I have a 2008 SXR with a "bogging off idle" issue that is kicking my ass.

Feb 9, 2015
Mission Viejo, CA

I have a 2008 SXR 800 that I completely rebuilt last year. New rebuilt Crank, (from Competitive Cranks), rebore and new pistons and rings. She's ran like a champ for more that 35 rides and then suddenly, a month ago out at Parker, she started having this bog off idle.

To describe the bog better, when you ride from the ramp in the no-wake zone at slow speed, you can feel this sort of low RPM hesitation, but if you give it just a bit more throttle, suddenly she picks up. As you continue through the no-wake zone, you can play with it going back and forth between this weird "hitch" that hesitates, then suddenly hits. Once out in the lake, she'll stumble and bog off idle, but once you're going more than ten MPH, and you get above the bog, she revs out like normal. From idle, she'll tend to stall if you don't keep jiggling the throttle.

Also, from almost a dead stop, if you just yank it full throttle, she'll die. If you're moving at around 5-8 MPH, and yank it full throttle, she'll run steady at only about 2000 RPM for about 20 feet,... then suddenly hit and rev out like normal.

You can actually ride her like normal if you keep her above the "rough idle/hesitating zone", but obviously I want the ski to run properly.

Immediately I tried different plugs, pulled the fuel lines, checked the on-off-reserve switch, even messed with the fuel screws a bit. but nothing helped. Realistically I hadn't done or added anything since the rebuild. We were riding on flat calm water so it wasn't like we were jumping in the surf and slamming it down. It just started doing this "bog off idle" deal out of nowhere.

So just to recap:
After i came home, I rebuilt the carbs with genuine Mikuni kits, took it to the lake and it didn't change a thing.
Then I swapped out my carbs from my 2011 ski, checked it at the lake and still no good.
I pulled the reeds and they looked brand new with each one sitting flush and sealing against the cage perfectly, (no gaps or daylight between each reed and its sealing surface on the cage).
I did a leak-down test of the crank, (ran a pressure check AND pulled a vacuum on it and it was perfect).
I checked the stator and crank sensor. They looked perfect and measured exactly what the service manual says they should be with an Ohmmeter, (plus I got the same measurements from the 2011 ski).
I looked for exhaust leaks in the engine compartment, but found none.
I cut back the spark plug leads, checked the return line to ensure that part of the system stayed pressurized, (it did), I checked the pulser line, checked all the wiring, took it to the lake and it STILL had the bog.

Then on Saturday, I swapped out the entire ebox from my 2011 ski and installed it in the 2008, (changing the entire ebox essentially installs a known "good" coil, spark plug caps, spark plug wires/leads, the CDI and all connections). I took it to the lake today and she's STILL bogging badly.

Could a faulty exhaust temperature sensor cause this bogging issue??
Sep 26, 2006
Greensburg, PA
I had my wife’s ski doing the same thing...It had a blown head gasket..,,I pulled head off after running it when it was bogging and there was water droplets on head & rear piston.....Just some food for thought.....

Dano 7
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