While
Quote:
Originally Posted by Mick
Bike has been running a little sick lately. Pulled the air box and throttle bodies to have a looksy.
Air filters are nasty. Not sure what color they were 8 years ago, but my gut is telling me they weren't brown and black. And the front intake valves are looking grimy. I would have thought both front and rear valves would look close to the same, but this isn't the case. Rear valves are squeaky clean.
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on the other hand we have
Quote:
Originally Posted by glockem45
The front spark plug is ashen/ clean looking, while the rear plug is wet and sooty.
I need to also check the valves for clearances, etc, and go through the entire bike this season. I am about to get the bike Dynoed, so I am looking forward to that.
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And nobody has addressed the issue of differences, and back to front and front to back confuses the issue even more..
We know that all front to back twins run a bit different, heat and cool different and also breathe differently.
I can;t find it right now but there is somewhere a huge technical article about airbox resonance and the problems of V twins, how one cylinder sucks the air of the other and flow is hardly equalized.
Don't stock air filters have differences front and back, a restrictor on one of them? If you can reverse them you can make a small problem even bigger. Neither BMC or K&Ns have this, only Honda does.
Some of the aftermarket airboxes have larger volume to help resonate better at higher rpm, so if you are running a rev limiter you may be losing hp with one.
Valve clearance can make a small difference but rpm range makes even more. If one of you is running between 4-7k 90% and the other is at 5-9k rpm the plug and valve findings may be different.
Then what you see in the plug may be different than what you see in the manifold. A richer cylinder could be having less or more back surge. I would think the rear tends to run a bit hotter at times and hotter cylinders feel richer than cooler cylinders.
When I first got my bike the rear plug was borderline fouling, I had ordered a pair from a local part store but couldn't wait 2 days. I took them both out and cleaned them as well as I could (burning after chemical cleaning helps) and switched them front to back. Haven't had a problem since and still have the two new plugs.
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