file button and show it of.
NGK has discontinued the non-resistor plugs, so the B8ES or B9ES plugs specified as an interchange for your machine might well be counterfeit. the newest manual i have is for the 1973 T140, and it specified the champion N3. but as the triumphs got newer than that they switched to different plugs as the cylinder head changed. look in a later shop manual for the appropriate champion plug, then you can decide what to install.