Carb tuning...

[iridewheelies]

I want to make my bike run better. Have a set of sync gauges still not too sure how to properly sync. The gauges are all pretty close when attatched...  bike had 4-1 Vance Hines with uni pods. It has 40 pilot jets and 115 mains I am pretty sure. Sometimes cruising around 4k rpm I'll grab a lot of throttle to feed the monster and itll stumble for a second then go but feels leanish. In low gears it goes real fast but I still feel there should be more there. Bikes due for a valve adjustment, and my brand new valve cover gasket is leaking. This bike has around 15k on it (12k on the clock) (anyone know how to fix the howling speedo?) Could use professional help on the carbs. I'm reading that they are pretty good carbs when tuned right... I feel like I may have to start at the float levels again, as the bike will run out of gas if you feel like going 80-100 for over a few miles. One of the vacuum lines going off the carbs is also melted a bit. Bike has new intake o rings and the boots r good. No leaks. Diaphrams r good. Carbs were cleaned a year ago roughly. They arent dirty...the bikes never been fine tuned. I want to learn how to make it run perfectly. I can also do powder coating if anyone wants to restore old nasty engine parts. I want to re do my head and jugs this winter if I end up doing valve springs and lap the valves... may do some other upgrades while I'm in there

[iridewheelies]

I also need an oil change. Shifts are feeling iffy, bike downshifts hard when clicking down the gears at higher speed. Also, ill click down at low speed (few mph) in higher gears and sometimes id have to let off the clutch a bit to get the gears to mesh and it go into gear. Upshifts okay under power just makes a good solid click. Time for detent kit ey? Currently have rotella t6 in the bike. May be open to upgrade to a better oil to preserve this old transmission. Bike sat for a long time. The sight glasses in the master cylinders were gone.

[oldktmdude]

   Sounds like you need to lift the needles by a groove or two. If you don't have adjustable needles you will need to get some washers (shims) to do the job.
Adjust by 1 groove lower initially, this should help a lot.
   Regards, Pete.

[iridewheelies]

Needles are shimmed already. Just add another tiny washer? Bike runs nice when its cold, goes right down to idle. When hot itll take a sec to come fully down to idle. I'm wanting to pull the tank and fix the valve cover leak tonight. So maybe I will shim the needles again and go for another sync.

[Pat Conlon]

Shimming the needle has very little to do with your idle.

Maybe this will help you: https://www.youtube.com/watch?v=DLldmBzqR_s

[oldktmdude]

   My shimming the needles comment was directed at your 4,000 rpm stumble. Pat is correct, it won't do anything to fix an idle problem.
   Regards, Pete.

[iridewheelies]

Will use that video when I am tuning the carbs. I'm trying to address all the issues/clues at once. Will reset idle and try tuning my screws. Video shows how to correctly tune the screws and how they relate to the pilot circuit. I still feel they are out of sync. I just wish i knew how to get it perfect

[iridewheelies]

Did some thinking, little bit of work on the bike tonight. Does it matter where the gauges are when syncing vacuum wise? Or just that they are all the same? Wondering if 115 main is enough since the needles are already shimmed, the bike does seem sluggish when u rev it, super slow back to idle. Should come back down to idle as fast as it goes up to redline. Idle hangs up a bit, when warm, I plan on messing with the screws tomorrow. Turning them in till it dies, baseline and just seeing generally how it affects throttle from idle, and I want to check the float heights as well. Because the bowls should not run low at high speed (even 70 mph) please note I have larger fuel line, gravity petcock with alleged "larger" orifices the fuel travels through... it seems I get answers addressing one little problem instead of a response addressing how the bike runs at idle and through the rpm range. I'm in omaha nebraska, 1k elevation. Super humid and hot. I just really need to fix how slow the bike revs down to idle.

[X-Ray]

I had a few issues last year when trying to get my '94 1200 to run correctly with Unipods, just could not get it right. So I gave the bike to a good Dyno Tuning mob, and they sorted it so well, but what they had to do to get it running perfectly was in the opposite direction shim wise to what so many others do. Just goes to show that no 2 bikes are exactly the same,     Hopefully the link works, have a dyno graph there as well,

https://www.facebook.com/groups/YamahaFJOwnersAust/permalink/1800279490275090/