Please be adviced, i am trying to learn from everyone so i can make my old bike as mechanically perfect as posible.

I am not sure i can trust my RPM gauge, i try to set idle using the gauge on the bike but it wont idle under about 900 RPM, i read that 900 is the idle i should shoot for but it appears to be too low. if i trust the gauge on the bike then 1,100 is just right.
Am going to go to AutoZone and get something else to check idle just to be sure. i want to post a clip of the bike idling but i think i have to become a paying member first.
Thanks for previous advice.

I forget to say that the bike is fully warmed but i have to adjust the idle after it has warmed up, usually make it lower.

 

1000 RPM is what i shoot for. Set the idle when it is fully warmed up, use the choke for about a minute [no more] when starting; use the throttle to keep it running until it reaches operating temperature and will idle on its own.

Following this procedure you will not have to re-adjust the idle each time.

Regardless of what the manuals may say i think 900 is too low. The oil circulation is much better at higher RPM. It sounds right to me around 1000.

You do not have to be a paying member. Upload the vid to YouTube and Copy/Paste the link inot your message here.

You could also check the pilot screw setting ...

Setting The Pilot Screw on Your IronHead

If the carb is old and dirty the pilot screw passage may be gummed up such that you will not be able to "gently seat" the pilot screw reliably. If this is the case remove the carb from the bike and clean it up. Some guys try to do carb work with the carb in the bike. IMO this is a very bad idea.

In the pilot screw passage there should be, in this sequence: screw, spring, washer, o-ring. [Often POs have installed these parts in the wrong sequence; remember that the purpose of the washer is to protect the o-ring from being damaged by the spring]. The screw usually comes out easily. The other parts may require some work. The best technique is to stick a pipe cleaner in the hole, twist it around, and, like magic, out come the other parts on the end of the pipe cleaner.

EDIT: The above info on the pilot screw applies to 1979 and newer carbs. For 78 and older there is nothing in the passage except the screw itself.

1. You need to have easy access to the pilot screw, easy enough to reliably judge "screw it in until gently seated". Loosen the front fuel tank mount bolt; remove the rear fuel tank mount bolt; prop the rear of the fuel tank up on a piece of 2X4; on some bikes this will not be necessary.

2. With the engine cold [so you do not burn your fingers] turn the pilot screw in clockwise until it is gently seated. Count the number of 1/4 turns as you do it; write the number down. Back it out to the original setting. You may need to return reliably to this setting after experimenting.

The "normal" starting point for this process is 1,1/4 [according to the 79 - 85 FM] or 1,1/2 [according to usual practice] turns out.

EDIT: An old HotXL magazine article recommends for Keihin butterfly carbs between 1/4 and 1,1/4 turns out. My experience is that this works best. If you are more than 1,1/4 turns out your pilot jet is too small.

3. The engine must be at full warm up. It will have very hot parts; to avoid burned fingers have a well lighted, comfy place to work.

4. Set the engine idling at about 1000 RPM. You want it to be idling at the slowest speed that is consistent with a smooth idle so that you can hear or feel slight changes.

5. Turn the pilot screw in clockwise until the engine idle becomes worse; tending to stall. Count the number of 1/4 turns as you do this. Then turn the pilot screw out counter clockwise until the engine idle gets good, then becomes worse, tending to stall. Count the number of 1/4 turns as you do this.

6. The best setting for your bike will be somewhere between these two settings. The FM says to use the leanest setting [most screwed in] consistent with a good idle quality. Some guys say to go between the two settings.

It should be between 1/2 and 1,1/2 turns out from gently seated. If it is not within this range you should change the slow jet.

EDIT: I follow the advice from the old HotXL mag article - set it between 1/2 and 1,1/4 turns out.

7. You may have to adjust the idle speed.

8. Make sure that the spark plugs are clean, then ride the bike around your neighborhood for 10 minutes. Keep it under about 15 MPH so that you are on the "idle port", not the "idle transfer ports", the "mid range port", or the "main jet" [see carb diagrams in FM]. Hopefully the plugs will come out a nice medium gray or tan color. If they are too dark you can screw it in another 1/4 turn; too light screw it out 1/4 turn, and try the ride again.

9. If they are really light or really dark the problem may not be with the pilot screw setting. For example, too light might mean an intake or exhaust leak, and too dark might mean the slow jet is too large [among other possibilities].

10. My experience with this process is that after making a change i have to clean the plugs and go for a good ride [say, a half hour or more] before i can trust that the new results are reliable.

 

Once you get the idle mixture set right, you can give the idle speed screw about a half turn in when starting the engine cold to give a little fast idle. I do this with mine and then it will idle without being coaxed with the throttle. After about 20 or 30 seconds I can begin to dial it back to where the warm idle speed is normally set.

 

Thanks guys.

So i should get one of the long speed screws for ease of adjusting.
right now i have the small screw and would need to carry a screw driver with me, i can go to Lowes and get a screw for that i think, i know they make a fancy one on JP catalog

 

It might be a special thread? so an ordinary bolt may not work. Bring the current one along and try it with some nuts to see what is the thread.

 

Dear sir you are correct, i took the bolt and narrowed it down to an 8/32 coarse thread, but NO. so i will go back.
I took a video of the bike at idle after i adjusted it, it idles fine and runs even better, but the RPM gauge jumps from 1,000 to 1,100. but am sure that it feels like less.
I have to electronically check the RPM or i wont trust anything.

now to figure out how to upload the video.

 

Upload the video to YouTube, then Copy/Paste the link from there into your message here.

 

I had put a Bendix carb on the old 76 iron, if I remember right it was around 1000 rpm after being warmed up. Make sure jetted right , that will make a major differnce.

 

http://www.youtube.com/v/xdo51TAJ_Hs?version=3"><param


IDLE VIDEO FOR YOU GUYS TO JUDGE.

I think it should work, let me know what you think. thanks

 

Just got a quick look at the tach during idle - looks to be about 1100 RPM?

I think it sounds like a good running IronHead at idle. I don't think it is missing or anything, just the lumpy IronHead sound. What to you and others think? This is difficult for me to judge

How come it goes so quiet when you rev it up? Is it just that the camera sound pickup is muffled?

I think the idle speed could [should?] be turned down a wee bit to about 1000 RPM.

Going back to your original post, but it wont idle under about 900 RPM, what happens? Does it stall? If this is with a cold engine then ok, but it seems to me that it should idle at even lower RPM than that when fully warmed up. I would not set it that low, but it should still do it.