1996 Bandit 12 Mk1 issues..

[mickb1]

Bit if advice please if possible.. I stripped and cleaned the carbs due to very uneven idle and a misfire from one cylinder, i used new  o rings etc new float needles and seats, reset the float heights as close as I could get them to 14.5mm( They were waaay off..), 

I put new standard idle jets in, new slide needles too as the old ones were badly ridged and worn on one side.., main jets are 112.5 as i have a kerker can on there , once I finally got the carbs back on (What a job, it kinda  reminded me of my old zrx 1100 ) it ran really well, main jets are 112.5, oh, there's a new Suzuki air filter fitted too..

Fast forward a couple of weeks and there's a low rpm misfire again, it was clearing itself after a few twists of the throttle but heading home today after a ride I stopped at a Cafe for a bite and a drink, started it up and It's misfiring and not wanting to clear, it was almost cutting out quite badly intermittently on the last few klm's home....

I got home and  the 1 and 4 outer exhaust headers were 20-30 degrees cooler than the 2 middle ones.. they are always uneven temps but I kinda thought maybe the 2 inner cylinders maybe run hotter too?

Coil dramas or still carby dramas? ? What say the experts?

[mickb1]

PS thanks in advance for any help

[DAZ]

Could be the coil for 2+3 as they share that one,  check not just the coil but the wiring to it for a slight break,all connections clean and secure ,also the ht leads for any signs of breakdown, high resistance or arcing out. 

Try new plugs if the existing one are sooty they will like to misbehave ngk have developed a reputation for poor quality control, so try swapping known working plugs into cyl 2+3

Then I'd be back to the carbs you say the needles were worn and ridged did you replace the emulsion tubes too as they wear too ?

 

 

[mickb1]

Thanks DAZ,  I changed the plugs for the second time last week,  and yep I used NGK..

Are denso any better? Or is there another alternative?

I didn't change the emulsion tubes as they looked OK, once the carbs were back on the idle was way smoother and not far off as smooth as the idle on my 1250 bandit so figured they were reasonably OK, no doubt if I pull the carbs again they will get changed, just in case.

I'll start it up later tonight when it's dark and see if I can see any arcing..

 

One thing I noticed was it was hard to get the carbs balanced but  the carbtune rods seemed a little sticky, so put it down to that as the bike was running reasonably smoothly..

Have cleaned them should be better next time.. 

Have ordered inlet rubber o rings too, I guess whilst the carbs were off last time I should have changed those too.

I'm sure I never used to have these dramas with carbs 40 years ago..:-)

[wraith]

Denso are much better.

NGK are only good for a paper wight and there not very good at that, they are a total waste of money and time using them.

[TonyGee]

one thing to think about is the two middle cylinders will run a little hotter as they are surrounded by two other cylinders.  some bikes use bigger main jets to help cool them down a tad.  like the B600

[FJD]

Dirt in the fuel from a rusty tank blocking the pilot jets ?

[gsx]

Agree with all of the above ,so plugs first and you'd be surprised how often they go down over winter , next must have is in line fuel filters ,trust me me latest acquisition is getting them