Gotta love it when it runs WORSE after you work on

[wolfman]

Long story short when I had the tank off the other day to fix the temp gauge weirdness, I also checked the air filter and accelerator jet patterns. ?What I discovered is that neither of them were spraying AT ALL. ?Took the carbs off, seperated them and removed the noozels, cleaned them and the pump passage, corrected a misrouted vacuum hose. (The transfer pipe from the pump to the other carb was connected to the breather filter tap ? ::) and the breather filter connection on the top of the carb to the accelerator pump hose... Any way, got the pump pumping, nozzles spraying perfectly, gave the bowls, jets and passages a good spraying out with carb cleaner for good measure, replaced a leaking carb drain screw with a spare from my "parts" carbs etc.. carbs back on, cables connected etc... prime/choke/start. ?Idle sucks. ?(It was perfectly smooth before) Suplimental starts are much harder than before, I even get kick back on the starter which was not there before. ?I am thinking the sync on the carbs is shot? ?(Of note: there IS a slight internal YICS box leak, but it was there before and DID NOT affect things the way they are now) Acceleration is better, cruising (constant speed) is WORSE bike runs hotter than it did. Idle is better with a slight 1/4 or so choke on, won't hold a consistant smooth setting without it. ? So I figure it's time to sync the carbs. ?I have a vacuum gauge, but the needle dance when attemptig to use it (yes even with aquarium valves) ?precludes any possibility of getting anywhere near an accurate sync. ?I am thinking of using the fish tank hose manometer method.. ?I am also curious about the idle mixture screws? ?How to adjust those? ?Before or after syncing? Advise from those more expirenced with these particular bikes is definately appreciated. ?I have synced carbs on both cars and bikes before, so I am aware of what needs doing, but my own expirence does not make me too arrogant to listen for an easier method!

[h2olawyer]

I've had that happen a couple times too!  It's amazing when you finally get something done that is supposed to make things better but the outcome is less than desirable  ::) and you ask yourself why in the #@!! did I do that?

When you separate the carbs, the synch will be lost.  There is some play in the holes on the brackets that attach the carbs together.  What synchronization does is set the butterfly valves so they operate the same amount at the same time from identical positions.  I usually try to get it to idle as best I can with the mixture then synch then do a final mixture adjust.  No matter what, the mixture must be adjusted after synchronization.  (refer to final paragraph)

I use the single clear tube with ATF to synch mine.  Under $10 in parts and seems to be very accurate.  Did it a couple weeks ago @ between 2000 ~ 2500 RPM.  Tiny (less than 1/8 turn) adjustments send the ATF balance inches apart!  At idle, the vacuum tends to be more unstable, causing the needles or ATF to "bounce".  You get a more accurate reading at engine speeds above 2000 RPM.  

You may not get a great idle without YICS repair.  When I did mine last year, it was shot both internally and externally.  No wonder the idle hunted between 1500 ~ 3500 RPM.  After repair, it now idles very smooth even down below 1000 RPM when everything else is set correctly.

The hotter running temps could be caused by running one carb leaner than the other.  Another symptom of carbs not in synch.  Leaner mixtures burn hotter.  When you reassembled the carbs, the butterflys came out of adjustment and one side lets in more air than the other, thus leaning out the mixture in the side getting more air, creating higher combustion temps.  Also, getting the hoses connected correctly may have had a similar or compounding effect.

Others may have different or better methods, but the above explanation is what works for me.

Hope this helps.

H2o

[wolfman]

In years past I would start by backing off the throttle stop (idle speed adjustment) screw completely, and then removing the linking (syncing) rod completely to ensure that both throttle plates were completely closed. ?I would then loosen the adjusting screw and lengthen/shorten the rod until I could place it back on without having either throttle plate move at all, then slowly and carefully tighten it with the throttle plates locked using a piece of metal or wood or whatever to prevent any movement. ?I would then turn the throttle stop screw back in until an idle speed could be obtained once the engine was started. ?I would then start the engine and run it until it was fully warmed up. ?Attatch a manometer (the shops tool not mine) and adjust as needed until everything was basically equal. ?With the manometer still connected, I would then adjust the mixture needles until bottomed or the idle got nasty rough, back out an equal number of turns on each one until the engine got nasty, and then adjust them equally and SLOWLY back in for "best idle" ?If the manometer readings went uneven again, I'd adjust the offending mixture screw to once again obtain a balance trying to err on the side of slightly rich rather than slightly lean. ?I would then recheck the manometer readings at a higher RPM (above the idle threashold) to ensure the carbs were synced at higher speeds. ?IF I was unable to achieve equality between cylinders at idle AND off idle RPM's, I would sync in favor of off idle. ?If the difference was quite horrible, I would try to strike the best balance I could between the two (idle and off idle). ?9 times out of 10 I could get a good balance at both. ?On the one odd time I could not, the carbs came back off and back apart as there was obviously a problem with the one that would not flow as well. ?I am REALLY hoping this will not be the case on my V as the carbs are a royal PIA to keep removing and reinstalling trying to chase down a flow gremlin!  To avoid the possibility of my marginal YICS canister fromscrewing up the readings, I figure I'll just disconnect it and use the YICS ports to connect my home made manometer.  Anybody see a problem with that or have any other suggestions?  Thanks H2O by the way, it's good to know them fishtank hose will work...I wonder if using a thicker fluid, say 90wt oil, would help slow the responce time of this homemade tool and help stabilize the readings some at idle?

[Lucky]

I would adjust the pilots both before & after synqing.  Adjusting synq for both idle & higher Rpm's makes little sense. your only going to have it synqed for whichever one you do last.  Personally, I synq mine at idle, she performs well throughout the entire Rpm range.  when was the last time you checked valve adjustment?

[scootertramp]

mine has a goode idle but PULLS one sided when at higher RPMS..  Of what is this indicitive? do I have a vac leak?
a fuel flow problem or air?
I notice a bucking motion at speed although it don't do it all the time..

[h2olawyer]

I'm not sure how well 90 wt. would work.  You would be sacrificing time & maybe accuracy.  The 90 wt. would take longer to move itself into balance and may want to adhere to the tubing more than ATF.  It takes a couple hours after filling the ATF in the tubing for it all to get to the proper place.  Using 90 wt. would probably take all day or more.

The YICS ports will not work for synch.  The vacuum taps right below the carbs will be much more accurate as they are right @ the carbs.  I don't think the YICS ports pull vacuum all the time - otherwise, the air/fuel mix would never make it into the chambers.  That repair is not difficult and after trying running mine with & without, the performance is noticeably better with it hooked up.

Scooter - the higher RPM surge is probably related to your carb synch.  It is probably a small obstruction somewhere in the fuel sections of the carbs.  Lucky will likely have a better idea of the places that would cause it.  Ever think about renting your bike out to one of them C/W bars?  Maybe it's about time to bring back the mechanical bull!

H2o

[wolfman]

I would adjust the pilots both before & after synqing. ?Adjusting synq for both idle & higher Rpm's makes little sense. your only going to have it synqed for whichever one you do last. ?Personally, I synq mine at idle, she performs well throughout the entire Rpm range. ?when was the last time you checked valve adjustment?

I sincerely doubt it has anything to do with the valve clearances as the bike ran and idled fine until I took the carbs off to "fix" them.  The valve train does not wear unless the engine is running...with a whopping 7200 miles on it at this point the valve train clearances are probably still close to factory OEM.  They are on my "to do" list for the fall just before she goes to sleep for the winter again though.