warm up

[elbandtioCA]

now that i finally have a running b4 i've spent the last few days riding around on it, naturally.  great fun.  i think i'm starting to learn some of the quirks of the bike when it does work (rather than the whole list of things that might keep it from running).  the bike pulls strongly and runs smoothly when it is warm, but that seems to take a while--about 15 mins or so.  until then, it runs rough with spotty power in the mid rpms--enough to make me a little uncomfortable pulling away from a stoplight.  since a fair amount of my riding is around town,  i'm not on the bike long enough for it to warm up well.  is this normal for the b4?  is that a sign of running rich or lean?  i have adjustable needles in and perhaps i could try a different clip position--just not sure which way to go.

also, until it is completely warmed up, there is a very noticeable loud buzzing/rattling that consistently kicks in exactly at 6000 rpms and above, and stops when you drop below 6k again.  it goes away when the bike is warmed up.  does this sound like a serious issue?  other than that, the bike is great, though i might try to switch back to a stock exhaust from the yosh which is pretty loud.

[GooseMan]

I cant really answer your other questions, but I do have a strange buzz/rattle at around 5000 rpm...sounds like something is loose on the bike, and buzzes or rattles at that exact RPM.

When I first noticed it, I tightened as many bolts as possible around the bike...the header bolts, where the engine bolts to the frame, triple clamps, side stand etc....and it seemed to go away! :D

Unfortunately, it decided to come back :( I really dont know what the hell it is, and its pretty annoying! Its possible it has something to do with the carbs being out of balance, as the whole engine would be slightly "off" and cause a strange buzz....thats my theory anyway!

[Krane]

Hi guys,

I'm new here but i have a bandit for 4 moths and i find excellent for city usage. About the warming up problem i didn't notice anything. I ride it for 20 minutes each morning, and a couple of hour in the evening/at night and it warms up pretty ok. In fact after 20 minutes in traffic, even when the traffic is light when i get to work the fan gets in. Also there are no spikes in throttle response for the mid range RPM.

Maybe you should check the air/fuel mixture because you might have a lean mixture.

Hope this helps.

[gsxr400 racer]

wasnt there a post on here about something coming loose in the collector on these bikes?

[elbandtioCA]

  yeah i guess i'm evidence of that.  actually i wouldn't even call myself a collector--i just got the bike without knowing what i was getting into. 

[magicGoose]

 

yeah i guess i'm evidence of that.  actually i wouldn't even call myself a collector--i just got the bike without knowing what i was getting into. 

Yep, you nailed it. The problem with so many of these bikes is that the collector has a screw loose.
But seriously, for the buzzing don't overlook silly things like the mirrors, or your keys, or something like that.
Steve

[PitterB4]

LOL!  Maybe that's why I got rid of my B4... I'm too well adjusted to own one!   

Where exactly in the RPMs is it rough?  Rough low-end (just off idle) running when cold sounds like you would be lean on your a/f screws.  Back them off a little and see if that helps.  I had trouble finding the sweet spot between rough-running when cold and being so rich that I hardly ever needed the choke. 

Which way did you move the clip and did it make it better or worse?  If it is in that 5-7K range, try lowering the clip to richen that range.  You may even want to try "half a clip position" by shimming them with washers. 

[elbandtioCA]

when it is still cold up til about 15 mins of riding it is rough right in the 5-7 range.  i can avoid it if i shift really early, but as you know this bike doesn't produce any power at that point.  i've got it on the middle of 5 clip positions. i was going to richen the air mixture screws today just to see if that helped, but it sounds like i might need to play with the clip position again this weekend.

[gsxr400 racer]

not at 5-7 it wont

[interfuse]

What's your warm up procedure? I've messed with these carbs loads. Cold my bike runs like arse at 8k (coughs sputters, starving for fuel). Once it warms up it pulls great to 14k. If you mess with it so it runs good cold, then your probably gonna have problems when it's warm (and vise vera). There's always a trade off. Try raising lowering the clip (raising the needle) on position and see what you think. It's all trial and error. Also the weather outside changes fuel atomization big-time. In the summer I open up extra air holes on my air box to compensate.

[Herr Tod]

The choke can fix that problem...

[elbandtioCA]

i'm getting better at using the choke to fix the cold running problem.  if i keep the choke 3/4 open for the first 10 mins on a cold morning (that is relative of course--i'm in the SF bay area) then it doesn't sputter around 5-7k.  but i still haven't gotten it right so that when i pull up to a stop, the bike keeps from cutting out. 

just an aside--i noticed that my airbox was slightly modified too, but no holes drilled in it--only the tube that runs along the inside was cut in half so that it was open for the entire interior length of the box.  is this a common airbox mod?  it seems strange because it still relies on a the same diameter opening hole that feeds that tube.  i'm sort of tempted to put everything back to stock, including the muffler and needles just to see how it runs, but maybe i'll regret that...

[Vidrazor]

Yep, the choke's the thing. I don't really need to keep it out all that far, I start the bike and then adjust the choke until it's idling around 2k. After a few moments it drops to ~1500 on it's own. I ride around like that for about 5-10 minutes, then take the choke out, and it's in the groove.