Can short shifting cause...

[FloridaKat]

a plug to foul prematurely? After running the bike fairly hard, I wanted to be ultra conservative and short shifted (i.e. skip a gear) to save fuel and keep the RPM's low. Got the Kat home, but this AM she stuttered and felt like she might be down a cylinder. I'm thinking a fouled plug, but not sure.

I kept the choke on for 30 seconds at 2K (like I have been doing for years), but after shutting the choke (I use the term loosely) off, she could hardly maintain an idle.

I then rode her for a little trip around the block, but she didn't feel good and had a little more popping (more pronounced at low RPM). Yes, the bike was warm and, yes, at idle she still felt like she was just going to stall.

Replace the plugs? It's been about 10K since I've changed them last.

[steves]

Fouled plugs are usually a fueling problem. Maybe a bad float level.

[Black_peter]

I'll go along with floats..
Maybe a stuck one?

Or it stuck and fouled the plug..
Also 10K is long in the tooth for a plug.

[FloridaKat]

A little more history....

she ran fine after a long run on Sunday. Filled her up with fuel and then she sat in the garage until Thursday AM. We got some pretty cold temperatures (I know it's relative) over the past couple of mornings (30's-40's). Why would this symptom show up after a few days of the bike sitting idle?

[steves]

A little more history....

she ran fine after a long run on Sunday. Filled her up with fuel and then she sat in the garage until Thursday AM. We got some pretty cold temperatures (I know it's relative) over the past couple of mornings (30's-40's). Why would this symptom show up after a few days of the bike sitting idle?

Bad gas, junk in the tank, time.

[arsenic]

can short shifting cause a fouled plug? Simple answer - no.

[The CyberPoet]

Short shifting won't foul the plug.

10k miles on the plugs may (they should typically be changed every 7500 at valve adjustment).

IMHO, most likely, your problem is temperature related since we recently went to some cold mornings. Easy fix is to increase the idle set screw on the left side of the bike so it idles higher when cold (you can turn it back down after it comes all the way up to temp, or just run your idle a bit higher in the winter) and let it warm up in place a bit longer. If it's parked on the center-stand, putting it in gear about the time you take off the choke will help as well (the rear wheel becomes part of the flywheel weight to keep it running consistently until warm).

I can't remember -- is there an Ivan's jetkit and advancer installed on yours or not? I ask because both of those mods make cold-weather start-up and warm-up go smoother/easier.

Cheers,
=-= The CyberPoet

[FloridaKat]

I can't remember -- is there an Ivan's jetkit and advancer installed on yours or not? I ask because both of those mods make cold-weather start-up and warm-up go smoother/easier.

No jet kit or ignition advancer.

Ran the bike in the garage for about 10 minutes to get her nice and warm. Same exact behavior was noticed. Fluctuation in RPM range ~1.5K and under (+/- 200 RPM). When the choke is all the way off the idle is very erratic and near stall conditions (and has stalled this AM before extended warm-up). Cracked the throttle hard a couple of times, but felt like there was a significant lag in response. Also, I noticed a little more vibration until the RPM's were north of ~2K, but could hear a definitive "pitter-patter" in the exhaust note that wasn't there before.

I'm going to change the plugs and see if that's the ticket. But, what could happen between parking the bike on one night (when it was running fine, warm) to this condition a few days later?

Another thought, what if a valve is enough out of spec. to cause one (or more) of the cylinder to run too rich?

From NGK's website under FAQ for Fouled Plugs...

"Prolonged idling or continuous low-speed driving may keep the spark plug from reaching its optimum operating temperature." - Although I may not have defined this properly as short-shifting, I wonder if running below 3K in 6th gear for a fairly prolonged period of time prior to shutting the bike off, could cause a plug to foul?

http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqfouled.asp

[arsenic]

well does your bike sound like a freakin' sewing machine? The valves would have to be way out of spec for that too happen, and the sounds would drive me nuts before that happened.

[FloridaKat]

well does your bike sound like a freakin' sewing machine? The valves would have to be way out of spec for that too happen, and the sounds would drive me nuts before that happened.

She's always had a tap to her in the engine compartment. CP and I did the valve adjustment about 10K miles ago. I'm pretty sure at least one of the valves are out of spec., but to have this problem occur "magically" overnight? I'm not so sure how to justify that.

[FloridaKat]

Here's some pics of the plugs....I know these pictures don't do it justice, but they all look normal (no rounding of electrodes, grayish/brownish color). Note: cylinders 1 and 4 spark plugs have the most rust. So much for my fouled plug theory!

[arsenic]

thats from your plugs being super old

[md86]

THey're a little dark , but look like they should still fire . I'd brush them off with a wire brush and pop 'em back in if they were mine .
Also , Char's first rally she swapped bikes with Keith to let him feel it out . He said it was running a tad sluggish , but got better as he whipped it a tad to blow it out . She had always ridden ULTRA-conservatively , she said . Yeah , it IS good to get the rpm's up once in a while . My mom's car gets the same way after a while . However , Kats run a little lean stock anyway , so ........ I'd think there'd need to be some other factors at play to cause it to foul out like that babying it .

[The CyberPoet]

Fluctuation in RPM range ~1.5K and under (+/- 200 RPM).

Bouncing idle is the classic symptom of carbs in need of sync because of changes in how the cylinders are building vacuum (which in turn relates the valve clearances). If you're 10k past your last valve adjustment, you're well past time-due for that too. Get in there and do it -- I showed you how last time, and as a single man, you should have the time...

The fact that most of the fuels in Florida now have alcohol probably plays into it too (alcohol changes the stoichiometric ratio, making previously lean mixtures even leaner), since you've never fattened up your fueling at all. At minimum, I'd suggest a fuel system cleaner to start, just to make sure the smallest passages are clear.

The rust on the plugs concerns me -- I've never seen rust on mine and I probably ride through far more rain than you do -- and makes me suspect that your weep holes are clogged for some reason. A pipe cleaner should remedy that (come from the front of the engine up through the weep holes).

Although I may not have defined this properly as short-shifting, I wonder if running below 3K in 6th gear for a fairly prolonged period of time prior to shutting the bike off, could cause a plug to foul?

Under 3k in 6th? Argggg!
Spin that puppy up! Burn that OPEC oil and keep her above about 4200 when cruising...

Cheers,
=-= The CyberPoet

[FloridaKat]

Bouncing idle is the classic symptom of carbs in need of sync because of changes in how the cylinders are building vacuum (which in turn relates the valve clearances).

Agreed.

If you're 10k past your last valve adjustment, you're well past time-due for that too. Get in there and do it -- I showed you how last time, and as a single man, you should have the time...

I agree, but is that symptomatic of my bike's problem? I'm not so sure. As far as me being a single man and having time, I guess that's a matter of perspective.

The fact that most of the fuels in Florida now have alcohol probably plays into it too (alcohol changes the stoichiometric ratio, making previously lean mixtures even leaner), since you've never fattened up your fueling at all. At minimum, I'd suggest a fuel system cleaner to start, just to make sure the smallest passages are clear.

I put in a little bit of Seafoam, but won't be able to see the effects, if any, until after the bike is running again.

The rust on the plugs concerns me -- I've never seen rust on mine and I probably ride through far more rain than you do -- and makes me suspect that your weep holes are clogged for some reason. A pipe cleaner should remedy that (come from the front of the engine up through the weep holes).

I'll do a visual inspection and clean the weep holes. The more I think about it, I wonder when I wash the bike and spray H20 through the oil cooler (to remove bugs/debris), that some of the H20 is "backfilling" the weep holes?

Under 3k in 6th? Argggg!
Spin that puppy up! Burn that OPEC oil and keep her above about 4200 when cruising...

That was only after running the Kat well above 7K for an hour or so. Don't worry, I'm keeping the P/E ratio of Exxon down!