I have a customers bike in her thats starting to stump me. It's a 2000 GSXR600. Customer dropped it off for a carb sync and tune. No big deal. It was barely idling and then when it did it would hang at 4k, pilot to main transition was terrible and it just ran a bit rough. I sync'd the carbs. Tuned out a ton of fuel (3 1/2ish turns down to 1 3/4). Still had a bit of a hang and I know it wasn't pig rich anymore so I checked the TPS. It was way out of spec. Replaced that. Hanging idle went away. OK so fast forward, it rides alright slight bump in transition but its pretty good. Customer goes on his merry way gets about 3 blocks away and the bike won't rev over 5k. My first thought was ok well maybe it wasn't hot enough when I adjusted it originally so I added a bit more fuel and it was pretty much the same. Guy leaves his bike. Back on the lift today, adjusting the idle screw it does NOTHING for the first full turn or so and then another 1/8th turn and it jumps 3k rims. It has NO air leaks (i checked for a while with starting fluid). Compression is 150psi across the board and the leak down is good (4 has a higher % but its not bad). Cylinder 2/3 plugs were loose. But the plugs themselves on all 4 look good. I notice the lights flickering on the dash pretty bad when it was running so I check the stator/rec/battery. Stator OK. Battery OK. Rec fails 13 out of 20 points. It does 66ACV @ 5k rpm but only charges 12.8v @ 5k rpm (spec is 13.5-15). Battery is ok and shows about 1v of AC current slipping by the stator/rec. Now I can't get this thing to run right, I check the sync again and #1 was out AGAIN. I resync'd just now and the bike runs about 85% as well as it should I just can't find the other 15%. TL/DR; Cant get bike to run smoothy and I'm missing something. I can't figure out why I can't get this bike to run as well as it should. It's *close* but not something I'm willing to let leave running like this. ANY ideas are welcome, I can't see the forest from the trees on this one.
It sounds like bad or low voltage. Can you add some power from an external source? I know that some bikes (yes, even carbs) don't like to run with dirty or uneven/low voltage. You might be right at the threshold for high rpm voltage to the coils.
I had that issue with a stator that at about 5500 rpm would be right at the point where the frequency was right to open a loose contact and it would rev over. It would do this after a while when the voltage dropped on the battery.
Check and make sure all the connections are good too. Could be a frequency that causes the connection to get worse.
After a decent night of sleep and some clarity (dropping my frustration from yesterday) it seems like this is is the most logical thing especially since I found a failing rectifier.
I'm going to check the voltage at the coils @ idle and around 4-6k to see how bad it is, I'll also check and see if it's getting any AC at it as well.
I'm so glad there are shops out there that still want to work on carburetors so I can refer customers to them.
Don't get me started. Last time we talked we had that 30 minute conversation about suspension after you gave me the wire colors for the auto blip. I could go on for days about wanting to toss every rack of carbs in the garbage.
Bad rectifier, bad ignition pick up, bad ignition coils and the CDI box MIGHT be dying. Everything is out of spec. Coil resistance is bad on the primary, CDI box is only putting out 110v of the 200v it should be, ignition pick up resistance is good but barely putting any voltage out.... Replaced the rectifier and the carb needles were shimmed up with 2 extra washers. I removed those shims and replaced the rectifier with a mosfet based unit. Bike idles awesome now, no more throttle hang or flickering lights but now we have ignition break up around 5K+. Customer just approved ignition coils and a new pick up. Slowly but surely this thing is coming around. Anyone have spare coils or ignition pick up for a 00 GSXR 600?
