My only issue is after a while of riding I start getting a misfire/backfire out the exhaust mainly-only during backing of the throttle a little at lower rpm. Say, cruising going 40mph at whatever throttle position to 30 mph and slightly less throttle position.
Last summer I could only get the machine to top out around 65mph. Since then I modified a new intake pipe to fit the existing oem box which also has been cut open more then last yr and prefiltered. I went from a stage 2 to stage 3 raptor (which is grizzly stage 2). I did a half shaft mod on my throttle body and smoothed out the lip on the inside of the body and edges of TB. Removed my Purple spring and went to an orange spring.
When I started tuning I zeroed out all the fuel table to start fresh and changed a little bit of the afr targets. This yr I hit 72mph and had to back off the throttle bc it was getting a little sketchy with all the bumps and laptop in my hand. I do believe it would have hit atleast 78. The rzr 900s I was already beating last yr have no chance at all this yr. So I’ve done something right so far.
My issue is I’m getting carbon build up on the base ring and up the ground strap of the spark plug which I believe is causing the misfires/backfire at low rpm/deceleration. Wot high rpm does not seem to be affected at all. From reading my plug I think I’m rich at idle and mid range. To me my WOT looks to be dead on. My timing on ground strap looks good to me too. The plug I’m using is the CPR7EA-9. Gas tank has half full of 90 and filled the rest of the way with 87, so 88.5 which is exactly midgrade up here. There is no ethanol added to the gas up here. I wanted to lower the octane from what I was running incase that was the issue and I have yet to rule that out yet. 11.1-1 compression with advanced ignition timing. Plug was brand new at beginning of this ride and yes I know I should put a new one in and do some runs, immediately shut off and then read. I’ll do that next time.
What do you think of my plug?
What’s good idle, mid/cruising and decel afr that y’all run?
