Reasons for decreased idle speed

[Lukich]

Hello.
My bike recently started sounding differently on startup and even stalled several times when I would come to a stop shortly after beginning a ride. I did some research, and it turned out it was idle speed, mine was somewhere around 900 RPM, wheres a recommended setting for SV650 2nd gen is 1300+/-100. I adjusted the idle speed and all is well again. My question is - this just started happening, is there a mechanical reason why idle speed would drop down? Or did somebody just messed with me and turned it down (unlikely, but I park it in SF, so who knows.)?

Thank you!
Luka

 

[Biga]

Someone could have messed with...
Vibration could also helped?

 

[motomania2007]

valve adjustment, throttle body/carb synch, poor fuel quality (degraded/contaminated fuel), restricted exhaust or intake

are just a few possibilities

 

[ST Guy]

Sometimes idle speed just changes. As long as your maintenance is up to date and it's running fine, I'd not worry about it. Often manufacturers will proved an easy way for the owner to adjust idle speed. For instance on the ST1100, Honda put a handy adjuster inside the gas tank filler door next to the gas cap. They wouldn't have done that if idle speeds always remained constant.

 

[MapleRoad]

Easiest first check: air filter.

 

[Busy Little Shop]

Idle setting is personal... I set my bikes idle to 0... it would
afford the maximum possible engine braking so I could run the bendy
bits by just rolling on and off the throttle with out brakes... No
idle was a sneaky way to eliminate 95% who asked "can I ride it?"...
I'd say sure but if you kill it you're done... you only get one try...

 

[augustiron]

Could be a failing throttle position sensor.

 

[bobl]

Could also be hot weather versus cold weather.

 

[kuksul08]

Weather
Crud in the idle circuit
Vibration
Fuel


what they said ^^^

 

[stangmx13]

400rpm is a big change. if it happened all at once, something is up. if it was gradual over a year, probably no big deal.

 

[puckles]

ive had a cam chain jump a tooth that made the bike have a hard time idling. lost a lot of low end torque. still pulled hard at the top. If i remember correctly, it was the intake cam that jumped retarded

 

[Lukich]

Thank you for your replies!

My bike's maintenance is pretty up to date, by me, not the mechanic, but the oil is fresh, air cylinder have been swapped recently, did a valve adjustment (mechanic) a few month back. I don't think it's the fuel as I use the bike on almost a daily basis.

I did move to a part of California that's somewhat warmer, so perhaps it's that. I'll look at the intakes some more and keep an eye on the idle.

Thanks again!

 

[bcj]

My k3 SV did that over the winter lay-up a few years ago. Only the once though.
There's a click pen type spring on the throttle body end of the idle adjust cable.
I think temp swings may have ratcheted it out slightly.

It's never done it again, but I'll note what the idle is now that I know that it's an easy fix.