Carb Noob

[KEITH KRAUSE]

I've always used the tank for a reservoir. Just place it on a workmate and add longer lines. But whatever you use be sure it's VENTED well so fuel will flow.
As for the rebuild kit mains, I don't know what manufacturer made them but be aware that not all makers size their jets the same way. For example, Dynojet sizes their jets by the actual size (diameter) of the hole. Mikuni sizes theirs by how many CC's flow in a minute. That's why a 130 Mikuni main jet is approx' the same as a 138 DJ main jet. Hopefully your kit really is the same as a 102 Mikuni.

 

[MisterCinders]

With my new valve cover gasket, I put the bike back together with extended fuel lines to the separate tank full of fresh gas. Ready to move forward with final adjustments and synching, I went to start her up.

At first, starter spinned but engine would not start. After some trial and error (mostly error) I determined that I was turning the idle screw the wrong way, thinking "lefty-loosey" would "open" the idle.

Once I got that straight, I dialed in the idle screw this morning and gave it a go.

With choke, the bike starts and idles at about 1,500. The weather is cooling off, but I find it odd that the idle is so low with choke. Adjusting the idle screw did not seem to encourage the idle speed above 1,500.

Bigger problem is that when I give it any throttle, it dies.

I also see that the float plugs are leaking a bit. Not a surprise because two of them were bowls that could not be separated from the plug and, therefore, still have crappy o-rings. I have new float bowls and will replace the bad ones with new o-rings.

When I rebuilt the carbs, I had little confidence in the air and fuel jet settings. Perhaps over-cautious, I was too squeamish to fully bottom out the screws at first. Realizing that error midway and generally skeptical of the prior settings, I set the pilot fuel jet to 1 turn from gentle bottom and the side air pilot jet to 1 1/4 turns from gentle bottom.

Recall the other stages of this saga:

Intake Boots are good and have new O-rings.

Valves are set to spec.

Airbox has new filter and looks pretty tight, though it is missing the snorkel.

While I get the concept, reading the symptoms of rich and lean baffle me. Is this starting problem a function of the air/fuel jet settings? Any ideas on how I can dial those in?

 

[MisterCinders]

Fired it back up tonight, same results.

A WD-40 test did not reveal any air leaks.

The No. 4 exhaust is ice cold.

Guess I am tearing her back down again. FML

 

[Big T]

Before you take the carbs off, do two things:

1. Check you spark plugs - are all of them wet? Esp #4?
2. Swap plug wires #1 and #4 and see if the problem stays at #4 or moves to #1

 

[MisterCinders]

Now I cannot even get it to start. Starter spins but it won't turn over.

 

[Suzuki_Don]

Bigger problem is that when I give it any throttle, it dies.

The engine will die if you use the throttle at all while the choke is in use. You can only use the throttle once the choke has been fully turned off.

 

[MisterCinders]

Pulled the carbs, changed out the float bowls and adjusted the fuel pilot screws to one turn from bottom. Re-did the bench synch. Checked the passages and they are clear.

Oiled the air filter lightly because it seemed a bit dry.

Put it all back together.

Bike starts and idles at 1500. Warmed it a bit and maintained idle without choke.

Any more than a hair of throttle, dies.

No. 4 cylinder doesn't fire. Exhaust for No. 4 is ice cold.

Swapped the leads and got the same result. Cold exhaust on No. 4.

Checked the plugs (which are new) for Nos. 1 and 4. 1 is dry and dark. 4 is dry and white.

The exhaust on 1 and 2 gets very hot after idling for only a minute or so. It is very cool (below 50 F), but after a minute or so of idle there is a light smoke drifting off of the head/exhaust point. Killed the engine at first sign of this, let it cool, and started it again. Same result. Idles for a bit, gets warm (except for No. 4) but dies with throttle. Again, this is without choke.

Running out of ideas at this point. I have gone completely through the looking glass here on the mechanic side (I have no skills, you see), but cannot fathom what is going on here. Am I making things worse??

Should I concede defeat and get it to a shop? Any Chicago GSers around to help solve the mystery?

 

[MisterCinders]

Bumping with a very basic question.

How the hell do I tell is this problem is rich or lean? I can't rev it enough (i.e., at all) to check compression or to get much of a plug reading.

On the one hand, death by throttle strikes me as a rich problem. OTOH, the throttle also increases the air flow, so it could be lean.

Is my bike Jack Sprat or his old lady?

 

[koolaid_kid]

"Normally" what you are describing is a lean condition. Is there fuel in the bowl for the #4 carb? Can you check to see if you are getting spark on #4? The easiest way is to use an inductive timing light because you don't need to move any wires. AutoZone might rent one to you.
I suspect #4 carb is not getting any fuel, but the only way to check is to remove the bowl. If you pull the carbs again, do this. Pull the carbs, remove the #4 bowl, reconnect the fuel line and turn the petcock to Pri. If fuel does not flow at all there is the problem. If it does flow, I would then check the float level.
Best of luck.
AFA a remote fuel reservoir, I went to AutoZone and purchase a plastic overflow tank for a radiator. $8, has 3 nipples on it. I used one to connect the fuel line to the carbs, and another for a vent.

 

[MisterCinders]

OK - plan of action now is:

1. Check the No. 4 plug for spark (please be this easy ray;
2. Check again for air leaks with spritz of WD-40 or carb cleaner;
3. Check for lean by hand covering the airbox while idling (mechanic suggestion);
4. Check for rich/lean with some idle jet adjustments;
5. Pull carbs and check float levels; and
6. Reclean carbs, spray out all jets, check all passages; and
7. Perform ancient ceremonial witch man ritual.

 

[cowboyup3371]

Please make sure you include pictures of number 7 as I may want that one in the future.

 

[Big T]

OK - plan of action now is:

1. Check the No. 4 plug for spark (please be this easy ray;
2. Check again for air leaks with spritz of WD-40 or carb cleaner;
3. Check for lean by hand covering the airbox while idling (mechanic suggestion);
4. Check for rich/lean with some idle jet adjustments;
5. Pull carbs and check float levels; and
6. Reclean carbs, spray out all jets, check all passages; and
7. Perform ancient ceremonial witch man ritual.

You're on the right track, but I wouldn't get too tangled up in the rich/lean issue as yet. But, did you check the sizes on the main jets and pilot jets? Confirm that they are all the same?

You swapping the #1 and #4 leads indicates that #4 is getting spark. Confirm it by pulling the plug and seeing if it fires.

Before you yank the carbs again, confirm that the enrichener on #4 is actually being pulled up. When you lift up the choke, do all 4 of the little arms pull up the little rods about the same amount?

No fuel to #4 is either faulty enrichener or a plugged pilot jet.

 

[MisterCinders]

I'll check the choke arm also.

Pretty sure I need to yank the carbs one more time. I am having doubts about the Bleeder jets, since I did not recheck those when I pulled the carbs last night.

 

[MisterCinders]

As for the main jets, they are all 102.5 and new. Of course, I cannot pull enough throttle to even engage the mains, so . . .

 

[Big T]

That's Ok

As long as you're keeping notes as you go along

 

[MisterCinders]

Never underestimate how stupid I am.

It took a lot of trial and error (again), but I figured out what was killing that cylinder and causing the throttle problems.

When I got home yesterday, I was convinced that I had a bad bleeder jet in No. 4, since I had not checked that the day before. So, I pulled the carbs, cleared out all the passages (they looked pretty clean though), bench synched them, and was ready to reinstall.

Then I recalled some sage advice from this thread. A ghostly voice of the koolaid kid spoke to me:

I suspect #4 carb is not getting any fuel, but the only way to check is to remove the bowl. If you pull the carbs again, do this. Pull the carbs, remove the #4 bowl, reconnect the fuel line and turn the petcock to Pri. If fuel does not flow at all there is the problem. If it does flow, I would then check the float level.

So I hooked up the fuel line first and fed the carbs off the bike. Sure enough, No. 4 was bone dry.

Pulled them apart again, ready to soak No. 4 overnight.

As No. 4 sank into the Berryman's like a captive Han Solo, I looked at No. 3. Perhaps a blockage there kept the fuel out?

Cinders, you moron, Berryman's cannot help you.

As I poked through the No. 3, carb, I was puzzled. The side channel into the float needle seemed blocked. Not at all clear and open like the No. 4 carb that was soaking. Hell, I could see straight through the channel on No. 4 . . . oh wait.

You are as clumsy as you are stupid.
​

Yes, I had foolishly switched the Nos. 3 and 4 carb bodies at some point. OF COURSE NO FUEL WAS GETTING TO NO. 4!

With the carbs in the correct order, re-synched, and everything reinstalled, the bike fires up, idles, enjoys throttle, etc.

Now I need to vacuum synch them and double check for air leaks. I started the air jet adjustments while idling, but I never could detect any idle change from turning them. Maybe it was just late for me, so I will check that again.

I also noticed very light wisps of smoke off the exhaust pipes where they come off the block. I think it may just be some junk burning off the hot pipes, but I kill the engine when I see it. Will set up a fan to keep the block cool when I vacuum synch.

Now if I can just figure out the whole rich vs. lean issue for these adjustments, I will be in business. Definitely going to ride the damn thing today.

Thanks to everyone for putting up with this saga and providing great advice.


​

 

[koolaid_kid]

WooHoo! I'm Obi-Wan Kenobi!
OTOH, you know what they say, almost anyone can get something right once in a while.
Glad you found the problem, and best of luck with the rest of your voyage.

 

[KEITH KRAUSE]

Yes, switching carbs 3 and 4 doesn't work well. You'd also have quite an intake leak if you hooked up the hoses the as normal.
You haven't posted in several days and my computer contracted a virus that shut me down the last 9 days. How did your test run go?
Also, I just noticed your signature says you ARE running pods now? Any previous advice I gave was only for the V/H pipe you mentioned. Pods completely change everything. You'll have to adjust the jet needles if you run pods. Factory setting will be WAY too lean.
If you need jetting help then let us know.

 

[MisterCinders]

Changed the main jets to 110, but will probably go to 120.

Also moved the needle clip down one below center. Now chasing the idle mix and an exhaust leak.

 

[KEITH KRAUSE]

Changed the main jets to 110, but will probably go to 120.

Also moved the needle clip down one below center. Now chasing the idle mix and an exhaust leak.

120 main is probably still lean. But as always, test first at full throttle.
Generally, one position richer on a stock jet needle isn't enough compensation for a quality pipe and pods. (Was your factory jet needle e-clip position at #3 ?) Test at 1/3 to 1/2 throttle.
You may be able to keep your stock #15 pilot jets but 17.5 may be necessary. You can try richer pilot fuel screw (underneath) adjustments first to see if that works in combination with the stock jets. If no joy by the time they're 3 turns out then you've passed their effective range and need the 17.5.
Be sure to remove the two floatbowl vent lines to help the bowls vent better when running pods, especially in windy conditions. Keep the ports open to breath.