To be Banned from this site?

[saaz]

I have tried using a drill bit to get the carbs statically within the ballpark. Every time vacuum guages are need to get the balancing adjustment right.

If you consult the factory workshop manual the procedures for synching the carbs are described using vacuum guages. It only takes very fine adjustments to get them right.

If you also read the manual, it describes that there are conditions to be met before synching..compression within set limits between cylinders, valve clearances etc. All this is not news!!!

[Anonymous]

Victor, you seriously think thousands of automotive engineers and mechanics are wrong and you're right?! I envy your self-belief!

Having read your post I have to tell you that you are basing your "theory" on one or two false assumptions.

Carb synching is done for exactly the reasons that you say it shouldn't be; that is as a final calibration (as well as is acheivable) to get all 4 cylinders producing the same amount of power. Its easier and cheaper than making the engine so accurate that doing the drill-bit thing would work alone.

Good luck with that wheel.

[Anonymous]

Detroit diesels are adjusted to synchronize each fuel injector (air is always wide open, no throttle plate) with each other, (called running the rack) not influenced by each cylinders ability to produce power, but to deliver an equal amount of fuel to each cylinder so potentially each cylinder can produce the same amount of power, resulting in a stronger, smoother, more efficient engine, and with equal mechanical loads.

I don't ahve any experience with Detroit diesels, but I did work a bit with the engineers at Cat when they were designing one of their new ECU's. Their diesels run at a constant air/fuel ratio, no matter the load. This to me excludes any comparison of diesel to gasoline induction systems.

[Anonymous]

Its not self-belief. Reading many of the threads here i think many riders are getting themselves into deeper trouble believing the power of vacuum tuning.

OK. This is my last reply.
I appoligize, didn't intend to be so brash. Just thought provoking.

Visualize this.

4 containers, equal size filled with water, (engine cylinder). On the bottom of each container is a hose that runs too a single variable valve (power demand). Above the containers is never empty tank filled with water and with 4 petcocks on the bottom (carburetor throttle valves), 1 each over each of the containers. The valve (power demand) on the bottom of the containers opens and water flows equally out of the 4 containers feeding the requested power demand. We open the 4 petcocks (carburetor throttle valves) above the cylinders to fill water back into the cylinders to maintain the proper level.

Vacuum Sync
Now, (1) of the containers has a little leak. So we now sync the 4 petcocks and open the one above the leaking container more to maintain the level in that needy cylinder. We open the single (power demand) valve fully. In response we now open the 4 synced petcocks (carburetors) fully, BUT only the one we previously adjusted greater can reach full open. The other 3 can not open fully because the adjusted petcock reached throttle stop preventing the other petcocks from opening any further. Now you have 1 cylinder that maintains the full level, but the other 3 can?t keep up cause they can?t reach the full open position and there respective cylinders can not maintain the water level.

Mechanical Sync
If you set all petcocks to open equally you would have at least 3 cylinders maintaining full cylinders, during full power demand. The fourth wouldn?t be far behind especially since the small leak at idle will diminish percentage wise as the demand for flow increases, and may not have any affect as you demand full flow. All 4 petcocks when open fully together have the potential to flow enough water to maintain the demands of the power requested.

All things considered, the age of the engines, degree of maintenance and abuse, we might be better to set the carbs mechanically, then locate and fix the leaks that cause a flow imbalance, if needed.

I think we may see more grinning faces, and less head scratching.

[Anonymous]

i know i said i would not reply but you are right it is thought provoking theory is great but it is only theory.. practise is what we do and it works i have been building and tuning bikes for 25 years we often set the carbs to a set height before fitting. it makes them easier to sync there is very few that don't run better when you sync them with vac gauges. so as you can see we already do as you want then find a improvement by further adjustment...the experiment has been done YOU ARE WRONG this is the provoking part of your thought .. ozman

[Anonymous]

it is my nature and my dicipline to question WHY i do something and fully understand what is being done. If anything, i thing i now have a very clear understanding of the process and what is trying to be achieved. Certainly i will perform both procedures. However, thats months away. And i am sure this post will be long forgotten.

[Hap Call]

it is my nature and my dicipline to question WHY i do something and fully understand what is being done. If anything, i thing i now have a very clear understanding of the process and what is trying to be achieved. Certainly i will perform both procedures. However, thats months away. And i am sure this post will be long forgotten.

Don't be so sure that it will be forgotten. It is posts like this that make everyone reanalyze what they do, and in turn often sheds new light on subjects that we take for granted. I remember a while back someone asked a question about the relationship between power and torque...that set off one heck of a discussion!!!

Hap
Keep questioning the obvious

[shaftzuki]

it is my nature and my dicipline to question WHY i do something and fully understand what is being done. If anything, i thing i now have a very clear understanding of the process and what is trying to be achieved. Certainly i will perform both procedures. However, thats months away. And i am sure this post will be long forgotten.

So you are just expressing your opinions ... I thought, for a moment, that you might need some help. 8)

Do you spend much time in the "reality" It's far more enjoyable to get them running (in any form) then it is to argue about how to get them running

[Anonymous]

ozman
with all due respect!
often we look back , and marvell at what once was considered common practice. And if you do that too long there is no progress forward.

[moto_dan]

ozman
with all due respect!
often we look back , and marvell at what once was considered common practice. And if you do that too long there is no progress forward.

If you really enjoy this sort of discussion, then you may find some interesting reading in past posts dealing with the use of jumper cables in the removal of stator covers and the insane RPM's of modern motorcycles. Would you happen to have a brother, cousin, uncle, etc. with the screen name of Fast68 ?

[Anonymous]

ill bet some of you guys even through wrenches!
lighten up, no argument

[shaftzuki]

Now that all of the name calling and other activities are out of the way ...

What part of the world are you posting from??

Tell us about your bike or bike(s) - 8)

[Anonymous]

just a Guy from Jersey.
1982 gs1100l, less than 12,000 miles. have had it only a couple weeks.
can't get enough of it.
1985 Honda Nighthawk
bought a 1978' gs750e new in 79', had it stollen in 80'
before that 650 BSA Lighting, talk about tuning carbs, try it with a couple Amol carbs and Lucas electrics, after you put in a cam and bore it out to 750.
but we wouldn't got there.
Hopefully in the future I am can have a more positive impact with my queries.

thanks for asking.

[Hap Call]

Is you GS1100L a 16 valve motor?

Hap

[Anonymous]

Not sure I remember correctly but think my GS carbs are synced at 4000 or 5000 RPMs, not at idle. Sure they are, remember using the idle speed adjustment screw to raise the RPM up and hold it there (with two large fans pointed at the engine). May compensate for some small differences using the vacuum gauges. Think tuners on other posts have noticed when they were compensating for a really weak cylinder. Some of the more experienced tuners on this thread probably know before syncing that they have a serious problem.