Yamaha XJR400 - Idle speed rocketing up

[Seb]

Hi, the fickle carbs on my XJR threw me a right curveball on the way home tonight, the bike ran sweet as a nut for about 20 minutes then suddenly decided it'd much rather idle at 4k rather than the usual 1k. It was almost as if I'd flicked the choke right on (except actually doing that would more than likely just stall it or stop it from revving freely). First sign I felt of anything going wrong was losing engine braking coming up to some lights.

Now getting these carbs running spot on has been a bit of a mission, one of the first things I had done when I bought the bike was to have the tank and float bowls flushed and the carbs balanced, the first attempt ended up with a warm idle of around 2k but the local workshop soon straightened that out and it's been peachy smooth if a little lean towards the top of the rev range. The carbs could do with a proper strip and clean session but the fuel tank (dodgy petseal job) needs replacing first.

Any suggestions or tips would be hugely welcome as this gremlin is a bit more sudden than the usual treats the bike seems to love throwing at me Would gunk from the tank be the culprit this time?
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2010 Triumph 1050 Sprint ST

[mattsprattuk]

airleak.
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Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!!
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[Seb]

On the inlet rubbers? That makes sense as the bike sometimes stutters over bumps. Ta!
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2010 Triumph 1050 Sprint ST

[0l0dom0l0]

Yeah, sounds like the carb rubbers are leaking.

A good way to check is to spray some WD40 on them and if the idle note changes then they are leaking.

They can be repaired with some rubber glue and electrical tape temporarily but will need to be replaced some time in the future!
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CBT Passed: 30/08/2009, Theory Passed: 31/08/2010, Mod 1 Passed: 6/9/2010, Mod 2 Passed: 13/09/2010. Restriction ended 13/09/2012.

Bikes: 2007 Derbi GPR 50, 1998 Yamaha Fazer 600 (written off), 2002 Yamaha Fazer 600, 1994 CBR 600F, 2003 Triumph Daytona 600, Kawasaki ZX6R J1.....Current: 2006 Yamaha FZ6, 1998 Suzuki TL1000R and a Honda VFR 400 NC30.

[mattsprattuk]

give me a text if you want me to have a look at it. It's about time you stopped being mugged off by wanky 'mechanics'
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Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!!
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith