Idle speed question?

[General Zod]

On cold start the idle on my bike is below 1000rpms.
So....I adjust idle screww to about 1300rpms.


Then, when it warms up and gets ridden for a few minutes, I'll stop and check the idlw.....it will usually read about 1500rpm or over......


Is there any way to keep the idle at 1200-1300rpm?

I feel like maybe something is wrong with my carbs? I DONT KNOW IF THERES SOMETHING WRONG OR IF THIS IS NORMAL FOR ALL BIKES?

[catfishk]

i am fiddling with the idle on my '83 GS450E in the same manner; turn it higher till it gradually warms and turn in lower. after a few minutes of riding i can adjust it to hang out at 1100 rpms and stay put.

[robertbarr]

http://www.cycleorings.com/intake.html

[derwood]

This o-ring leak that gets mentioned all the time doesn't apply to 4 valve heads, at least not any I've owned.......oui?

[imtheredguy]

i have the same problem with my gs550, is this common among these bikes????? mines an 82 ,and i thought it was just age. also, i have absolutly no idea where the idle screw is. this is the oldest bike i have and am not very good with older bikes. i think its somewhere near the trip-tree.
someone please help.

[DimitriT]

I was chasing the idle on my 550 after I rebuilt the carbs. The way I got it fixed was by first getting the carbs synched and then adjusting the idle mixture screws and the idle speed knob.

A lean idle mixture will increase the RPMs as it warms up so you probably need to enrich the idle mixture by turning the idle screws out a little and turning the idle knob in a little.

You need to find that zone where the motor will run lean enough to keep the plugs clean on idle but not too lean as to speed up the idle when it gets hot.

Also, are you using the choke? The motor needs to be on choke for a while on my bike (a mile of running at least or five minutes sitting) before it will ilde. Otherwise it will struggle to stay running.

[Rich1135]

idleness

This sounds normal to me, you just need to set the idle speed with the choke off and the engine up to working temperature, say after you've ridden for a few miles. No bike with a big lump of aircooled engine, carbs and manual choke is going to run and idle right on the specified rpm in the cold start situation that you describe. They all need a bit of balancing with the choke when cold but should settle down to a steady idle after a few minutes or miles. Any bike I've owned has been like that, all of them were Suzuki GS/GSX and one Kawasaki Z (the Kawa was much worse!).

[nabrams]

Yeah, the idle speed knob is supposed to to be set (to aboout 1100 RPM) when the bike is FULLY warmed up. The bike is not supposed to idle at 1100 when cold without choke.
Besides that, you may have an air leak. But, in your case the difference is so slight that it might be "user error" - i.e., trying to constantly re-adjust the idle knob instead of setting it for the fully warmed condition.

[chuckycheese]

Normal

It sounds completely normal to me, too, unless it takes a long time for the bike to warm up. If so, it's probably running lean. Take care of that, if that happens to be a problem. After that, adjust your idle when it gets warm and all should be well.

[General Zod]

i am fiddling with the idle on my '83 GS450E in the same manner; turn it higher till it gradually warms and turn in lower. after a few minutes of riding i can adjust it to hang out at 1100 rpms and stay put.

i cant do that with mine..
its either going way too high or way too low.
it wont EVER stay put!!!!!!
dont know what to do?

[General Zod]

Yeah, the idle speed knob is supposed to to be set (to aboout 1100 RPM) when the bike is FULLY warmed up. The bike is not supposed to idle at 1100 when cold without choke.
Besides that, you may have an air leak. But, in your case the difference is so slight that it might be "user error" - i.e., trying to constantly re-adjust the idle knob instead of setting it for the fully warmed condition.

when i set it to 1100rpm on a fully warmed up engine, then it wants to CRAOK OUT at a steady 1100rpm.....


so I bring it up to 1200-1300rpm AND it wants to go over 1500rpm...

SO I DONT KNOW WHATS GOING ON?!!!!

[nabrams]

when i set it to 1100rpm on a fully warmed up engine, then it wants to CRAOK OUT at a steady 1100rpm.....


so I bring it up to 1200-1300rpm AND it wants to go over 1500rpm...

SO I DONT KNOW WHATS GOING ON?!!!!

In that case, I'd say you've most likely got VERY imbalanced carbs (needs a carb sync) or a very minor air leak. Check the compression for each cylinder. If there's more than a 10% difference between any two of them or if any have below 110 psi then you've got a problem that would affect idle. Now, if either condition is true, you MAY be able to salvage the situation with a good carb sync, but if the compression numbers are really bad then you WILL need to address that (go ahead, ask me how I know). Very low compression is often due to insufficient valve clearance, but it can be due to a head gasket leak, bad rings, etc.

[kurifu]

This may not be very likely, but I had a similar problem about a month ago, when I took my carbs apart to clean them one of the carbs (I have CV carbs) was missing the large spring that goes in the top and pushes the CV down when you let off the throttle. Even with the slide moving freely I found this cause an instable idle, fixed instantly once I replaced the spring.

O-Rings are probably a great place to start, but if you havn't checked your carbs since you have owned the bike, you might want to take a look, since it only take about 5 minutes to confirm that they are all there.

[catfishk]

i ordered the o-rings. less than $2, might as well.

i actually posted on a different issue earlier this month where my bike will idle high for a few seconds at a light, then fall to idle at 1100 as it should be. again, o-rings are the suspected cause.

myself, i have burned myself reaching for the idle screw too many times!

General Zod, my bike never quite acted like yours as it doesn't have an issue maintaining that low idle. hmmm...

[General Zod]

This may not be very likely, but I had a similar problem about a month ago, when I took my carbs apart to clean them one of the carbs (I have CV carbs) was missing the large spring that goes in the top and pushes the CV down when you let off the throttle. Even with the slide moving freely I found this cause an instable idle, fixed instantly once I replaced the spring.

O-Rings are probably a great place to start, but if you havn't checked your carbs since you have owned the bike, you might want to take a look, since it only take about 5 minutes to confirm that they are all there.

i have both springs in the slides......