Bike cuts out at lights when hot

[WD Forte]

Me old CX thing runs just fine and starts well, but when it's at running temp it will falter and sometimes cut out at lights junctions etc
I hate having to keep revving it when this happens.
Normally it ticks over like clockwork

It's done it before
One time I found the exhaust headers were leaking and nipping them up cured it.
This evening it started doing it again and tomorow I'll have a look at it
but inviting any theories/tips at what to look for in case I haven't considered something.

It's not a CDI lump BTW in case anyones reckons the stator coils are failing, I upgraded it to a TI motor ages ago
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bikers smell of wee

[andym]

Vapour lock?

[Kawasaki Jimbo]

Raise the idle a little? My bike can hold a smooth idle at just below 1000 revs but it won't pick up the throttle cleanly unless the idle screw has a few more revs dialled in.

[weasley]

In warm weather or in cold? I’m thinking about carb icing.
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Yamaha XJ600 | Yamaha YZF600R Thundercat | KTM 990 SMT | BMW F900XR TE

[redeem ouzzer]

Either tweak the idle or lean it off slightly on the pilots.
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Be a REAL MAN!

[Nobby the Bastard]

Rubbers between the engine and the throttle bodies are perished.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[kgm]

[andym]

I replied to this thread because I have the same issue with my bike... I think

For example I find myself in the city centre with the whole ride 10 yards and stop for 2 minutes then repeat..... so the 150 miles of country roads I've just ridden were fine with 2 stops

This is not a problem for FI engines allegedly, but carb'ed bikes suffer with the ethanol content in the fuel because it has a lower boiling point.... hence causing vapour lock.

I've looked in to sorting it on my bike, but learned to live with it for now.... but if you were to fit a modern fuel pump then it would mostly* fix the problem



* I've not bothered to buy a new pump because it's one of the quirks I've learned to live with, (fast bikes don't like slow speed etc).

[jaffa90]

Have you tried using the choke to see what happens when you stop?

[RhynoCZ]

[fatjames]

Maybe a restricted fuel filter? Not sure that would only make a difference at lower RPM though.

[WD Forte]

Thanks for replies and suggestions

I didn't get chance to do much yesterday
Last night I wondered that if it was caused by leaky headers
almost 2 years ago, they may be a bit iffy again by now so I've ordered new ones
which I'll fit as part of this weeks check over
It's due some springtime tlc anyway.

Vapour lock? possibly, but normally it doesn't suffer this even when the ZXR 750 fan I fitted cuts in
and that moves lot more hot air over the engine than the stock mech fan.
It is temp related though so not dismissing anything out of hand.

Restricted Fuel flow? I considered this but dont think so as it doesn't have a vac tap which can be troublesome
and runs Ok at wider throttle openings

Cracked carb rubbers? sorted ages ago with heat shrink and they're tested for leaks from time to time
but will check them again of course.

Choke fiddling? haven't tried that, worth looking into as it may give clues

I'm also wondering if I've set it up borderline lean so any small variation can push it over the edge
so to speak
Will continue to test, examine and twiddle with stuff
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bikers smell of wee

[WD Forte]

Update :
No progress on the hot cutting out thing yet because other
things took precedence.
Soo, when I started to tinker with the bike again plus do a pre mot check
I see the front tyre has a damaged side wall!
Got new Road rider fitted and while the wheel was off decided to tart up front end and give it some TLC.
I have put some new exhaust header seals in just for the hell of it as 2 years ago doing that fixed it.
Should be back on the road again v soon and will see how it runs.
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bikers smell of wee