Spark Plug - wrong model fitted to trimmer - could it cause problems?

Hi all

I had some problems with my Tanaka trimmer last year and had it fixed (and serviced) by the local repair shop. It's not behaving too well now either so I have cleaned the air filter, and ordered some replacements. I will also replace the spark plug, but was going to try giving it a clean up as well (and check the gap). It was replaced when the machine was serviced.

Upon checking I see they put in a NGK BMR6A. The manual calls for a NGK BMR7A. I *think* the only difference is the Heat Range.

It's all new to me, so I wondered whether this difference in heat range is important or not? Should I be asking the repair shop why they fitted the wrong one? Could it have caused damage to the machine?

Many thanks

 

Your best going online to see what difference it will make, shop will not admit it’s wrong if they put it in and try to fob you off with it supersedes etc.
Did it run better when you got it back after service, or was it the same if you asked them to service it to run better then they didn’t do a good job.
It could be as simple as a carb clean.

 

Hi,

Looking at the specs for those plugs , as you say there is a slight different in running temperature, plus a difference in the inbuilt interference resistor, which I doubt would cause any serious problems.

For the sake of £3 , worth putting in the right one , just to be sure

Good video explaining the plugs codes.

 

The wrong grade of plug in a two stroke can sometimes cause serious problems. At worst, it could mean a holed piston. Having said that, the correct grade of plug can be the wrong one, dependent on how the machine is used. If it is used "lightly" then a softer (plug with higher number) would generally be used to prevent them fouling. On the other hand, if the machine is used "heavily" then a plug with a lower number than standard would be used, as heat from heavy useage stops it fouling. The standard grade is nothing more than a general recommendation, that would be the best one to use in most circumstances.

Back when I ued to race two stroke motorbikes, I would always have with me not only a range of plugs, but a range of jets, etc. also. No two settings would be the same from circuit to circuit. On "the Island" they would even change between practice and the race itself...

 

Many thanks for the helpful replies.

@jimcubs I "inherited" the machine last and it wasn't hardly working when I got it. So yes, it was working after the service and fix (although it took two visits). It's quite chuggy and all over the place on idle, but I've never had one before so not sure how normal that is. The actual problem I'm having though is that's it's stopped reaching full power / RPM when on full throttle. So I've cleaned the air filter and thought I'd either clean or replace the plug.

@ricky101 OK, I'll get a replacement. But I'll give this one a clean too as I'm learning and I've never cleaned a spark plug before!

@Sandy Ground Very interesting, thanks. I tend to use it "heavy" - usually on full gas so to speak. Tbh, I've quite a novice and have not got round to looking into how to use it properly. So that's subject to change But - from what you say - perhaps a 6 was the better choice for how I've been using it.

I'll get to cleaning it as it is quite black. I run 50:1 - or thereabouts. Only recently discovered how inaccurate the mixing bottle is!

Cheers

EDIT - well, I say quite black, but I don't really know what I'm talking about so here's a pic instead:

 

40 or more years ago, I would have agrred entirely with that, now only partly.

In the first instance, I would have changed the plug for a good on, and possibly even the plug cap. Over the past few years, I've had to change a couple of those. Quality is not what it used to be!

As long as a quality brand of synthetic two stroke oil is carefully mixed in the correct ratio, then modern 2T's dont really need to have the need to have their exhaust system cleaned. Not even sure that the correct stuff to do the job can still be bought anyway. I've a 30 year old Stihl here, the only thing I've ever needed to do with that is change the fuel line twice, and retorque the cylinder once.

Rather than do a compression test, I would run a leak down test. It tells a lot more. It is more difficult to do, and more than likely outside the possibilities for most.

One thing that I would probably be doing is looking more towards the carb settings.

 

@Fat Controller Do you mean a two stroke like this one?

 

If we were foing to develop a them of innuendo, then I would mention the worlds most inappropriately name moped with a small two stroke...the Norman Nippy....Oops! I just did!