Synced carbs, still can't lower idle-Need Help

[sloppydawg123]

Started of by taking the carbs apart and cleaning them. Put new main jets in because they were the wrong size. Now it's got good throttle response and starts easy. But the idle jumps aroun 3-5k and doesn't seem to have a reason, will just change as it sits. I double checked the float levels and got the idle down a little, long enough to do the carb sync, but after i got all four carbs synced, seems to go up again. I soaked the carbs in water as they ran to try and find a vacuum leak, and also used starting fluid, couldn't find any leaks.

Another thing i found strange, after the carb sync, which should make the cylinders pull the same, exhuast pipes 1 and 3 were much hotter than 2/4

ANY IDEAS?

[steves]

idle hang is a vac leak, or a bad synch.

If you have cold pipes, then you still have dirty carbs.

[Black_peter]

The hot pipes are running lean most likely.
Soaking the carbs with water isn't likely to tell you anything. Starter fluid? Don't know, never tried that, most places use propane or WD40 I hear works.
I agree with Steve, if you think the carbs are clean and they still don't run right?
They are not clean. Now what about the FA screws? Those, and the seats need to be really clean. Also it goes, screw, spring, washer, oring. Make sure the o-rings are in good shape. Lastly did you set the FA screws all the same?
The creeping idle is probably leaning out. That might be a clogged tube if the float height didn't fix it.

[sloppydawg123]

Yeah i set them all to 2 1/2 like most here seem to recommend, I think I'll go through everything again, take the carbs back apart and make sure I'm not missing something on the cleaning and recheck those float heights. Just trying to see if anyone had another possible culprit to look for I haven't tried yet

[Black_peter]

I would triple check those FA screws..

[sloppydawg123]

Went to check the carbs again, not sure how i put them together so wrong. Missed the seats for the springs on a few of the needles, causing them to not drop down. it's amazing they ran at all. The carbs are soaking right now, hopefully good as new when it's all back together

[Shipster]

I suggest that when you put the carbs back in the bike, that you put in new plugs as well. I had a similar situation where I forgot to put a spring in when I rebuilt the carbs. I had been running the bike trying to adjust everything as well, but it still ran bad. Finally I figured out about the spring (someone helped with that part!), but when I did have the carbs back together right #1 pipe wouldn't get hot. Finally swapped plugs 1 and 2, and low and behold #2 was then not getting hot. Apparently since I had forgotten a spring on the #1 carb, all that running had fouled out the plug. This was confirmed when I moved that plug to #2 and then it wasn't getting hot. A swap of that plug had everything running MUCH MUCH better My guess would be that if you were missing something as well and it wasn't running right before, the plugs may be fouled, and will need to be changed. Just my .02!

[Black_peter]

Went to check the carbs again, not sure how i put them together so wrong. Missed the seats for the springs on a few of the needles, causing them to not drop down. it's amazing they ran at all. The carbs are soaking right now, hopefully good as new when it's all back together

That's why when it comes to carbs I'm a broken record about the FA screws..
Partly because I know they are critical, partly because I have made quite a few mistakes with them myself..

[steves]

Make sure you have the springs on the FA screws as well.... some people don't have them

[hardlydangerous]

You may want to replace the intake manifold o-rings if you still have a an air leak.
A hanging idle is usually an air leak, but an idle that is just all over the place, could be something other then an air leak.

a friend bought a nice 89 Kat last fall, 4 hours away from my shop.
I heard the bike run, it had a high idle, it was loud and had the bad cam chain tensioner spring. plus a full exhaust and needed to be jetted but the bike was in good shape and ran ok. i knew I could get it to run much better easily.
When we got out on the road he complained about the idle, but more so it used 3X the fuel that my bike did the trip back.
when we took the carbs apart, all 4 of the slide springs were not installed... they were just laying under the caps, all 4 mixture screws were set differently and 3 emulsion tubes were gummed up.
Once these minor things and the cam chain spring were replaced and repaired the bike ran awesome