Hi All

I have naturally ran the spark plug in my 2005 txt pro 250 that came with the bike NGK BPR6ES, after looking at the manual online i have noticed this says run BPR5ES.

I know the difference is heat range but should I use the 5?. Also could this be the reason for a smoky bike ( even with a fully cleaned system, running good fuel with low mix).

Thanks!

BPR5ES is the oem plug. when I first bought one from the local motor factors they said it was the same plug used in an old vauxhall! very cheap, less than £3 if i remember correctly. the BPR6ES will run cooler and the plug will foul.......... assume that this will help create the smoke if everything else is ok.

It should have in what the manual says 'BPR5ES' and 70:1 fuel mix. I am assuming you are in the UK

But be aware there are a few mistakes in some of the manuals.

It should have in what the manual says 'BPR5ES' and 70:1 fuel mix. I am assuming you are in the UK

But be aware there are a few mistakes in some of the manuals.

hello! my manual says 50:1 which is ok with castrol power 1 but smokier with putoline strawberry trials stuff (last time i'll use that - smells like a pungent car air freshener, while the castrol smells a little bit castrol R - ish.......)

Pat

splitting the questions up

Should you run the BPR5ES?.... Most gas gas bikes in the UK weather, running standard squish / compression do! As you say its all about the heat range. With plugs you want them to get hot enough to burn off any oil / contaminants but not so hot that it causes pre-ignition under heavy load. People far more experienced than me come up with the heat range that suits our bikes. If it isnt detonating with a 5 and the plug colour is good after a plug-chop.. stick with the 5. If its detonating then go colder (6).

Would this be the reason for a smokey bike?.....No! if the bike isnt misfiring then the plug isnt negatively affecting the running. If your running a reasonable oil mix (for me ~80:1ish) It'll be smoking because its running rich or is pulling in oil from somewhere else.

Dom

Thanks for your replies

I currently run 70mm castrol tts for 5 litres super unleaded, i will try a clean out of the exhaust and running the 5ES to look for a difference.

Has anyone had any noticeable difference from the iridium 5EIX plug? Or am i just wishing?

Pat

The 5EIX plug uses a fine wire electrode (of a higher quality / hard material). This has the following benefits:-

• smaller diameter core electrode requires less voltage to initiate the spark
  
• Smaller diameter improves resistsance to plug fouling.
  
• Smaller tip footprint reducing flame masking and other gas flow issues in the combustion chamber.
  
• Incorporates a slightly modified earth electrode to give similar benefits to above.
  
• Expected life span improved due to the higher quality materials.
  

However...

Most of these benefits are aimed at very high performance engines that run richer oil ratios, higher compression, high revs, ignition systems at the edge of their performance.

Given that trials engines operate at the other end of the spectrum (weak ratios, low compression, low revs etc) i would say that there is marginal or no benefit other than life span.

So, wont do any harm, but not much good either (for increased cost).

Dom

You can buy BP5ES plugs at motor factors for less than £2 each.

another vote for BPR5ES plugs here.

its an extremely common plug, and as said, less than £2

I prefer to use the BP5ES but if I cannot get that one I get the BPR5ES which is the Resistor version of the plug. From what I understand the Resistor keeps the radio on your bike from getting interference from the plug when it is firing. Now I don't have a fancy radio on my trials bike (just the one rattling around in my head) and I prefer that if I don't need an extra bit then I don't use the extra bit.

But on the flip side the Resistor plug does work just fine and I have not had any adverse effects from using it. (but I do notice the buzzing static in my head is a bit less with the R plug. )

and just think of the weight saving on not having a resistor in the spark plug.

bou got one with a castrol sticker on it.

and just think of the weight saving on not having a resistor in the spark plug.

bou got one with a castrol sticker on it.

Well there went the weight savings if he stuck a sticker on it.

The resistor is only to quell radio frequencey that could interfere with some types of electronic ignition. There is no effect on performance.