990 Duke stalling/bogging down after hard braking/downshift

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Juggs
Minimoto racer
 
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990 Duke stalling/bogging down after hard braking/downshift

Postby Juggs » Thu May 17, 2018 8:07 am

ADVICE NEEDED!!..

Last night my 2007 990 Superduke started giving me a new issue.

When de-accelerating hard & downshifting, say from 4th to 2nd for a corner or island when you get back on the throttle it bogs down & tries to stall.

A couple of times the bike totally cut out which was pretty dangerous!

Always starts back up, rides fine on WOT & up shifting etc , it’s literally only when your scrubbing speed off & then re-apply the throttle.

Any advice greatly appreciated as I go to the Isle of Man TT in a couple of weeks so need to get to the bottom of the issue ASAP!
Cheers

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No. 47
Master of the twisties
 
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Re: 990 Duke stalling/bogging down after hard braking/downsh

Postby No. 47 » Thu May 17, 2018 8:54 am

Try the search button................................................here's a 'starter for ten' viewtopic.php?f=5&t=5742&hilit=hard+braking%2Fdownshift
'08 ex-Battle race KTM Superduke 990 R No.47
'08 OE KTM Superduke 990 R
'01 Ducati 996S

Juggs
Minimoto racer
 
Posts: 6
Joined: Mon Apr 09, 2018 8:34 pm

Re: 990 Duke stalling/bogging down after hard braking/downsh

Postby Juggs » Thu May 17, 2018 9:24 am

Cheers for that mate, I will have a read through the link.
I had a search before posting & thinking it may possibly be the clutch switch just throws me a bit with it bogging down as anyone reporting the clutch switch issue seems to get a total cut out.

My bike doesn’t seem to do that much, more so the bogging down.
Best comparison I’ve got is experiencing fuel surge in a car when cornering hard then when your straight it totally clears.
It’s not lean angle related on the bike but the symptoms are very similar if you follow me.

Cheers for the reply , will continue to search.

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No. 47
Master of the twisties
 
Posts: 2955
Joined: Sat Jan 10, 2009 5:14 pm
Location: London and Kent

Re: 990 Duke stalling/bogging down after hard braking/downsh

Postby No. 47 » Thu May 17, 2018 11:00 am

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

Juggs
Minimoto racer
 
Posts: 6
Joined: Mon Apr 09, 2018 8:34 pm

Re: 990 Duke stalling/bogging down after hard braking/downsh

Postby Juggs » Thu May 17, 2018 11:40 pm

Thanks for the links No.47 helped narrow it down & gave a list of items to try to get to the bottom of my issue.

Had some time spare tonight so tried to rule out a few things, done the following:

Cleared the brass jets going into the inlet manifold & vac pipes running to map sensors
Double checked mounting of motohooligan air box & rubbers, air temp sensor etc
Checked fuel & any other vac lines visibly for kinks
Lifted tank & generally checked for anything being loose or disconnected or trapped wires
Checked SAS delete plates are tight & emulators still in connections
Same for o2 deletes
Cleaned BGP & any others with toothbrush & contact cleaner
Didn't go as far as removing the airbox or throttle bodies though

Nothing obviously wrong, loose or disconnected but rules it out so worth a shot.

Then moved on to trying my Lonelec cable & tune ECU gear , was hoping to do a fault code read & check the TPS sensor & adjust but unfortunately my laptop would not connect :-(

Settled for cleaning side stand switch & doing the 15 minute ECU reset

Went for a test ride with high hopes & stalled at the first island, but when blipping the throttle trying to pull away which its never done before.
Started straight back up as per, got on a dual carriage way & done some heavy braking & downshifts, to simulate the fault & problems is still there.
Sure enough bikes bogging down & feels like its trying to stall when getting back on the gas, then tried a heavy braking in a single gear with no downshift or use of the clutch (try to rule out clutch switch +5000rpm thing) the bike still boggs down & acts up.

I then brimmed my fuel tank with shell 97 & rode in the same idiotic manor, this completely eliminated the problem!! Hurray!
With a full tank I could brake so hard to the point it was lifting the back wheel, get straight on the gas no issues no bogging or stalling.
Add in 3 downshifts to the point it gets wheel hop, nope all is well bike pulls cleanly after scrubbing loads of speed off (i.e as you would setting up for a tight corner)
Happy Days!

Or so I thought!

Rode around like this, hard acceleration then hard braking & generally arsing about to try to put the bike under the conditions where the fault occurs, sure enough after about 30 miles its intermittently coughing & bogging down after hard braking & downshifting.

So when the problem came back I tried the rubber band to permanently close the clutch switch, doesn't seem to make any difference really bike still bogging down after de-acceleration.

Could anyone shed any light on this please??

To me it seems like a fuel surging/starvation type problem but its never done this before & I could understand if it was the last 1/4 of a tank but 30 miles off brimmed surely not?
Thinking fuel filters maybe but then wouldn't it be a problem more apparent when on WOT when the fuel pumps under high demand?
Rolling on the throttle or snapping the throttle open causes no issues at all, bike pulls cleanly to the limiter, this issue is directly linked to de-acceleration & heavy braking only.

More than welcome to suggestions & running out of time before my trip, stressed! :-(

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No. 47
Master of the twisties
 
Posts: 2955
Joined: Sat Jan 10, 2009 5:14 pm
Location: London and Kent

Re: 990 Duke stalling/bogging down after hard braking/downsh

Postby No. 47 » Fri May 18, 2018 10:25 am

Given your deadline, suggest trying following in order:

- sort out TuneECU connection and check out TPS, etc (but no fault codes indicated by flashing FI light?),

- buy some tank foam cubes eg https://www.merlinmotorsport.co.uk/p/sa ... -tank-foam,

- check fuel pump pressure, ideally by gauge connected at fuel line QR connectors, when bike bogs down/stalls and if it drops at that point, pull fuel pump and check filters and for possible cavitation caused by overheating and/or failing pump - alternatively, swop out fuel pump for new/known good used one.
'08 ex-Battle race KTM Superduke 990 R No.47
'08 OE KTM Superduke 990 R
'01 Ducati 996S


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