I have a 1994 RF900 with about 46,000 miles on it. I change oil, oil filter, and plugs every 4,000 miles and use Mobile 1 Racing 4T 10W-40 & K&N filters. There are no vacuum leaks, fuel filter is clean, I only run 93 unleaded, and I don't redline it, it has a Vance & Hines muffler with the bake removed (previous owner's doing). I put about 20,000 on it with no issue until around 6 months ago.
After having some carb issues, I cleaned and rebuilt the carbs, cleared all the passageways, installed new teflon spacers, orings, and factory replacement jets (stock sizes, anyway) from factory pro including the aftermarket emulsion tube and needle which were both severely worn (it was explained to me that they're factory spec but more durable and the needle has adjustment slots for tuning).
So, after putting it all back together, it runs. But that's about it, and it's finicky.
Inconsistent idle and hesitation from 0-1/8 throttle and severe lack of power from stop are my current problems. It pops on decel and occasionally at idle, but I know that's a product of the exhaust mod.
I followed factory pro's instructions, verified the main jet size is good by trying the three available sizes and found the best pull at full throttle is the stock size. I don't really know if the float height is set correctly (.27” from the pilot jet to the highest part of the float as per the manual), I've tried .31" and .25" as well with no noticable change in performance. I set the needles at the 3rd position, then 2nd and 4th with no noticable change a so it's currently in 3rd. I've been trying to set the idle mixture screws, but I can't for the life of me figure it out.
Cylinders 1 and 4 always respond predictably to a mixture change, but 3 and 4... Not so much. It's also damn near impossible to balance the carbs, cylinder 4 always pulls more vacuum than the other cylinders, about 5" or so on the gauges.
So I'm lost, I love this bike but I can't justify bringing it to a shop to charge me what the damn thing's with just to tell me what's wrong with it.
I would love to hear any input, thank you.