A BP7ES spark plug is specified for the Rev3. The previous owner has a BPR5ES in there. Aside from the heat range being wrong is there any benefit (or need) for it to be the Resistive "R" type?

I think Beta UK were recommending a 5 for the 250 for Uk use.I use a 6 because I'm all for compromise.I think there is a resistor in the cap?as well and all I know is that some 2t run better without resistors.I have run both in a Rev 3 and have never noticed any difference whatsoever.??

Gday, there is no performance benefits from using one plug over the other, however using the wrong type can cause issues with the CDI (changing secondary current amounts) on our bikes. The resistor is fitted to reduce RFI (Radio frequency interference) which can play havoc with other electronic systems typically in fuel injected vehicles. Its always best to stick with what is recommended by the manufacturer. Also important - how does the plug look? Running too hot a plug can melt pistons in a short time.

Cheers,

Stork

I've not looked at the plug yet, I'm pretty sure my bike has a high speed misfire, which I've had before on a car when I used plugs that were too hot in heat range. The reason I'm not certain, is that I've only ridden it twice, and I'm not completely familiar with the engine yet - but I don't thnik it should misfire at high revs, the power should just go flat shouldn't it?

Regarding the resistive plugs, I had a case were I used a non-resitive plug where it was specified to use a resistive one. The engine would run and then cut out after a while. Put a resistive plug in and it was fine. Must have been the CDi getting overloaded... I guess with the Beta where a non-resistive is specified, either will do?

Gday, go with a standard plug, and have a look at the one thats in there now. Fouling is most likely the problem, which can be caused by wrong heat range, blocked air cleaner, incorrect jetting or float levels, or incorrect fuel/oil mixture. I ran 70:1 in my Techno with standard carb settings and standard NGK plug and the plug was coffee brown always - perfect. Get your plug from any car parts place, they are much cheaper and the Beta plugs are a very standard easily available type. You shouldnt experience a miss fire, they do go "flat" through the range. While you are kicking around that area, make sure the plug cap is OK and check the connection between it and the plug lead. Often corrosion here can cause issues.

Cheers,

Stork