Running lumpy, or just a V Twin?

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Iceycold
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Running lumpy, or just a V Twin?

Post by Iceycold » Sun May 12, 2019 5:45 pm

Hi guys,

I am the proud owner of a 2014 SuperDuke R, I bought it 2 weeks ago and I am so in love with it. Its my first KTM and my first V Twin after riding big Jap inline fours for nearly 30 years!!

The bike runs very very well... but.... I have noticed that in Street mode at low revs, it is quite lumpy, and doesn't feel like its running very smoothly. It runs better over 3k, but under it seems to really not like it. It is better in Sport mode, but the throttle is snatchy at low revs. Rain mode is smooth.

The bike is standard (I believe) apart from a Remus end can which has no baffle in it.

I am thinking about balancing the carb bodies and checking all the vacuum pipes etc. But wondered if anyone had any sage-ly advice about what to look for, or is this normal for a big v-twin?

Any help or advice greatfully received.

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Re: Running lumpy, or just a V Twin?

Post by Spiff » Sun May 12, 2019 10:46 pm

I have seen some bikes run worse when an after market exhaust and/or intake is used. They need a better map. If the cat is still in place you probably don't need to worry about it. That said, my bike doesn't like to be lugged either. Keep the revs where it is happy, and GHL.

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Re: Running lumpy, or just a V Twin?

Post by scrubrunner » Mon May 13, 2019 9:13 pm

Spiff wrote:
Sun May 12, 2019 10:46 pm
I have seen some bikes run worse when an after market exhaust and/or intake is used. They need a better map. If the cat is still in place you probably don't need to worry about it. That said, my bike doesn't like to be lugged either. Keep the revs where it is happy, and GHL.
+1 on what Spiff said particularly on lugging them, quick fix is either gain a couple of teeth rear sprocket or drop 1 at the front - most people are throwing 16s on the front around 3yrs ago I decided to go 2 teeth up on the rear & it made a world of difference, having said all that enjoy your bike life's too short to not ride a sdr
sdr makes ANY day above ground a good day

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Re: Running lumpy, or just a V Twin?

Post by Spiff » Tue May 14, 2019 6:32 am

What is the RPM in 6th at 80mph on your bike?

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Aussie Dave
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Re: Running lumpy, or just a V Twin?

Post by Aussie Dave » Thu May 16, 2019 7:47 am

Iceycold wrote:
Sun May 12, 2019 5:45 pm
Hi guys,

I am the proud owner of a 2014 SuperDuke R, I bought it 2 weeks ago and I am so in love with it. Its my first KTM and my first V Twin after riding big Jap inline fours for nearly 30 years!!

The bike runs very very well... but.... I have noticed that in Street mode at low revs, it is quite lumpy, and doesn't feel like its running very smoothly. It runs better over 3k, but under it seems to really not like it. It is better in Sport mode, but the throttle is snatchy at low revs. Rain mode is smooth.

The bike is standard (I believe) apart from a Remus end can which has no baffle in it.

I am thinking about balancing the carb bodies and checking all the vacuum pipes etc. But wondered if anyone had any sage-ly advice about what to look for, or is this normal for a big v-twin?

Any help or advice greatfully received.
Cheers icecold from Aus,

I have the SDGT version and yours will be very similar...... they really don't like under 4500rpms as they have a very light crankshaft weight and max compression (13.6 - 1). So they have to rev to be nice. (Also, the standard mufflers on the R & GT have no baffles either..... the cat converter did that work).

Don't tamper with the throttle body balance just yet..... it reads like you are seriously chugging the engine by riding at ridiculously low rpm - here's what I did to make mine much nicer in traffic...... ;)

I changed my rear sprocket (+2 teeth to a 40t) and that made day to day traffic very much easier - you know, 3rd gear was happy at 60kph/35mph speed zones, instead of swapping to 2nd and back all the time in traffic.

On the GT it brought 6th gear into play at 110kph/65mph? instead of 125+/80mph with the oem gearing. The reason it's better to swap the rear sprocket vs the front is, the SDR & GT have a "quick change" system courtesy of the single sided swingarm design...... quite literally, it takes only 15mins to change a rear sprocket :!:

To change to a 16t front will take much longer and you will need an air tool to rattle the sprocket nut free/tight again. You should not require any chain links though the adjuster will need to be a max loose. (Also 1 tooth on the front sprox would be about 3.5 teeth on the rear.... might be too much).

If that still isn't smooth enough (I ride mine mostly around 4-4500 rpms (ie 3rd gear at 60klicks, 4th @ 80k 5th @100kmph and 6th for 110+ ) then either buy the O2 fuel dongles & plugs for removing the closed loop sensors or....... try this mod I just stumbled onto.....(it's free, and I have no idea why it works, but it does)... place a 2mm thick Cu washer (12mm ID) under the O2 sensor probes on your headers..... it will smooth out the under 4k rpms almost as well as the resistor dongles (330k & 1000k ohms) you can buy for $70 Aus or $35Euro/US........

It was always a myth that big twins could be ridden at 3k rpms....... BMW 1200RT's need/like to be rev'ed - only the big fat cruisers can chugg along with low oil pressure at low speed/2k rpms...... not a highly strung 1290 motor.

;)

PS The 1290 motor is quite friendly anyway, but many have put the fuel dongles on to richen up the low rpm map...... becareful though, if you have a decated (?) used bike..... I suspect it would/should have the "Booster Plug" fitted to the airbox to compensate for the cat converter removal...... check this out first - does it have a 'link pipe' (narrow tube) instead of a big fat catalytic converter box ? and a booster plug attached to the airbox temp sensor up under the tank? - that mod richens the whole rev range to compensate for no cat.

It's always a challenge to work out what a previous owner has done to a used bike..... maybe he took all the good gear off it before trading in..... maybe it had a Power Commander map before you got it.....????
Current delights...1290GT-2017, CBR1100XX-2005

Prev loves...Capo1200TP-014, CBR11xx-002, 2xFZR1000genisis-94, FJ1200-89, FJ1100-84, XS1100P, VF1000F-83, CX500, VF750S, KZ1000J1-81, KZ1000ST-79, CB750F2-77, CB360T-74, CB175.. started it all in 1974 ;)

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Re: Running lumpy, or just a V Twin?

Post by scrubrunner » Sat May 18, 2019 11:40 pm

Aussie Dave wrote:
Thu May 16, 2019 7:47 am

lso, the standard mufflers on the R & GT have no baffles either

To change to a 16t front will take much longer and you will need an air tool to rattle the sprocket nut free/tight again. You should not require any chain links though the adjuster will need to be a max loose. (Also 1 tooth on the front sprox would be about 3.5 teeth on the rear.... might be too much).
Dave I have to skid you up here bloke, the muffler has an inner tube that actually works very well as a baffle, it was 1 of the very first mods I ever tried back on my 15

as to a rattle gun to pull the front no way - anyone ever walks near mine with a rattle gun they're going to walk away like John Cleese doing a funny 1 because that's where the air tool will be, before I went to a 40 I did the 16 front - took better part of 15mins including nut scratching & coffee slurping time, most do it because of the economy compared to rear sprok prices but yes +2 teeth on the arse end is awesome for my riding compared to turning it into a trials bike with the -1 front

say no to rattle guns!!
sdr makes ANY day above ground a good day

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