Bike that stops when you sit on it?

[Sirjohnsavile]

I have a Suzuki burgman an250. Recently it starts ok and ticks over and revs. However if I sit on the seat it cuts out. So I took off the seat and sat on the frame. Same thing...it stopped. It restarts when I get off the seat. Very mysterious..any ideas.
____________________
Arpete

[jaffa90]

EEEEEEEERRRRRRRRR, tilt sensor when up righting the bike or smothering the air intake.

[sickpup]

[Rogerborg]

Yup, wiring. Check for wiring that's being strained or rubbed when the suspension compresses.

<Tefanecdote> I inflicted this on myself when I fitted an oversized aftermarket CDI under the seat. Every time I hit a bump I strained the cables and the bike cut out. </Tefanecdote>
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[bugeye_bob]

I thought that owners of the 250 Burgman had to have the mini RFID chip inserted in or around the anus, then paired to the bike as a security feature . . . . .

[Sirjohnsavile]

Took off air filter, changed fuel filter. Checked fule pump, checked coil, checked side stand cut off switch.....no difference. Or runs on full throttle when i sit on it but anything less and it stops. Running out of ideas. Sorty ran out of ideas. CAnt think what it could be.Slent 3 days on it so far...
____________________
Arpete

[jaffa90]

[Rogerborg]

Hmm.

Taking all your symptoms at face value, I can think of two unlikely causes, which I throw out there just for quirkiness.

1) Compressing the suspension is causing something in the transmission (belt + shaft?) to engage the centrifugal clutch and stall it out at idle.

2) Even wilder, it's vaguely conceivable that you've got a crankcase breather that's being pinched when you sit on the seat, and it's over-pressuring the crankcase and stopping the piston at idle. I mention this because the AN400 had issues with sucking oil from the crankcase into the airbox and one bodge was to plug the airbox and re-route the breather... somewhere else.

That said, I'd still assume that your fuelling problem is electrical until it's been absolutely ruled out. Particularly so if it cuts out immediately when you sit on it, rather than struggling and then dying.

Which is a closer description of what's happening?
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[Sirjohnsavile]

Well on idle the engine cuts out when I sit on the seat. If I get off the seat quickly it picks up again . I lifted the seat and took off the plastic cover. I found that if I press in the frame heavily then the engine cuts out. If I start the engine and rev it alot whilst holding the brake(it's an automatic) then it doesn't cut out until I ease off the revs. I've checked for any blocked or pinched file pipes but none are apparent.
____________________
Arpete

[Sirjohnsavile]

Furthermore the engine cuts out immediately not as if it were a fuel shortage where it might do a few seconds later.
____________________
Arpete

[Rogerborg]

[WD Forte]

Just looked in as the title begged for "stop sitting on it then"

As the engine is part of the suspension It could any cable
or connector between engine and frame getting a bad contact as it flexes.
I'd start with the ground cable/s first
____________________
bikers smell of wee

[Nemo]

It doesn't like you
____________________
Previously owned: Kawasaki KH125, Suzuki GP125, Suzuki GX 125, Honda CB125 TDC '83, Honda ntv 600, Kawasaki ER5, Kawasaki ZZR600, Aprilia RSV 1000 Mille
Now own: Ducati 848 evo

[lilredmachine]

Does it kill the ignition totally? No lights on dash etc as it is pooping out?
____________________
Bikes: too many, too much for one man to maintain anyway.

[Hawkeye1250FA]

[WD Forte]

OK
the BCF crowd are sensitive souls who wouldn't dream of causing offence, so I'll ask.
How heavy are you?
Is there a chance your enormously fat arse cheeks are restricting the air flow to the engine?
I don't judge, we don't do that here, just asking
____________________
bikers smell of wee

[Sirjohnsavile]

Sorry 12stone 13 but the air filter is off and it runs perfectltbwell til the engine flexes then immediately cuts out .it has to be electrical surely. Just cleaned starter motor earth. Cdi unit cables inspected and it still ticks over nicely. Gonna try and put a news ignition unit on when it arrives as I said earlier cos can't think of anything else.
____________________
Arpete

[Sirjohnsavile]

Sorry 12stone 13 but the air filter is off and it runs perfectltbwell til the engine flexes then immediately cuts out .it has to be electrical surely. Just cleaned starter motor earth. Cdi unit cables inspected and it still ticks over nicely. Gonna try and put a news ignition unit on when it arrives as I said earlier cos can't think of anything else.Coulnt be faulty stator could it cos battery is always charged
____________________
Arpete

[Rogerborg]

[Sirjohnsavile]

Sorted it thank goodness. It was loose spade fittings on the coil. Thanks to all those who gave suggestions
____________________
Arpete

[lilredmachine]

[Rogerborg]

Congratulations on finding it. Loose connections are a right sod - give me a broken wire every time.
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[Hawkeye1250FA]