Read my plug

[bacon]

This isn't a plug chop so I realize a truly accurate read can't be done, but how does this look? 08 bugeye with Athena Sport BBK and 85 main in a stock carb. Running a BR9HS plug. Send to run well. Starts easy, decent power throughout the band, rings fairly cool with about 230 being the max I've seen. This is with maybe 20mi on it with 2-3 mile Rides each time. A little cleaner then I thought, but I know it's oiling as I can see faint smoke when accelerating (and I can smell it) and it runs cool. Just don't want to torch a new BBK

[pili]

Looks rich but it's better to err rich than lean. You didn't mention exhaust so I take it you're running the stock can? If so I'd say an 85 main is a bit much. I run an 82 on one of my bugeyes with a Malossi kit and stock can, along with a 46 pilot. Runs perfect and plug looks normal. Your temps are cool, maybe too much so.

[billwill]

This definitely looks rich to me. Hard to say where your are running rich but I would try lowering the main jet and/or needle a bit. Keep an eye on temps while doing so but 230º is very cool and you have room to lean things out. Aim for temps closer to 300º.

BR9 plug could be too cool for this and you could try swapping out for a BR8 first. That may be the first thing I would do.

In the end, keep a close eye on temps and you'll be ok. Aim for a plug color that's "coffee brown" or light tan but temps will tell you where you're at.

[bigmatthew86]

Personally I aim for 350. 230 is way too cold.

[bacon]

This plug had pretty minimal use on it and I agree it is likely rich. I havent put much effort into tuning this thing as it's the stock setup and I intend to order new exhaust and 19mm carb for it today. Just wanted to get some affirmation that I wasnt going to burn up the new top end before I get the new goodies. For the most part it runs pretty well - took it out for about 15mi last night ripping on it pretty hard and it seems to run fairly good in the upper half with a little hesitation down low. It'll do about 42mph on the flat, more with a slight tail wind or decline in the road. I also have an 82.5 main, but I'll probably just leave this for now and tune the new carb.

The BBK I have is all aluminum and I was told that they need to run the BR9HS. Is that not true? I think I have a BR8HS sitting on the bench I could try.

[billwill]

May 13, 2024 10:32:47 GMT -5 bacon said:

This plug had pretty minimal use on it and I agree it is likely rich. I havent put much effort into tuning this thing as it's the stock setup and I intend to order new exhaust and 19mm carb for it today. Just wanted to get some affirmation that I wasnt going to burn up the new top end before I get the new goodies. For the most part it runs pretty well - took it out for about 15mi last night ripping on it pretty hard and it seems to run fairly good in the upper half with a little hesitation down low. It'll do about 42mph on the flat, more with a slight tail wind or decline in the road. I also have an 82.5 main, but I'll probably just leave this for now and tune the new carb.

The BBK I have is all aluminum and I was told that they need to run the BR9HS. Is that not true? I think I have a BR8HS sitting on the bench I could try.

Ahh good call. I would stick with the recommended plug and try to get the jetting right first rather than start fiddling with the plug.

Aluminum kits can even withstand higher than 350, although 350 is a good target max temp. With hard running, my MXS will shoot up to 390-ish but that kit isn't made for sustained full throttle use.