Suzuki Bandit GSF650 2007

[Murakami]

I've taken on a project GSF650 that has been sitting in a garden for a few years managed to get it going but the bike cuts out at 3k rpm.

I've replaced and cleaned

1. spark plugs

2. oil and filter

3. air box and new filter

4. New fuel

4. Stripped and cleaned carbs

So I've striped the carbs down and clean them. (Pilot Jet where almost blocked)
Everything else looked good just a little brown at the bottom of them.

It runs much better but there is still a problem.

With it cold the choke works to well though it revs its nuts off with half the choke open.
once its up to temperature with just a little bit of choke it kills the bike.

When its up to temperature It revs as normal for the first rev then with each other rev it gets weaker and weaker until the 3rd or 4rth it stalls.

I think its an air/fuel mixture issues... I'm not sure.

If anyone has had the same issue or ideas greatly appreciated!

Cheers!

[that_impulse_guy]

your choke works fine, thats how they are. Its actually a fuel enrichment circuit, its not an air choking circuit. So you put it on to start the bike when cold, but if you leave it on then a few seconds later the revs rise and rise and then you turn the choke down a but, then a bit more..etc.

If the bike is warm and you add choke...it may or may not die. If it does, thats not a negative indication.

What you're saying about blipping the revs etc, assuming the engine is warm at that time I would go look into how much fuel is flowing from the petcock, I'd check the vacuum hose that goes to the petcock, I'd check the intake rubbers for cracks, and I'd check the float levels.

I'd do all these checks because you've obviously done all the other things, like setting valve clearances and checking the carb mixture screws and syncing the carbs.
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[stinkwheel]

I agree, sounds like it's running out of fuel. Blocked/ineffective fuel tap or filter? Blocked tank breather?

If the tap has a prime position, I'd try seeing how much fuel runs out with the hose disconnected (you want a stready stream rather than a dribble). Try running it with the tap on prime and the filler cap open.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Robby]

I would go with general purpose fuel system filth as a first guess.

You found muck in the pilot jets, so there's some crud somewhere to cause that. Most likely place to find it is rust in the tank.

Seeing as it tends to be a ballache to chase down problems in carbs, you might as well do the job right and do it once. Clean carbs, clean fuel lines, clean fuel tap, fit a fuel filter. Clean the interior of the tank really well. If you find rust in the tank, take care of it.

I don't know if these bikes have anything in-tank, like a pump, filter or fuel level sensor. If they don't, great, you can use all manner of mechanical and chemical processes to remove rust. Phosphoric acid is my favourite.

If there is a pump, filter or sensor in the tank it makes things more difficult. Phosphoric acid eats away at aluminium, possibly also brass.

Then after all that work, you find out the problem was a weak battery or poor earth all along.