cant get my idle

5,000 rpm's is NOT Idle.
5-Grand means your Throttles are open.

Getting the Linkage Connection to the Cable stuck behind the Head is commonplace.

Manifold Clamps interfering with Linkage, another.

Mis-alignment of the Bodies will bind Throttles open.

"Something" is opening the Throttles.
Try touching the Sync Screws with a Tuning Screwdriver and see if the Linkage is binding.

 

So before I did my valves the idle was like 4000 rpms. And my neighbor said the same thing so I disconnected my throttle cable and gave it gas by hand the carbs come back down but not the rmps. They were level after I cleaned them. Took them off again today to bench sync an put a level back on top just to see cause i read that it was very important to have them level and they were. Tomorrow when I get them back together I will try touching the sync screws but I think i already tried that. Had the same problem since the start. I must be missing something. I could take some pics of the springs and post them but not one is criss crossed or stuck.

 

Mine has a throttle adjustment that I can turn by hand. I had to turn it down so the butterflies were basically closed in order to get it down to 1000.

 

I have one too and turned it down all the way same idle. Something has to be opened still like rick said. Its gotta be something stupid. Hopefully! Just don't no what. FYI Checked my compression and averaged 130. All pretty close. Thank you everyone for the responses keep them coming.

 

Took the carbs off again. Did a good bench sync. Double checked everything again. All good. Put the carbs back on and... I got it to idle at 1200 rmps ran it for about ten minutes or so. There was a slight hesitation when I gave it gas before it came back down. Maybe a second or two. Is this do to out of sync carbs. Haven't synced them yet I was looking for a write up on the home made yics blocking tool. I saw a write up about one and it said it was 3 or 4 dollars. Haven't been able to find it again. Anyone have it??? Or the oil soaked rag way. Is it as simple as soaking a rag and stuffing it in there??? Does anyone have a write up for that one??? Thanks everyone for all the help. It looks like this bike might be getting close!!!

 

Cut the Hem off a T-shirt.
Then, ... cut the Body in a continuous Strip about 3/4 of an Inch wide.

Wet the Strip with Marvel Mystery Oil.
Use a narrow Dowel or Brazing Rod to pack the YICS Channel tightly with the Cotton Strip.

http://xjbikes.com/Forums/viewtopic/t=4 ... +yics.html

 

Thanks rick

 

Here are some pics of my carbs. Can anyone tell me if something doesn't look right. Keep in mind 30yr old springs. Not sure what to do. My next thought would to go back and realign the carbs.

 

The studs that hold the spring on the opsosit side of your adjustment screws.To me it looks like its (They) are missing the pic is small I might be wrong

 

I got a pic. of a brand new set of carbs. And everything looked the same. Except that mine are 30 yrs old. Went to sync the carbs and got them all close. But when I took the vacuum gauges off I saw that 2 of them were not even close to zero where they should be when they are not in use. So I'm taking them back. (harbor freight fuel and vacuum gauge testers 15$ each times 4) Does anyone no of a good set that works good with these bike or should I make a homemade one??? Thanks again everybody!!!

 

Have you WET-SET the float levels yet? I didn't see it anywhere above.

Bench sync is more accurate if you key off the tiny holes in the top of the carb throats in relation to the edges of the butterflies than use any sort of feeler gauge.

A genuine Morgan Carbtune (4-stick manometer) only runs around $100; and there are less expensive equivalents by Motion Pro and other aftermarket companies for what you paid.

Did you block the YICS for your sync attempts?

 

Thanks Fitz.
Wet set twice. Almost did it again today. Fuel levels need to be at 2mm +/-1mm below the carb body-to-float bowl seam. Marked the carb body and all were perfect.

Not sure if I follow the "key off the tiny holes in the top of the carb throats in relation to the edges of the butterflies". I have bench synced them at least 6 times using a business cards. The tiny hole that your talking about is where the pilot screw if all the way down pokes through??? Every time all very close and I open and close them with each adjustment to make sure they all go back into place.

Will look for the Morgan Carbtune manometer.

Blocked the yics with 3/4 inch strips of a shirt soaked with Marvel Mystery Oil like rick said. (should I get the blocking tool)?

Today I backed off the pilot screws a 1/4 turn and a very small change for the better but still not sure but i THINK its running lean????????????????

 

Thanks Fitz.
Wet set twice. Almost did it again today. Fuel levels need to be at 2mm +/-1mm below the carb body-to-float bowl seam. Marked the carb body and all were perfect.

Not sure if I follow the "key off the tiny holes in the top of the carb throats in relation to the edges of the butterflies". I have bench synced them at least 6 times using a business cards. The tiny hole that your talking about is where the pilot screw if all the way down pokes through??? Every time all very close and I open and close them with each adjustment to make sure they all go back into place.

Will look for the Morgan Carbtune manometer.

Blocked the yics with 3/4 inch strips of a shirt soaked with Marvel Mystery Oil like rick said. (should I get the blocking tool)?

Today I backed off the pilot screws a 1/4 turn and a very small change for the better but still not sure but i THINK its running lean????????????????

 

Look in the top of the carb throats. Look CLOSELY and you'll see three tiny tiny TINY holes. As the butterflies open, they uncover these holes.

Use the relationship between the first tiny hole and the edge of the butterfly to compare the positions of the butterflies in the carbs rather than trying to "feel a gap" to set them. Open the throttles slightly, and see where #3's butterfly is in relation to its first tiny hole; then compare the others and adjust so they all match. You can get much closer this way than you can with feelers. Just always be sure that when you're done, all 4 butterflies will close fully with the main knob backed off.

Mikuni apart: http://xjbikes.com/Forums/viewtopic/t=31061.html

 

Thanks again Fitz. I was able to locate to the tiny holes and match them all up to the very first one. Put it all back together and same thing Idle will either hang up around 3000 rpm and slowly come back down and die. Once in a while it will idle around 1100 rpms give it gas and it will still just hang up there. When the idle is low I turn it up and when I even touch it a little it just shoots up to 3000 rpm and if its high turn it down it just dies. Just replaced the throttle cable. Nothing interfering with it or anything else. Tried with and without the cable.

For fun I took them off again and adjusted the butterflies closed. It would idle with the choke on and my throttle response was great. No hanging up or anything. turn off the choke and for course it will die unless I give it gas. And the throttle response is still great no hang up. Why would this be??? Still trying to figure it out. Thanks

 

One more thing. I got under my bike and was inspecting the exhaust and found 2 tiny pin holes on my muffler. (1 on each) They seem to be in the same place but I haven't measured yet and they don't look like its from rust. But there is some condensation now coming from them. Air temp 70. Stock exhaust. Anyone have them as well or should they be welded up??

 

That's what the holes are for; helps to keep the mufflers from rusting out (as quickly). Water vapor is one of the products of the combustion of hydrocarbons. When the exhaust is cold (technically when it's at, or below, the dewpoint) condensation will form. Once the system heats up sufficiently the vapor will go along it's merry way, continuing it's journey to become one with the sea.

 

And the story goes on. I got a little mad ripped the carbs off again and... complete tear down of the carbs. Instead of boiling them I went with chem-dip. (Which I don't think made that big of a difference) Ok so I cleaned the gas tank out. (Which if your gonna clean the carbs might as well do that too and get a inline fuel filter) Still kicking myself in the a$$ for not doing this first. Everything cleaned now again. Putting the rack back together. STOP!!!!!!!!!! Flush, level, and Plumb...

Are there any how too's??

Carb alignment... Don't want to put them back together until 100% sure.

I use a level on all sides to make sure there are no gaps and that everything matched up properly. Is this sufficient? Or should i be doing something else?? Wouldn't the support brackets align them though??? (Couldn't be that ez just curious why they don't)

The 2nd carb... ???return string???? not sure the name of it. (On the outside that closes the buttfly valve.) Seems to not what to snap closed as all the other carbs. Will the other carbs assist or Do I need an new one or can i wrap it around one more time to get a little more tension???

And we'll go from there.

Thanks again everyone.

 

check the write up for realignment of carb rack...see page 27 & 28

Throttle Shaft Seals

 

carb #2 - this is off my 1982 XJ750J Maxim.....

note spring placement.....included shot of other side