Dyno tune help, rear cylinder randomly going lean, no reason

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07orangeSD
Minimoto racer
 
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Joined: Mon Jul 27, 2015 12:37 am
Location: Ulster County, NY

Dyno tune help, rear cylinder randomly going lean, no reason

Postby 07orangeSD » Thu May 17, 2018 4:31 pm

Bike is at a shop being tuned (they are familiar with v-twins and work on Ducati / euro bikes).

They are tuning each cylinder individually, front went smooth and is spot on.

The rear is giving them problems, they get it damn near spot on and then it just goes lean for no reason.

They are thinking some debris in the fuel rail or injector/bad injector.

Anyone ever run into this or have any ideas?
07' SuperDuke (Orange)
Full Akra exhaust and Akra tune (will be Dyno tuned soon), R&G tidy tail, Skidmarx screen, Dunlop Q3's, Renthal bars, [Motohooligan air box, secondary's, SAS plates, tank brackets, upper and lower sliders]; Lots more to come.

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No. 47
Master of the twisties
 
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Joined: Sat Jan 10, 2009 5:14 pm
Location: London and Kent

Re: Dyno tune help, rear cylinder randomly going lean, no re

Postby No. 47 » Thu May 17, 2018 6:00 pm

Leaky TB rubber?
'08 ex-Battle race KTM Superduke 990 R No.47
'08 OE KTM Superduke 990 R
'01 Ducati 996S

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Motogoon
Two wheeled terror
 
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Joined: Thu Jul 07, 2011 6:53 am
Location: NEW Zealand

Re: Dyno tune help, rear cylinder randomly going lean, no re

Postby Motogoon » Thu May 17, 2018 7:06 pm

Sounds similar to the problem the previous owner was having with the blown up 05 model I bought. They tried everything while tuning but one cylinder just kept going lean. After stripping it down the plug for that injector had some water corrosion and that wire also had an exposed part. It's still not known for sure if that caused the leaness and subsequent piston breaking but nothing else out of the ordinary was found so worth a check I guess!


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