Carbs cleaned; what first - Colortune or Sync?

I just got done cleaning my carbs, correctly I hope. Now I'm wondering what tool to buy first a Colortuner or Syncronizer?
I haven't put it on the road yet due to a leaky petcock valve which I'm replacing.
When I do run it on the center stand (not in gear) it runs ok with the cold start (choke) on. But when I twist the throttle it bogs down and stalls.

What do you all think?

 

Until you can get the tools ... set-up the Pilot Screws to Factory (2.5 turns out) - to - Factory + 1/4 turn (2.75 turns).

Factory should get you running decent. The additional 1/4 turn might add a very small percentage enrichment. Until you have test equipment; your working Old School. (Nothing wrong with Old School ... just about the same results -- only takes longer to find the right mix.)

If 2.75 doesn't work ... add an additional 1/8th turn on all of them until you get a nice idle. You'll hear it.

 

I'm of the opinion you should invest in the carb syncronizing gauges first, followed by the Colortune. I ran for years without the Colortune but the syncs were not something I was willing to let slip by.

 

I too have same problem.
Does anyone have a Pic of where pilot screws are located on an 82 xj750?
I'd like to reset to Factory specs, and I am not Carb smart.

 

I would have to advise against it. Noone still has factory fresh carbs. You must also realize that the factory assembles to 2.5 turns out then allows the dealer to tune with a bridge four gas analizer. 2.5 is a starting point not a correct setting. If you want to tune your carbs then colortune.

 

Well ... let's all take a step back in time BEFORE there was ColorTune!!!

On 99.999% of all the bikes made with EGA ports at the bottom of the front header pipes ... after a year or so -- those little hex bolts were a permanent part of the header. The time and labor to drill tham out and re-tap the ports made EGA-ing bikes a thing of the past. The EGA machines have long since been "Yanked-Out" of Dealerships ... after it was determined that the analyzer was NOTORIOUSLY inaccurate.

The most talented Yamaha Tech I have ever met ... has his "Apartment Complex looking-like" set of tool boxes with every Special Tool needed to service everything Yamaha Motors has ever created.

With ALL those tools ... there is something NOT among his extensive inventory.

That being: A ColorTune Plug.

I AGREE that it is very nice to be able to peek into the combustion chamber and see the blue color of a rich mixture creating a Bunson Burner-like flame.

You can accomplish the same results without ColorTuning and be within a single digit or low, low double digit percentage of what is achieved by ColorTuning. ColorTuning isn't the only way to set those screws.

Factory (2.5 Out) + .25 Added is an ideal starting point to tune the engine for a good idle.
Patiently "Tweaking" each screw IN to hear the idle stumble ... then, OUT to where the idle is best ... by going beyond the point where there is no improvement ... then, "tweaking" to the spot where the adjustment of the screw has Maxed-out ... and no further improvement occurs ... will do just fine. You can make the bike idle like the Atomic Clock that way.

The most important factor in "Old School" tweaking is: You won't set-up the carbs LEAN that way.

Running RICH is GOOD. Running lean -- so that the power stroke uses the oil sheen on the cylinder walls for fuel -- is what kills engines and costs you fortunes in repairs.

Run a small -- SMALL -- percentage RICH:
Engine runs cooler.
Valves, seats, valve seals, rings and piston tops are NOT in danger of being burned or cooked by a slightly rich mixture.

Conversely: You can cause catistrophic damage to an engine running lean.

How do you know if the engine is running lean?
It's starved for fuel ans stalls alot.
The plugs are too clean for their own good.
The enging runs HOT ... and you can feel the excessive heat trying to escape to the atmosphere.
You have to add oil every so often and your bike don't leak.

Here's my nickel.
Gimme 3-cents change!

 

Due to fast idle issues with my bike I stripped and cleaned the carbs. Now I am trying to set them back up again and I need some clarification on the "Old School" method. I don't have a colortune yet and want to ride without idleing at 3500 and backfiring all the time. Do you tweek each carb individually or do a 1/4 turn on each while listening for the stumble? If you do this individually, how noticible will the stumble be?

 

Individually ...

You will "Hear" the engine getting ready to stumble ... further tweaking it lean might even stall it.

Having recently Colortuned a pair of 750 Max's ... I got a feeling you should start-off the tweaking with the screws set to ... "Three-and-a-skootch" ... only because it seems to me that -- that's where they wound-up being moved-out-too ... to get that "just-right, Bunsen Burner Blue" that the Colortune makes it so easy to find and set-too.

Try it. But, tweak IN -- "Listening" for the idle to fall-off. When it does ... and IT WILL ... bring it back to the spot where it started actin'-up.

Do One ... then, Two ... Three ... and, Four -- separately.

When you get her idling like a pettin' a kitten ... microscopically, ADD a --(non-technically described degree of measurement which cannot be used in this forum for it's inappropriate nature) -- OUT -- and that should do the trick!

 

Is there an old school way to sync the carbs? Just in case the screws were adjusted out of wack. Also to get me by while I wait for the syncing tools, i.e. the YICS tool and gauges.

 

Whip up a pair of the manometers (check out the stickies on the top of the forum pages), do a static setting of your butterfly valves and finish them off with the homebuilt meters. You should do fine and the results should last you a while, at least until your tools arrive.

 

Hey Robert, how does one accomplish a "static setting of the butterfly valves"?

 

Beb
The big thing here is to preset your mixture screws to 2.5 to 3 turns out. (don't bottom them out hard or you could damage them)
Then you need to sync the carbs.
Then try to get the idle smooth at 1050 rpm and adjust the mixture screws then resync them again to be sure
then reset the mixture again.
reset the idle speed and you should be ready to go!

 

Chacal, I've observed a few members post that they simply used a paper clip lodged between the carburator throat and the butterfly valve disk to set the static distance. The syncronization screws are used to adjust the valve height. You want them to just touch the paper clip when it is inserted into the space beween the valve and throttle bore. You should just see a bleed hole visible along the lower lip of the valve disk. Clear as mud, right?

 

The Old School Method
Static Tune & Bench Sync

Using the shank of a small, Number Drill* (Or the Red Tube from Carb Cleaner) set the Butterfly Valves to an equal, mechanical, operating tollerance. Measure Butterfly's to bores values at Bottom Dead Center.

Adjust Sync Screws as needed to bring the four Carbs to an identical clearance.

Static tune.
Bench sync.
Carb tuning proceedure for equalizing butteryfly's after backing-out the Syncronazation Screws to lube and prep for fine-tuning and adjusting.

 

sorry about the name mispelling I ment it to be Ben

 

When I took the carbs off my bike, the #4 butterfly was the only one that had a gap at the bottom. The rest are closed tight. Should there be a gap when the carbs are sync'ed? I am wondering if this is part of my high idle problem.

 

Well, then ... lets give those carbs a (no pun intended) "Starting Point."

Bench Sync 'em in the same order you'd sync the carbs if the engine was running and were hooked-up to the gauges.

Use the Idle Adjustment Rod to open the butterfly's and establish a BASE clearance for Number - 3.

The Idle Adjustment Rod is the sole adjustment for Number - 3, which has NO Sync Adjustment Screw.

Establish BASE value on Number - 3 before continuing to adjust the others. Then, set the other three to the BASE Value setting on Number- 3 by adjusting the other's in this order -- after lubing the Sync Screws and moving the Sync Screws to work the lube all along the screw threads and their threaded connection to the linkage.


First -- Sync the value of Number- 1 ... to the Value of Number- 2. (Even if you have to tweak with two ... to get a preliminary set of 2 after breaking loose those screws and oiling them.)

Step 2
Adjust the Value of Number- 4 to precisely match the BASE Value of Number- 3 -- by adjusting the Sync Screw of Number- 4.

Step 3
Adjust the Value of Number-2 to precisely match the BASE Value of Number- 3.
(Since 1 is mechanically linked to follow 2 ... it comes along for the ride when you adjust 2-to-3.

Check final adjustment for 1, 2 and 4's precision adjustment to Number 3.

+++++
Keep plugging, Dude ... we shall be victorious!