Hesitation at wide throttle/high speed - ideas?

AtomicBanana · 18 Oct 2011 at 10:46

So my XJ600 has picked up a little issue which is worrying me atm.

I've been riding it 110 miles a day for about a month with 0 issues, however this morning it began to hesitate/stutter slightly with a wide throttle (doing ~85 in top gear). At first I thought I was just being buffeted by the wind, but I soon realised it was the bike itself. it felt like a tiny loss in power, as if something was grabbing the bike and letting it go very quickly. I watched the revs and they didn't really seem to change, and wind noise is too high to really hear the engine.

Worried, I dropped down to about 60mph in the same gear, and the problem seemed to go away. When I sped back up to 80, it came back again. I dropped back down for the next part of the journey, but again was able to do 80+ no problem for the final leg. As I came into town, going up and down the gears, the bike felt 100% fine.

I can only think it's maybe a minor fueling issue? As it seems completely fine at lower speeds.

paddy · 18 Oct 2011 at 10:50

Does the issue occur if you hold the engine at the same revs as 85mph in top - but in a different gear?

If you hold the revs constant through the range when parked up does the same thing happen?

I'm guessing fueling, but also check your plugs and air filter etc are all clear

AtomicBanana · 18 Oct 2011 at 11:16

Yeah, I'm going to try this on the way home, assuming I can get it to happen again.

I'll give the plugs + filter a quick look when I get in too. Not so much fun when I need this thing to be functioning to get to work!

paddy · 18 Oct 2011 at 11:18

Dirt in tank and kinked fuel lines would be an easy initial check.

kippermitten · 26 Oct 2011 at 16:04

Sounds like a fueling issue chap, had similar issue with my 1997 cbr600, turned out the tank and fuel lines where chock full of crud.

helpimcrap · 27 Oct 2011 at 19:13

fueling issue - check all as said. some are dead easy to check and don't require much know-how but other stuff will.

also check there isn't an air leak in the inlet rubbers. it would happen in every gear though so apply same throttle and same revs in lower gears to see if it happens then too but this can apply to the fueling too.

saying that though it could be carb icing if it has been really cold where you are around freezing? at 85mph that would be amplified due to temperature.