Intermittent hesitation around 4K RPM

boozedog

boozedog

contributing rider
Joined
Apr 27, 2023
Messages
6
Location
PA
Hi everybody, just bought a used Svartpilen 401. I have noticed that this bike has a tendency to hesitate at about 4K RPM at partial throttle in 2nd gear. I haven't really noticed it happening in any other gear. The bike lurches and lunges and then accelerates as normal.

Anybody else seeing anything like this? I haven't done any mods to this bike (yet). It is a used bike with about 7K miles on it.

Thanks!
 
Hard to say.

I tried running some Star Tron through it in case it was bad gas. But it doesn't really seem to be improving.

Big lurch/hesitation between 3K-5K RPM at partial throttle, I'd say about 1/2 the time it does it when accelerating through that range in the lower gears

Oddly enough it doesn't really seem to do it once you're in the higher gears. Ocasionally it will hesitate at higher RPMs but it's not as common.

@Ben Dover no there is no backfire or popping, just a sudden momentary loss of power then it regains it.

Will have a look at the air filter. I don't know if it's still under warranty, I bought this bike used.

Thanks all for the replies
 
Big lurch/hesitation between 3K-5K RPM at partial throttle, I'd say about 1/2 the time it does it when accelerating through that range in the lower gears
Things like this can be cause by vibration effecting electrical connections. Definitely worth checking the battery terminals are tight, the sidestand switch and terminals aren't loose etc.
As JJCool suggests, If the engine revs when it loses power, that might be a sign of clutch slipping.
Definitely check the air filter too.
 
No it's not clutch slipping, that much I can say for sure

The engine revs do not increase during the hesitation. It does seem to me like a momentary fuel delivery interruption or an ignition interruption

I will check that side stand switch for sure

Also might try to get some GoPro footage of the phenomenon ... stay tuned
 
Have you treid an ECU reset?
The 15 minute idle reset thing.

If it were me, and I bought a used bike, I would probably change air filter, fuel filter, spark plug and reset the ecu.

On the 401 that is like 20 bucks and about 45 minutes if you have a the spark plug socket and a proper torque wrench.

And it will probably save you 5 bucks in gas in the long run.

🙉
 
@BISavage I did some searching on the forum and didn't find an answer -- does anyone have suggestions for brand/part numbers for a new air filter, fuel filter, and spark plug? Or should I just get it from the dealer?
 
I would get at least the fuel filter from a KTM / Husky dealer, probably the plug too.

Air Filter
HFA 6303 - Hiflo Filtro (normally much less expensive)
93006015000 - Original

Fuel Filter
93807018000 - Original

Plug
93839093000 - Original Bosch
93839091000 - Small Grey Rubber Seal for Plug (in case you lose it or its broke)
Alternative Plug
LKAR8A9 - NGK (personally never tested on 401)
LKAR8AI9 - NGK Iridium (personally never tested on 401)
MOR12LGS - Brisk Lambo Design
 
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