synch then tune?

[82Shafty]

I was curious about the equivalent of the gauge vs the manometer.

The book shows a line going through the manometer and how you are supposed to set the levels according to that, but I was trying to figure out how high the bar is placed, the measurement; the standard.

Perhaps the line is imaginary and it only used to show the relationship between the four cylinders. Subjective in a sense that every bike is a little different but as long as you set the relations accordingly, you will be ok.

[duaneage]

As the saying goes: Don't make a science project out of this.

THe idea is to get the carbs balanced, not pulling a specific value. The relationship between them is what is important.

[nert]

As previously stated, these bikes are known for wanting to be warmed up. Since you are located north, may be more obvious to you. Have you determined if your choke is working properly on all (4) carbs?

I run my GS1100 even when its cold out, 30'-32' (when i am desperate to ride). I always start full choke on (no throttle) it starts immediately then i just move the choke for steady run keeping rpm below 2k. After a minute or so waiting for stable idle of about 1200, (still partial choke) i begin to drive away. I use partial choke for the first .75 to 1 mile range (under 30 mph), at which point i begin a steady 50 mph cruise (turn choke completely off) for a total of 3.5 miles, seems pretty warmed up now. At which point i think my bike runs better 30' to 70' ambient air, cool air and all than it does in lets say 90' weather, especially after many miles.

Totally warmed idle for me is 950. Its smooth, regular, and reduces the "clunk" when shifting from neutral to first. I have no reason to idle at 1000 to 1100 which others seem to prefer.

I don't use a vacuum gauge set I use the Morgan Sync tool. (very nice) Does the vacuum gauge set provide away of syncing the gauges?
I don’t believe the numbers are all that import in terms of what they represent or how much. I think they have to be set equal or relative as indicated I do NOT use the idle screw to elevate the idle speed when performing a sync. I prefer to use a lovely Vanna type assistant to hold throttle, because that is how the carb bank is operated. The idle screw will actually torque the linkage ever so slightly to provide a slightly different reading. (and as you and I discussed earlier, it is about trying to eliminate error with precision) I like to “blip” the throttle between adjustments as well, again to naturalize all the linkage and connections between the carbs, and then continue syncing until I am satisfied. I will check at various RPM as well. My Nert carb Sync screw modification does make this a much easier task. I also made nice little curved tubing extensions that remain fitted to the vacuum ports for easy hook up of sync tool. (careful to keep length of extensions equal or length of all 4 hoses connected to extensions equal)

One other item that made a significant difference in good solid performance is correct and equal, fuel bowl level. I find that due to diff in float weight, tension, valve and seats, etc, manual setting are only just “good enough”. The clear fuel line method (boiler tube) as described in the OE books looks very good. I built a fuel bowl (from a spare) with a clear window and target scribe mark, indicating the correct fuel level. Then on a bench, leveled for and aft, side to side, I run fuel to the carbs, from an elevated tank, check the fuel level for each carb and adjust as needed. It’s a time consuming process. Each fuel bowl needs to be drained, removed, adjusted, installed and refilled many times to get all four carbs equal. (very anal).

IN theory, I should be able to connect a fuel manifold across all (4) fuel bowls allowing all bowls to naturally “seek” their own level equally relative to the highest set fuel float.
Only potential problem I can think of is, what effects, when the bike is put on a side stand or steep angled cornering. Don’t have the time to find out!!


And I just love “stone stock”.

[82Shafty]

Well, as I continue to search for perfection I keep finding another reason to spend more money LOL.

Nert, I am not sure if you want to kick me in the shin now or later but I finally read an article on the intake o-rings.

Like I said before, when this bike is fully hot, she runs great to the point of you better hold on or your coming off, but anything before that and its coughin and spitting and won't rev after a couple mins with the choke.

It will fire right up and run great with the choke on but don't try to rev it. It's about 80 degrees and it takes a good 15 minutes to warm up. My theory is that the crummy little o-rings swell enough and with the bike being hot enough the lean mixture works after the 15 mins. I did spray around the intake boots but not the o-ring area. I am going to try that tonight with the bike is cold and see if I can get it to respond.

If so then it's back off with the carbs and a re-synch and tune. Shoot only it takes about 15 minutes to remove tank, airbox, and carbs and that's because I am being as careful as I can with those parts.

[nert]

I hear ya. Still gotta do it myself.

Depnding upon what you where spraying, just being in the area of the carburetor boots oftens affects a differance when the o-rings are leaking.

The worn o-rings are associated with an erratic idle, and one that is slow to return to idle speed when the throttle is closed as well. I usually change them every couple years.

keep at it. report progress and clues.

vic

[KEITH KRAUSE]

Your previous posts are all about synching and how to adjust the mixture screws. Your first post only describes a problem of the bike stumbling slightly at 2-4K rpm's. You mention no other symptoms.
Now it appears you think you have an intake leak. An intake leak has a very classic symptom; the rpm's rise significantly as the motor fully warms up.
If this is your scenario...hard to start, takes a long time to warm up. As it's warming up, the idle (if set to factory spec) is around 900 to 1,100 rpm's. As soon as the motor warms up completely the rpm's are much higher. So high that you decide (depends on the rider I suppose) to lower the idle to factory spec by backing off the idle adjuster knob. The bike idles fine now but after you turn it off and it cools completely, you find that the bike will only start again if you turn up the idle adjuster knob again or give it some throttle. Even with throttle (which by-passes the choke circuit) starting is difficult. This cycle continues every time the bike goes from cold to hot.
That's the classic intake leak symptom. Spraying water mist (lowers the rpm's) to expose the leak doesn't always work. Spraying something flammable will cause the rpm's to increase but is bad for rubber parts and is messier and more dangerous to use than water mist and will also not always expose the leak. If you have this symptom, I guarantee you have a leak and the manifold o-rings (if used on your model) or the manifolds themselves are failing. If your rpm's do not rise as I said above, it's doubtful you have an intake leak...at least an intake leak like I've ever seen. Any air leaking into the fuel stream between carb and cylinder WILL result in a very lean mixture and irratic combustion that results in the rpm's increasing "on their own". The only time an intake leak won't have this symptom is if the leak is so large that the bike simply stops running or won't start at all.
You can of course make sure the carbs are "popped' into their manifolds correctly and try tightening the clamps better before checking the manifolds/o-rings. The clamps must be the factory style too. No general purpose hose clamps should be used because they don't clamp and apply pressure to the exact area needed to seal correctly. If you have o-rings, replace them all, coat them with some hi-temp bearing grease and torque to about 6 ft/lb unless your manual states otherwise. I always replace the stock Phillips manifold screws with Allens so I can torque them and the Allens make future maintenance easier too. Removing the manifold bolts can be difficult sometimes so use a GOOD fitting bit to avoid stripping the heads off.

[82Shafty]

she will idle baby smooth and runs like an ape once you are riding for 15 mins. I can even fatten the old girl up at idle but when you first fire this thing up it is poppin and spitting and sounds like its firing on two cylinders. This is at 80 degrees.

I will check it again tonight and I have been around many vacuum leaks with hunting idles and such, but again, that was with cars and even a few two-strokes with the crank seals being junk.

http://www.cycleorings.com/intake.html

the carbs are pushed in correctly an it still utilizes the factory clamps that grip the boots nice an tight.

When I get this thing dialed in the way I want it to be I will be sure to put together a list of trials and tribs to aid someone else in their quest to restore factory performance.

[82Shafty]

ok so I got a chance to do some tinkering tonight. I spray'd (dribbled) carb cleaner on the number one cyl boot cyl head side and it made a good diff in idle quality as I had expected, but as the bike reached operating temp, the spray no longer made a difference.

Idles at 900 all day, does not rise up after being warmed up, I synch'd all gauges on one carb, re-synch'd, then tuned for max rpm and fattened 1/8 turn out.

Bike revs great, idles like a kitten, go to take it for a ride in the street and it still breaks up under 3G WTF? Anything over that and it pulls hard with NO breaking up. Perhaps the transitional orifice is clogged. I spray'd all holes that I could find and blew 120 psi compressed air through the disassmbled carbs, but anything is possible.

My pop is ordering the 4 o-rings for it and I told him worse case scenario I will dip all the carbs during winter and start from scratch. I also will have him order a valve cover gasket so I can perform a clearance check. 9700 miles on it I suppose it wouldn't hurt.

I just find it hard to think the valves would be out of spec with 9700 miles only because before the bike sat, it didn't have this problem whatsoever.

[duaneage]

All the adjusting in the world is for naught with a vacuum leak. Luckily the rings are still available and are very cheap. As to the vavles being in spec or not I prefer to measure things and see for sure rather than assume they are correct. If the 600 mile checkup was never done they might be farther out than you think.

Remember, the difference between a great mechanic and a good one is in the attention to details. That a proper set of wrenches.

I used 10 mm bolts on my intake boots, I like the way they looked and are stainless (pretty!) steel. I also replaced most of the philips head screws with allen head bolts. torque them to 6 foot/lbs, no more.
You seem like a detail oriented guy so get a real good torque wrench that reads 0-240 inch/lbs for working on the bike. I torque everything with the calibrated wrench, prevents repairing things.

[82Shafty]

I am a big believer in the fine details. Of course me trying to cheat with just a quick carb cleaning just so my pop could get some riding time in, as expected, is haunting me.

Every fastner has a torque specification and thank you for the heads up on the 6 ft lbs.

I figured it was worth the gamble. Sometimes ya win, sometimes ya lose. :-|

I should have known better because I am a terrible gambler.

[tconroy]

I've tuned and re-jetted a lot of these old bikes over the years. I don't try to get too scientific about it. Hurts the head.
I believe in checking/adjusting all the basics first, such as compression, valve clearances, ignition timing/spark quality, clean parts throughout...only after I KNOW the bike is ready for carb work do I tune/re-jet the carbs. This may seem like more work to some but it saves time and frustration down the road.
I then bench synch as best I can, start the bike, warm up completely and set the mixture or separate air/fuel screws for best idle using 1,000 rpm's (or factory recommended idle rpm) as a base idle, vacuum synch at approx' 3,000 rpm's, double check the vacuum synch, then double check the mixture or air/fuel screw adjustments and fine tune if necessary. Works for me.

Yep! What Keith said!!!

[cberkeley]

I like that shop-vac plan. As I was reading this post, that idea poped into my head and as I read further along, there it was. .....COOL!!