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4k-4.5k rpm stumble

Started by cbartlett419, July 07, 2008, 09:06:16 PM

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cbartlett419

I have an '02 m750sie (cut/cored slipons, pods, no emissions) that has developed a stumble/sputter @ around 4k rpm and clears up around 4.5k rpm. Oil temp crests @ 240. I live in houston and commute daily. Am I a self inflicted victim of the dreaded lean sputter? Have I cursed myself in my pursuit for a more naked, naked bike? anyway...has anyone tried a fuel pressure riser to correct the problem.  [bacon]

Howie

Quote from: cbartlett419 on July 07, 2008, 09:06:16 PM
I have an '02 m750sie (cut/cored slipons, pods, no emissions) that has developed a stumble/sputter @ around 4k rpm and clears up around 4.5k rpm. Oil temp crests @ 240. I live in houston and commute daily. Am I a self inflicted victim of the dreaded lean sputter? Have I cursed myself in my pursuit for a more naked, naked bike? anyway...has anyone tried a fuel pressure riser to correct the problem.  [bacon]

A CO trim adjustment and throttle synch wouldn't hurt.

cbartlett419

local shop says 2 hours labor, that sound right?

Howie

They may be giving themselves a little extra room for diagnosis.  IMO, better to estimate 2 hours and in the end charge for one than going the other way.

Mr Earl

Quote from: cbartlett419 on July 07, 2008, 09:06:16 PM
I have an '02 m750sie (cut/cored slipons, pods, no emissions) that has developed a stumble/sputter @ around 4k rpm and clears up around 4.5k rpm. Oil temp crests @ 240. I live in houston and commute daily. Am I a self inflicted victim of the dreaded lean sputter? Have I cursed myself in my pursuit for a more naked, naked bike? anyway...has anyone tried a fuel pressure riser to correct the problem.  [bacon]

I tried a Techlusion TFI fuel manager to fix this problem in my M800, and it worked beautifully.  The bonus of way better performance through the whole RPM range was nice.  My understanding of the ECU trim adjustment is that its effects taper off as RPM increases.  So to fully correct a lean mixture at 4000 RPM, the idle mixture might need to be overly rich.  If your 750 is anything like my 800, it needs more fuel than the stock ECU can deliver - for optimum performance.
Leo Vince CF slip-ons, '01 SS900 fully adjustable Showa forks w/ST2 springs, rebuilt S4 shock w/Ohlins spring, 748 dog bone, Swatt clip-ons above the triple, Sargent seat, Duplicolor-Dark seat cowl, Rizoma grips, Techlusion TFI, SBK front fender, Evoluzione slave, BMC sport air filter, 14-tooth sprocket, Desmotimes caseguard, S2R side panels, Pantah belt covers, fake CRG LS mirrors, extra black zip-ties, right grip control imprint on tank, de-cannistered, Ducati Meccanica Bologna key ring

Howie

Quote from: Mr Earl on July 08, 2008, 09:08:53 PM
I tried a Techlusion TFI fuel manager to fix this problem in my M800, and it worked beautifully.  The bonus of way better performance through the whole RPM range was nice.  My understanding of the ECU trim adjustment is that its effects taper off as RPM increases.  So to fully correct a lean mixture at 4000 RPM, the idle mixture might need to be overly rich.  If your 750 is anything like my 800, it needs more fuel than the stock ECU can deliver - for optimum performance.

True about the trim.

clubhousemotorsports

The trim functions on the 5.9ecu are across the board so it is changing fuel with a broad stroke.Richer at 1000rpm same amount of fuel added at 5000 and 10000rpm. Now this does not mean that the bike will be rich in those areas just that you have no way to select where the bike gets richer.The 5.9 (and newer) ecu have the ability to richen a bike way more than it should be.

The low $$$ set up is to find the lean spot and then richen it until it is acceptable . You then need to use the other fuel injection settings to make the bike driveable down low.  Does not always happen, thats when the aftermarket fuel modifiers (powercomander,techlusion,etc) can be a real useful tool.

good luck

cbartlett419

Thanks for the input everybody. Thought I'd see if a hardware change could solve it. I think it's an inevitability that I piggyback the ecu, just kinda hoping not...peace ya'll

OT

Did this start after the silencers were cut/cored or was it there beforehand?

cbartlett419

digging this one up for various props and a progress report. to answer your question OT, yes, and it only got worse w/ the pod installation. i scored a Techlusion FI box from a member(thanks Chill) and am thoroughly pleased. the system is super easy to install(4 wires, took me less than an hour) and equally easy to negotiate. the manufacturer wrote fantastic tuning instruction and are readily available for questioning via a forum on their homepage http://www.techlusion.com/    the scoot is running like a champ.  [moto]

Mr Earl

Congrats!  Glad yours is working out.

Here's some interesting reading from someone I believe is one of the better Ducati wrenches.  Too bad he's on the flip side of planet earth.

http://www.moto-one.com.au/performance/800monstercamtiming.html

Take a look at Brad's red pot setting.  I thought his setting must have been bike-specific, but over several weeks of riding and adjusting, I wound up at the same setting.  BTW, don't try to cruise at any rpm above the 4th pot's setting - it doesn't like it.  My 4th pot is set at 6000 rpm.
Leo Vince CF slip-ons, '01 SS900 fully adjustable Showa forks w/ST2 springs, rebuilt S4 shock w/Ohlins spring, 748 dog bone, Swatt clip-ons above the triple, Sargent seat, Duplicolor-Dark seat cowl, Rizoma grips, Techlusion TFI, SBK front fender, Evoluzione slave, BMC sport air filter, 14-tooth sprocket, Desmotimes caseguard, S2R side panels, Pantah belt covers, fake CRG LS mirrors, extra black zip-ties, right grip control imprint on tank, de-cannistered, Ducati Meccanica Bologna key ring