Makes me wonder about the bikes maintenance history. If the previous owner changed the cam chain shoes and the oil pump wasn't reassembled right and allowing the engine to sump oil, as previously mentioned. The sump is usually "dry", if oil is collecting in the sump the flywheels are spinning into the oil adding resistance to the spinning flywheels. Also certain years had the wrong size injectors, not providing enough fuel.

 

It almost feels like its skipping on gas for a sec but i guess it does feel like the brake catches for a sec. Ill check that asap for sure. I didnt have the o rings the other day when i did all that work, now i do

 

If it's just a momentary thing, it's likely not sumping. Sumping doesn't come on real fast or clear real fast.

Another thing to look at is the external fuel line.. The locking detent ***** wear into the coupling and allow the fuel to shut off. If the issue is common, you can try holding up on the coupling to see if it cures the problem.

 

I'm betting on the tuner being done incorrectly. Start with the easy stuff first - checking codes and the tuner!

 

Maybe I missed it, but did you say it just started doing this recently, or has it been that way since you got it? It really sounds like it goes too lean or too rich in that RPM and load range, which would be a tuning issue, but it wouldn't have just come about.

Rule #1: when something goes wrong, undo the last thing you did.

 

Just started about a month and a half ago. I thought at first it was bad gas. Fuel fresh tanks later still happening. Tried fuel cleaner, no success. Then like i said, new pump, fuel lines, filter, engine rebuild, etc. still happening. Havent messed with the tune in almost 3 years, been running strong as hell. Gonna try o2 sensors next

 

Since this happens between 3000 and 5000 rpm the o2 sensors probably aren't the answer. You should be running in open loop in that range and the o2 sensors aren't doing anything. It also depends on how it's tuned. Closed loop is disabled on my 07 so the o2 sensors never do anything. I'd throw the money at resealing the intake manifold and buying a fuel pressure gauge. If your TTS will allow you to read sensor status you can go to the bike when it's completely cold and see if temp sensors are reading ambient temperature. Same for the MAP sensor. 100 kpa is atmospheric pressure...it will vary a bit with elevation

I have this cheap fuel pressure tester from Amazon. You have to connect the test line to the intake and then connect the line from the tank to the test line. It ain't fancy but it works.


Edit: Did you think you bought some bad gas or has the bike been sitting for months with ethanol gas?