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Hey everyone,

I recently picked up a 2002 SS 750 in great condition. It was obvious that it had collected dust but was garaged the entire time. From the dealer records, it had been serviced (regular maintenance) within two years of my purchase. So far, everything has been exceptional except for one thing; around 2000 rpm's, the bike will sputter (very hard to explain in words). It doesnt do it at any other rpms and will do in almost constantly if you hold the throttle at the 2000 mark. I thought it may be an issue with old gas or possibly with gummy fuel injectors but I had undergone full seafoam treatment twice with two tanks of new premium gas. It also seems to increase rpms even when I hold the throttle at constant (seems to be more pronounced at lower rpms).

Any help would be greatly appreciated! I would be happy to clarify anything.
 

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Since you've burned through two tanks of gas, it's safe to assume that it's not stumbling at other rpms.

At 2,000 rpm the throttle body butterflies are just opening a bit. Over time (especially with crappy EtOH fuel) a varnish can build up. This can change the air flow. Take off the air filter and look into the throttle bodies. Open the throttle and run your finger along the surface where the butterflies close...is there a ridge of varnish? Spray some carb cleaner on a rag and clean that area up.

Let us know what you find!
 

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Yes, follow mlukason advice but in general, a motorcycle engine that develops it's maximum power above 8K rpm is not going to be all that happy trying to cruise at 2000 rpm. You basically expose the asymmetrical nature of the cylinders (small differences in compression, ignition, fueling) when you are trying to push the bike so far on each ignition. You really have to have a high state of tune to support that. Now, if it won't accelerate smoothly from a stop or from 2500 rpm, you need to investigate. The likely culprit on a Ducati would be valve adjustment. When the valves are out of adjustment on a Ducati, the opening and closing cams shift in opposite directions and change the cam timing. In addition, when the chrome starts to flake on a defective rocker arm, a common problem, performance problems occur because the overlap changes.
 

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When riding at 2000 rpm make not of the throttle opening. Then when your checking the injectors reproduce that throttle opening and open and close the injectors to that throttle position to make sure the synchronization is close. It should help to synchronize the throttle bodies as close as you can.
 

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At that rpm on a bike of that era it could be a few things. As others have said the bikes are not going to run well at that rpm as they are not designed to cruise at that low a RPM , this does not mean it should not pull cleanly from idle through the 2000rpm band. The bike should idle around 1200rpm + or - 100rpm and start to make "usable" power around 3500-4000.

Not to knock the people who did the maintenance but how is their reputation? There are shops who "do service" but simply set things based on the greatest specifications that allow the least amount of work and the most amount of profit. Ducati people in the area will know if the shop is a stickler or just the only place available. There are a few things that make the bikes run best but some are not commonly done due to time= money.

The Synchronization as mentioned will be very important as the throttle will be mostly closed at that rpm and slight changes are magnified. On an injected bike if you sync. the throttle bodies you change the TPS setting,similar with changing the idle. If the Throttle position sensor is not set right you might have a rich or lean spot that again is magnified at low throttle openings.

Is the airbox stock (closed lid)?
has the ecu been re-mapped?
is it backfiring (some call it a cough) in the airbox?
Are you asking for it to be better than they will be?
have someone with a similar 750ie to try yours and see if they are the same or you are just asking more from the bike than is probable due to the low rpm's
 

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What is the 750's configuration?

E.g. open airbox, DP or similar exhaust system, stock or DP ECU.

My mistake, but when I fixed it to be freer flowing, the fuel mapping was wrong and it seemed like a cough when I opened the throttle at low RPM/TP.

RPM at steady TP "racing" could be a lean condition.
The 15M ECU is not the most sophisticated kid on the block but can be improved.

I certainly experience the engine racing with my boat motor and lawn mower when I turn off the fuel supply to empty the float chamber (obviously carbed) that induces a lean condition.

My guess is that as you have tried Seafoam you are in the US.
If you are in Australia use the PM option to contact me and I will see if I can help.
 

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As my Sicilian grandfather would have told you " The Ducati she's a no like a da putt-putt-putt, she's a like a da Zoom-zoom-zoom ! "
 

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valve clearances (closing), belt tension (we had issues with 750SSie when a bit too loose. ?), syncronisation, idle mixture, mapping, chain condition and tension, gearing.

or just go a bit faster. you don't ride at 2,000 rpm.
 

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As my Sicilian grandfather would have told you " The Ducati she's a no like a da putt-putt-putt, she's a like a da Zoom-zoom-zoom ! "
Did your Sicilian grandfather also drive a Mazda? ;)
 

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No , a '49 Dodge with a flathead six. It went putt-putt-putt.
 

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As my Sicilian grandfather would have told you " The Ducati she's a no like a da putt-putt-putt, she's a like a da Zoom-zoom-zoom ! "
Really. If ya wanna putt-putt-putt at 2000rpm, then either buy a Harley or a Moto Guzzi. Even the goose won't enjoy 2K all day. Two words: Down shift
 

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Mine will do it, but it took a lot of fine tuning to get there. Normally I just give her the gas so that bit from idle to 3500 or so is gone in a second. That's parking lot rpm up to where the motor is happy. Carbies are happy on throttle opening, even just a little throttle opening. I think that a product of the vacuum slide arrangement. The slides like to dance around a little at steady rpm.
 

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My Mikuni carb equipped SS also perfectly happy @ sub 3000RPM cruise....open/close throttle transitions @ light load. I'm frequently riding very tiny, bumpy, twisty backroads...slow stuff.

As duc96cr states, some careful carb tweakage paid off in a very friendly off/on transition and (barely cracked) throttle cruise.
 

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I have a 2002 900SSie running open airbox and Termi cans and run standard ECU. I would consider it to be running as good as possible with standard ECU and no tuning/mapping done. Below 3000 rpm really is not usable, it is doable, especially at speeds below 50 kph, but it seems much happier cruising between 3500-4000 rpm and closer to 4000 rpm at +140 kph.

Guess, depending on mapping and tuning, that the rpm is irrelevant, you know when it runs in the sweet spot or not.
 

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I will add that one persons acceptable is another persons un-rideable.

I have had customers who have found the bikes "running great" where they were barely running but because it was the best (or only) experience they had they deemed it great. Yes the carbureted Ducatis can be made to function at low rpms I have yet to find much reason to keep them there but as others have said there is little reason to be that low short of being in stop and go traffic stick in first gear. If that is the case I would simply lower the gearing some to raise the rpms to a better zone.
 

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I had a customer who had a gl1000 goldwing and it was the best bike ever made...
next he bought a BMW k100 and the improvement was enormous, you just could not ask for a better bike.......
He just switched to a Honda shadow 1100 and he does not know how he could have owned the prior bikes ............

In this trajectory he should be on a 2000 -2010 bike next and will not know what to do with himself. Some times you are best to have low expectations and just enjoy the ride.
 

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And remember the K100 was a clear step up from the goldwing, even though it smoked like crazy if you used the sidestand...lol

Brad I would be quite happy with a monster/supersport 400, but aren't we due for you to build a full race 400 and document it? I will have to check your site to see if you have done this already but surely you could hit 60hp and have the worlds trickest/most expensive 400 monster. I wonder if there was ever a race class in japan/ Italy for them. Now that I mention it there is new classes over here for the little bikes ninja 300,cbr , R3 and ktm390 supposed they let in a Ducati 400. The RC390 and R3 are putting out 40hp on my dyno with good torque on the ktm but not much with the R3. I Ducati 400 could be a fun sneak into those classes but the 400 never came here.
 

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yeah, i'm really trying to avoid the pointless here*. imagine an m600 with 1/3 less performance. it's not scintillating.

i do have some 620 cams that have been modified to fit in 3 bearing heads that i'll put in though. curious to see if it peaks the power earlier.

* well, wait until you see the wheel swap and you'll truly see pointless. you now that feeling you get when you've dug half a hole and realised it was a really bad idea, but you're half way there and half a hole is still a hole anyway. and you're standing in it.

my time frame between concept and execution is an issue. short concentration span leads to parts bought leads to "wtf was i thinking" when the later on eventually rolls around for implementation.
 
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