I'm Trying but: I could use a little help to get me on track

[Rickrod3]

Hey Guy's

As much as I hate to put you guys through the newbie carb thing; I'm afraid I'm in need of some help.

I have gotten my bike started.

Here is how it runs or doesn't:
With the choke on full after about a 10 min warm up I can hit the throttle rev it up to 5K (would probably rev higher) and seems fairly responsive. I do get some popping out the exhaust left side only.

With the choke half on it will idle I could rev the engine response is not nearly as good and will only rev to about 3K.

With the choke off it will only start if I hold the throttle 1/4 open if I keep hitting the throttle it may stay on but for all intents and purposes will not run.

I have been through the carbs twice.

Thinking out loud:
I think I can eliminate float height as the problem since; it will start Idle and rev on full choke.

Next I would suspect the slow circuit.
On the 2nd cleaning I targeted this circuit. I was able to blow carb cleaner in the pilot jet and cleaner came out the single large holed by pass the 3 small holes behind it and the air intake jet.
I would think that would indicate its clear.

Being that it will run on the choke it seems to make sense that the problem is carb related or, is the choke somehow able to mask another problem?

I'm reading and learning as much as I can but, would appreciate some help on this.

As my signature says I have plastic floats. I have them set @24mm.
stock jetting with 4 into 2 pipes open side slash
I replaced one of the emulsion tubes part #2H7 149 41 02-00 in the #1 carb with mikes 48-0662

TIA
Rick

[XSokieSPECIAL]

Rickrod3,

You said in the "getting cold feet" thread that you had it idling on it's own and you were going to sync. What happened?

Did you ever sync them?

[Rickrod3]

I know its not really idling right.
I guess I can sync her on the choke,see if she will run with it off. If it does sync her again.

Or should I be looking at something else?

Rick

[petejw]

Hi Rick,
If your running the bike on the choke, sounds like you might have
a problem with your pilot circuit, or you could be running xtremely lean,
also running on the choke will eventually foul your plugs and make the bike run like crap,
what have you set your idle mixture screws at?
dnt know what model bike you have, but make sure theres no
broken mixtures screw tips, that can cause the problems you describe.
Float height i would set according to the year of the carbs not the type of float you are using.
The best way to check float height is with the bike running in 4th gear and from 2000rpm hit full throttle, the bike should be smooth all the way to redline,
but your not upto that stage yet.
With the emulsion tube, if you only replaced the one, is it the exact same as the other 3, thatll give you problems if there not.

[XSokieSPECIAL]

Unfortunatly I went through this same he!! when I went through my carbs.

I would say set the idle up to where it'll idle and then start adjusting the mixture screws one at a time until you find the sweet spot with each one.

While your doing this the idle should increase a little at a each time you find that sweet spot on each carb. You'll probably have to back off the idle screw before your finished going through all of them.

When you set the idle down start all over with the mixture screws again and do the same thing.

When you get it idling as good as you can that way, SYNC.

Then start the ENTIRE procedure over again. adjust-sync-adjust-sync

Do this as many times as it takes to get everything dialed in.

This is kind of a tedious operation but as far as I know it's the only way.

OH, BTW---you will want to keep something like a box fan blowing at the engine to keep it from getting overheated. That'll throw your adjustments off.

That's the way I did mine. Someone else here might be able to help you out making it easier. I don't know.

[DGXSER]

You did not mention if your using a factory air box or pod filters. If pods, you may need to rejet.

Not sure if they still are on there, but I bought a colortune without the mirror for $35. A colortune works great for tuning. Sometimes you may need to fine tune after, but it will definitely get you close enough to eliminate these issues. If you find your out of adjustment to the mix screw and still lean, you need to go up a jet size.

Synching is definitely needed as well.

[XSokieSPECIAL]

Where did you get a colortune for $35 all of them I've seen are $60 +.

I want one.

[DGXSER]

Someone on Ebay had a few without the mirror, was selling them for $35.

[XSokieSPECIAL]

Don't suppose there is any more available.

[Rickrod3]

Thanks for the input.

I'm running stock air box.
My signature has model and mods I did to the bike.

From what I'm reading my slow circuit Isn't delivering enough fuel which makes sense.

In my first post I wrote:
Next I would suspect the slow circuit.
On the 2nd cleaning I targeted this circuit. I was able to blow carb cleaner in the pilot jet and cleaner came out the single large holed by pass the 3 small holes behind it and the air intake jet.
I would think that would indicate its clear.

Assuming It clear; that would leave adjustment of the mixture screw.
It may be too lean.

Am I correct in saying turning it in would richen the mixture?

I was a little overlmed but thanks to you guys at least in theory its starting to make sense.
Choke enriches the circuit and it runs so the Idle circuit needs to be richer.

I'm charging the battery I'll give it another crack tommorrow.
Once I get it to Idle I'm going to sync her.
At this time I'm interested in getting her to the point wear the engine reasonably runs so I can move on to other issues like: brakes and tires wheel bearing lube.
After it can be riden I'll fine tune jetting and color tune.
Thats my plan anyway.


It helps to talk about these things
Rick

[XSokieSPECIAL]

This is from the "Mikuni Motorcycle Carburetor Theory 101" I think I already posted for you.

The pilot circuit has two adjustable parts, fig 2. The pilot air screw and pilot jet. The air screw can be located either near the back side of the carburetor or near the front of the carburetor. If the screw is located near the back, it regulates how much air enters the circuit. If the screw is turned in, it reduces the amount of air and richens the mixture. If it is turned out, it opens the passage more and allows more air into the circuit which results in a lean mixture. If the screw is located near the front, it regulated fuel. The mixture will be leaner if it is screwed in and richer if screwed out. If the air screw has to be turned more than 2 turns out for best idling, the next smaller size pilot jet will be needed.

Here it is again;

http://www.iwt.com.au/mikunicarb.htm

[Larrym]

I have been through the carbs twice.....

Being that it will run on the choke it seems to make sense that the problem is carb related or, is the choke somehow able to mask another problem?

I'm reading and learning as much as I can but, would appreciate some help on this.

TIA
Rick

You are so gonna jump back when this thing runs like it's s'posed to.

I hope that tomorrow's tweak and test turns out to be the magic moment but just in case it doesn't:

Let's treat this as if this were an episode of "CSI" and you're trying to solve a Crime. (Actually, it is a crime when these things don't run right...) I know you've made your best efforts thus far and that the culprit hasn't been found or brought to justice. I say we round up the usual list of suspects and bring'em in for questioning. Who knows...You may/may not have missed one of these repeat offenders. They are listed in no particular order. Just some of the bad guys that cause owners grief until they are taken off the streets.

1.) Diaphrams: usually punctured, torn, or melted. When I say melted I mean chemically melted because the PO sprayed carb cleaner into the front orifice of the carb without removing the diaphragms first.

Tested by lifting the slide, plugging the proper orifice/hole in the airbox side of the carb with your finger, and seeing if the slide stays up. If it falls then you've found a bad diaphragm or the seal at the top of the carb is bad due to the diaphragm not being installed right. (Little notch in the carb where it's s'posed to fit...)

2.) Enrichment plunger seals: Usually melted chemically. Usual cause is again the use of the carb cleaner straw being put into an orifice without removing the plunger.

Tested visually by removing plunger body and inspecting the seal.

3.) Slide needles: Usually not in the correct "position". These needles have clips which allow them to be placed in different positions of height. IIRC they have to be in the middle position. (Someone can always correct me if I'm wrong but please refer to the repair manual or do a search on the site here...) Usual cause is that the PO tried changing the needle height in an effort to change the mixture instead of re-jetting.

Test: remove tops of carbs and look inside slides.

4.) Diaphragm springs: Usually weak or sometimes the wrong part.

Test: with engine running examine the slides. They all should be about the same height and all should respond similarly to changes in throttle.

5.) Improper Idle air, Idle Fuel, main Jets, emulsion toweres: Usually the "right" part as told by the place selling them but not the right part as far as experienced by those owners who try to get them to work right.

Test: Remove all jets and compare them with the pics on this site. There's a thread somewhere in the last year which had pics of the "wrong" jets placed directly alongside pictures of the RIGHT ones. Determine which kind you have.

6.) Blocked orifice at bottom of idle jet: Usually owners fail to notice that at the bottom of the carb where the main/idle jets are located, there is an orifice that goes sideways. It can't be unblocked by spraying cleaner straight into and down(up??) either with the idle jet in or out of the "tower."

Test: remove cover screws from idle jet and examine sideways orifice.

7.)Blocked Idle jet side passages: Usually owners do not remove the jet from the tower and only spray cleaner straight in and down(up??). This jet has small holes in the side that must be clean as well.

Test: Remove jets and inspect small side holes visually.

8.) Butterfly Shaft Seals: Usually melted chemically. Can occur if PO throws entire carb body inside carb "dip" cleaner.

Test: Uhh....I dunno. Honest. Never had that one happen to me but others here on the site have. How to know/test if they're good or bad?? I'm drawing a blank.


So that's the top 8 "Most Wanted" off the top of my head. Would be nice if it rounded out into a top "ten" list. Only you know if you missed any of these things in your first two go-rounds with the carbs.

As far as the tweaking and testing goes, I've never had a set of carbs fail to start and run well after doing the bench synch and setting the Idle mixture screws out 1 and 1/2 turns. Doesn't mean that applies to your situation.

AFAIK, the more you turn the idle mixture screws OUT...the richer the mixture becomes.

When you get it right....you'll know.
(So will your immediate neighbors if those turnout pipes sound like I think they do....)

[Rasputin]

A vacuum leak can also cause this kind of problem. Check where the carb boots meet the engine and your hoses and vacuum plugs for sure. A shot with a propane torch will usually reveal a leak. You will notice a definate change in the way runs if the propane finds its way into a vacuum leak.

[XSokieSPECIAL]

A vacuum leak can also cause this kind of problem. Check where the carb boots meet the engine and your hoses and vacuum plugs for sure. A shot with a propane torch will usually reveal a leak. You will notice a definate change in the way runs if the propane finds its way into a vacuum leak.

Of course without the torch lit.......Right?

[Rasputin]

Darn it I always do that kind of post. My bad. Of course it will be much more useful with the torch unlit. Thanks XSokieSPECIAL for pointing that out.