Hotter running plugs?

450roo

450roo

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Nov 10, 2020
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Location
Adelaide, South Australia. Australia
The bike runs well but I get sooty plugs and perhaps a little less milage than I should, OK a little rich, I'm running NGK br8eix, would running br7eix make any difference?
What are your thoughts?
 
I've got a 500T that has uni foam sock filters, always has run a bit rich and fouled B8ES plugs, like a set every year with cleaning/sanding now and then. Could always tell when it started to run rough it was time to clean or replace them. I believe it was mostly the low end, as I replaced the main jets to compensate a bit for high RPM but it's harder to tune the stock carbs in the low to mid range if I recall. I switched to B7ES plugs a few years ago and I have not really had the same issue at all. Kind of anecdotal, and just my experience, but might be worth trying out for a bit.
 
Hey, Roo, the hotter plugs would likely help burn off more of the soot — I've noticed that as well, but I'm using non-resistor and non-iridium plugs.

My understanding was that iridium plugs are less likely to foul in the first place and from your description it doesn't sound like your plugs cause a perceivable running issue. Just the observed soot?

I also have the impression that you tend to make long rides and I assume you're running good RPM for those rides. Is that true? Is this your 450 (you also have a 500T?)? What is your main jet and carb model?

What is the status of your ignition timing and advancer springs? I've tinkered with different replacement springs and rapid plug fouling has been a common downside to springs that delay the start of the advance curve.
 
stl360+450 said:
Hey, Roo, the hotter plugs would likely help burn off more of the soot — I've noticed that as well, but I'm using non-resistor and non-iridium plugs.

My understanding was that iridium plugs are less likely to foul in the first place and from your description it doesn't sound like your plugs cause a perceivable running issue. Just the observed soot?

I also have the impression that you tend to make long rides and I assume you're running good RPM for those rides. Is that true? Is this your 450 (you also have a 500T?)? What is your main jet and carb model?

What is the status of your ignition timing and advancer springs? I've tinkered with different replacement springs and rapid plug fouling has been a common downside to springs that delay the start of the advance curve.
Click to expand...
It is a 71 model 450 only is the right side plug. The timing is spot on and there is no tendance for the revs to hang, usually a sign of weak springs. Yes long rides a normal ride is about 150 miles, mostly about 4000 - 6000 rpm on the flat roads that translates to 50 - 70 mph.
The bike does not consume a lot of oil, a150 mile ride uses about 250 mil, about 8 fl oz.
 
It might help to see what the plug looks like, but I'm not sure I'd do anything in this case. I'd be a little hesitant to expose the motor to more heat for long highway runs, especially when the left side is looking good.

I had asked something similar in another thread, but thinking more about stop and go riding in the city. There were many helpful responses, some of which may be useful to you as well.
 
Given the length of your rides, it would be a cheap insurance policy to bring BR8EIX plugs along to swap in if you notice any symptoms of overheating. I assume you already carry some tools.
 
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