A journey through a hanging idle.

go to a auto parts store and ask about free rental of tester

 

don't these Kawasaki shims have a tapered edge?

 

Yeah I need to get ahold of a better tester for certain.

XJ, as far as the eye can see, no. They were square.

 

Suzuki does.........

 

I've decided to hold off on any further tuning until I get my color tune in the mail.

It might be nice to compare carb three to the rest of them and see what's happening inside the cylinder.

 

not firing rich or lean would look the same to one of those colortune plugs.
try some old-school on it. get a t-shirt rag and stretch it tight then put it over the intake of 3. that will make it richer and it might fire a bit. now you have a clue.
then take the cap off of #3 plug, put it on and off a few times until you can tell when it makes contact with the plug. now put it on but stop about 1/4 inch from contact. start it and see if it fires.
you should hear the spark jumping the gap. this usually makes a fouled plug fire.

 

Starter fluid or propane in the #3 inlet will also tell you whether it's not firing because of no fuel.

A more reliable compression test would still be good.

 

I'll try these here in the next day or two.

SQL, mind elaborating on which inlet? The vacuum inlet?

 

No. The inlet from the airbox into the carburetor.

 

Back! Fuel levels set, compression tested. 120 on 1,2,4 and 150 on 3. 1 tbsp of oil into 1,2,4 and it got the reading to 150.

Anyway, after setting the fuel levels and bench syncing, I put the carbs back on and tested the compression listed above.

Then I took the bike for a quick ride to get it to operating temperature. Low and behold, I have all four cylinders firing from the get-go now, so that is a plus.

Upon my arrival home I immediately vacuum synced the carbs while the engine was hot. I always sync the carbs with the idle adjustment screw all the way out so it isn't touching the carbs. That isn't a problem, is it?

Anyway, after I synced the carbs I moved on to using the colortune.

I am having a hell of a time finding "Bunsen Blue" especially on carb 1. I swear that to get it even remotely close I had the airfuel screw turned all the way out, and all the way in, and everywhere in between. Still couldn't find it.

At this point the bike was at normal operating temperature, and even with the idle adjustment knob backed all the way out, it idled a little higher than I think it should. Not much, but I'm noticing the RPM's not dropping super quickly from 2500 down to 1,000 when I give it a rev at normal operating temp. I wonder if this semi high idle (about 1200) is affecting my ability to use the colortune. Anyway, going to try a colortune again tomorrow when the bike is merely warm, not hot, to see if I can find the blue across the board.

For reference, here's the bikes specs again:
13,000 miles
Valves in spec
Fuel levels set
Carbs rebuilt last year by me
No vacuum leaks
124 mains
Stock Pilots
two washers to shim the needle and raise it.
Pod filters
Stock header to collector, no muffler.

Still a bit of a hanging idle. Problem free otherwise.

 

Pilot fuel jet or internal passage is still clogged.

Shouldn't be an issue. Once you get around/over 2000 rpm's it would become an issue.


Try the colortune on that cylinder again, this time open the choke a bit, the choke gets fuel via a different circuit, you should see the blue color then.

 

well yes, it's a real big problem. the engine shouldn't run with the idle screw out all the way. if the idle screw is out all the way, the #3 butterfly should be closed all the way. since the other butterflies are following #3 as it closes, they will be closed too, or very very close.
could one or more butterflies not be lined up in the carb bore and jamming slightly, stopping before it closes completely and holding the other butterflies open.

 

that could be the carb that's closing first and holding the rest open. if #1 is closed all the way, you'll never get color because it isn't firing

 

This could happen if the carbs aren't properly synced. BrosefStalin, what tool did you used to sync your carbs and how did you poceed?

 

The idle screw MUST be in contact with the #3 carb linkage or you don't have a true baseline to work from.

 

I'm gonna jump in here, too--- are doubly- sure that your air jets under the diaphragm are in the correct spots?

 

Oh boy,
So yes, I bench and vacuum synced them with the idle screw backed out so far as to not touch the plate it uses to adjust carb 3. With the choke completely off, the bike won't idle very long until it's warm. But I can say with certainty that the bike will run at operating temperature with zero choke/zero idle screw input. With that you're able to deduce that my butterflies are out of alignment?

They all looked very well aligned when I broke the rack and re assembled it last year. So you guys think it's time for me to pull the carbs off and undo all the butterflies, then re-adjust/re-align/re-loctite them?

Or should I First bench and vac sync with the idle screw screwed in...how much is too much or too little input for a sync? I feel silly not knowing this.

Also, hogfiddles, yes. 100% certain. They're all in this order:

 

Ok

 

no need to pull them. Adjust the idle screw till you get a definite increase in idle speed, now #3 is in charge. whatever the rpm's are do a sync, close doesn't have to be perfect. Now set the idle to 1100/1300 and sync again. now the idle screw should control rpm's from real fast to stops running. the mixture screws should be about 2.75 out.
personally, i'd lose those shims under the needle. They don't really make it richer, just change when the mixture changes in relation to the vacuum.
i can't remember anyone changing needles but 750 needles in 650 carbs would richen the midrange better than needle shims, 750 guys are out of luck.

 

I asked the question about the tool you used to sync, because some vacuum guages may give inconsistant readings.