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idle rpm too low?
- Thread starter AG650
- Start date
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- Tags
- carburetors engine
Hi AG,
sure there is very little oil flow at low speeds but the engine will not be making any power either so it will not need much. An idle set as slow as she will run will work fine.
sure there is very little oil flow at low speeds but the engine will not be making any power either so it will not need much. An idle set as slow as she will run will work fine.
CDNTX650
XS650 Guru
I wouldn't run below 1100. When it's super hot out I'd rather have the rockers and cam getting oil.
chizler62
XS650 Addict
My concern for a "low Idle" in a XS650 engine would be crank/rod pins/bearings.The loads are, IMO, sort of similar in theory to starting off in 3rd gear all the time.
jd750ace
Front Toward Enemy
Manufacturers select idle speeds appropriate for starting, oiling, fueling, and lack of timing chain or valve train backlash. Run it lower if you want, just tell us what takes a shit after a while, so the next time this question comes up, we can be more specific!
People are always trying to slow the idle down on Road Stars to that lumpy, lopey, this piece of shit can barely run sound and I'll never understand why. I get that your XS can slow down significantly and not sound like that, but seriously, the idle point carries a number of factors.
People are always trying to slow the idle down on Road Stars to that lumpy, lopey, this piece of shit can barely run sound and I'll never understand why. I get that your XS can slow down significantly and not sound like that, but seriously, the idle point carries a number of factors.
My tach has been calibrated, and this is what 1100rpm sounds like.
When I first got my XS running, I thought the 1200 idle spec seemed and sounded high. It was a bit higher than my other bikes. I was able to turn it down a couple hundred RPM so I did. But then I started experiencing random stalling at stops. Setting the idle back up in the 1100-1200 range cured that. I've come to the conclusion that this is what this motor needs and likes. I've grown used to it over the years and it sounds normal to me now. It also allows the bike to idle on its own at about 1000 shortly after a cold start without me having to hold the throttle cracked open a hair. It took some fiddling to find this setting where it would idle cold but not too fast hot.
You will read here about many who constantly crank their idle speed up when cold then turn it back down once hot. I've got mine dialed in so I don't need to do that. For the first few miles after a cold start, I will keep slight pressure on the throttle at stops to up the RPMs a few hundred (and avoid those random stalls) but that's it.
You will read here about many who constantly crank their idle speed up when cold then turn it back down once hot. I've got mine dialed in so I don't need to do that. For the first few miles after a cold start, I will keep slight pressure on the throttle at stops to up the RPMs a few hundred (and avoid those random stalls) but that's it.
angus67
Welder's penetrate deeper!!
Mines at 1100, and have no stalling, but it does stall when cold, so I bumped it up to 1200. I have a 2003 suzy marauder, and anything under the specified idle speed dosnt give enuf oil pressure to the lower bearings. The marauder has car type bearings and need pressure, but our xs's use caged rollers and don't need much pressure. I think the xs runs at 11lbs? my suzy needs 25lbs at idle. Many have lost the marauder engine by dropping the rpms to get the potato-potato sound just to look cool. face palm.
angus67
Welder's penetrate deeper!!
double post
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I put an oil-pressure gauge on my XS1B back in 1974. Cold startup would show about 15 psi. Once up to Texas summertime temp it would drop to near zero! (***Panic***)
So, updated the oil pump from the 6mm rotor to the later 8mm rotor.
During our hot temps it would hold about 2-3 psi.
This still bothers me...
Peejay
XS650 Member
Also, you may find that with CV carbs, too low idle rpm will cause cut outs as the airflow velocity drops with rpm, less vacuum is generated, the needle can settle lower into the tube and cause variation that dips below 'running' speed causing a stall.
Just a thought!
Just a thought!
jd750ace
Front Toward Enemy
With the throttle plate closed, the vacuum is at it's highest value.
True but only on the engine side of the throttle plates..........
what he says about low venturi effect sounds reasonable to me.
IMHO one of the prime reasons the idle spec is 1200 is no charging below that, you are pulling down the battery as you sit at low RPM.
jussumguy
XS650 Addict
Wasn't the 1200rpm idle speed to get the charging system in its range of effectiveness ?
Yes, 1200 rpm is just at the rpm where the stock alternator starts to produce more voltage than the battery. As the rpm drops to say 1100 rpm at idle, you start drawing current from the battery and the voltage drops off to 12 or 11 volts depending on the load at that time. The stock OEM flasher unit will stop flashing, if the turn signals are selected.
At around 1200 rpm, with rising rpm,the alternator starts sending some current into the battery and the voltage starts to rise 13 volts and greater.
My turn signals would sometimes stop flashing while I was at an intersection waiting to turn
This was due to my rpm being a little on the low side. I replaced my stock flasher unit with a Tridon flasher that is not dependent on voltage/current. So, now even if my rpm wanders down a little low, my flashers always keep flashing, which is a real safety benefit.
At around 1200 rpm, with rising rpm,the alternator starts sending some current into the battery and the voltage starts to rise 13 volts and greater.
My turn signals would sometimes stop flashing while I was at an intersection waiting to turn
This was due to my rpm being a little on the low side. I replaced my stock flasher unit with a Tridon flasher that is not dependent on voltage/current. So, now even if my rpm wanders down a little low, my flashers always keep flashing, which is a real safety benefit.
jd750ace
Front Toward Enemy
I understand what you are saying, and what he is saying, except idle don't have shit to do with the needle. The slide is not lifting at all at 1200 rpm. There is no flow through the needle jet at that point. Potentially not enough pressure drop across the air bleed could result in loss of fuel feed. That I understand, but I think internal lash, oiling, and charging dictate the idle speed more than worrying about the carb. I can turn any of my 3 twins down below 600 rpm, and they still fuel.
NONclow
Confirmed Laquer Breather
.......They don't call it a pilot/idle circuit for nothing.....
Agreed on the charging system effective range.
On to the oiling, Indian chief, flathead, warmed over motor, roller bearings throughout, hot psi: 5. Cool thing 'bout it, when at idle (or if moving, if balls big enough
) open the front cap to see the oil return sqirting back into tank; oil pump is workin'.
It'd be cool to machine a hole in one of the valve covers on an XS to then blow a pyrex bubble window, and secure/seal from inside to witness rocker spray....
...............*hearing all the PMA guys idle screws loosening up as I type this*.......
Agreed on the charging system effective range.
On to the oiling, Indian chief, flathead, warmed over motor, roller bearings throughout, hot psi: 5. Cool thing 'bout it, when at idle (or if moving, if balls big enough
) open the front cap to see the oil return sqirting back into tank; oil pump is workin'.It'd be cool to machine a hole in one of the valve covers on an XS to then blow a pyrex bubble window, and secure/seal from inside to witness rocker spray....
...............*hearing all the PMA guys idle screws loosening up as I type this*.......
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You're right what was I thinking?
angus67
Welder's penetrate deeper!!
smell it! percolators....the bastardization of the Arabica bean. But I must say, coffee presses are a bitch!
I think some one a few years back had attempted a valve cove out of polycarbonate?
I should take a cover and a chunck of poly to my favorite machinist to see it it works. Sure gets hot though. What are the oil site glasses made out of on the later years?
I think some one a few years back had attempted a valve cove out of polycarbonate?
I should take a cover and a chunck of poly to my favorite machinist to see it it works. Sure gets hot though. What are the oil site glasses made out of on the later years?
