Number 4 Carb won't Synch!!!!! I need some advice...

[KEITH KRAUSE]

Since your pilot screws have been moved and you have no idea where they are, I would seat them lightly and turn them out to 1 1/2 each to start. BE SURE to adjust the side air screws for the highest rpm at normal operating temp'.
When the carbs are manually synch'd well, you will usually see 3 cylinders drawing about the same mercury and 1 cylinder high at first start up. Lower the high cylinder by turning the adjuster screw counter-clockwise. This raises the slide and lowers the vacuum level. From this point, just small adjustments should be needed to get all 4 levels within 1 cm of each other. If done correctly, the cylinders will all be drawing the correct amount of mercury. People have problems sometimes because they over adjust. If the adjuster screws are turned counter-clockwise too much, the vacuum drops and the rpm's rise. Eventually, the slides/rpm's rise so much that the idle screw knob has no effect. At this point, the engine needs to cool down and you should manually synch' and start over.
On the other hand, if you turn the adjuster screw clockwise too much, this forces the slide down until it actually starts lifting the other 3 slides up. This bottomed out slide will have a very high mercury level as you found out earlier.
If you try my suggested needle/main settings, go test ride and see what she does. Do some faster riding with some roll-ons at about 65/70 mph.
If she passes that test, do some slower city riding for about 10-20 miles.
At these slower speeds you are on the needle with some overlap effect from the pilot circuit. Take some plug reads to see if you need to play with the pilot screws some more. They are sensitive and just 1/8 turn can change the plug color noticably. Since you are starting out with them all "ballpark' adjusted, you will most likely need to adjust them a little differently from each other. Do what the plugs say. If you adjusted the side air screws for highest rpm, don't touch them.

[Anonymous]

OK Guys,

Keith, I used your reccomendations for carb set up (e-clip on #4, Large nylon washer on top...thin on bottom...138 mains...Pilots 1 & 1/2 turns out). I didn't put the metal washer on top, as I will be into a new Vance & Hines 4-1 within the month. Got the carbs synched and went for a ride. The bike ran good cruising and during high-speed roll on's, but would cough and miss during acceleration within the 2000-4000 rpm range. When I got back from the 18 mile ride, I did a plug read. Cyls. 1-3 were all a light tan (first time ever!) and cylinder 4 was dark brown. I went ahead and LEANED out the #4 pilot 1/4 turn but haven't ridden it since.

Let me know if I'm on the right track so far...

Now, I haven't really messed with the air screws as of yet. Could this be the reason i'm getting the miss during acceleration?...Am I needing to lean out the pilot screws?... or am I needing to lean my needles out 1/2 step more?

I must say...the tan plugs were quite exciting!!!!

Thanks again for the advice...

[KEITH KRAUSE]

# 4 seems to want to run richer than the others. I have to wonder if you have good compression in that cylinder? If you can, check it.
There are of course many other things that can cause a cylinder to run richer. I know you said the carb parts are put back in correctly and the carb is clean. I assume the synch' is good. You also say you have replaced the ignition/coil/plug and the spark was good. Did you check the float height? Should be at .94-.95",(factory calls for between .90-.98").
Sorry, I'm getting ahead here. Yes, you need to set the side air screws like I said. Actually, you should have done it before the carb synch'. The pilot screw settings sound good and the #4 adjustment you made makes sense to me too. Remember, there's nothing unusual about all 4 pilot screws being set differently from each other.
I hope your rich #4 is jetting related and not a compression problem.
"Coughing and missing" is a common discription but still not easy to interpret. I take it as a rich condition, especially considering the dark plug and your electrical improvements.
So, I would first adjust those side air screws like I said. This will make sure the fuel going up the needle jets and pilot jets is properly atomized.
Set them on a warmed up motor. Don't touch the pilots, test ride first.
Make sure you have solid connections at your #4 coil/lead/plug cap.
Go test ride and let us know if that coughing/missing has cleared up.
Of course you know the V&H pipe may require you to tinker some more when you put it on but we'll come to that bridge when we cross it. I would suggest some new exhaust gaskets, especially when changing to a new exhaust. Also, I have heard that spraying some hi-temp paint inside the new pipe header will help minimize golding or blueing of the chrome. Be very careful when you remove the exhaust bolts, they can be stuck.
Also, if the bolt flanges are out farther on the V&H pipe (as mine were) compared to your existing pipe, you will need longer bolts. I had to buy some that were 5mm longer than the originals. If you have the same situation, don't try to make the short ones reach, they won't have enough bite and WILL strip. Vice-versa can also happen. Make sure you check the flanges for any differences. Good luck!

[Anonymous]

Keith, You asked...

Did you check the float height? Should be at .94-.95",(factory calls for between .90-.98").

Uhh..could you put that in mm's? (lol) I don't have a way to measure .94". Therefore, my floats are all set to 24mm's. I think that's right.

Yeah, the coils/leads/plugs are good...Also, the Dyna 3 is nice, so I got good hot spark, but I don't have any way to check compression. I was hoping that the comp. is ok, since a "new" top end was allegedly put on it at 44k (10k miles ago), but maybe I better have it checked.

I'll set the air screws and ckeck it out...I'll get back to you soon...

Thanks again

[KEITH KRAUSE]

Keith, You asked...

Did you check the float height? Should be at .94-.95",(factory calls for between .90-.98").

Uhh..could you put that in mm's? (lol) I don't have a way to measure .94". Therefore, my floats are all set to 24mm's. I think that's right.

Yeah, the coils/leads/plugs are good...Also, the Dyna 3 is nice, so I got good hot spark, but I don't have any way to check compression. I was hoping that the comp. is ok, since a "new" top end was allegedly put on it at 44k (10k miles ago), but maybe I better have it checked.

I'll set the air screws and ckeck it out...I'll get back to you soon...

Thanks again

25.4mm = 1", so 24 mm is within that range. Just thought I would ask about your floats.
Yeah, set the air screws and test ride. I hope that does it. Your jetting settings seem correct since 3 of your cylinders have good plug color. So hopefully some adjustments with the pilot and air screw will get #4 right too.
Talk to you later.

[Anonymous]

Hi Keith,
Do you think that the fuel vents have a noticable restriction of fuel flow? On my 81 and 82 the vent Ts are a much smaller bore than the ports in the carbs but they sure do keep out a lot of dirt. On my #1 carbs I tend to find a ton of dirt in the incomplete vent port (it is on every carb but dead ends on the outside two). I was thinking about leaving the vents out until I found this.

Cheers, Steve

[KEITH KRAUSE]

Hi Keith,
Do you think that the fuel vents have a noticable restriction of fuel flow? On my 81 and 82 the vent Ts are a much smaller bore than the ports in the carbs but they sure do keep out a lot of dirt. On my #1 carbs I tend to find a ton of dirt in the incomplete vent port (it is on every carb but dead ends on the outside two). I was thinking about leaving the vents out until I found this.

Cheers, Steve

I know for a fact the VM carbs venting ability is inadequate if quality pod filters and 4-1 pipe are installed. Fuel starvation will happen.
I'm sure the CV carbs are also affected but it may be to a lesser degree. I've never tested for this on a bike with CV's. I would follow the requirements for the jet kit or call the maker. I've never had a problem with dirt entering the floatbowl vent nipples.
Did I answer your question right, or did I misread it?

[Anonymous]

You answered my post perfectly.

[KEITH KRAUSE]

Ok, glad to help. You can contact www.dynojet.com
I don't know what brand of jet kit you have but if they tell you it's a requirement in their kit instructions, then it makes sense to me it would be the same for all brands of kits.
You can also ask the members here. I'm sure many of them have jet kits on their stock CV carbs.
I wish I could see the vent area on your carbs. I wonder why you have a problem with dirt accumulating?

[Anonymous]

Update & a question

Here's the latest...

I adjusted the air screws for the best idle and went for a slow (less than 45mph) speed ride. After the ride, I checked the plugs. 1 & 4 are alittle rich, so I leaned pilots on said cylinders 1/4 turn. 2 & 3 still look good (light tan). The bike is running pretty good. I hope the pilot adjustments will bring the plugs around....I'm tired of going into the carbs :?

Now, one more question for you all...

My bike (78 GS1000) has a small, well medium oil leak. I thought the leak was coming out of the left-side stator cover, so I pulled it off, put on new gasget and silicon, but the leak was still there. The more I got to looking, it seemed to be coming from BEHIND the stator cover (on the outide), so I pulled off the front sprocket cover and found a dime-size hole drilled in the case up in the corner directly behind the bulge where the starter gear is housed. I think this is where the oil is coming from. Can anyone tell me what the purpose of this "hole" is and should it have a plug in it?

I'm asking first because I don't want to pull the newly siliconed stator cover off if I don't have to...

Thanks again

[Dink]

That hole is in the bottom of the starter motor housing. I would say you need to replace the o-ring on the flange of the starter where it goes through into the stator case.
Dink

[KEITH KRAUSE]

Hi. You say the bike is running pretty good, so I assume the "cough and missing" at 2-4,000 rpm's has cleared up? You say 1 and 4 were a little rich so you turned those pilots in 1/4 turn. Once you're getting close, a 1/4 turn is a lot. You may want to go back out 1/8. Just do as the plugs say.
As for your leak, from what I remember 4 years ago when my engine was re-built, I too had a small leak as you describe. I also checked out the hole you are talking about and asked Vance & Hines if they forgot to plug it. They said it does'nt have a plug. I also went to the local salvage yard and the owner say's that hole is not plugged. It's part of the crankcase breathing design? He showed me a GS1100 motor and it also had an unplugged hole. Think about it, why would they drill a hole just to plug it up? Some of my leaking was a bad o-ring on the starter motor shaft, where it inserts into the case. Take off your stainless steel starter motor cover and you can see if the o-ring is leaking. I still have a small leak somewhere that I just cannot pin point but I can live with it. If you do completely stop your leak, please let me know what you did.
So you're tired of getting into the carbs? My friend, re-jetting sometimes does'nt come easy. I could tell you some horror stories but I'll spare you the details. I just hope your bike is running good and that my trials and errors have made your re-jetting less trouble. I know how frustrating it can be. Patience will reward you with a bike that you enjoy riding every time you get on it. Let me know if you have any more questions.

[Anonymous]

Yeah, after looking further into what was going on, it became obvious to me that the hole is simply a drain port for water, oil, and the like. I pulled my starter and replaced the o-ring on the shaft, but I haven't run it yet to see if I've stopped the leak. If it still leaks, i'll try a bigger o-ring.

Actually, i've gotten pretty proficient at pulling and tearing into the carbs. I'm just ready to go on to the next project on the bike for awhile. However, all of the input that the guys on this site (esp. you, Keith) have given me has been invaluable. Thanks again, for all of the knowledge that you all have shared and the time you've put in to answering my questions. Ya'll are awesome.

The carbs are getting close...I'm gonna run it some more this week and do some more plug reads. My new Vance & Hines Megaphones are coming in Tuesday! I'm pretty pumped about that.

Thanks again & God Bless

[KEITH KRAUSE]

OK, sounds good. So the 2-4,000 rpm cough/miss are gone? I'd like to know what settings have worked on our bikes. This helps with giving the next owner good info.

[Detman101]

Remove the 2 floatbowl vent tubes. They restrict the venting.
Keith.

Is this true? When I called the shop in my area they said that I had to plug the 2 vent nipples in between the carbs. They said that was the reason my bike was idling at 5k rpm.
I don't know what to do now...

Dm of mD