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Discussion Starter #1
My 620 has run rich since new.
-- plugs solid black after a few 100 miles when replaced
-- smells rich when followed on another bike
-- blows black smoke during high rpm

Seems to run fine though. My mileage has been running in the upper thirties and oil consumption is about a qt. per 1000 miles (has been since new). I have just passed the 5000mile mark.

I am running near open pipes, my stock air box and filter is clean, k&n crankcase breather clear and clean (no blow by observed), and run 89 octane fuel.

I know I need to let the dealer check, but I don't trust them, they seem clueless, and have always done my own.

The things I know to do are:

-check feul pressure (spec?)
-check TPS adjustment (I found values and procedure on an australian site that seem clear enough)

What else??
I assume there is a temprature sensor that feeds the computer that could be bad...

Any help would be appreciated.
 

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I would agree you're running rich, as I get 42-46mpg with my S4, with basically the same motor mods.

I think you should be getting high 40's mpg or better with your 620.

I'm sure folks with 620's will share their FHE.
 
M

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Discussion Starter #4
Actually I meant 87 octane (regular). I had run midgrade originally, but have run 87 for the last 2000 miles or so. No difference observed.

Thanks, Ed
 

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"near open pipes"? could this be the cause of running rich??or would this have the opposite effect?
K&N crankcase breather??
could this be too much mod for the ECU??
 

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My 620 is stock , I get 40+ mpg. I probably use 1 quart of oil per 1000miles (running full syn) I have n't ever checked the plugs yet.
Why are you checking the plugs so often?
My bike doesnot smell "rich" or blow black smoke.
Could it be the enrichner knob is not shutting off completely?
What is your rpm's at idle?
I run 92 octane ( thats what we were told to do by FBF)
 
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Discussion Starter #7
Why are you checking the plugs so often?
I've been watching the plugs to give me an indicator of mixture.
The enricher only adjusts idle speed, and does not effect the mixture. Idle when warm is either side of a 1000rpm . I've tried all octanes, but see no difference..(this is a real can of worms on this site). The crankcase breather is fairly recent..It shouldn't effect the computer.

Yes, the open pipes should lean it out, not richen.

Glad to here I am not the only one that sucks oil.
 

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tried all octanes, but see no difference..(this is a real can of worms
Yeah I was trying to whisper that!!
The enricher only adjusts idle speed, and does not effect the mixture
I don't want to sound mechanically stupid, but how does the enrichner adjust idle speed?
 
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Discussion Starter #9
It is nothing more than a cable that opens your throttle plates a hair (it is adjustable independent of your main throttle). I guess "enricher" isn't really a good term for it. Fast Idle control would be more acurate.
 

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tps adjustment etc. should have been checked at the 600 mile service. bring it back to the dealer and have them go over the adjustments they didn't do, check fuel pressure, and check over your whole FI system with the Mathesis. don't pay them anything, since it should have been adjusted at the 600 or it is a warranty problem. of course, if you want, tip the wrench who works on your bike.
 
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Discussion Starter #12
if you're running rich, a simple way to lean out the system and get a bit more power while you're at it is to hack open the airbox lid. you'll want to drop in a more durable air filter to fend off the elements, but the increased intake will lean-out your mixture a bit. worth trying and free!! drill a pilot hole in the lid big enough for a jigsaw blade to pass through, and zip away! example:

http://www.ducatipipemod.com/s4/mods/airbox/airlid06.jpg
 
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Discussion Starter #13
Yeah, but that just seems like a bandaid covering the real problem here. Are the spark plugs sooted with oil or unburned gas? How was this bike broken in? Are the rings sealing as they should be? Could you have some poor valve seal issues? What does the compression test show? There have got to be ways to narrow the possibilities and solve this problem. If I were going to change any parts as a test it would be the E.F.I. temp sensor as it's responsible for telling the e.c.u. that the bike is up to temperature and to lean out the fuel mixture. If the sensor fails the e.c.u. will always think the bike is cold and will run a richer fuel mixture to compensate. Does any of this make sense?
 

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This is a big one, either big problems, meaning lots of headache work, or not much to worry about. I don't think that you are doing any damage to your engine, but something is not right. Your on the right track, check the:
air filter -yours is clean
check plugs and gap-carbon fouled (or are they oil fouled, different story)
check valve clearences:
check cyclinder compression pressure, 3bar:

If these are all in good order, it is probably your idle mixture. You might have to bring this into your untrustworthy shop to have looked at, and if you did the previous checks, you can cut straight to the chase with them.
Your idle mixture can be adjusted in your ECU. You can replace the EPROM chip to alter the fueling/ignition system, but you might have to get all up in there and adjust the throttle bodies, idle mixture and all kinds of crap. You also might need a manual for this work.
I would cut the air box because I believe that the open pipes (how open) might be to much for the bike??. You need to get more air into the system, so cut the box, quick fix. But if these problems occured when you had your stock pipes, the problem might be deeper. Sorry about the run-on ;)
 
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Discussion Starter #15
The plugs are definitly gas fouling. (My oil consumption is still a little high though.) I broke in the bike reasonably careful..proably easier than 80% of most people. I have been on synthetic since the 600 mile mark (I don't know what it came with). I questioned the dealer about the use of synthetic since I thought that dino oil would be a better choice for the first 2000 miles or so to help breakin. The dealer assured me that synthetic was best.

I have the tools to check fuel pressure and compression. I plan to do that this weekend. I can check valve clearances also, but I didn't think it would effect mixture much. Im getting close to the 6k check any way. The bike seems really strong for a 620. I have ridden with another 02 620, and could pull on him easily on hills.

The bike ran rich with the stock pipes also. I have been running a set of modified 900 ss pipes lately.

I also have tenativly ruled out idle mixture, because the bike blows black smoke when WOT above about 8500. I have followed behind my son several times on his Ninja. He loves this test...I seldom let him on the duc.

I live in the south east corner of TN. My original dealer was in the knoxville area. ( i am not "close" to anything) I guess GA or NC would be my best bet, but I don't have any info on any of these dealers.

The temp sensor (behind the head light?) is on my list. I assume there is a resistance/temp relation to check. I asked the dealer about the factory service manual...said three to six months to get.
 
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Discussion Starter #16
I can't fathom why the temp sensor would be behind the headlight? It should be on the engine somewhere. I'll check mine when I get home and offer an update. Remember, the sensor should tell the e.c.u. that the engine is up to operating temperature and that it's time to lean out the fuel mapping. Some e.f.i. systems actually use two sensors, one called a thermal time sensor and one a temp sensor. I'll double check the monster, but my understanding of current motorcycle e.f.i. for air-cooled engines leads me to believe that there would be only one temp sensor, and it must be located on the block, ideally out of the air flow so it won't get false cold readings.
 
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Discussion Starter #17
Okay, got home and took a look. It's gotta be the sensor on top of the clutch cover. We all know that the sensor below the clutch is the oil temp sensor that causes us so many problems when the connector gets loose and we get the eternnal "Lo" reading or the "---" instead of an actual temp reading. The sensor on top has to be for the e.f.i. since it's too low on the engine to serve as an oil pressure sensor, I think. Hope this helps!
 
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Discussion Starter #18
The sensor behind the headlight is for ...I think...for ambient temp and/or barometric pressure. It looks like a connector with a "stem" out to the side. Page 50, part 4 on the Ducati parts manual. The description is "sensor".
 
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Discussion Starter #19
Yeah, that makes some sense. In the car industry we use ambient temp sensors, but they're usually tied into the air conditioning systems on cars with auto air/climate control or they're used as sensors for in-car displays of outside air temperature. I guess they could serve as temp sensors for e.f.i., but it doesn't sound like a reliable way to judge engine temperature for fuel mapping. What if your bike was at full operating temp while parked outside on a freezing winter day? The temp sensor would then read the outside air and tell the e.c.u. that the bike was cold when in fact it was hot. The result would be a rich running condition. Make sense?
 
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Discussion Starter #20
Wait a minute! Brain phart! The ambient temp sensor would relay info relating to air density to the e.c.u., which would also determine mixture settings. The colder the air, the higher the air density, therefore you have more air to work with. As air temp increases density decreases and you have effectively less air to work with. The e.c.u. must balance both air density and engine temp to calculate proper fuel metering. If this sensor were to fail you would experience a rich or lean condition depending on which way it was telling the e.c.u. to meter. Make sense? I would still put my money on the engine temp sensor if I were going to throw a part at it.
 
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