Hey guys, Im trying to sync my carbs on my 99 f4. i have the sync gauges and when i hook them up to the vacuum ports attached to the air box my gauges start going crazy, has anyone had this problem or am i doing something wrong. I followed the service manual and i am sure i have the gauges hooked up right. I also hooked a vacuum gauge up from my mighty vac kit and that gauge does the same thing. It does not change when i rev the engine up either they still go whipping back and forth. Any help greatly appreciated
Thanks, Josh

 

Check your idle, when's the last time your valves were adjusted? I'm not a bike tech but when a vacuum gauge starts jumping on a car we start looking at valves.

 

what vacuum gauge are you using? you're not use one meant for boost are you?

 

the gauges are deffinetly for doing carb syncs. The bracket which holds the gauges says carburetor synchronizer on the top and the gauges read vacuum and also show late timing and stuff like that on the pressure side of the gauges. I have not done a valve adjustment yet the clock is only 15,000 miles do you think that is the problem? the idle is also right on.

 

hmm, thats really odd then. i would suggest connecting carb #4 to only one guage and recording the reading. Then disconnect and tube and plug it back into the airbox. Then connect the hose from carb #3 to just one guage and adjust that sync screw to match the same reading. and so on.

 

Disclaimer - I just joined the group and don't own an F4/F4i just yet, but I had the same problem on my SV650 with gauge type synch. You may need restrictors in the lines leading to your gauges. Too much vacuum can make them really jump around. I have the motion pro carb synch and it comes with restrictors for the same reason. You can pick them up and most autoparts stores.

 

ahh yes, that is true, i did forget about the restrictors. You will need them.

 

You need restricters in there. You also many need to calibrate the vacuum gauges to each other. Try this first.

 

thanks for informing me on the inline restrictors, i did calibrate all the gauges with a mighty vac. Im going to get the inline restrictors and let you know if that works

 

i too want to try syncing my carbs and herd you can 1 by 1 with a vacuume guage,any1 done this,how good does it work?