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chicagobikefan

Inside of exhaust sooty black

8 posts in this topic

I'm continuing to tweak the number of disks / jet sizes in my uncorked '05 XR650L. I have 58/165 with 9 disks. Plug is white and clean, but inside of Supertrapp IDS2 is sooty black after about 300 miles. Is black soot inside the exhaust to be disregarded? It doesn't mean a rich condition, does it, even though the plug is white? Sounds like the white (lean) plug is telling me to remove some disks to richen things up... I'm confused; help me, exhaust experts :thumbsup:

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I'm continuing to tweak the number of disks / jet sizes in my uncorked '05 XR650L. I have 58/165 with 9 disks. Plug is white and clean, but inside of Supertrapp IDS2 is sooty black after about 300 miles. Is black soot inside the exhaust to be disregarded? It doesn't mean a rich condition, does it, even though the plug is white? Sounds like the white (lean) plug is telling me to remove some disks to richen things up... I'm confused; help me, exhaust experts :thumbsup:

How does the bike "feel" or run? Any hesitation or bogging? If you go too rich you'll end up not burning all the air/fuel mixture, especially in a low(er) compression XRL motor, which means more carbon build up. You might be able to notice that unburned fuel smell when revving the motor well past idle.

Any bogging in the mid to full throttle range could mean the main jet is too rich. On the other side, if it leans out before 80 mph top speed, it's probably too lean. Ideally, you only want to upsize the main jet 1 to 2 sizes larger once the motor has leaned out depending on engine mods.

Also, a lot of the "black soot" can be attributed to a richer pilot circuit during warm up. The XRL benefits from the richer pilot circuit because it eliminates that annoying off-idle bog.

But then again, I might not know what I'm talking about... :thumbsup:

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when I purchased my Supertrapp IDS2 last year, a small slip of paper was included with the paperwork ... Supertrapp stated that the 'quiet core' in the pipe was equal to 6 discs, .... more discs would make zero difference, as the core will only pass what it was designed for ... (I run 8 discs, anyway, it's just the outlaw in me) ... I suspect if your pipe gets a bit of soot just from the 'choke' while starting, the soot will remain for quite awhile, regardless of fuel mixture ... I think that may be what you're seeing ... go by the spark plug readings, and be sure to check the plug after a good high-speed run, and fast shutdown ... :thumbsup:

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Its tough to read the exhaust , because if you're rich anywhere (idle, mid, top-end) the exhaust will soot and stay there.

If you only have a rich spot, and lean everywhere else, the plug will get cleaned if you shut it down outside the rich spot.

Dave

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Its tough to read the exhaust , because if you're rich anywhere (idle, mid, top-end) the exhaust will soot and stay there.

If you only have a rich spot, and lean everywhere else, the plug will get cleaned if you shut it down outside the rich spot.

Dave

Don't all carbureted ICE's have rich spots? Especially ones equipped with accelerator pumps? Throttle modulation allows us to richen or lean out the mixture.

Isn't this normal?

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also, if your "plug is white and clean" , it sounds like you are already running quite lean ....

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Don't all carbureted ICE's have rich spots? Especially ones equipped with accelerator pumps? Throttle modulation allows us to richen or lean out the mixture.

Isn't this normal?

I think you can get something without an accel. pump (like an XRL) close enough that you won't have any soot- but basically, yeah, that's why its tough to go by the exhaust pipe.

Dave

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Thanks a lot for the info, guys. I'm going to be taking the Supertrapp down to 5-6 disks just to see how it runs. But, we got snow in Chicago last night and right now all the little puddles are freezing over so I'm nervous about taking it out...

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