KTM - Brisk spark plugs

June 2002

We got on the track of these spark plugs through some very positive articles in the German bike mags 'Motorrad' and 'MO'. Brisk plugs are well known as a cure for the dreaded "Konstantfahrruckelen" from fuel injected BMW boxers. A thing that even BMW wasn't able to solve for years. Free translated this means constant speed jerking, a thing that drives a lot of boxer owners nuts.

Anyhow, the weird ZC/ZS type Brisk plugs only have a central electrode and seem to work really good in a lot of engines. An article in 'MO' magazine shows dyno comparisons between 10 different plugs ranging from the cheapest standard plugs from Champion and Bosch up to most fancy and horribly expensive Iridium plugs from Denso and NGK. And of course the Brisks. They stand out big time with more power, more torque, lower fuel consumption, better throttle response and smoothness. Both Motorrad and MO usually are quite sceptical and very thorough in their testing.

The absence of the mass electrode allows the central electrode to be put deeper in the combustion chamber. The sparks occur between the central electrode and the lighter coloured small band, halfway the isolator towards the thread (see picture). It's not squeezed between the central and mass electrode but 'out the open'. This construction allows - or is even aimed at - sparks to jump over at 360 degrees around the central electrode. The first and strongest spark will jump where the mixture is the most dense and rich because it has the lowest resistance. So it kinda seeks out the best point to spark automatically. Clever huh?...

An email to Brisk got us the right replacement for the standard plug. ALWAYS check this with Brisk for your engine! They use a different coding system so you can't compare them with normal plugs. A wrong type of spark plug can lead to very nasty and expensive engine damage! The replacement plug for the NGK D8EA, DPR8EA and DCPR8E - common in most LC4s - is the Brisk BR14ZC.

Install the BR14ZC with a tightening torque of 20Nm (more than usual) and make sure the removable top-cap is really tight.

The improvement is clear straight away. The KTM SMC 660 already is a good starter but now you hardly have to use the choke either. With the stock plug you had to ride a few hundred meters before closing the choke to avoid the risk of stalling the engine. With the Brisk you can close the choke right after firing up and just take off. Then the improvement continues and builds. The engine spins smoother, vibrates less and there is less chain-snatching in traffic. It pulls stronger throughout the rev-range. Most clearly at low and high revs. As a result, acceleration is better and the topspeed is higher. On both our SMC's the Brisks give roughly 10 KM/h more topspeed! Academic on an SM bike but it clearly shows what these spark plugs can do. At the time of this writing we've done some 250 KM's with the Brisks. The silencer exit has turned a few shades lighter in colour. Without any other changes to the setup, is a very good sign.

All these things clearly point at a better combustion. The engine feels 'round' and almost 'soft'. In a positive way that is... VERY good! I still have a feeling of slight disbelief that only a weird spark plug can do this.

At only 12,50 this ranks very high on the Bang-for-the-buck chart of mods to improve your bike.

Last modified: 07-09-2009