As it goes from cold to hot the idle gradualy creaps up from about 1200rpm to 2500rpm, I cant think of what would cause this, the bike runs great, idles great and revs out cleanly except the idle just creeps up... gunna pull the carb over the weekend any ways I think...
Why, Why, Why...
Started by Brumby Boy, Sep 24 2009 07:54 PM
30 replies to this topic
Posted 24 September 2009 - 07:54 PM
As it goes from cold to hot the idle gradualy creaps up from about 1200rpm to 2500rpm, I cant think of what would cause this, the bike runs great, idles great and revs out cleanly except the idle just creeps up... gunna pull the carb over the weekend any ways I think...
Posted 24 September 2009 - 08:05 PM
Does it stop at 2500rpm? Did you set your idle with the bike fully warmed up?
Posted 25 September 2009 - 01:57 AM
Na the revs keep climbing with the temp but it usualy stops around 2500rpm which is where the bikes temp sits at normal operating temp
no I set it cold so it would idle once a little warmed up, and not continually stall every time I pull up at a set of lights for the first 10/15 min of riding, if I set it warmed up it wont idle at all until its completely warmed up and I just don't have the opportunity to warm it up much/at all at 5am when I'm heading to work
no I set it cold so it would idle once a little warmed up, and not continually stall every time I pull up at a set of lights for the first 10/15 min of riding, if I set it warmed up it wont idle at all until its completely warmed up and I just don't have the opportunity to warm it up much/at all at 5am when I'm heading to work
Posted 25 September 2009 - 06:59 AM
My '93 XR600R does the same - I've cleaned the carb, air filter, checked the fuel tap and ensured that the fit of the boot and intake is good a million times. Normally I have time to warm it up to temp, but would like to know why this happens.
Posted 25 September 2009 - 07:06 AM
Brumby Boy said:
Na the revs keep climbing with the temp but it usualy stops around 2500rpm which is where the bikes temp sits at normal operating temp
no I set it cold so it would idle once a little warmed up, and not continually stall every time I pull up at a set of lights for the first 10/15 min of riding, if I set it warmed up it wont idle at all until its completely warmed up and I just don't have the opportunity to warm it up much/at all at 5am when I'm heading to work
no I set it cold so it would idle once a little warmed up, and not continually stall every time I pull up at a set of lights for the first 10/15 min of riding, if I set it warmed up it wont idle at all until its completely warmed up and I just don't have the opportunity to warm it up much/at all at 5am when I'm heading to work
Ah, well then you don't have a hard problem to solve.
I had the same problem on the 650r. If you wanted a fast warmup and set the idle cold you would get a hanging idle/1900rpm idle when fully warmed up. If you set the idle to 1500rpm while hot, it took 2x as long to warmup and would sometimes die when coming up to lights/stop signs.
You're going to have find a point between the cold idle and hot idle settings that you're comfortable with. One that doesn't require excessive amount of time to warmup but also doesn't raise the idle past a point you're comfortable with.
If you're worried about noise to the neighbors, you could turn in the idle screw 1/2 a turn so you can get it off choke and then turn it out again when you leave.
Posted 25 September 2009 - 07:46 AM
it is one of those inexplainable things, I think, maybe somehow, Honda inherent. My 1972 XL250 idle would also climb the same way, when it was brand spanking new.
Posted 25 September 2009 - 08:01 AM
You need to rig up a remote idle adjuster like on an Eddy or FCR so you can just reach down and lower your idle when it warms up.
Posted 25 September 2009 - 08:05 AM
Set it at about 1600 hot.
Then just be mindful of the weak idle when cold.
Then just be mindful of the weak idle when cold.
Posted 25 September 2009 - 09:42 AM
Just dial up the idle when it's cold and dial it back down after it warms up. :thumbsup:
Posted 25 September 2009 - 10:35 AM
not sure what bike we're talking about here but i'll assume it's gotta choke leaver somewhere? after rejetting my xrl it warms up incredibly fast, i pull the choke to the half notch to start, it runs for 3 minutes idling kinda fast then i can turn off the choke and it idles nice and low. consequently i think my bike is using more oil or losing it haven't bothered figuring that one out yet. i've always set my idle so that it runs fast with the choke on and once warmed up choke off normal idle. this other way around business you've got going sounds weird, i'd suggest a slightly richer jetting or playing with that fuel mixture screw to if it gets any better.
Posted 25 September 2009 - 11:15 AM
Brumby Boy said:
Na the revs keep climbing with the temp but it usualy stops around 2500rpm which is where the bikes temp sits at normal operating temp
no I set it cold so it would idle once a little warmed up, and not continually stall every time I pull up at a set of lights for the first 10/15 min of riding, if I set it warmed up it wont idle at all until its completely warmed up and I just don't have the opportunity to warm it up much/at all at 5am when I'm heading to work
no I set it cold so it would idle once a little warmed up, and not continually stall every time I pull up at a set of lights for the first 10/15 min of riding, if I set it warmed up it wont idle at all until its completely warmed up and I just don't have the opportunity to warm it up much/at all at 5am when I'm heading to work
These air-cooled motors are a bit cold blooded. Takes a while to warm up. It's fine to ride with the choke on for a few minutes just don't forget to turn it off.
It's best to set the idle speed after the engine has fully warmed up. What mods have you done, if any? That can have an effect on the idle speed or ability to hold idle, especially if it has or hasn't been rejetted to compensate.
Try backing out the pilot screw at the bottom of the carb about 1/2 to 1 full turn counter clockwise after it's been warmed up. It might help to first turn it in clockwise until lightly seated to find out how many turns out it was initially. Don't want to back it out any further than 3 1/2 turns because any more than that & it can fall out. Don't ask me how I know about that... :smashpc:
Keep Ridin'
D_D
"It can't be the rider, it's gotta be the bike. Yeah, that's it..."
Posted 25 September 2009 - 03:03 PM
Old Dog said:
You need to rig up a remote idle adjuster like on an Eddy or FCR so you can just reach down and lower your idle when it warms up.
Thats gunna annoy the piss outta me...
Dual_Dog said:
These air-cooled motors are a bit cold blooded. Takes a while to warm up. It's fine to ride with the choke on for a few minutes just don't forget to turn it off.
It's best to set the idle speed after the engine has fully warmed up. What mods have you done, if any? That can have an effect on the idle speed or ability to hold idle, especially if it has or hasn't been rejetted to compensate.
Try backing out the pilot screw at the bottom of the carb about 1/2 to 1 full turn counter clockwise after it's been warmed up. It might help to first turn it in clockwise until lightly seated to find out how many turns out it was initially. Don't want to back it out any further than 3 1/2 turns because any more than that & it can fall out. Don't ask me how I know about that... :smashpc:
Keep Ridin'
D_D
"It can't be the rider, it's gotta be the bike. Yeah, that's it..."
It's best to set the idle speed after the engine has fully warmed up. What mods have you done, if any? That can have an effect on the idle speed or ability to hold idle, especially if it has or hasn't been rejetted to compensate.
Try backing out the pilot screw at the bottom of the carb about 1/2 to 1 full turn counter clockwise after it's been warmed up. It might help to first turn it in clockwise until lightly seated to find out how many turns out it was initially. Don't want to back it out any further than 3 1/2 turns because any more than that & it can fall out. Don't ask me how I know about that... :smashpc:
Keep Ridin'
D_D
"It can't be the rider, it's gotta be the bike. Yeah, that's it..."
It's a 94 600R as I forgot to mention, It's stock as a rock as far as I know except a O/S 9.5:1 piston Thanks to Honda's stock choke butterfly, now it just has a piece of ally plate cut to size...(not done my me I bought it that way)
I also dont use the choke because it wont run with it on...
Posted 25 September 2009 - 03:05 PM
Oh and it has a Big Bill's Thunder Series slip on muffler
Im going looking at a 05 FS650E Berg shortly too so I may just be loosing this bike anyway
Im going looking at a 05 FS650E Berg shortly too so I may just be loosing this bike anyway
Posted 26 September 2009 - 04:30 PM
Pulled the carb this morning around 2am because I couldn't sleep and its got a 65 pilot and a 165 main or is it the other way around? I cant remember, and the clip is on the bottom slot on the needle, other than that I couldn't see anything that stood out as possibly being wrong, I'm going to set the idle cold at half choke and see how my problem goes
Posted 26 September 2009 - 04:44 PM
Did you ever consider that you may have an intake manifold leak. I had the same idle problems you described and that was the problem my bike had.
Posted 26 September 2009 - 04:59 PM
My '81 XR500R did the same damn thing. It was annoying but I got used to it. I thought the bike was just cold blooded.
Posted 26 September 2009 - 07:50 PM
2nd on the intake manifold leak... There is an O-ring that gets squished and can leak, and my intake had a big crack in it. EXACT problems as described. Try starting the bike and lightly spray around the manifold with some starting fluid and see if the RPM's vary... If so, ya got a leak!
Good luck!!!
Good luck!!!
Posted 27 September 2009 - 04:26 AM
Yea na no leaks, that was the first thing I checked, I spoke to my Uncle (a mechanic same as me but knows more about carbs than me) and he looked at it and reckons that it just how they are, they are the most basic of basic carbs, the only carb he's seen that's more basic than it is the one on his old postie bike and that if I want to fix it I'll have to fit the flat slide pumper carb...
Posted 27 September 2009 - 06:18 AM
I have a 2006 650R that has done the same thing since new. Put on an Eddy, and it still does it. Not carb related. It is something inherent to these big motors. Drag on the oil pump or cam chain or something until the oil heats up?
Not sure what causes it, but I have the adjustable idle and use it.
Not sure what causes it, but I have the adjustable idle and use it.
Posted 27 September 2009 - 06:33 AM
Brumby Boy said:
"...I'm going to set the idle cold at half choke and see how my problem goes"
...that's not the proper way to set the idle... :bonk:
...you set it with the bike properly warmed up and choke off...it's not rocket science. :thumbsup:
Brumby Boy said:
Yea na no leaks, that was the first thing I checked, I spoke to my Uncle (a mechanic same as me but knows more about carbs than me) and he looked at it and reckons that it just how they are, they are the most basic of basic carbs, the only carb he's seen that's more basic than it is the one on his old postie bike and that if I want to fix it I'll have to fit the flat slide pumper carb...
your Uncle is correct...even when properly jetted on a non-enricher type choke carbs if you can't get over the fact that you may have to assist the bike(apply throttle) for 30 seconds to a minute or two depending on temperature before it will maintane it's own idle...then your only real choice is fuel injected bike since flat-side carbs will still require a warm-up period. :smirk:
i really don't understand the big deal since bikes have been this way for years but obviously it's a problem for you.
:cheers:
