K&S 10-2122 Straight 5K Ohm Resistor Spark Plug Cap for Triumph
The K&S Resistor Spark Plug Cap PN MBI-10-2122 (K&S part number 10-2122) is a straight-type, 5K ohm suppressor cap that replaces the NGK SB05F (NGK stock no. 8080). It is a direct-style replacement for a cracked, corroded, or high-resistance plug cap on Triumph motorcycles that use a screw-on HT lead and a straight resistor cap. A worn plug cap is a common, overlooked cause of misfires, hard starting, and rough running in wet weather. Replacing it costs little and takes only a few minutes.
According to K&S Technologies’ product release, the 10-2122 is a straight cap for 14mm-type plugs, with 5KΩ resistance, a terminal-stud connection, and a 7mm–8mm wire range. It comes with waterproof rubber caps for both ends.
Features and Benefits
- 5K ohm (5,000 Ω) built-in resistor suppresses radio-frequency interference (RFI) that can disrupt electronic ignitions, ECUs, and audio or communication equipment.
- Straight (0°) body matches the NGK SB05F profile for a clean, in-line fit where the lead approaches the plug straight on.
- Terminal-stud connection snaps onto plugs with a solid or threaded-and-capped terminal, the configuration used on NGK motorcycle plugs.
- Waterproof rubber boots at both ends seal out water, road spray, and wash water, helping prevent tracking and misfires.
- Screw-in HT lead receptacle accepts standard 7mm–8mm copper or steel core ignition wire.
- Sold individually, so you can replace one damaged cap or order one per cylinder for a matched set.
Specifications
| Manufacturer | K&S Technologies |
| K&S Part Number | 10-2122 |
| Modern British Iron Part Number | MBI-10-2122 |
| NGK Cross-Reference | SB05F / 8080 |
| Cap Style | Straight type |
| Resistance | 5KΩ (5,000 ohms) |
| Plug Size | 14mm-type plugs |
| Plug Terminal | Terminal stud |
| HT Lead Diameter | 7mm–8mm |
| Includes | (1) resistor cap with both waterproof end rubbers |
| Color | Black |
| Quantity | Sold each |
Fitment: Match the Cap to Your Plug
Spark plug caps are sized by plug type, not by motorcycle model. The K&S 10-2122 is the 14mm-plug version and replaces a straight NGK SB05F cap. Before you order, check the code printed on your old cap or the plug listed in your owner’s manual:
- Your old cap reads SB05F (or 8080): the 10-2122 is the correct replacement.
- Your Triumph uses 12mm or 10mm plugs (for example the 12mm NGK DPR8EA-9 in many Hinckley twins and triples): K&S lists the 10-2222 (NGK SD05F) as the straight 5K ohm cap for 10mm and 12mm plugs.
- Your Triumph has a 90° elbow cap: choose an elbow-type cap instead, such as the K&S 10-1122 (NGK LB05F).
- 2016-on liquid-cooled Bonneville-family twins use a factory cap with a special cylinder head seal. This cap is not a direct replacement on those models.
If you are unsure, call or text us with your model, year, and VIN, and we will confirm fitment before you order.
Installation Tips
- With the ignition off, pull the old cap straight off the plug. Do not pull on the lead.
- Unscrew the old cap from the HT lead counterclockwise. If the lead end is corroded or frayed, trim about 1/4″ (6mm) back to clean wire.
- Slide the rubber boot over the lead first, then screw the lead clockwise into the cap until it is fully seated in the brass spike.
- Roll the boot over the top of the cap to seal the joint.
- Press the cap onto the plug terminal until it clicks into place. Check that the plug-end rubber seals fully.
Pair the new cap with fresh plugs. See our NGK DPR8EA-9 spark plug, NGK Iridium IX CR9EIX, and NGK LMAR8A-9 listings. If the bike still misfires after a new cap and plug, test the coil and leads. Our shop also carries the OE-style replacement ignition coil for Bonneville and Thruxton models. Bringing a stored bike back to life? See our guide to resurrecting a ran-when-parked Hinckley Triumph.
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Frequently Asked Questions
What is the K&S 10-2122 spark plug cap?
It’s a straight-type 5K ohm resistor spark plug cap from K&S Technologies for 14mm-type plugs with a terminal stud. It accepts 7mm–8mm HT leads and includes waterproof rubber boots at both ends. Modern British Iron sells it as PN MBI-10-2122.
What NGK cap does the K&S 10-2122 replace?
It replaces the NGK SB05F, NGK stock number 8080.
What is the resistance of the 10-2122 cap?
5K ohms (5,000 Ω). Note that it’s 5K ohms, not 5 ohms as some listings incorrectly state.
Will this cap fit my Hinckley Triumph with NGK DPR8EA-9 plugs?
The DPR8EA-9 is a 12mm-thread plug, and K&S rates the 10-2122 for 14mm-type plugs. For 10mm and 12mm plugs, K&S lists the 10-2222 (NGK SD05F) as the straight 5K ohm version. The safest check is the code on your old cap. If it reads SB05F or 8080, this is the correct part.
Does it fit 2016-on liquid-cooled Triumph Bonneville, Thruxton, or Street Twin models?
No. Those models use a factory plug cap with a special seal at the cylinder head, so this cap is not a direct replacement.
Do I need a resistor cap if my spark plugs are already resistor type?
Not always. Many systems are designed for a total amount of suppression. Check your ignition maker’s or Triumph’s recommendation. Using a resistor cap with a resistor plug is common on modern motorcycles. Too much total resistance, however, can weaken the spark on some older or aftermarket ignitions.
What size ignition wire does this cap fit?
7mm to 8mm diameter HT lead. The lead screws into the cap’s internal spike.
Is it waterproof?
Yes. Each cap includes rubber seals for both the wire end and the plug end to keep out water and prevent misfires in wet weather.
How many do I need?
One per cylinder: two for a twin, three for a triple. The caps are sold individually.
How do I know if my spark plug cap is bad?
Common signs include misfiring or cutting out in the rain, hard starting, a rough idle, visible cracks or carbon tracks on the cap, or corrosion inside it. A multimeter across a 5K ohm cap should read about 5,000 ohms. A much higher reading or an open circuit means the cap should be replaced.
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