Spark plugs are a key part of maintaining a petrol power tool, especially STIHL chainsaws, and you may think that one spark plug is much the same as another. A standard NGK spark plug and NGK spark plugs sold by STIHL may have the same part number stamped on them, but the STIHL NGK spark plug has some key differences.
The main differences between the STIHL NGK spark plug (right) and the off the shelf NGK plug (left) are:
- The union nut (1) of a STIHL spark plug is fixed in place. This ensures there is no spark gap which could impair performance or potentially ignite gasoline fumes.
- Interference suppression resistance (2) is tuned to STIHL machines for the optimal spark and efficiency. This protects the machine’s ignition module from early failure.
- STIHL spark plug sealing ring (3) is coated for a better contact and corrosion resistance, given that these tools are used in challenging and often wet environments.
- The electrode gap (4) is aligned to STIHL products for optimal compression.
For the best performance from your STIHL tool, we recommend that you always use the STIHL NGK spark plug.
The spark plugs are listed in the “Technical data” chapter of your machine’s Instruction Manual. For more information and to order your genuine STIHL spark plug, contact your local Approved STIHL dealer.
I need 2 R10 Spark plugs (1spare) for my long reach hedge trimmer
Hi John, thanks for your comment. We don’t sell any spare parts directly, so we recommend that you speak to your local STIHL Approved Dealer to order the part. You can find your nearest one here: https://shop.stihl.co.uk/pages/dealer-locator
Thanks, STIHL GB
NGK makes plugs with the same part number that are different? I am skeptical.
Hi, thank you for your comment. We understand how there could be some confusion, which is precisely why we wanted to write this blog post, with clear pictures showing and explaining the differences. Thanks, STIHL GB
Ok guy’s you have outlined the differences and you say both companies use the same part number.
So when I’m handed a Stihl NGK spark plug in the shop will it say Stihl on the box and is the plug it’s self stamped with the Stihl logo?
Hi, thanks for your comment. Once they are out of the box, there isn’t anything to obviously identify it so the best option is to make sure you ask for an official STIHL spark plug from a STIHL Approved Dealer. Thanks, STIHL GB
I’ve a 028 Wood Boss saw. I’ve been going through coils like crazy. A friend said that I should measure the resistance of the spark plugs in my collection. I just found a NGK. It had much high resistance than the rest.
Today, I put a nee coil in it. The saw started, ran pretty good but seemed as if the H carb setting needed a tweek. By the time i got the screwdriver, the saw died, not to be started again.
I called a technician friend. He suggested testing spark plug resistance. All my plugs except one were low ohms. The plug in the saw was one of them.
Is this the reason I’ve been having coil failures? Going to try that NGK tomorrow.
Hi, thanks for your comment. We recommend that you speak to a STIHL Approved Dealer to make sure that you get the correct STIHL spark plug as not all NGK are the same as STIHL NGK. One of our Product Experts has also said that they believe the older 028 Wood Boss saws had a different ignition coil so your dealer will need the serial number of your saw to confirm the correct part. I hope that helps, thanks, STIHL GB
Has a more proper or upgraded spark plug been introduced to the MS 462 c-m since the owner’s manual was created? I get conflicting and convincing input that the best spark plugs to use is the ngk cmr5h for the higher heat rating (it seems that the 5h is a hotter rated plug than the 6h).
Hi, thanks for your comment. We’ve only ever recommended using the NGK CMR6H with the MS 462 C-M. We use this same spark plug on many other machines too as it’s proven to be reliable and long-lasting. No STIHL machines are currently recommended with the NGK CMR5H, so we would recommend taking the chainsaw to a STIHL Approved Dealer if you are having reoccurring problems with the spark plug. Thanks, STIHL GB
I have been trying to replace my spark plug NTK R BPMR7A for my Stihl BG 50. I was told to get the CMR6H . I went to a O’Reilly store where they gave me a similar spark plug . E3.12. My leaf blower sounds like it has no spark. What us the correct spark plug?
Hi, thank you for your comment. The BG 50 needs a WSR 6F spark plug. I hope that helps, thanks, STIHL GB
Hi,
We’ve a Stihl FS55 and it’s using a CMR6H spark plug instead of the common BPMR7A.
Numbers on the bar code are 4140-012-2355
819677704
Is our strimmer legit?
Hi, thanks for your comment. We’ve checked our system and we can see that serial number on there. The CMR6H spark plug is correct too. Thanks, STIHL GB
Hi I’ve read all the comments, took out my spark plug for the first time on our blower and it’s a Bosch one?? How is that STIHL?
Hi, thanks for your comment. STIHL use a number of spark plugs and many are manufactured by companies such as Bosch and NGK to our specific STIHL specification. As you can see from the image on the blog, the two STIHL plugs are made by NGK, one of which is the STIHL NGK version. The same applies to Bosch spark plugs – there are standard Bosch spark plugs, and then STIHL specification Bosch spark plugs. Thanks, STIHL GB
I’ve just exhumed my Stihl leaf blower from the garage and tried to remove the spark plug. None of my collection of spark plug spanners are able to access it due to the configuration of the access point: they are all too long, and or don’t fit the plug. Can you confirm that the plug size is 5/8 inch? I can then go and buy the right spanner!
Hi Steve,
Thanks for your comment. We would suggest using a STIHL combi spanner, which should have been included when you purchased your machine. If you need any further support, please speak to your Local STIHL Approved Dealer.
Thanks, STIHL GB.
What’s the right spark plug for a MS-170 chainsaw?
Hi, for MS 170s produced after 2015 the spark plug required is an NGK CMR6H.
Thanks, STIHL GB.
Anyone know where I can find a complete rebuild kit for a Stihl 046. It was sold in 2000, so probably manufactured either 1999 or 2000. It needs all the bearings, I might as well replace the crank shaft and piston just so I don’t have to try and remove the arm between the wrist pin and the I’m guessing these are counter weights that rotate and push the piston up so combustion can push it back down. Anyway, the guy that I got it from sand blasted the piston and the entire crank shaft without removing the bearings. So now they have ground glass blasting media in the bearings. It just seems easier to replace the entire crank shaft all the way through to the piston rather than two to press out this pin holding the arm to the weights so I can get the bearings out. Anyway I have the saw completely torn down since I’m sand blasting the crank case in order to repaint it before putting it back together. So I been like I said the entire crank shaft, piston, wrist pin, and all applicable bearings, as well as the crank case gasket, the crank shaft bearings and oil seals, carburetor gaskets/seals, intake boot, impulse line, drum, clutch, sprocket, oiler, oil uptake line and filter, fuel line and filter, fuel tank vent, ignition module with kill line, exhaust gasket/seal (it does not have a decompression valve. I can probably reuse some of the parts I have what came with it, but if I’m tearing this saw down all the way to splitting the crank case and sand blasting and repainting it I mean I might as well go ahead and replace everything that could go out in the near future. It was sitting for years before it was given to me and I have had it for 2 years. It has been torn down for about 8 months as I work on it. So all the parts have had quite a while just sitting with no oil or anything to keep the pliable parts pliable and the other parts moving so they don’t stiffen up and fail shortly after being put back in service after sitting so long. I would rather just go ahead and spend the money to do it right. But I’m dreading having to make a list of parts and track them down one at time to order them and would prefer just to buy a rebuild kit, or a lot to rebuild this aspect and a kit to rebuild the other aspects etc if you know what I mean. So, anyone got any ideas? I’m planning on using this saw with my chainsaw mill. Before you stress that it’s not big enough I’m but cutting huge pieces. I mean at these most I’m cutting 6′-8′ long and 12″-18″ wide. I would get 1 maybe 2 decent pieces out of a long. A lot of it will be for rough cut lumber for like lean to, or processing small pieces of cedar that I can then run down my router table and cut a lip on her edge that is half the thickness of the board and that also being the width of the lip to give myself as much surface area as possible to glue and clamp the joint. Since my planner is only 12 1/2″ then I can’t do huge pieces to run through it and plane down so I have to either glue and clamp smaller pieces or drill through the side of thick pieces and bolt them together. I glue and clamp the smaller pieces and bolt the larger ones. Then use a belt sander to be even everything out. So the 046 will work fine for the size of the lumber I will be milling. I just need to know about the parts.
Thanks for any help.
Hello, thanks for your comment. We stock all the spare parts for the 046 and these can be ordered via a STIHL Approved Dealer. Although we do not have a re-build kit available for this model, our dealers have access to software that allows spare parts to be found and ordered very efficiently. You can find your nearest STIHL Approved Dealer here: https://shop.stihl.co.uk/pages/dealer-locator. Thanks, STIHL GB
Where or how are your plugs identified at genuine “STIHL” if it’s not on the plug. Is it on the box? Or do I just have to take the dealers word that it is.
Hi Kathy, thanks for the question. STIHL machines use a variety of STIHL, NGK and Bosch spark plugs, all of which are supplied to the dealerships by STIHL. If you’re unsure, please email a picture of the spark plug to enquiries@stihl.co.uk and we’ll be able to verify. Thanks, STIHL GB.
All but the RF suppression resistance would be easily applied to a stock NGK plug before putting it into the Stihl box. Would be interesting to use an ohmmeter to check that resistance for a stock NGK plug vs a Stihl plug, hard to imagine that NGK would change the resistance without changing the part number. And while too high a resistance might cause poor performance and too low a resistance might cause interference with a nearby AM radio, that ignition module would have to be of awfully poor design if a different resistance (perhaps due to a faulty plug wire connection or fouled plug or burned out gap or inadvertent grounding) causes damage to it. Personally, I’d be fine with trying a stock NGK plug after setting the gap. Counterfeit NGK parts might be more likely to impact saw performance, though I’d say “could ruin your engine” is mostly scaremongering so long as the threads match and it doesn’t extend too far into the chamber:
https://www.ngkntk.com/newsroom/feature/emea/2020-1/counterfeit-spark-plugs-the-ignition-villains-that-could-ruin-your-engine/
Thank you for your comments regarding spark plugs. We’re always heartened to hear of people making careful choices about the service of our products. One of the most direct ways you can see the differences first hand with this topic is to purchase one of our plugs, and an off the shelf one to compare. The easiest way to identify the difference between the two is the unscrewable top cap, noting there is a different air gap around the electrode, although the model number stays the same. Some of your other comments make reference to a blog created by NGK themselves so we can’t really comment on their content. We make no claims that use of a non-STIHL off-the-shelf plug would ruin our engine but we know that they certainly will not run as well. We also have definitively found certain non-resistor plugs to cause repeated ignition module failures with our machines so we would always recommend that you purchase a genuine STIHL plug for your machine.
Thanks, STIHL GB.