stumbling

[JayRo]

I just got a '99 B12 about a week ago and the bike seemed to run fine up until recently.  I haven't put more than 200 miles on it since I got it and it runs like it is going to run out of gas.  Whoever had it before me put a K & N airfilter and drilled another 2 inch hole in the airbox.  Exhaust is stock, don't know if the jets are stock, but I pulled the plugs and had quite a bit of soot on them. Didn't look right for a bike that is supposed to run lean.  I pulled one of the basins on the # 1 carb, which plug seemed to be the worst and things didn't look at all dirty.  I tried running some seafoam in the tank to see if it would help before I started yanking things apart but I don't want to run it that long for fear of damaging something.  I am still waiting for my Clymers manual to come in the mail and my wife is telling me I bought a POS.  Help.

[fartndust]

black "soot" on your plugs would indicate an overly rich condition.  With a K&N and the 2" hole one would have to assume that the jetting is not stock, as more airflow would contribute to an even leaner burn.  Ideally, your plug should have tannish (light brown) color to it.  Too rich can be as harmful to your motor as too lean, believe it or not.  
HOWEVER;  If those plugs have been in there for a long time, and the fuel had been in the tank for a while, you may have fouled those plugs.  Since I'm leaning towards believing your not sure how old the plugs are...check the gap on them, look at the electrode....or better yet, toss 'em in the trash and start with a fresh set...a plug change is waaay easier than a jetting change, and a good place to start.  

[Maniac]

^^^

Well said! I can't count the number of times this has worked for me on previous bikes. Just because it seems to simple to work, doesn't mean it won't.  

[tacoman]

Start with the simple items first.  I have some good stories of people (including myself) doing a ton of work only to find that "simple" item.  Change plugs, is the fuel petcock "on" and not on "prime", How does your fuel smell?  Old gas has a smell all its own.  A little stabil with a top off of fresh fuel will work.  I once completely rebuilt an entire clutch only to find out it was a bad cable.  Too many other stories like it

[JayRo]

Looks like I'll be getting a set of plugs today.  If there is a jet kit installed, which there apparently is, aren't you supposed to drill out the covers for the mixture screws, because all of mine are in tact?  But thanks for the replies so far.

[PeteSC]

Thank gawd for the $1.29 autolites!   Whn in doubt, I whip them out!
 I let my b12 sit too much, and frequently foul the plugs with old gas, trying to start it. (even with Stabil)
  Fresh gas, plugs, and a little Techron gets her going.....

[PitterB4]

If there is a jet kit installed, which there apparently is, aren't you supposed to drill out the covers for the mixture screws, because all of mine are in tact?

It could be a DIY job where someone swapped out mains and/or shimmed the needles and didn't mess with the screws??  

[Daytona]

Hey all!! MY B12 98 Plugs fouled if i looked at em wrong!! Needed some NOW! Picked up a set from Wally World (walmart) champions, $2.00ea (they stock em and say they fit in a wide array of suzuki's) Got to have em! they have a much longer insulator (hotter plug) Installed em 10k ago! looked at em when i did a valve adj, looked great! Don't judge a plug by its color unless its been stopped @ its optimal running point. Your eng doesn't need to run at its best @ idle, 4500 should be your test rpm. If it just started running bad it sounds like plugs! but did you forget to move the start up lever back to run??? My plugs fouled out dead (NGK's) every time i did that!! Also if your weak cyl is #2 the weak vacume may not open your fuel valve (petcock)?

[JayRo]

I got the plugs today and put them in.  Once I warmed it up, I took it for a ride and my butt puckered when I cracked the throttle wide.  Thank God for that nice corbin seat keeping my cheeks in place.   I thank all of you for your replies.  It is amazing how one can over analyze problems.  The thing I hate the most is when my wife saw me cleaning the old plugs, she told me just to get some new ones.  How can I, in my right mind, listen to a woman who still cannot figure out how to use the DVD player.  Oh well, live and learn. Thanks again.

[Red01]

Sounds like the plugs have done the trick for you. Great!!  

You didn't say what kind of condition the K&N was in. They do need to be cleaned and re-oiled periodically. If the filter is dirty, it will give you a rich condition. Hate to see a fresh set of plugs have a short life if your filter is dirty.

 

[JayRo]

I did clean and oil the filter when I had the bike apart. That was one of the first things I did.  I figured that it couldn't hurt.  Since there is an apparent jet kit and K & N filter in it, do you think that it would be a good idea to add an aftermarket slip on?  It has the stock can currently but I always heard that what restriction you reduce on the intake, should be done on the exhaust as well to maintain balance.

[Maniac]

thing I hate the most is when my wife saw me cleaning the old plugs, she told me just to get some new ones.  How can I, in my right mind, listen to a woman who still cannot figure out how to use the DVD player.

 

[Daytona]

I did clean and oil the filter when I had the bike apart. That was one of the first things I did.  I figured that it couldn't hurt.  Since there is an apparent jet kit and K & N filter in it, do you think that it would be a good idea to add an aftermarket slip on?  It has the stock can currently but I always heard that what restriction you reduce on the intake, should be done on the exhaust as well to maintain balance.

That Big, heavy, TOO quiet of A thing should have been the first thing to go! IMO the B12 only needs a good core canister! Air box holes,jetin?,time adv etc is ??? If you want more from a bike, get a gsxr or R1! IMO!  

Hey! Help me pull myself out from under the bus i stood in front of!! Old geezer (me too) Did i "P" in my own DEW on this one or what! What i meant to say was a FZR1 (GToEdit). Its just that what makes these bikes so dependable, reasonable, torquie', drivable, and comf'y is Bandit. 7lb in a 3 bag ok! 10lb not for long! (JMO)

     

[Red01]

If you want more from a bike, get a gsxr or R1! IMO!

But GSXR's & R1's aren't as comfortable. Some of us are old geezers who don't want the monkey-humpin'-a-football ergonomics of a repli-racer. I love the looks of most of those hyperbikes, but I want to ride my bike for more than an hour at a time, and I just can't do that anymore in that position. If I could stand it, I'd be all over one of those new yellow & black Laguna Seca paint jobbed R1's.

 

[tacoman]

I'm with Red on the sport bikes.  I had a gixxer 1100 which was fun but after about 150 mi you're done.  Get out in the boonies and you'll always see the sportbike riders riding with one hand, feet off the pegs, trying to relieve pain and get some circulation going.