Yamaha TRX850 Enthusiasts Forum

Not wanting to spend big bucks on a flash carby balancing rig, I looked at Youtube and found a cheap way to do it.
Use only glass bottles not plastic (don't ask how I know this).
I bought $2 glass water bottles from BigW, large chair feet from Clark Rubber, as well as 6mm ID and 3mm ID pvc tubing.
Auto transmission fluid (1 litre, half in each bottle) just the right colour and safer than water. The plenum chambers (40mm pvc) soften the vacuum and slow the fluid movement (would suggest using a fan to cool the engine as it takes awhile to balance the carbys).
I placed markings on the bottles at the 95mm mark, from the bottom of the bottles, then at 5mm intervals to 110mm, to allow easy viewing of the fluid movement.
Connect the larger tubing to the two vacuum hoses, I bought plastic joiners from Repco.
After removing the tank, I connected my testing fuel supply (old lawnmower tank), started the bike and let it warm up, then turned on the pedestal fan, this kept the operating temperature close to normal.

I had to turn the engine off to adjust the balancing screw due to its location. I only turned a quarter of a turn at a time.
The idle speed will need to be adjusted continually.
I managed to get the levels close but not perfect, but it did sound better.

Excellent work Sir! Does it feel any different afterwards?

I know mine are way out since I replaced the emulsion tubes, jets and needles but I can live with it. It's just a little lumpy at low revs or when tricking along.

I have noticed that there is less vibration at 80kph than before. Idle is a bit lumpy.

very tidy, I did a similar thing but a simpler version.

Just used a bit of timber and a long length of 6mm clear hose. I compared tested it against a pair of vacuum gauges and found I was able to get a more accurate balance with it.