Bandit Alley

GENERAL MOTORCYCLE FORUMS => GENERAL MECHANICAL & TECHNICAL => Topic started by: kraig1 on October 01, 2005, 09:35:40 AM

Title: flat spot?
Post by: 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????
Title: flat spot?
Post by: Red01 on October 01, 2005, 07:27:32 PM
Need more info.  :grin:

Which Bandit do you have?
Any mods?
How long since it's seen any service?
How long has it been doing this?
Title: flat spot?
Post by: kraig1 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
Title: flat spot?
Post by: Red01 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.
Title: flat spot?
Post by: kraig1 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
Title: flat spot?
Post by: Red01 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.
Title: flat spot?
Post by: kraig1 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?
Title: flat spot?
Post by: Red01 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.
Title: flat spot?
Post by: kraig1 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?
Title: flat spot?
Post by: Red01 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.
Title: flat spot?
Post by: kraig1 on October 01, 2005, 08:31:53 PM
thanks I will post my findings tommorow
Title: flat spot?
Post by: kraig1 on October 02, 2005, 04:42:03 PM
hi, spraying carb cleaner on the bits that matter had no effect.
Title: flat spot?
Post by: turbo-bob 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
Title: flat spot?
Post by: kraig1 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
Title: flat spot?
Post by: mike 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, :)
Title: flat spot?
Post by: turbo-bob on October 06, 2005, 08:56:17 AM
Quote from: "mike"
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, :)


  ^
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   Yep.  :wink:
Title: flat spot?
Post by: kraig1 on October 06, 2005, 01:24:24 PM
hi, when it first started doing it nothing had been touched exept for the fuel tap in the tank it was running fine one day and the next day i changed the fuel tap because the old one had started leaking a bit and thats when the problem started so i put the old one back on but it still played  up. the fuel tap i put on was one i had bought from e bay and thats why i took the carbs to bits incase there had been any dirt in it and it had gone into the carbs as i forgot to clean it before i put it on..
Title: flat spot?
Post by: mike on October 06, 2005, 11:03:41 PM
I dunno what to tellya Kraig.  From your explanation, it sounds like all these changes took place right around the same time.

You might want to try disassembling and reassembling everything to do some detective work, and pay close attention to detail, take reference notes for evaluation after reassembly.  Then start making changes and notes until you narrow it down.

I guess yourother option would be a mechanic, but you kow how expensive they are, not to mention some are good and some are not.

Good luck,
Title: flat spot?
Post by: kraig1 on October 07, 2005, 01:20:01 PM
thanks it's winter soon i'll take it all to bits and check it out.