Topic: how did I manage to make it run rich?

[supersport]

hi all-
apologies if it has been covered, but it seems to be doing exactly the opposite of what everyone says it should be.

I just put pods on the cb400f because the stick filter was gone and had been replaced with  very chintzy piece of uni foam. 
I am at altitude, so my guess was that it would be running a bit rich anyways.
I put the pods on and it was very weak, couldn't get it to run out past 7000.  Half the power it used to have. So I thought it must be too lean, so I raised the needle up by lowering the clip one notch, as per the diagram that is often posted on here, and I drilled out the jets about 10%.  The stock ones are 75's, and I couldn't locate an 85, so I thought I would drill it out to figure the proper size until I can locate real jets.  Also cleaned out the slows with a wire, new plugs, checked the points, etc.
Problem is that now it runs rich.  Plug shops reveal a lot of carbon.  The bike is was ok at WOT but sputtered it's way up to 6000, where it smoothed out.  I had to crank the idle adjust screw all the way in just to get it to idle, but it sits at about 1200.  The idle mix screw is at 1 1/2 turns out as per clymer.   I bench synced the carbs and then synced them on the bike, but I can only get it to pull about 8 cm of vacuum.  If i crank the screws down more it gets way out of sync and eventually dies.  I put the stock airbox back on, but it didn't help.(probably too rich for that now) and now I can't even get it to idle. at all.  runs when you hold throttle open, but immediately dies if you let off.  still have that idle speed screw all the way in.

also , it has spontaneously stared not running on cylinders 2 and 3.

What gives here? am I missing something? it ran like a top before i started screwing with it, of course, and now I wish I hadn't.
Thanks all- eagerly awaiting advice, would love to ride over the long weekend!

[Tim2005]

Can't help wondering just what "and I drilled out the jets about 10%" means. You need to be very precise with jet drilling (see other topics on here somewhere), but anyway 85 is a lot for a 400f, especially at altitude... I'd suggest that if you want to stick with the pods you get hold of a set of 78 mains and go from there, get the top end jetting sorted first, then the midrange, and finally the bottom end and tickover. Alternatively, ditch the pod filters, get a stock element and go back to 75s, pods are a #$%* to set up on a 400f and give little, if any, gain.   

For comparison, my 400F, running a 460 kit, yoshi pipe, pods, yoshi cam plus other mods ran too rich on 85s (air/fuel ratio 12:1 at the leanest), it's now on 80s and screaming happily.

[supersport]

the way I can figure it, stock main jet is 75, so ten percent more would be about 83.  I drilled it with a #65 wire drill, which is about 85.  In retrospect, maybe that is a bit much, but is that enough to cause the major problem it is having?  I agree that the pods are a #$%*- I am guessing you would say not worth it?

Does raising the needle have any impact here?

[TwoTired]

apologies if it has been covered, but it seems to be doing exactly the opposite of what everyone says it should be.

Everyone?

I just put pods on the cb400f because the stick filter was gone and had been replaced with very chintzy piece of uni foam. 

You reap what you sow.  If you'd rather ride than spend lot of time re jetting/adjusting, put it back to stock.  Honda had a very streetable formula, that didn't include pods.

I am at altitude, so my guess was that it would be running a bit rich anyways.

Not if you tune for that altitude.,  But, then you will run lean at sea level.

I put the pods on and it was very weak, couldn't get it to run out past 7000.  Half the power it used to have. So I thought it must be too lean, so I raised the needle up by lowering the clip one notch, as per the diagram that is often posted on here, and I drilled out the jets about 10%.  The stock ones are 75's, and I couldn't locate an 85, so I thought I would drill it out to figure the proper size until I can locate real jets. 

Any powder burns on your shoes?  Slight limp perhaps?

Also cleaned out the slows with a wire, new plugs, checked the points, etc.

You done good with that!

Problem is that now it runs rich.  Plug shops reveal a lot of carbon. 

You mean, on the center electrode insulator, right?

The bike is was ok at WOT but sputtered it's way up to 6000, where it smoothed out.  I had to crank the idle adjust screw all the way in just to get it to idle, but it sits at about 1200. 

All the way in opens the slides.     Are your head pipes hot across the bank?

The idle mix screw is at 1 1/2 turns out as per clymer. 

Which applied to bike in stock configuration and no air filter mods.

 I bench synced the carbs and then synced them on the bike, but I can only get it to pull about 8 cm of vacuum.  If i crank the screws down more it gets way out of sync and eventually dies. 

Pretty low vacuum.  Vacuum leaks?  Valve adjust?  Compression check?

I put the stock airbox back on, but it didn't help.(probably too rich for that now) and now I can't even get it to idle. at all.  runs when you hold throttle open, but immediately dies if you let off.  still have that idle speed screw all the way in.

also , it has spontaneously stared not running on cylinders 2 and 3.

Okay, its official, you're in flail mode, falling sky not withstanding.

If it is running as rich as you say, you may have fouled your spark plugs.  Either torch clean them (propane torch) or replace them.
Head pipe temp even?
Clean carbs contaminated by chunky fuel?  ALL of it is supposed to be liquid.  Rust scale from tank?

Have you moved ALL of the synch adjusters toward the end of their travel?

After you check the above, then lower your slide needle to lean the midrange throttle settings between 1/8 and 3/4 (suggest 2 notches from where you last set it).  Drive for effect.  Report what you find.

Cheers,

[supersport]

Replaced the needle at stock setting, in the middle.  bike runs horrible, sputters, sounds rich but I haven't had a chance to pull the plugs. 

[supersport]

Bike wants to idle at 3-4k.  When I turn the idle adjust screw )not the air screw) out it does nothing for a couple turns, then instantly the idle drops to zero and the motor dies. it won't restart until you turn the screw back in, at which point it will again idle at 3-4k.  sometimes it creeps up to 5. have I done something weird to the vacuum or something? i have synced the carbs, but vacuum was a bit low when I did so.

[crazypj]

according to my reference book, 65 drill is 0.90mm, way too big. you should have used a 67 or 68. With stock airbox removed the carbs can (and do) tilt backwards and make bike run rich as fuel level gets higher. I found you have to arrange some sort of device to lift back of carbs ( usually use a coil spring off one of filter mounts.)
You really need to check the pilot system first as thats where your low rpm/idle problem is going to be. Airscrews about 3/4 to 1 turn out, can always go further to lean things out a bit.
What altitude are you at?
PJ

[supersport]

I'm a mile high.  interesting to hear about holding the carbs up= totally makes sense, and I haven't considered it at all.  Will try that, although I have put the stock airbox on and it is still quite problematic.  it runs fine initially, although idling high as mentioned above.  only lasts for a few miles, though, as it starts bogging, missing, and eventually gets to the point where it won't run (due to richness).  could this be an improperly mounted carb situation, like you said?

[HondaMan]

At a mile high, jetting should start out 10% lean on these bikes. For example, my 750K2 stock was 110 jets (in the Midwest), I switched to 100 and it's still a little rich up here. Heading up into the hills makes it worse.

Float levels too high will make everything rich, uncontrollably so. Changing carb angle really screws up float levels, too. Go back to stock jets, re-angle those carbs, but most of all, buy new plugs. It will likely never idle again on those plugs unless you sandblast and clean them with Brake Cleaner or alcohol (the clear kind, like at Walgreens...  ).