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View Full Version : Carb Mixture (pilot) screws?


barryware
03-01-2007, 02:12 PM
My kids 2004 Kat600 has sat for a couple of years (on and off). Last season, it was only ridden once.

We were not aware of the bowl drains so you all know what has happened.

It idles like crap, pops on deceleration, hard to keep lit when you first start it.

So.. I decide to take off the carbs and give them a good cleaning. The first thing I checked was the position of the idle mixture screws..

The screw plugs were already removed by the bike shop when it went in for its 600 mile service.

The position(s) are all over the place. From left to right (when sitting on the bike), 1 is 3 1/4, 2 is 4 1/4, 3 is 2 3/4, and 4 is 3 3/4.

Should I put them back where they were or should I open them all the same when I put it back together? I have read a bunch of posts stating where to set them but they are all set the same.

I'm not a bike mechanic but I am pretty handy at this stuff. In the old days of multi-barrel automobile carburetors, you would adjust the idle mixture screws to get maximum RPM. Once you had them set, if you open one a bit more, the RPM would drop and if you closed it a bit from max RPM it would drop also.

Same with a scoot? Advise? Any one near Chicago that wants to clean the carbs and sync em after I get it back together?

steves
03-01-2007, 02:38 PM
Those settings don't sound right. I would think start at two turns out and see how that goes.

With a jet kit, you usually start at 2.5 turns out.

I think my pre was 2.25 turns out when we drilled the caps out.

barryware
03-01-2007, 04:28 PM
Would they adjust the same as I explained on a multi barrel automobile carburetor?

Also... As long as I got your attention, the idle RPM adjustment is bottomed out and the scoot idles at a bit over 600 r's. It has been this way since it was new.

Now that I have the carbs out, I can see that the do-hicky that engages the idle adjustment (the throttle cables also attach to this), has a tiny allen set screw.

Can I reposition this by loosening the set screw and get the idle adjustment closer to the middle of its travel? I am trying to get the internals of the carbs clean and it reassembled without having to touch the sync screws.

I gotta tell you guys... We screwed the bike up by letting it sit without draining the fuel out of the carbs. Once in a while it got started and then it would sit again which just made matters worse.

The boy, moved to Arizona and no longer wants the bike. He claims that the life expectancy for a bike rider is about 3 days out there.

I just want to get the carbs cleaned so it runs right. It has 2200 miles on it which I know I put on 1K just playing around with it. Need to get it sold once I correct the self inflicted problem with the dirty carbs.

I can't find a carb stix to rent and I really don't want to spend 100 bucks for a one time use. Don't really want to take it to a shop because I don't trust any of them and then there is the issue of getting it there (to the shop) once it is put back together.

Anybody know who may rent the stix or know where to purchase an inexpensive set that is functional? I don't want to buy junk but I don't need the best either.

KatanaJim
03-01-2007, 04:37 PM
Make your own carb vac gauge. There is a thread on here about it. Cost me $6 in parts and works pretty good!

steves
03-01-2007, 04:46 PM
Would they adjust the same as I explained on a multi barrel automobile carburetor?

Also... As long as I got your attention, the idle RPM adjustment is bottomed out and the scoot idles at a bit over 600 r's. It has been this way since it was new.

Now that I have the carbs out, I can see that the do-hicky that engages the idle adjustment (the throttle cables also attach to this), has a tiny allen set screw.

Can I reposition this by loosening the set screw and get the idle adjustment closer to the middle of its travel? I am trying to get the internals of the carbs clean and it reassembled without having to touch the sync screws.

I gotta tell you guys... We screwed the bike up by letting it sit without draining the fuel out of the carbs. Once in a while it got started and then it would sit again which just made matters worse.

The boy, moved to Arizona and no longer wants the bike. He claims that the life expectancy for a bike rider is about 3 days out there.

I just want to get the carbs cleaned so it runs right. It has 2200 miles on it which I know I put on 1K just playing around with it. Need to get it sold once I correct the self inflicted problem with the dirty carbs.

I can't find a carb stix to rent and I really don't want to spend 100 bucks for a one time use. Don't really want to take it to a shop because I don't trust any of them and then there is the issue of getting it there (to the shop) once it is put back together.

Anybody know who may rent the stix or know where to purchase an inexpensive set that is functional? I don't want to buy junk but I don't need the best either.

You can bench synch the carbs using the adjustment screw. It should be on the top of the spring, between the two carb banks. I think it's just a flat head screw. http://www.motorcycleanchor.com/katana/trinc/sync.htm

You can adjust the idle screw just by turning it up or down a little bit. I think the bike should idle around 1000 RPM.

Here's a thread on cleaning and rebuilding the carbs...
http://www.katriders.com/forums/viewtopic.php?t=23982&highlight=carb+synch

Here's another with pictures:
http://www.katriders.com/forums/viewtopic.php?t=19942

barryware
03-01-2007, 06:27 PM
You can bench synch the carbs using the adjustment screw. It should be on the top of the spring, between the two carb banks. I think it's just a flat head screw. http://www.motorcycleanchor.com/katana/trinc/sync.htm

You can adjust the idle screw just by turning it up or down a little bit. I think the bike should idle around 1000 RPM.

Here's a thread on cleaning and rebuilding the carbs...
http://www.katriders.com/forums/viewtopic.php?t=23982&highlight=carb+synch

Here's another with pictures:
http://www.katriders.com/forums/viewtopic.php?t=19942[/quote]

I have read through most of the posts before I embarrassed myself asking questions.

The current setting of the mixture screws have me boggled. I paid extra at the first service to have the caps removed and the mixture screws opened a bit. On the invoice the dealer called it "fuel Screws" and charged the kid (I actually ended up paying for the service) an extra 50 bucks. After close inspection, I think they screwed up (no pun intended) one of them. You can see the drill mark in the screw and I can't get this one all the way out. Locks up, won't come out any farther. They are no longer there or I would bring them the carbs to fix the one mixture screw.

Can't see the pics in the one thread... Just red x's

The idle speed adjustment... It is screwed all the way in. Some how, I have to reposition the relationship between the the do-hicky that it engages with which also connects to the throttle cables. I see a little allen set screw. I was wondering if I can reposition this do-dad to get the idle speed adjustment closer to the center of travel.

KatanaJim
03-01-2007, 06:44 PM
Drilling into the screw head and stripping it, is a pretty common occurence. There is a brass plug covering them from the factory which requires removal before adjusting. You have to drill it then thread a screw in and pull it out.

md86
03-02-2007, 01:34 AM
Ok , since the pilots were all over , you can assume one of 2 things .... either someone DID do an idle drop , or they worked themselves loose . Personally , I'd set them back where they were and see what it does once cleaned :dunno: . If it don't feel right , or plugs get black , I'd go with the 2.5 turns instead and start over .

barryware
03-02-2007, 10:10 AM
Thanks for all the advise.

Lets say that I don't want to trust anything and I want to adjust the idle mix screws from scratch.

Would the procedure be the same as in a multi-barrel automobile carburetor?

That is, adjust the mixture screws for maximum RPM. Once adjusted, if the screw is turned either in or out, you should see a drop in RPM?

I still want to get the idle speed adjustment closer to it's center of travel. Right now, it is screwed in all the way and there is no more unless I trim the spring a bit. I can see an allen screw on the piece that is on the carb. Unless somebody knows about this, I don't want to mess with it. Is the allen screw what holds it on to the shaft? Is it pressed on? Would a Pic help?

If I can rotate this piece lets say 10 degrees or so, it would put the idle speed adjuster more in the center of its travel. Like I said, right now, there is no more to go.

barryware
03-02-2007, 12:38 PM
Just an update in regards to bringing up the idle speed.

The do-dad that attaches to the carb throttle shaft has a roll pin, not an allen set screw so there is on way to reposition the "stops".

My options are:

Remove the spring from the idle speed adjustment to allow more "clockwise" adjustment. This may cause it to change by itself from the vibration when the engine is running.

Use a thinner washer under the spring - however I may only get an additional turn out of it.

Shorten the spring - grind it, cut it.

Put a little "fug" on it and "fug it"

I think I am going to buy a set of sync gages from JC Whitney. I know they are not top quality but they are 56 bucks and I only need them once.

If anybody wants them once I am done, lemme know or I can just sell them with the bike.

Teh_K
03-02-2007, 12:52 PM
From what I've read from a few others on KR, yes - the idle-drop method of adjusting carbs will work... and probably has the benefit of being fine-tuned for each carb specifically. If I had the tool (or wasn't too frugal to buy it), I would try it. Otherwise, I think the stock setting for a 600 is 2-and-5/8th turns out.

The CyberPoet
03-02-2007, 02:13 PM
Stock USA setting for a 04 Kat 600 are:

Warm idle: 1200 +/- 100 RPM (1300 +/- 100 if it's a Calfornia model with the pollution control)

Needles are identical to Canada's, which should put it at 2-5/8ths turns out, as Teh_K said.

If it holds idle at 600 RPM and the idle adjustment wheel is turned all the way counter-clockwise, then you've got something else going wrong (pilot jet passages still clogged or rubber o-rings under the pilot mix screws bad).

Suggest you might want to try to track down another set of carbs on eBay (98 - 06 Kat 600 are identical).

Good Luck!
=-= The CyberPoet

barryware
03-02-2007, 02:57 PM
Goos to hear from you again Cyber.

Since the bike was new, the idle speed adjustment was all the way in. Now that I have the carbs out, I see how it works.

Basically, if you turn the idle adjuster out just a couple of turns, the throttle plates are touching the carb body. I would think that there should be plenty of adjustment.

I don't have anything back together yet. I was going to try to clean the carbs without separating them but after looking everything over, I don't believe I will consider that an option. As long as I am doing it, I might as well do it right.

I didn't want to have to buy a sync gage(s) but too late.

I took a little off of the idle speed adjuster spring. Now I can get about 3 - 4 more turns on it and that should do it.

A quick question...

How does the "Jet Needle Stopper" come out of the diaphragm? Just pull it or give it a twist? The pictorial in the manual doesn't show it or explain how to remove it. It just says to remove it.

I don't want to remove it incorrectly and break it.

The CyberPoet
03-02-2007, 03:48 PM
Reference Image (04 Kat 600 Carb blow-away diagram) (http://www.ronayers.com/fiche/300_0362/carburetor/carburetor.bmp)

If you're talking about items #7 thru 13 in the above pic, and how to pull them out #14, just pull (I use a pair of bottlenose or needlenose pliers to grab item 7). Twisting won't hurt, but it won't make a difference to getting in/out (at least that I've ever noticed).

Cheers,
=-= The CyberPoet

barryware
03-17-2007, 02:00 PM
Those settings don't sound right. I would think start at two turns out and see how that goes.

With a jet kit, you usually start at 2.5 turns out.

I think my pre was 2.25 turns out when we drilled the caps out.

Just an update.... I cleaned and put the carbs back on. I opened the mixture screws 3 turns....

It won't idle @ 3 turns. I opened all the pilot screws to 4 turns. Now it idles but not so good. I thought I had a way of adjusting the mixture screws (home brew tool) but it didn't work out so well so I ordered a tool from Pro-Motion. Once the engine gets hot, it is not so easy to get something in to the mixture screws.

It is close... One big difference, when the choke is on (I know it is not really a choke - it's an enricher) it idles at about 5K. So.... even though I disassembled the carbs and cleaned them, there may still be a piece of s#it somewhere in one of the low speed circuits. This tells me that it is starving for fuel at low speeds.

For now.... The carbs are synced. One effects the other so we will see where this goes. (If you open a mixture screw, the vacuum drops)

I did not want to use the B-12 stuff I bought. Smells strong and I am concerned about the plastic floats. So I got some Sea Foam.

My plan is to fill the carbs with S/F and let it sit till my adjustment tool arrives. The engine will run on S/F so maybe I will start it everyday and replenish the S/F in the fuel line to make sure the stuff works its way into all the little passages.

What is the best RPM to sync the carbs? At 1500 RPM the carbs show completely synced, but at 3K, they are a little off.

Gracia's..

steves
03-17-2007, 02:03 PM
Dude, 4 turns is way rich!

barryware
03-17-2007, 03:23 PM
Dude, 4 turns is way rich!

I understand... Won't idle with less.

When I tore the carbs apart, the floats were all over the place which maybe explains why the mixture screws were all over the place (look at the beginning posts). The floats were better than 5mm apart.

The weird part, this scoot is pretty much brand new. Nobody went into the carbs and adjusted the floats. It came from the factory the way they are.

Now they are perfect... Maybe a little higher than factory spec (because it looked to low to me), but they are all the same. You can run a straight edge across them and they are PERFECT!

We paid for the fuel screws to be drilled out and opened up at its first service (don't EVER let anybody else do your work... Cost me a tap to chase the threads in the carb body and two fuel screws because the shop that did the work, wrecked the fuel screws and that damaged the threads in the carb body(s) (two)

Makes no sense to me... Thats why while I wait for the tool I need to do an idle drop adjustment, I am going to run Sea Foam through the carbs(reading other posts, that is supposed to be the best). Even though I soaked all the parts in B-12, maybe I didn't let it soak long enough and there is still some s#it in the tiny passages.

This scoot ran like a raped ape (never saw a raped ape run but I am told that they run good) before sitting on and off for a couple of years.

When we first started noticing that we were having problems, the first thing I did was drain the fuel tank and fill it with fresh fuel. That didn't make any difference so I changed the plugs. The two center cylinders were running much leaner that the two outside cylinders if you look at the color of the plugs.

It's a good thing that the boy has a full face helmut with a smoked shield so that nobody knows that an old man is riding the bike (except for the beer belly) :D

I used to be a pretty good mechanic/technician when it came to automobiles. In todays environment with electronic sensors and computers, if you don't have the right tools, your lost. However, there are still three things needed. Fuel - Air - and Spark.

I have spark (tested it with a scope I borrowed), Air is a gimmy, so all that is left is Fuel.

I am missing fuel in the low speed circuit(s).

I'm gonna get this bitch.. I've never been beaten by a machine in my life. I'm not going to start with a scoot that isn't even mine (belongs to the kid).

The scoot is blue over white.. I am told that those colors are the fastest. :D

BarMatt80
03-17-2007, 04:34 PM
sounds to me like it is time to take it to a dyno shop with ega and have it fixed with all the right tools and then all you have to worry about is putting gasoline in it.

barryware
03-19-2007, 09:09 AM
sounds to me like it is time to take it to a dyno shop with ega and have it fixed with all the right tools and then all you have to worry about is putting gasoline in it.

Nope... Gonna fix it myself. I bought a set of sync gages and over the weekend, I ordered a tool to get to the pilot screws while the engine is running.

I ran a bit of sea foam through it this morning and I plan to start it a couple of times a day with the S/F for just a few minutes so that the stuff soaks in to all the tiny passages in the carbs. (it is already running better) Once the tool gets here, It should be all cleaned out. I must not have cleaned the carbs well enough when I took them apart.

If I had to guess, there are two (maybe three) tiny holes/passages behind the mixture screw tight under the butterfly(s). I think that is where my problem is.

Knowing what I know now, I should have just ran the S/F through it without taking anything apart. Assuming that the stuff works as well as other posters say it does.

All the damage to the carbs were from taking it to a so called "professional" (the dealer) for its first service. Excluding the carbs fouling up from letting is sit without draining them.

I have always been a do-it-yourselfer. I enjoy tinkering. I don't trust anyone when it comes to repairs. If someone else is doing it, they don't care. They just want you money.

BarMatt80
03-19-2007, 07:50 PM
good for you barry, i know where you come from. I have never had anyone do any kind of work on my vehicles except alignment and state inspections. My problem is well I am to impatient, and have to much going on in life and I just want my bike to be able to hop on and go. I can get one carb right, just problem is just doing it 3 more time for me atleast. What pilot screw tool you get?

barryware
03-20-2007, 08:38 AM
good for you barry, i know where you come from. I have never had anyone do any kind of work on my vehicles except alignment and state inspections. My problem is well I am to impatient, and have to much going on in life and I just want my bike to be able to hop on and go. I can get one carb right, just problem is just doing it 3 more time for me atleast. What pilot screw tool you get?

The tool I ordered (didn't arrive yet), is a Motion Pro 08-0119. It was 30 bucks from their website.

I have been running S/F through it a couple of times a day. Man... Really smokes and belches and I have to keep my hand sorta over the airbox intake to keep it lit. When you block off the airbox, I believe it raises the main jet slides.

I'm gonna wait for the tool and see if I can get it to idle right. If not, I gonna rip the carbs apart again. As I said, I believe that my problem is in the two or three little ports under the butterfly's.

When I cleaned the carbs, I didn't let the body's soak for too long. I was using B-12 and it sure smelled strong. The crud I could see, it took it right off. Probably should have let them soak over night.

When I was done with the solution, if you let it sit in the tray I was using for a while, you could see the crap that came out of the carbs. Kinda like a light brown sand would start to form.

I know there are lots of posts about cleaning carbs. What is the best solution to use? Cheap & EFFECTIVE.

When I went to the parts store and asked. The little honey brought me over to a shelf and wanted to sell me a gallon of something that was 50 bucks. I choose the B-12 instead. When going back through some posts, I think the B-12 is more of a fuel additive than a cleaning solution. I bought both a spray can and a couple of cans of solution.

What about Kerosene? Would that work? Thats cheap...

A couple of Pics...

BarMatt80
03-20-2007, 02:39 PM
as far as cleaning those small holes cut a wire brush brissel(sp?) and stick it in the end of a match. That way you can hold on to it and run the brissel through all the holes in anything to clear them out. i don't know about soaking in kerosene, i soaked mine in carb cleaner, but i took them 100% a part, even the butter flies and soaked them for 2 days, then made sure I rinsed with water many time before i put them back together. I don't know if you could get away with keeping the butterflies in because atleast on the pre98 there is a little felt piece that seals them. Don't know if the carb cleaner would eat them up. I used my dad's 5 gallon barrel of carb cleaner, but any parts store, napa, advanced, auto zone, and i'm sure checker or any other part store out there they sell a 1 gallon bucket(looks like a paint bucket) for less than 20 bucks.

oh yeah NICE tv choice!

barryware
03-20-2007, 03:16 PM
oh yeah NICE tv choice!

I brought the scoot to work for storage over the winter. We bought two of those TV's for displaying some mumbo-jumbo at a show.

Unless you are watching hi-def, the TV's suck. All pixelly. Kinda funny... The boss thought he got a great deal when he bought two of them @ 3800 each. A couple of weeks later, I did a bit of online shopping.. You can get them all day long for well under 2K. Probably less expensive now.

But I digress...

I took the carbs off again and I found a piece of nylon tubing that fits into the pilot and main air jets on the back of the carbs. I closed the fuel screws and gave the tube a quick blow.. I am getting air from the ports so I don't think there is anything blocked. However, air does not mean fuel. I took off a float bowl and when I blow into the tube, I can hear the air coming from the jets.

So... Either everything was clean and I just got paranoid or the S/F worked. I will have the adjusting tool late tomorrow so maybe by the weekend, I can give it a lash.

BarMatt80
03-20-2007, 05:59 PM
yeah all hidef tv's showing non hidef tv or anything else sucks, almsot like zooming in on a pic.

well let us know how it goes.

barryware
03-20-2007, 06:16 PM
well let us know how it goes.

After checking the blockage or lack of it by blowing through the pilot and main air jets, as well as taking the bowls off once more, I feel a lot better about the whole thing.

One thing is for sure, the S/F did a nice job of working its way into everything. I found when I removed the carbs one more time, that the mixture screw on #3 was all the way in. I suspect that my home brew tool did this and I didn't know. I could not "feel" the engagement of the tool and the mixture screw so I am blaming the tool but I really did it.

The reason I had to put my hand over the air intake on the air box to get the scoot to light running on 100% S/F, is because the stuff is a lot thicker than gasoline (physics 101 :oops:). Couldn't get enough through the idle jets to keep it running. My hand in front of the air intake raised the slides.

UPS tracking the adjustment tool says it will be delivered tomorrow. Lunch time tomorrow, I am going to run out the S/F (you gotta see this, smoke and belching like I have never seen, pretty cool). Put gas into the IV bottle and let that run a bit so come Thursday, we should be ready for a tweak and weather permitting, a road test with the IV duct taped to my chest.

md86
03-22-2007, 01:48 AM
Putting your hand over the airbox gives you less air , and thus more fuel , so it'll run higher rpm's , and yeah , that'll raise the slides . Until you foul out your plugs anyway ..... If it'll even RUN like that . I kinda doubt mine'd run if I covered the airbox with my hand .

barryware
03-23-2007, 06:39 PM
Done.... Fixed.... Perfect...

For Sale!

Anyone interested?