Carb Tuning and Valve Adjustment 85' Fj1100

[iridewheelies]

The bike reads 12,300 on the clock, has 4-1 Vance Hines, Uni dual filters, 40 pilots 115 mains, im at 1080 ft elevation. the plugs have always been dead lean, super white. ive got the bike torn down to replace the valve cover gasket and check/shim the valves. ill be surprised if i need to shim them the bike starts right up every time, no backfires. i could move the timing chain side to side on the cam gear it didnt seem that tight but everything looks brand new in the top end besides all the paint being burnt off the head. the bike is a cold blooded bitch and doesnt seem to run very smoothly. it has a lot of vibration.. when warm it rides pretty good, zero bog. i just feel like its got the hanging idle, slow to return to idle... i have a sync tool, i got the carbs off i think i might rebuild the chokes on them... ive never successfully synced but i think i have a good idea how...  just wondering if i should bump up the jets or ? a good sync and tune will definitely be a good fix but carbs are out of my age i dont have years and years experience with them.

[oldktmdude]

   If you're running lean with 115 mains, I suggest you have a vacuum leak.  While you have the carbs off replace the intake boot "o"rings. These are a common problem for "slow to return to idle" issues. Also check the intake rubbers for any cracking or wear issues around the internal carb mounting surface. Also check that you don't have a vacuum leak in the "CDI" unit. This is also a common problem with earlier models.
  Regards, Pete.
PS. while you're checking your valves, make sure the valve timing is correct.

[Pat Conlon]

All FJ plugs are white, that is, all FJ plugs that still have the oem vacuum advance hooked up to them.
http://www.fjowners.com/index.php?topic=11690.0
Your jetting sounds fine with those mods. I suggest lifting up the needles 1 step or at least 1/2 step.

Clean your carbs, change the o rings (esp. float needle seat o rings) adjust the needles, go ahead and check your cam timing, it couldn't hurt (only 12.3k miles?) adjust the valves, sycronoize the carbs, adjust the idle mixture via blip test...set final idle speed, ride it and then re-evaluate.

[iridewheelies]

i am presuming that the 12,3xx is original miles. i bought the bike at an auction not running. had been sitting long enough that the sight windows for the brake and clutch masters were rotted away. tons of rust in the tank. my fuel gauge dont work cuz the float and electronics were so rusted. as for the needles, they are shimmed with rpm shims but i did replace some larger "custom" shims with them. float heights are 21-23mm. the diaphrams are mint. the bike does hum pretty nice goin down the highway, i am just fine tuning the thing, and mostly wondering if i can get my plugs lookin a bit cleaner. the bike only gets 93 octane. will check cam timing while i am checking valve clearances. ive been around the intake boots they also look mint. its got new o rings as well. going to pull the carbs off the rack and run them through an ultrasonic cleaner. will get back to yall in a bit once the weather warms up and i am able to start syncing the carbs.

[Miker]

I appreciate all the great advice on this forum.  Does anyone know what the factory mixture screw settings are?  Just curious as I think it would make a good starting point.  I may have missed the answer in the manual. 

I am running 4 into 1 Supertrapp full exhaust, K&N filter, and stock air box.  No idea what's in the carbs.  I just decided to check carb sync after a year of owning and riding as I feel there has been a gradual loss in power.  Tons of carbon in the pipes, which have also blued over time.  Plugs are always dark.  So, I assume the screws have turned out over the last year. 

I'm using a home made manometer.  The 3 & 4 screws are over six turns out.  The one and two are five.  That sounds like a lot all around.  The number two carb vacuum is the strongest out of all and always almost sucks the liquid into the carb unless I blip the throttle or kill the engine.  I can't seem to sync 1 to 2 as needed per the instructions in the Haynes manual before this happens.  So I'm stuck there without further action.  I suppose I'll take off the air box and visually see the sync issue.  Probably end up removing carbs to review the jetting and thorough cleaning anyway. 

[Miker]

I just found this page.  Two turns out!  No wonder everything is black haha.  I'll try what is outlined here:

http://www.fj1200.info/carbtuning.htm

[Miker]

Sorry to hijack this thread. Seemed like a similar scenario. There was a vacuum leak in carb #2. Fixed that and synced carbs. Seafoamed everything. Now just have to play with mixture screws until I get it right.

[bigbore2]

Go to Motion Pro.  They have an excellent tutorial on carb synchronizing.