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Discussion Starter · #1 ·
I recently bought a CX500 cafe project. The previous owner had pod filters and a really nicely fabricated custom exhaust on the bike but stock jetting (i know, right), so it was running lean as hell. I changed the jets to 90 / 120 mains, which significantly reduced the "lean" symptoms (popping / backfiring, rough acceleration, difficult starting, etc).

The stator was also shot so I recently swapped in an Ignitech, G8 stator and new regulator/rectifier. My charging system is good but popping / backfiring returned. I just increased jet sizing to 95 / 125 and the bike is idling smoother than it ever has. Virtually no popping / backfiring, starts right up and has incredibly smooth and powerful acceleration from the bottom of the RPM range to about 7,000 - 9,000 (estimate, I don't have a tach) where it starts bogging really bad. This is most noticeable in 5th gear on the freeway.

What could be causing this? Is there something else in the carbs that needs to be adjusted (shim needles? floats?) or could it be something else like the fuel filter? Like I said the bike runs better than it ever has up until about 7,000 rpm and then its like starving for fuel.

Thanks guys.
 

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Bad pods + vac leaks at a guess. Can we get a photo of the inside of one of your pods?


I'd try new plugs, test the resistances of the plug caps {should be either 5000 ohms or 0 ohms}.

Run through this.

You can ignore 8/9, 5/9, 3/5 and 7/5, but you are still using the rest. 2/5 and 6/5 are the main items of interest.

 

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Discussion Starter · #8 ·
Bad pods + vac leaks at a guess. Can we get a photo of the inside of one of your pods?


I'd try new plugs, test the resistances of the plug caps {should be either 5000 ohms or 0 ohms}.

Run through this.

You can ignore 8/9, 5/9, 3/5 and 7/5, but you are still using the rest. 2/5 and 6/5 are the main items of interest.

I installed a brand new set of K&N pods. Insides look good. But I'll run through those resistance checks again.
 

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Discussion Starter · #9 ·
or the carbs are gunked up so bigger jets are letting it squeak by
They looked clean from what I observed while changing jets but I haven't torn them completely apart yet. I know 95/125 seems a bit rich but I didn't think it that unreasonable seeing as the common jetting for just pods is 90/120, but I'm running pods + a pretty free-flowing exhaust. But you're the carb expert!

IMG_0739.JPG

Here's a look at the plugs. The right carb was getting most of the backfiring before I increased jet sizing and as you can see the right side plug is still looking pretty lean.

image1.JPG

The left side plug is darker but still dry, not wet.

image2.JPG
 

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Don't these carbs have 3 jets: Idle/LowRPM/HighRPM?

My thought is that maybe the High RPM Jets, which should start in at around 7000 RPM, may have a clog or are the wrong size? My 2 cents anyway.
 
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