Things that go pop? Back firing in the airbox - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 3 (permalink) Old 06-13-2017, 03:55 PM Thread Starter
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Things that go pop? Back firing in the airbox

I previously mentioned that I suspect that my bike is running rich below 6k RPMs and it seems to be confirmed by backfires in the airbox (feels and sounds like a single small firecracker in front of my nuts occasional after engine braking at low speeds.)

I have a very old looking PCII. Any possibility to fix the too rich condition myself? Custom map install or other means of tuning? Or I need to suck it up and pay for my first Dyno tune? This is my first experience with FI tuning....will i miss being able to rejet and adjust my carbs myself?

Will be my first time pulling the bike apart (need to install an alarm & tracker anyways) but the bike has Leo Vince SBK slip ons, stock headers, and an unidentified (German) CF airbox and aftermarket filters.

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post #2 of 3 (permalink) Old 06-13-2017, 06:47 PM
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Don't know if I've heard of anyone on this board running a PCII. Some of us still run the antiquated PCIIIr. Including me, never a single hitch with it. With that airbox and slip-ons I suppose you need some fuel map corrections, otherwise I'd say just bypass/unhook the PCII.

I've read just enough about the difference between PCII and the PCIII series to suggest scrapping that PCII. LDH explains about it on his mods page.
Mod Instructions Page

That site, and the Honda Service Manual, were my bible for the first two years when I was doing all kinds of stuff to my bike.

Will you miss working on the carbs you ask?
I've cleaned, rejetted, and complete overhaul on about 3 different carbs. My 2 stroke jetski, my 450crf and the OEM carbs off a 79 goldwing. I'll take FI all day every day!

John, 2000 RC51 #000100

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post #3 of 3 (permalink) Old 07-14-2017, 04:31 PM
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Check valve lash? Possibly some fire is leaking back into the intake when the valve should be sealed shut?
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