Table of Contents
Husqvarna Spark Plug Fitment Chart
|Manufacturer||Model||Standard Plug||Iridium Plug||Electrode Gap|
|HUSQVARNA||701 ENDURO||LKAR8BI-9 (Inner)||LMAR7A-9 (Outer)||0.9 MM|
|HUSQVARNA||701 ENDURO (EURO 4)||Outer LMAR7DI-10||Inner LKAR9BI-10||1.0 MM|
|HUSQVARNA||701 SUPERMOTO||LKAR8BI-9 (Inner)||LMAR7A-9 (Outer)||0.9 MM|
|HUSQVARNA||701 SUPERMOTO (EURO 4)||Outer LMAR7DI-10||Inner LKAR9BI-10||1.0 MM|
|HUSQVARNA||FE 501||NGK LKAR9AI-10||1.0 MM|
|HUSQVARNA||NUDA 900 / R||NGK LMAR8C-9||0.8-0.9 MM|
|HUSQVARNA||SM 125 S||NGK BR9EG||–||0.6 MM|
|HUSQVARNA||SM 125 S||NGK BR9EG||0.5MM|
|HUSQVARNA||SM 510 R||NGK CR8EB||NGK CR8EIX||0.7 MM|
|HUSQVARNA||SM 610||NGK CPR8E||–||0.7 MM|
|HUSQVARNA||SM 610 I.E.||NGK CPR8E||–||0.7 MM|
|HUSQVARNA||SMS 630||NGK CR8EB||NGK CR8EIX||0.7-0.8 MM|
|HUSQVARNA||SVARTPILEN 701||Outer LMAR7DI-10||Inner LKAR9BI-10||1.0 MM|
|HUSQVARNA||TE 125||NGK CR8E||NGK CR8EIX||0.7-0.8 MM|
|HUSQVARNA||TE 250 4T||NGK CR8EB||NGK CR8EIX||0.7 MM|
|HUSQVARNA||TE 300||NGK BR7ES||NGK BR7EIX||0.6 MM|
|HUSQVARNA||TE 510||NGK CR8EB||0.7 MM|
|HUSQVARNA||TE 610||NGK CPR8E||–||0.7 MM|
|HUSQVARNA||TE 610 I.E.||NGK CPR8E||–||0.7 MM|
|HUSQVARNA||TE 630||NGK CR8EB||NGK CR8EIX||0.6 MM|
|HUSQVARNA||TR 650 STRADA||NGK MAR9A-J-G06||0.6 MM|
|HUSQVARNA||TR 650 TERRA||NGK MAR9A-J-G06||0.6 MM|
|HUSQVARNA||VITPILEN 701||Outer LMAR7DI-10||Inner LKAR9BI-10||1.0 MM|
|HUSQVARNA||WRE 125||NGK BR9EG||NGK BR9EIX||0.5 MM|
Reading your spark plug
The image of the spark plugs above shows four common conditions that you’ll find your spark plugs in. From left to right the plugs are Normal, Rich, Lean and Very Lean. Full descriptions below.
Before you throw your old spark plug in the bin, check them to get an understanding of how well your engine is running.
If the plug is brown or light grey your can assume your engine is in good condition and the spark plug is functioning well. Even when a plug is in good condition small deposits will accumulate. This is normal.
There are many different causes of spark plug fouling. If the plug has oil on it, then it’s oiling up and may not work efficiently, potentially causing a misfire or stuttering under hard acceleration. If it’s just dark or black the bike could be running too rich. A heavy accumulation of carbon on the nose can cause a leakage path to earth. This can cause misfires and poor engine starting.
Causes: The causes of this can be anything from, a rich fuel mixture, too much choke, long periods of low-speed riding or idling in traffic, a blocked air filter or the plug’s heat range is too cold.
If the engine is running lean then the spark plug has a grey colour but you’ll probably see some black deposits on there too.
Causes: Insufficient cooling, blocked injectors, too lean a fuel mixture
If the engine is running dangerously lean the whole plug tip will be grey or white. If the temperature is over 850-degrees, pre-ignition may occur. Engine power will be reduced and you risk piston damage.
Causes: Insufficient cooling, blocked injectors, too lean a fuel mixture, ignition timing too far advanced, excessive combustion chamber deposits.
Motorcycle Spark Plug Fitting Guide + Tips
- When you’ve removed your spark plugs, check the condition of the threads in the cylinder head and put a cloth over the cylinder head if you’re going to leave it exposed.
- Install each spark plug by hand until you have wound the thread a couple of turns. This reduces the chances of you cross-threading the plug.
- Torque the spark plug up to your manufacturer’s recommended settings. If you don’t have a torque wrench, then get the plug hand tight and then add a ½ turn for a plug with a gasket, and more like a ¼ turn for a tapered spark plug. Over-tightening can snap the spark plug – a nightmare.
- Don’t put any lubricant or thread lock on the spark plug. Inspect your spark plug caps and replace if required.
Iridium Spark Plug vs Standard
A regular spark plug uses a copper central electrode whereas an iridium spark plug uses, you guessed it, iridium.
The metal in a spark plug has a single purpose: to channel the electrical energy through the spark plug. Iridium is far harder than copper and this allows the spark plug manufacturers to create a plug with a sharper ‘tip’ which better focuses the spark around the centre electrode without compromising its service life.
A typical copper spark plug will last around 20,000 miles and most get changed at a major service (usually around 16,000 miles) but an iridium spark plug will be good for around 50,000 miles and you do see people running them to 100,000 miles with no issues.
Copper is generally seen as being the best metal to use in terms of conductivity but iridium plugs are seen as premium as they last longer than standard plugs and can be built with smaller tolerances. Iridium spark plugs also have lower voltage requirements, meaning they perform better when starting and idling and some manufacturers also claim they offer a better throttle response.
Iridium plugs are more expensive than copper but seeing as they last longer and offer a more consistent performance throughout their lifetime, many bikes opt for an iridium ‘upgrade’.
Spark Plug Removal
If you’re going to be doing any sort of work on the bike, treat yourself to a decent set of tools. Most of mine are from the Halfords Advanced range (formerly called Professional).
They have a lifetime guarantee and for an amateur bodger like me, they’re perfect.
The image above shows their 100pc range, which costs around £125. It’s a comprehensive bit of kit and includes a 1/4″, 3/8″ and 1/2″ drive, alongside plug sockets, universal joints and a wobble bar. Pretty much everything you’ll ever need for any motorcycle maintenance job.
Motorcycle Spark Plug Removal Tools
If you’ve not changed your plugs before, give yourself a couple of hours to complete the task. Here are the essentials you need for smooth re-plugging:
Your owner’s manual
You’ll need this to help you find the location of your spark plugs and how to access them. This may sound simple but often the manual offers up some time-saving tips for your particular model.
A spark plug socket
You’ll need a deep socket. A decent tool kit will have them. Don’t get confused between thread size and socket size. Motorcycle spark plug socket sizes are usually 16mm, 18mm or 20.6mm (21mm will do). Whereas the threads are usually 10mm, 12mm or 14mm. When it comes to motorcycles, access is usually tricky, so my tip is to buy a magnetic spark plug socket like this one. Once you’ve undone your old plug, this will help you remove it with far less effing and jeffing.
A wobble socket / universal joint
You’ll be lucky if there’s a straight line to your spark plug, so a universal joint will get you the angle you need to apply some torque. Again, a decent toolset will have one.
A 3/8″ drive
You could buy a specific spark plug T-bar but your home tool kit will have the drive you need to connect to your plug sockets.
A spark plug gap gauge
This nifty little tool only costs a few quid and will help you set the correct gap for your spark plug. However, modern plugs are almost all motorcycle-specific fit and so they come ‘pre-gapped’ and you won’t need to touch them. If you’re running a classic bike, you’ll probably need to set your gap and if your bike’s not running right, a gap tool can help you rule out a potential incorrect gap issue.
A torque wrench
It’s important to properly torque your spark plugs. Too tight and you’ll risk snapping it or it will be a mission to remove. Too loose and you risk an electrical short. Your owner’s manual will have the correct torque settings.
Motorcycle Spark Plug FAQ
What are the common motorcycle spark plug sizes?
Thread diameters of 10mm, 12mm, and 14mm are the most common. In fact, when it comes to motorcycles, it's rare to find any other sizes in use.
How long should a spark plug last?
Motorcycle spark plugs usually last around 16,000 miles, or at least this is when most manufacturer service schedules recommend you change them. That's typically once every other major service. However if you use Iridium spark plugs they will last a lot longer, usually well over 30,000 miles.
How do you clean motorcycle spark plugs?
Just remove the plug and use a wire brush to gently brush off any deposits on the electrode. Don't use a power tool, by hand is all that's required.