Rough Running ST

My '00 Sprint ST seems to lu-r-r-ch between 4K - 5.5K RPM.
It feels almost like I'm running over breaks in the pavement.
I've watched the Tach, and it doesn't "seem" like a slipping clutch, more like my engine is cou-gh-ing.
Ugh, I have committed a sin or two:
I lost a half quart of oil due to a loose drain plug. I was flat broke, so I added a semi-synth blend to my Motul fully synthetic. I don't know how serious this is, but I thought I'd mention it.
The bike is kept outside at present, in the rain, frost, etc...
I ride it EVERY DAY; It is my only transportation.
Other than the lu-r-r-ching between 4 and 5.5, it runs great.
I do have those little "pops" that others have said are quite common, but the bike is rock steady.
I'd appreciate any advice/insight from the more informed Tri-guys (or gals)
Thanks Fueler

[deller4210]

Say, is it more like sputtering? I mean is the power delivery clean below and above the mentioned RPM and as you accelerate through 4 to 5.5 K RPM it simply sputters and clears up. Also, if you hold the RPM steady in that range will it sputter continuously or for only a moment and then clear up?

Thanks for the quick response, Dell.
Sputtering? Hmmm, it's more like a hiccup. If I hold it in that rev range it goes on and on.
Below that, above that -- Fine.
The bike will fly off the line, and pull hard from 6K to whatever. But from 4 - 5.5 ...
It's -- maybe sputtering is the right word. It's almost like my old Honda CB900. There was a flat spot in the carbeuration in order to comply with EPA regs, or something like that. It seemed lean at 4.5 - 5.5. This is a lot like that.
This is a relatively new phenomena. I think it's been getting worse, but I didn't really notice until my wife said something. The bike is no where near cutting out or anything like that, it's just a drag going down the freeway because it actually feels like it's lurching if I have to stay in that rev range.
Any ideas will be appreciated. fueler

[dolson]

Can you get your map checked? These engines are maped lean especially in mid range for EPA and something could have whacked it.

Clean all electrical connections from the Sagan to the injectors. A little corrosion can raise resistance and potentally screw the signals up. Plugs get funky too.

I wish I would have been able to read this sooner as I just got done spending most of the day at my dealers and he's pretty good with advice.

Will have to wait till Tue. now.

Don

Thanks, Don. I'll give the connections a look-see tomorrow. If your guy has any ideas, I'll appreciate hearing from you. If I can't find the problem within a week or so, I'll take it in here in sunny Sacramento. fueler

[preachp]

Hi Fueler,
You are not using the kill switch to shuit down the bike are you? If you are, don't. Use the key to shut down the engine. Weird things happen when the ECM does not shut down correctly.

Preachp

[ This message was edited by: preachp on 2004-02-08 07:43 ]

[deller4210]

I think dolson is on the right track. It sounds like fuel delivery and any interruption in the signal to the fuel injectors could cause your problem. There is also the possibility that you have a hosed injector that is providing a poor spray pattern in that range.

Thanks guys.
Yeh, my gut feeling is fuel delivery, so I put some Berryman FI Cleaner in yesterday. It will also disperse the moisture, if there is any.
I put a few miles on her and did notice some improvement -- a little smoother, maybe. I need to run her more.
I'm headed out right now to check the connections and such.
Talk to ya later. fueler