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Wandering idle

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  • Wandering idle

    Ive truly had it with this demon bike. The carb has been rebuilt with the standard crap. A 40 pilot jet, a 3.0 max grizzly needle seat assembly, the 172.5 main, 4th groove needle, pumpless, no AIS. After the rebuild, when cold, it idles kind of low. I don't mean "cold on just started", I mean for up to10 minutes. After 10 minutes, the idle slowly increases until I could put it in gear and it turns into cruise control idling at around 1200. On cold start, I use the choke and have to keep the gas on or it will die. Sometimes a small backfire through the carb which is more like a light cough. After it gets warm, no issues with that or dying. It is the 3rd time I've driven it since the carb overhaul and thought it was fine after the overhaul. When it gets warm, I typically lean over and turn the idle down. So when I start it cold, no idle without the hand throttle. I'm truly sick of this bike. I'm an inch from selling it. $1800.00 or best offer. 53,000 miles.
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  • #2
    Set the idle to about 900 when the engine is good and hot and then leave it alone. I've always had to run mine with the choke halfway out for a little while while going through town. If I get on the highway immediately then I can go ahead and push the choke in. What you're experiencing sounds normal to me.

    Until the manifold gets hot enough to vaporize the fuel running down it in droplets the bike will need some extra fuel from the enricher to run right.
    Scott B.


    • #3
      Like Scott said. Set the idle to 900rpms on a hot motor.
      On a cold start, pull the Enricher full out.
      Push the start button. Don’t touch the throttle.
      The bike should start with a high smooth idle. Don’t touch the throttle.
      After about 5 or 10 seconds, the bike will get a rougher lumpy idle. Don’t touch the throttle. Simply push the Enricher in about halfway. The idle may still be a little rough, but will smooth out. Don’t touch the throttle until you’re ready to ride off. Leave the Enricher out about half, until the bike runs okay without any Enricher. It might take 10 minutes or 10 miles.

      if you’re doing all of the above, and the bike has a bad inconsistent idle when warm, then I’d be looking for an air leak.


      • #4
        Like Tex said, set the idle when *fully* hot and leave it... Then work your way from there. It's normal to leave the enricher pulled out for 10 mins. I use it everytime I start the bike, unless its fully hot. I my bike, I have to pull it out about 3/4 at start, then as I ride off, I push it in to about half way. You can feel the notch in the knob. Then after roughly after 10 mins of riding round town I push it in all the way. Unless I go straight to the freeway, then like Tex, I push it all the way in once I get going. That's normal.


        • #5
          Earlier this past summer I had a idle issue. I drained the float bowl thought maybe had water in it. Then i tightened the clamp around the carb to the manifold....Bingo! Like the others say here idle speed needs to be set on a hot engine only not cold.


          • #6
            I never cease to be amazed at people who turn the idle down on these bikes, and are then disgusted with the bike, because it is somehow the bikes fault. Surprise surprise, the bike develops idling and starting issues.
            There is no lope in the idle at 900rpms. It sounds high and smooth compared to lumpy and loopy.

            Another thing to remember is as soon as you twist the throttle on a cold start, while using the Enricher, you might as well remove the Enricher, and throw it in the trash.
            The Enricher works off of vacuum. Twist the throttle and the throttle plate in the carb throat opens, the vacuum is gone. Kaput. Now, your cold start is really a mess.

            While I’m on the subject of things not to do, don’t quickly and repeatedly twist the throttle. It’s referred to as blipping the throttle. These bikes are not Maserati’s. They’re more closely related to John Deere’s. If you repeatedly blip the throttle like a teenager at a stoplight, the bike will spit back through the carb.

            ....poster grumpily steps off his soapbox, kicks it off to the side, and exits stage right.....


            • SKWEARpeg
              SKWEARpeg commented
              Editing a comment
              Then you know it’s not a “choke”

            • texasscott1
              texasscott1 commented
              Editing a comment
              Choke, Enricher - choke is just easier to say. Anyway, has anyone noticed that the choke, enricher knob has the international symbol for choke printed on it?

            • SKWEARpeg
              SKWEARpeg commented
              Editing a comment
              Please dear, don’t let the children pit us against each other like this. They’ll end up in jail, or worse.

          • #7
            Originally posted by SKWEARpeg View Post

            ....poster grumpily steps off his soapbox, kicks it off to the side, and exits stage right.....

            But at 900 RPM's


            • SKWEARpeg
              SKWEARpeg commented
              Editing a comment
              ......and knowing full well how to spell!

          • #8
            Thanks for your insights kwearPeg.I am not trying to start an argument and I value everyone's advice one this lovely bike O mine. I have valid issues with this bike. It has it in for me. Lol. That's what my teen used to say when getting a less than acceptable grade in regards to her teacher. I rebuilt the carb because it had extended crank times, gas puke, and really bad mileage. I haven't driven it enough to know about mileage b/c I have another bike that I truly enjoy. Nonetheless, the bike probably needs a decompression solenoid, and an owner replacement, aside from other small things. I have put a lot of time into this bike with various other problems and want to get it into selling condition. But I did enjoy being on the other side of your rant if it made you feel better.
            " class="bbcode-attachment thumbnail" alt="" />


            • #9
              Agree. Your hot idle is excessively lean. As said, set it correctly when the engine is HOt, not just 5 minutes idling in the driveway.

              Wherever you go in life, ride there if at all possible.


              • #10
                ....and not just at an “idle”.

                .....these bikes will operate as low as 650rpms when they run well, and the idle is turned down to a point where the bike still runs reasonably well, but will idle without dying.

                When I bought my first Roadie, I did similar to what you’re doing now. I adjusted the idle so the bike would run good when it was warmed up. I was significantly surprised when I bought an EzTach and found out what 900rpms sounds like. I always joke about how I thought it was going to leave without me.
                I rode for a few months, and started thinking it sounded like it was idling high, and turned it down a bit. The next time I checked the idle on a hot motor, it was close to 750rpms because I was a dolt and turned it down.
                I reset it, and vowed never to touch it again on a whim.
                My sig pic bike, is even more particular. The idle needs to be closer to 950rpms, for it to start the way it should, when it’s warm.
                The idle screw is just a throttle stop. When it’s turned down to much, the bike will be to Rich at the start. If the idle is to high, the start will be lean.

                Go back up the page to my post where I detailed the proper starting procedure for the bike. That is exactly how it should work if the idle is set correctly, and there are no other issues.

                The fact the bike runs fine when it gets warmed up, and you turn the idle back down to whatever, is a pretty good indicator it’s either your preferred starting procedure or the idle is set wrong. Set the idle correctly on a hot motor.....900rpms......., and then don’t mess with it again.

                ......and, it’s not a Choke. The Enricher adds fuel and air, to make a rich start condition. A Choke shuts off or limits the air, to make a rich condition.
                When the Enricher is pulled out, and you are messing with the throttle, you’re working at cross purposes with how the bike is designed to operate. You’re hurting yourself.


                • #11
                  In an age of fuel injected engines where all you do is hit the starter, and go, it’s hard to describe proper starting etiquette on a carbed bike that is pretty sensitive to adjustments. EPA mandates left carb tuning to the designers with little room for error when the end user got the hammer and pry bar out to tinker with it thinking there’s room for improvement. Even small engine carb tuning is history. Gone are the days of broad mixture results simply by turning a mixture screw. No main jet adjustable needle or an idle mix screw to be found today. No choke either. Just a primer bulb to flood the cylinder with enough fuel to fire it off.

                  So, here we are. Either FI, or older EPA carbed engines that demand strict attention to settings that must be adhered to, especially if it’s not in ones forte to reach a desired setting from experience on the first shot.


                  • #12
                    Sounds like a leak somewhere.

                    Some things to consider: make sure the intake boot on the carb is seated properly and not over tightened. Some people have success with spraying starter fluid around the intake manifold to see if the RPMs climb. [But it's doesn't always work. I didn't work for me even though I had a leak.]
                    - Are you running a stock air box with that K&N? If not, what do you have?
                    - Did you check the exhaust nuts? Are they too loose or too *tight*?
                    - Did you bend the exhaust flanges from over tightening? [very common]
                    - Are the exhaust seals in good shape?
                    - How did you seal the vacuum port on the intake manifold when you removed the AIS?? [Vacuum plugs dry out and crack due to the heat of the motor.] <- My bet is on this one.
                    - Is your intake manifold cracked *all* the way through? [Surface cracks are normal, but the manifold is so thick, they don't always go *all* the way through. Shine a light inside the manifold to find out.]
                    - Has the intake manifold *ever* been removed? [If not, DON"T! ... Unless it's cracked all the way through obviously.]
                    - Did you replace the float needle when you went pumpless? [Is that what the "3.0 max grizzly needle seat assembly" is for? I've never gone pumpless.]
                    - What is the fuel level set at in the float bowl?
                    - What is your PMS set at?

                    Hang in there, I know it can be frustrating, been there myself. But with everyone here we'll figure it out... it can be only so many things, just work your way down the list, starting with the easiest, and cross them off... and never assume something is OK because you "already did that'. I spent TWO YEARS chasing a very similar problem because of "I already did that".
                    Last edited by Doc_V; 10-07-2018, 07:43 PM.


                    • #13
                      I have a problem when I set the hot idle to 900rpm its fine for a few mins but then drops down to 600 and up to 1100. The pump died a few years ago and was setup for pumpless and was running good. I did a service last week plugs oil and a clean out of the carb and it was running fine until yesterday. Bike started fine I was having a smoke before leaving when the idle started to wander.


                      • #14
                        Have you checked the carb heater to see if it is working? The carb heater works when the bike is cold to help atomizes fuel thru the idle mixture ports.


                        • #15
                          1st of all old school carb'd v-twin air cooled motors like the R* has dont have near the control over idle speed (esp carb'd with hvy 20w-50 oil even in warmer temps cold) in the 1st 15-20+ mins required for the motor and oil to get close to or up to full op temp then todays efi controlled motors do so keep that in mind.

                          If your older R* doesnt have any other issues affecting idle speed like vacuum leak issues on intake manifold,dirty aircleaner,older plugs,dirty fuel filter (should have been changed when carb was rblt) then do this and you should be good to go.

                          * Ride the bike 15-20 mins to ensure its up to full op temp.

                          * Now (with air cleaner assembly still on motor to dont remove it) adjust idle speed to a min of 900-950rpm which is yami's rec idle speed.
                          But i found 950-1k rpm to be best idle rpm for the carb'd R*'s i have worked on because it helps reduce the amount of spit/pop back thru carb when coming off idle which is comon with lrg dist old school carb'd v-twins esp when idle is too low.

                          Properly adj accell pump to shot fuel as soon as throttle plate in carb begines to move also helps reduce spit/pop back thru carb coming off idle & or when bliping throttle along with the bit higher 950-1k idle rpm i rec too.

                          * Now adjust idle mixture to obtain the best smoothest stable idle speed you can.

                          * Lastly reset idle speed to 900-950rpm and your good to go.

                          Again,dont pay much attention to idle rpm & expect it to be pretty stable for the 1st 15mins of run time in warmer temp (20-25mins in cooler temp) too due to reasons i stated above earlier in this post and you will find that when the motor & oil are up to full op temp 15-20mins riding post cold startup that the idle will be pretty darn stable most of the time even on your carb'd R* when carb is setup/adj properly and there are no other issues with vacuum leaks etc as already stated above.

                          If you follow/do exactly what i rec above i'd very surprised if your R* doesnt maintain a decent stable idle when the motor & oil are to full op temp post 15-20mins of riding time & ignoring idle speed variation from cold start till the motor & oil are both up to full op temp which you need to do because last time, " your R* isnt efi controlled " that by design has less idle variation over the motors entire operation range temp wise vs an old school carb'd motor.

                          Good luck.



                          • #16
                            thanks for the options will test the carb heater and follow scottw's advice.


                            • #17
                              I had a wandering idle issue after working on carb the last go around. After fighting idle changes at every other stop light for a couple days , i tore back into it only to find i had forgot the idle screw tension spring . This was my issue, but its a easy check just to eliminate the possibility that is was overlooked.


                              • #18
                                Ok guys update found a small crack (hair line) on the Coasting Enricher ???? I think this maybe the problem. When the bike is up and running at temp it could be giving me a vac leak. About a 1cm long (sorry 5 to 6 mm) could this be the problem guys.


                                • #19


                                  • #20
                                    Hey folks, I'm back from what was an eternity. I have not yet worked on the old R* and may start later this week. As I said, I got another girl in the garage. I am ordering all original equipment for the carb and going back the way it was along with a new ENRICHER and an intake gasket. Oh, also going to replace the decompression solenoid. It may be several more weeks before I get it all done. No big deal. Taxes aren't due until July.
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