Idle woes and dies in gear?

[chukidrifter91]

Hey guys I bought a stock 91 bandit 400 non running at first (needed a charge before it ran just fine  in Neutral).   So i got it home and after a charge and a few cranks she fired right up, BUT my idle is quite strange...

the issue? it surges to 2.5k on the lowend to 4-6k high end with the choke on.  With the choke off, it will settle down SOMETIMES to 1-1.5k after idle adjustment but usually lingers around 2.5-3.5k.

So I figured id just compensate it and take it for a test ride in front of my house, with a large grin intact.
I get ready, pull the clutch and pop it into 1st, let the clutch out, Instantly dies. In any gear.

If i try to start in 1st, it moves forward even with the clutch compressed.

Research has dictated me to check out a few diff things:

1. kickstand safety switch - working fine, no gunk around it and travels smoothly.  kickstand fully compresses it when up.
2. idle adjustment screw - tinkered. lots of back and forth adjustment.
3. choke cable? - unsure how to really see issues, seemed fine on inspection (Im a mechanic, good knowledge of such things, seemed fine.)
4. clogged idle jets? - Carb work = no fun for me, but the previous owner had a reciept from a shop that did carb work, and bike was running fine and riding after it was performed in 09.
5. clutch - Carrying over from my automotive days I despise, electrical, and transmissions, IMO its a big box of witch craft so idk what to inspect here really.


So anyone got any ideas? This is my first bike, and id really like to be able to enjoy some riding this season

any and all help would be very much appreciated

cheers guys!  - Kai

[Chris H]

Hi Kai,

Sounds like the clutch needs some minor adjustment, if you remove the dome cover down on the front sproket cover you can adjust it, BUT the cutting out sounds like a carb related problem to me unless you have a clutch switch. I read some USA bikes have the clutch switch, ive no info on this as im in the UK.
It cannot be stand switch as this cuts the engine as soon as you put the bike in gear and not when you let the clutch out.

[interfuse]

Your clutch definitely needs some adjustment. I'd sort that out first.

And seeing it's your first bike, I'm going to ask...

Are you twisting the throttle to prevent it from stalling while releasing the clutch?

[chukidrifter91]

Your clutch definitely needs some adjustment. I'd sort that out first.

And seeing it's your first bike, I'm going to ask...

Are you twisting the throttle to prevent it from stalling while releasing the clutch?

lol absolutely am, 5sp 240sx and drifting/autox has taught me much of trans control...man bikes are touchy haha

Hi Kai,

Sounds like the clutch needs some minor adjustment, if you remove the dome cover down on the front sproket cover you can adjust it, BUT the cutting out sounds like a carb related problem to me unless you have a clutch switch. I read some USA bikes have the clutch switch, ive no info on this as im in the UK.
It cannot be stand switch as this cuts the engine as soon as you put the bike in gear and not when you let the clutch out.

Will do, I do not believe theres a clutch switch according to the owners manual, I will give the clutch adjustment a shot tomorrow

[interfuse]

It's not the clutch switch either. All the clutch switch does is prevent the starter from turning unless the clutch is pulled in.

[chukidrifter91]

well, am not gonna be able to deal with the clutch today, got called into work :( but any ideas about the rpm spikes? 


I've read it could be due to a leaking system but i've meticiliously gone over every seal and clamp from the airbox to the carbs and cant find any leaks

bandits got demons :(

[cardinal0]

you could try disconnecting the stand kill switch and see what happens? I had similar prob and it worked when I cut it. just rememeber to put your stand up.lol

[chukidrifter91]

well, after a new battery, patching up all torn wraps on the harness (and inspecting with no issues), it started up

after a lot of clutch adjustment, i was still moving in first but it didnt die immediately

i actually rode it for a second then got rained on!


whats left now is the rpm spike, i tried to let the bike warm up for a long time, but still it continued

also my idle air control screw seems to not be doing anything now...

[chukidrifter91]

oh also it only ran and rode around with choke not all the way on.  fully opened it would die instantly

[interfuse]

No need to turn choke all the on. I only use like 1/2 or 3/4. Just enough to get the bike started. Then I slowly decrease the choke as it warns up.

[chukidrifter91]

er by on i mean i pull it back to start, but as i push it forward it will die even after it warms

the idle adjustment screw i think may be the issue as it doesnt do anything anymore...

[interfuse]

Fluctuating idle can be caused by a bad regulator. Search the board lots of discussion on how to test it. If I had access to a computer I'd post some links, but it's too complicated on a phone.

[interfuse]

If it doesn't idle without choke then you've probably got plugged idle jets. Also lots of old discussions on fixing this problem.

[chukidrifter91]

well, i reassembled and cleaned the carbs thouroughly and that seemed to do the trick although my idle air screw still doesnt seem to have effect...

but the good news...shes running...STRONG and my lord, i LOVE from 5k onwards haha, this bike just puts smiles on my face


however it doesnt run with choke all the way off, and engine dies at speed sometimes... :/