Still having trouble syncing

Alright, someone just explain this to me plain and simple please.
I'm clearly doing something wrong.

I've tried to sync the carbs 2-3 times now with the 2 bottle sync tool.
Carbs were bench synced and fuel levels set.

I warmed the bike up, started with 3&4, moved onto 1&2 then did the pair 2&3.
All the while after every adjustment i'd blip the throttle, kept the idle at 1o50 or so.
Get to 2&3 and here I am adjusting the screw and trying to bring the idle down from 2k
but to no avail will it come down, but! They were all balanced so I finished up and took it for a run.
The bike actually idled at 1100 or so after it warmed up.

Figured all was good, then the bike started bogging down a bit on take off, figured it was running rich.
Checked the plugs and #3 was wet and no longer firing, check the fuel level and sure enough it was out of whack.

Take em off, set the fuel levels again, bench sync them again cause f*** it why not at this point.
Put em back on, fire it up, 6k idle, use the rod and bring the idle down to 1050 and here we are, ready to go but afraid to go through the process again for nothing.

Mixture screws are set to 2.5 this time for this go around, last time I've had them at 2.75 but i've never seen such fouled plugs.

Someone set me straight please, I'm tired of doing this process ad nauseum to come to the same result.

 

I'm no expert on the carbs of a Seca, but it does seem very strange that the fuel level on #3 got wacked out, like there was some obstruction in the feed that gave you a false reading along the way. I'd say break the rack for a full clean but I'd be afraid that would sound discouraging! Everything I've heard of those Mikuni carbs is that they reward fastidiousness, so not surprised you're finding it challenging...each time is a learning experience tho.

If you don't have a colortune I highly suggest beg/borrowing one. While it won't solve your wet plug, I have found it instrumental in getting a handle on the old bike running lean on some and rich on others, rather than guesstimating the mixture screws.

 

colortune for sure
I also recommend Morgan Carb Tune Pro
it is pricy, but so simple and easy to use
I changed valve shims this winter
took it for a ride pre carb tune
backfiring, ran like crap.. 8 mins with a carbtune
purring like a kitten, and screaming like a lion..

 

do you use or need to use the YICS rod?
what type bike are you talking about?
I have read here that you sync then adjust mixture then resync and re adjust mixture

i think your doing it in the wrong order
http://www.xjbikes.com/forums/threads/82-maxim-75-carb-sync-procedure.34249/#post-296879
-Block YICS.

-Set idle up to around 1100rpm using the big knob.

-Adjust #1 so it matches #2.

-Adjust #2 (due to the design of the linkage, it will bring #1 with it) so it matches #3. Now #1 and #2 should match #3.

-Adjust #4 to match #3.

Unblock YICS, set idle to spec. Done.

If you're not using a 4-stick manometer, but a two-bottle rig or other two-carb comparative setup, you can check #1 against #3. If not balanced, run back through the sequence again.

If you make any drastic mixture adjustments afterward, you'll need to go back and re-sync.

 

Blocking the YICS is optimal, but also optional.

 

some would say it is a must to block it
others will say you don't have too
I have done it without blocking
and it worked just fine

 

I haven't been blocking YICS.

I gave it another shot on Tuesday.
4 synced to 3 within half a turn, things were looking good.
1&2 synched together took a little while but I got it there.
But 2 just won't sync to 3, turned the screw all the way in or all the way out but 3 is just still pulling more vac.

Gave up, bike runs fine.
Now I'm just checking my plugs after my rides and slowly setting them to optimal!
Plugs 1&3 were super lean, 2 was rich and 4 was just about perfect!

 

Run a unlit propane torch or spray carb cleaner around the carbs while the bike is running. If the idle goes up there is a vacuum leak. There must be absolutely no leaks in order to synch the bike.

Gary H.

 

just sprayed some carb cleaner at the carbs, happy to say nothing happened!
the plot thickens...

 

Do you have one cylinder with very low compression, if so that could be the reason you can't get 2 & 3 to sync.
I have a colortune plug and used it to close the pilots until I got a white, or lean, condition and then opened them until I got a blue color. Then I installed new plugs and rode about 20 miles and read the plugs and tweaked them --no more than the width of a dime-- until I got perfect colored plugs. All mine are set between 1 1/2 and 2. Using new plugs from a somewhat lean condition makes it easier to see the color changes.

 

HOW did you do your bench sync?

As far as the YICS tool......I have one, it's still in the package----I don't use it. Never needed to.

Dave F

 

I have yet to do a compression test, I should get around to that... is there a how to around here? Also, if the compression for one or more cylinders is low, what's the usual follow through? Valves? Cause I've already checked and adjusted them this winter.

I did my bench sync as per the how to on this forum!

 

So, what exactly did you do?

 

I used 4 strips of business card.
Turned all adjustment screws in.
Got one pinched in carb #3.
Turned idle adjustment screw #4 until it grabbed it's strip.
Moved onto #2 and did the same and then #1 so that it also matched.

Then i just made did minute changes so that they all matched #3.
When I put them all on the bike the idle was super high so I brought it down to 1050.

 

compression test
http://www.xjbikes.com/forums/threads/the-information-overload-hour.27544/

 

when using the 2 bottle method ,are you supposed to go by the fluid level in bottles or the fluid rising up into the common tube?
it would seem to me the rise in the tube would be the measure. right side rising left side pulling more vacuum. no rise equal vacuum

 

you watch the water in the bottles. no rising or falling is balanced. you can watch them for five minutes if you want to.

 

Yup, exactly.
1&2 don't move a mm nor do 3&4.
But 2&3 and by extension 1&3? willy nilly.