1995 XCR 600 Won't Stay Running
Hello all - first post here, I found the site by trying to troubleshoot my sled and it seems as if there's a lot of good information but not the answer to my problems so far. Here goes.
My XCR will not start and stay running reliably. It ran just fine all last year, I rode it off the trailer and about 500 yards without a problem this year and it quit and hasn't been running since then. It will start and run temporarily if you use starting fluid or pull the plugs and pour a bit of premix into the cylinders but quickly dies. It will continue running at times if you spray a bit more starting fluid into the airbox but not always.
I have cleaned the carbs multiple times, they were spotless from my cleaning last year but I wanted to eliminate that right off the bat. The bowls were full of fuel. Needles and seats are good and I checked the drain ports in the block with almost nothing coming out of them. Carbs are very clean and in the same configuration as last year when it ran just fine. I have disconnected all lines to the fuel pump to check operation. All cylinders are receiving fuel from the pump, the tank to pump line flows just fine, and the impulse line draws a vacuum. Fuel is from last week so it isn't old and gummed up.
All of the cylinders get plenty of bright blue sparks when I pullstart. I have changed plugs several times, using BR9ES gapped to between .018 and.020". I have checked kill and ignition key switch both operationally (multimeter) and by unplugging the white/black wire from the cdi. I have checked the stator resistance at the plugs and all appears to be within spec (I had to use a 1996 shop manual and the wire colors were different but I was able to surmise from the resistances across the different wires that it was ok).
It has backfired a couple of times while trying starting fluid and blown the airbox filter off a couple of times (which I find funny for a 2 stroke). If I pour a bit of gas down the cylinders and start it up it runs just fine for a couple of seconds and sounds plenty strong. It dies as soon as the fuel is used up. I know it sounds like a fueling problem but I can't imagine how if the carbs are clean, pump is functioning properly, and the plugs get wet with fuel after repeated attempts at pullstarting.
Please help if you can, I'm thoroughly stumped. I have all the ingredients (air, fuel, spark) but cannot for the life of me figure this out. I'm wondering if it might be an erratic CDI unit, appears there is no way to check that out either with a multimeter.
Thanks in advance!