Stuttering Start

[Barbarian]

For the past few weeks starting has been a hassle.
It doesn't matter whether I have the choke full open or closed, if it's warm or not, the Bandit hiccups on the first turnover but refuses to catch.

Often it takes 3 or 4 tries before finally catching.

What generally succeeds is closing the choke, but pulling back on the throttle so that when it does catch it revs up to 8000 rpm for a split second.

Once it's going it never stops... so does anyone have any suggestions before I begin going through the troubleshooting pages of the service manual one-by-one?

[pmackie]

Have you tried some fresh fuel?

As we head into fall, the Vapour Pressure of the fuel you buy is raised to allow the engine to start easier (actually, in the spring and through the summer the vapour pressure is lowered, to limit evaporation and lessen the formation of ground level ozone).

Anyway, if the fuel in your tank, or you favourite station, has not been replenished with higher vapour pressure fuel, a common symptom is harder starting (especially with carburated engines).

Try fresh fuel first...

[Barbarian]

Well, I had to tank up tonight and ended up doing it at the  Ultramar close to work instead of the Shell near home. I'll see tomorrow if that has an effect (but I still plan to check the plugs).

Weather's been all over the place too. It's been 23 C for the past few days, and last week it was down to freezing...

[Nitro]

The vacuum section of the petcock may be sticking in the closed position. Try prime the next time if it's still difficult to start.

[Barbarian]

Petcock? We don't need no stinking petcocks!

In all seriousness the 2005/6 650s have a vacuum-dependent fuel valve that you never touch. The only way to check it out is to remove the gas tank, then disconnect the valve and make sure it's not gummed up.

[Mongo]

Petcock? We don't need no stinking petcocks!

In all seriousness the 2005/6 650s have a vacuum-dependent fuel valve that you never touch. The only way to check it out is to remove the gas tank, then disconnect the valve and make sure it's not gummed up.

I had the same problem with mine, I replaced the fuel valve and the problem went away!!

[Barbarian]

I think the gas at a different station did the trick. Full choke in the cold and it fires. No choke, bit of throttle after being in the parking garage at work and it fires.

[pmackie]

Errractic starting this time of year is pretty common, due to the fuel needing to change to higher RVP. We have the most fun with customers who only get deliveries seasonally, and have full summer (low RVP) gasoline on hand. Usually a top up with fresh higher RVP gasoline, and everything settles down.