Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board Bosch Super 4 spark plugs

Hi,
I have a 1966 BSA B40 which runs well but can be a little temperamental to start.
A friend uses the Bosch Super 4 plugs in an old car and they work brilliantly, so I wondered if they might help the old B40.
There are many different models so I wondered if anyone else had tried them and would recommend a particular model/type.
Regards, Graham.

In my Unit Singles I run projected tip spark plugs for easier starting, these put the spark further out into the combustion chamber, the BSA spec ones are further back and shielded from the fresh mixture coming in as you kick the bike.

Also I have gone to Iridium NGK's for less fouling and longer life.

So a std projected NGK is NGK BP7ES, Iridium is BP7EIX on my B44, B40 may need a hotter grade plug depending on the tune.

The P stands for projected tip, you can x ref to a Bosch or Champion equivalent.

Ive used Bosch Plugs and have been really happy with them. Cant remember which ones but they were supposed to be the equivalent to Champion N3

If carburettor and ignition settings are as they should be, there is no need for any "special" type spark plugs. All makes work very well. If something changes for example with the mixture, there is differences between spark plugs. My experience is that Champion is the best in various circumstances.

If an engine is difficult to start, filing the earth electrode back so the end is at the centre line of the centre electrode will help.
It unmasks the spark without affecting the heat range

Tend to agree, when I was doing my brace of B44s getting the carb just so was the hardest part. Once done and I learned how to start them (an important step!) I tried several plug manufactures and types. I ended up importing some Champion N4s (not available here) and the bikes just feel "happier" with them.

Firstly we have to remember that when these engines were designed that magical fluid called PETROL existed
Now we have his horrid mix of light fuel oil , scrap solvents and anything else that will go bang inside a cylinder .
Thus what was in the mechanics guide to engine tuning mignt not necessarily apply.
Add to that spark plugs with unglazed nose insulators and a fuel that is very conductive at cylinder pressures and you have the recipe for trouble starting.
And this ignores local factors like the actual O2 content of the air where the poster lives , humidity & air temperature .
So every bit helps , particularly on an engine that is very fussy about starting proceedures .
Like kommando I usse projecting tip plugs when ever possible and it does make for more reliable starting

I'm on CA gas. Worst there is. NGK's have always worked well in everything I've run. Especially like the iridium's now. Set them and forget them.

Thank you all for the feedback.
I currently run an NGK BP7ES plug and thought I try a projected tip version and a slight hotter plug so a BP6EIX.
However, Googling where to get one, the only listings are for a BPR6EIX.
I gather the R stands for resistor but is that ok ?
Regards, Graham.

This reminds me of a Scotch Tape advert that used to be on the TV back 80s/90s (or at least the last bit of the advert/song)

You may or may not be surprised to know that the fantasicly expensive engines used then to find the AKI of gasoline are fairly identical to the ones still being used today.

NGK now only do R plugs, should not make any difference as long as your HT lead is solid copper type and your plug cap is not a resistor one.

Thank you, I'll check tomorrow
Appreciated, Graham.

Bit of a shame no one could answer the question at the beginning of this thread. Bosch super 4 plugs were often found at popular retail outlets like Halfords at very reasonable prices. Probably the easiest way of working out what they could be used for would be to read up what car they were spec'd for and then look up alternatives for that car. Information on these plugs not easy to find.

I tend to think sparkplug threads are a bit like oil threads.............

Personally, i've never had a preference, just use something within
the heat range specified. The plugs in my bike have never been
changed they are B8EV's left over from my racing days. They've
done at least 12 years and 20k+ klms and still work fine. I couldn't
put up with an ignition setup that was dependant on a specific type
of plug or a brand, with a decent EI the plug will fire properly.

All,
I certainly agree that there is very little information on the Bosch plugs.

I checked my setup and the 'R' plugs would need some changes.

A friend of mine gave me a Bosch WR78 super 4 plug today that he uses in his MGB and it fired up second kick and ran on a fast tick-over for 45 minutes with no problem, so I'm a happy person. Need to give it a good road test soon.

Thank you all for all your help and advice, much appreciated.

Regards, Graham.

I would check the plug color to ensure you have got the right heat range, ideally this needs to be done at idle, 1/4. 1/2. 3/4 and wide open throttle settings.

With 4 electrodes, I expect the plug will result in better combustion and maybe a bit more power, but who knows.

I would also look at the coil and whether it can support 4 sparks all at the same time, the original coil used by BSA may need upgrading to something better.

You don't get 4 sparks, the single spark takes the path of least resistance so as the 4 electrodes decay the single spark moves between them.

Used the predecessor with 3 electrodes on my MK2 GTI Golf, it was a way to increase the life of the plugs and extend the servicing interval.

Interesting, I didn't realize it worked like that, I guess the idea is that the plugs last longer as when one electrode becomes worn, another takes over.

In my race bike I use a "surface discharge" plug, in effect an infinite number of gaps and the spark isn't masked by the electrode
Only £70 a pop
4463 by Sigma Projects, on Flickr

you need to make a thread about your bikes.

The plugs specified for the BMW K100 are X5, but that's a 10mm plug. The plugs specified for the VW type 4 engine (Early 70's Bus and 412) are Bosch W 145, Champion N-88. I have no idea of the Bosch numbering system.
I've used NGK B7EV and EX in an A65 with good results, but I've only used Champion N3 in Triumphs.
I put Autocraft plugs in my Ford and NGK in my Toyota. Never tried Bosch in anything British.
Never used anything but Bosch in my Volkswagens. Some time you just gotta go with what the manufacturer recommends.

Example


NGK B8EV replacement spark plugs

Accel 112
Accel 142
ACDelco 41XL
Autolite 4053
Autolite 4063
Autolite AG23
Autolite XS4063
Beck Arnley 176-5045
Beru 14-3CS
Beru 14Z-3CU
Beru Z38
Bosch 0241252522
Bosch W3CP
Bosch W4CC
Bosch W4CP
Bosch W4CS
Bosch stk 7530
Brisk LOR12LGS
Champion 307
Champion 805
Champion N2C
Champion N3G
Champion OE040T10
Champion OE078
Champion OE078T10
Champion stk 805
Denso 4030
Denso 5316
Denso 5713
Denso IW01-24
Denso IW24
Denso W24ES-GU
Denso W24ES-U
Denso W24ES-ZU
Denso stk 4032
Eyquem 0911007073
Eyquem 0911007223
Eyquem 805LP
General Motors 5613161
Honda 98079-58644
Magneti Marelli 062120107312
Magneti Marelli CWP9L
Mitsubishi MZ602035
Motorcraft AE23
NGK stk 6824
Splitfire SF405C
Toyota 90098-74036