Hi! New B4 owner..

[sclay115]

I just thought I would introduce myself here, I just recently acquired a 92 B4 (8pm last night). And then proceeded to scour the internet for resources for this seemingly super rare machine. They don't really seem too common here in the states (compared to elsewhere). I did have a few questions however, and this seems like the best place to ask them. We unloaded it off the truck, started her up, and I rode it around the block, and ran fine. And this morning, I go outside to admire my new bike, and it wouldn't start. I’m new to bike carb's, but I come from a few carb'ed cars, and I remember my days of tuning triple webers like it was yesterday, and the aggravation it was.

But I’m wondering if there is a common issue for the 400s, it's getting fuel, haven't checked spark yet, but I would assume so, since it ran not but 12 hours ago. When I started it last night, I just bumped the starter and it kicked beautifully, so I’m not sure what the issue is. Should I be using full choke? I have heard some bikes don’t need it, but as I said, I’m totally new to bike carbs. But I’m definitely ready to learn.

oh, and I thought you guys would like to know, my last bike was a Honda(gasp) CBR 600rr, and I hated it, great motor, great chassis, but try riding that thing for more than an hour, no fun. And it had no character, all plastic and without a big Honda label, looks just like any other wanna-be racer. And do you know the first thing my girlfriend said to me about the B4? (She isn't really into two wheels) she said it looked more like a motorcycle, like a piece of art. And you know what? I think she's right, I think the styling of the trellis frame (mine is red with flat black tins) is just so 'right'. I love it. Anyways, pictures to follow! Sorry for the long post, but I just had to tell you guys/gals about that.

[andrewsw]

Hey hey  

If you're like many others here, you'll go on to really love that bike and probably never part with it. More than one person has said "from my cold dead hands" about their B4.

As far as starting when cold, I have always had to choke my 2 B4's even in the summer, though if its been run in the past couple of hours, it starts okay without. Depending on temperature anywhere from slight to full choke and then, again depending on temp, for a few seconds to a couple minutes of choke fiddling before she's warm enough to stay running. ymmv.

I have never needed any throttle to start when choked but will often use a touch of throttle to start when warmed -- two reasons: 1) I like that nice BRAP out of the Yosh pipe on starting and 2) I don't like the way it just sort of lopes its way into running without a little throttle. THis is my experience from my two B4's, ymmv significantly.

I think you'll find, compared to your 600, that the B4 is a blast: you can push the bike hard without breaking quite so many laws, and you can out corner just about any other bigger bike on the road. In fact, its frustrating when riding in a group as they methodically pull away in the straights while you have to take it easy in the corners. I often will hang back purposefully so that I can run a couple corners at higher speeds while catching up to the group. So long as theres not a ton of straights, it works pretty well.

anyway, enough rambling. There's some great help on this forum so ask away, and once again

 

[sclay115]

So I’ve spent most of the morning fiddling with the bike, and I’m just having a heck of a time starting it. I checked the spark, and it seems to be there, it just doesn't look very strong, compared to what I’m used to on cars. I’m assuming, smaller engine, smaller spark, but I’m not sure. It doesn't even appear that there is fuel getting to my cylinders, which is strange, because it obviously did not too long ago, the bowls have fuel, and the tank has fuel, it's just not making the trip to the combustion chamber.

I guess I’m just relatively carb illiterate, but hopefully I can work this one out soon. I wanna ride!

Steve

[andrewsw]

what exactly does it do when you try to start it? does it just spin? does it pop and wheeze and die? etc etc.

you might pull a plug or two and see if there is fuel in the cylinders.

who started it yesterday for the ride home? you or the seller? if it was you, was it already warmed up when you got there?

[sclay115]

Edit: ok so it started once, ran for a few seconds, and then it shut off. But as far as what it is doing when I’m trying to start it, it just cranks over, it occasionally tries to fire, but not often. I’m not sure, I’m going to throw it on the battery charger, run some errands, and then try it when I get back. Who knows, maybe it needs some alone time.

Steve

[andrewsw]

was it choked when it started? that's what mine does if its not choked enough. Then it'll have trouble starting again...

also, some times when the CDI is starting to fail, it'll be hard to start. there are many threads here about B4 cdi's, look around.

[sclay115]

was it choked when it started? that's what mine does if its not choked enough. Then it'll have trouble starting again...

also, some times when the CDI is starting to fail, it'll be hard to start. there are many threads here about B4 cdi's, look around.

Yup, i did see those, looks like it would be a wise thing to do, even if it hasn't failed yet.

steve

[sclay115]

Ok update, got it running, but here is what is happening. It will start, full choke, and run about 2k-3k rpm. However, even if I attempt to move the throttle in any way during this time, absolute stall. And if I roll out of the choke at all, it will stall. Runs/sounds good when it is running, just wont' stay running for the whole 'riding' thing. Any suggestions guys?

Steve

[andrewsw]

How long are you letting it warm up? whats the temp there?

mine shows this behavior as well when under choke -- throttle will mess with it big time. I believe this is normal because the choke is already dumping fuel into it, opening the throttle allows it to suck more fuel causing it to bog down. I usually have to let mine warm up on the choke for at least a few seconds, when its cold out (below 50 of so) I let it warm up for 30 seconds or more. Others may tell me i need some tuning to fix that, i don't know.

Gentle fiddling with the choke can keep the revs down around 2k, as the revs climb I slowly work the choke down until its almost off, then shut it and it'll run. Basically, you've got to let it warm up before the choke comes off..

If it won't run off the choke once its warmed up, then you've likely got a idle-mixture problem or the idle is just set too low. try adjusting the idle up a bit until you can get it running. Mine usually idles at about 1k when still cold but warm enough to run, once it warms up it idles around 1.2-1.5k, but the guage is not to accurate :).

Is this bike stock? and more importantly to your problem, are the carbs stock?

[sclay115]

I believe so on the stock part. It has a Yoshi pipe, But i believe the carbs are stock. However, I attempted to let the bike warm up for at least like ten minutes. And it was still exhibiting this behavior. How do i adjust the idle mixture on these carbs? And I'm assuming they all adjust seperate right?

steve

[andrewsw]

once its warmed up, can you keep it running with the throttle (choke off)?

on the bottom side of each carb right near where it atttaches to the intake, there is a little screw. If your carbs are stock, there will be a cover over the screw which needs to be removed. If that cap is not there, and there is a little slotted-standard brass screw in the hole, then you carbs are not stock. base setting for the idle-mixture screw is 2.5 turns out from lightly seated. Mine are running about 3 right now with a yosh exhaust and K&N filter.

With that yosh exhaust (is it full? or just a slip on?, the full is a 4-2-1 system) you probably need to rejet and I'd bet that its already been done.

The idle adjust is on the left side, below the carb bowls, a little black plastic knob. use that to adjust the idle speed.

Obviously the bike was running yesterday, so I doubt anything is far out of whack, at least so far that it won't run.

You might need to pull the carbs and tear into them and see what's going on, but you're outside my troubleshooting ability. post up a new thread with a relevant title and link back to this thread so others can see the history. You're probably not on the radar with your "New B4" type of title.

for great cv carb tuning information google on "factory pro" and "cv carb tuning". there's some great info there.

[gsxr400 racer]

SOUNDS TO ME LIKE THE PLUGS ARE BAD  AND IF THEY ARE YOU GOT THE TIPPICAL BAD ORING IN THE CARBS SYNDROME.(sorry) caps!!!
at worse case cinerio electricAAL PROBLEMS . charge the battery fully if it dont start then buy some cr8e plugs fire it up with those if it runs for a few and then has the same symptoms go at the carbs thats my suggestion.
cheers welcome aboard

[doqq]

sorry to jack your thread but i have a similar problem but the starter button is effective erratically.  Like sometimes it will try to crank and other times i get absolutely nothing.  im assuming its electrical. how would i check it with a  multimeter?

[andrewsw]

trace the wires, pull the ends off. set your multimeter to resistance, you should get max resistance with the starter button out, min resistance with the button in.

[interfuse]

sorry to jack your thread but i have a similar problem but the starter button is effective erratically.  Like sometimes it will try to crank and other times i get absolutely nothing.  im assuming its electrical. how would i check it with a  multimeter?

Clean the contacts on your safety switches. It's probably the clutch switch thats causing you the grief...