No Engine Braking, Burbling, Weird Running - 600RR.net
Troubleshooting Having trouble with your bike? Common know issues or trobuleshooting questions here.

 
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post #1 of 3 (permalink) Old 09-07-2018, 11:42 AM Thread Starter
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No Engine Braking, Burbling, Weird Running

Hey all!

Here goes my troubleshooting post, I'll try to give as much info as possible here to help those reading. I've done quite a bit of work already, and nothing seems to affect the issue.

The Bike:
-2008 CBR600RR
-40k Miles
-Oil change done 4k miles ago, oil level correct
-Spark plugs done 8k miles ago
-Valves have not been checked in quite a while, but I have my doubts that they are causing this issue. I may be wrong.
-Custom slip-on cat-back exhaust, with baffle
-Pair DELETED
-Exhaust valve is still there and moving

Symptoms:
-While the bike is on the rear stand, in gear, clutch out, the idle is around 2k RPM, with the wheel spinning
-At the above idle, the bike does not run smoothly (see video)
-When riding, there is little to no engine braking, most noticeable between 6k and 3k RPM
-When the RPMs fall, they fall fast, but there is noticeable hiccuping as they fall
-I'm pretty sure this is expected, but as the clutch lever is released, the idle raises to 2k RPM.

Troubleshooting Done:
-Removed airbox, cleaned all sensors, cleaned air filter, reseated connections, reassembled.
-Removed and inspected AICV valve, looks perfectly clean, no gunk
-Removed PAIR system, blocked off with rubber caps and zip ties for now.

Here is the video of what's going on on the stand:
https://youtu.be/GTWe-qiU6tc

Thank you for your help, look forward to getting this fixed!
Simon Jones is offline  
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post #2 of 3 (permalink) Old 09-07-2018, 12:11 PM Thread Starter
Training Wheel Hero
 
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Here's my logic so far:
-When I turn the bike off while in gear and moving, the engine braking behaves as expected.
-Fact: Engine braking is completely (like 98%) dependent on manifold/intake vacuum.
-Fact: There are two ways air can get into the CBR600RR intake. 1) Butterfly Valves, and 2) IACV
-The butterflies are completely controlled by my throttle, no electronics, and I'm not moving them when I turn the engine off.
-Therefore: The manifold vacuum must be being changed by the IACV being closed when I turn the power off.

So my question is, why is the IACV at least partially open when I'm both in gear and the bike is at 170+ degrees, and closing when the bike turns off?
Simon Jones is offline  
post #3 of 3 (permalink) Old 09-07-2018, 12:27 PM Thread Starter
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In addition, if the IACV were incorrectly open, shouldn't there be a high-idle issue when the bike is actually at temp?
Simon Jones is offline  
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