Author Topic: flat spot? (Read 6410 times)

kraig1 · « **on:** October 01, 2005, 09:35:40 AM »

hi, when I go above 70mph shut the throttle off and open it up again the bike stutters, it feels like once youve shut it if you open it, shut it and open it again fast. it has also started doing it if I ease off the throttle and open it up again, . the longer you leave the throttle closed before you open it again the worse it is. it's not just 6th gear it does it in i've done it in 4th and 5th too. is it a flat spot and what can i do about it????

Red01 · « **Reply #1 on:** October 01, 2005, 07:27:32 PM »

Need more info.

Which Bandit do you have?
Any mods?
How long since it's seen any service?
How long has it been doing this?

kraig1 · « **Reply #2 on:** October 01, 2005, 07:35:53 PM »

hi, it's a 96 bandit 600, it has a race exhaust but that was on it when i bought it 12 months ago the problem started about 4 months ago, since then i have had the carbs of a couple of times and cleaned them, checked the fuel cock and pipes, set the carbs up, new iridium plugs, new coils,checked the compression,new air filter,i think thats it

Red01 · « **Reply #3 on:** October 01, 2005, 07:53:04 PM »

Sounds like a lean condition on accel... Check for vacuum leaks on lines, caps & manifolds. Might wanna take a close look at the vacuum diaphragms again to be sure they aren't damaged in even the slightest way. They should be nice and supple.

kraig1 · « **Reply #4 on:** October 01, 2005, 08:03:27 PM »

one of the rubber things that attaches the airfilter to the carbs looks a bit warped could it be this, i also tried adjusting the mix but apart from use more fuel it didn't do anything

Red01 · « **Reply #5 on:** October 01, 2005, 08:09:15 PM »

Possible, though not as likely. Normally, a problem between the airbox and carbs isn't going to cause you that much of a problem unless it's obstructing airflow.

I'd still be looking for a leak in/on the carbs or between them and the engine.

kraig1 · « **Reply #6 on:** October 01, 2005, 08:13:56 PM »

it'll do 0 - 130 without a problem it's only when the throttle is eased off or shut of and opened again and from what ever speed it's opened up at it'll go right up to 130 again without doing it. thanx i'll have a look tomorow and get back to you.
p.s.
whats the best way to check for vacume leaks cos wouldn't it be sucking air in? not out or am i being thick?

Red01 · « **Reply #7 on:** October 01, 2005, 08:22:36 PM »

Yes, it'll be sucking in. You'll need to spray something combustible around suspected areas - something like carb cleaner or WD40 - and listen for rpm changes. It's probably gonna be a small leak since steady state and slower accel demands are OK, just falls flat when there's a large demand and then fuel catches.

If it had always been doing this, I'd tell you there's a jetting problem, but since it seems to have changed many months after the exhaust change, that leads me to believe it's not jetting.

kraig1 · « **Reply #8 on:** October 01, 2005, 08:26:06 PM »

ok thanks a lot for your help i will try that in the morning as it's 12.25am and i don't think me neighbours would be to happy if I started it up.one more thing do you know if the exhaust system is the same for the 600 and 1200 bandit?

Red01 · « **Reply #9 on:** October 01, 2005, 08:29:53 PM »

Factory pieces are not the same, but 1200 parts will fit the 600. The 600's factory header won't fit a 1200 because the downtubes are shorter.

Aftermarket slip-ons that come with midpipes will fit both bikes of either generation.

kraig1 · « **Reply #10 on:** October 01, 2005, 08:31:53 PM »

thanks I will post my findings tommorow

kraig1 · « **Reply #11 on:** October 02, 2005, 04:42:03 PM »

hi, spraying carb cleaner on the bits that matter had no effect.

turbo-bob · « **Reply #12 on:** October 06, 2005, 12:47:11 AM »

Quote from: "kraig1"

hi, it's a 96 bandit 600, it has a race exhaust but that was on it when i bought it 12 months ago the problem started about 4 months ago, since then i have had the carbs of a couple of times and cleaned them, checked the fuel cock and pipes, set the carbs up, new iridium plugs, new coils,checked the compression,new air filter,i think thats it

Two thoughts............

Carbs set up........what changes

Try std spark plugs !

my .02

kraig1 · « **Reply #13 on:** October 06, 2005, 04:06:43 AM »

hi, when you say carb set up do you mean balancing them cos I have done that every time I took the carbs off but I will try standard plugs.
thanx

mike · « **Reply #14 on:** October 06, 2005, 04:56:15 AM »

Quote from: "kraig1"

since then i have had the carbs off a couple of times and cleaned them, checked the fuel cock and pipes,set the carbs up, new iridium plugs, new coils,checked the compression,new air filter,i think thats it

If you've done the bold above recently. That's what Turbo Bob is referring to... Go back and recheck everything. You could have missed something very minor in reassembly if you've pulled the carbs recently. Something has obviously changed, no matter how minor or miniscule it seems; carbs can be touchy creatures especially in quad banks.

Good luck, :)