VFR 750F 1990 Carb Balancing..will not idle

Hi All,

I wonder if anyone can point me in the rite direction..

I am trying to sync my crabs on the bike with some issues...Firstly, it will not idle unless I have the choke on...the idle screw hanging on the frame is fully in but still no idle. it stalls as soon as I release the choke.

|Secondly, I am not sure how the crabs are numbered cylinder wise..I will try and attach a pic...but as you sit on the bike how are they numbered and which is the static one that cannot be adjusted and used as reference.

Also, what should the readings be on the my vacuum gauges?

The idle needles are at 2.5 turn out from stop.

Many thanks in advance

Max

 

Sounds like clogged pilot jets to me. Can't do a synch unless it will idle. Carb cleaning is in your future.

Carb numbering starts on the left side as you sit on the bike, the most outboard is #1 (rear left). The base carb is #2.

 

Cheers Kenny,

Removed the crabs and completely cleaned it all out...all jets taken out and checked cleaned and passages blown with compressed air.

upon starting wit choke the bike idles with choke at about 2.5RPM.....once warmed up without choke it will not idle...I did a bench sync before installing the cards and 1, 2 and 3 are pretty much inline at 5hg..the forth one is a little below at around 4-4.5Hg.

Allthrough the revs fluctuate allot up and down.

With the choke on..if I spray carb cleaner at the rubber boots it alters the revs up .....time for new boots do ya think?

until I get it to idle reasonably I cannot adjust.

Thanks again for your help.

 

sounds like some boots are needed or tightened

 

Cheers T,

Leaky rubbers must be repaired. The choke allows a massive amount of fuel thru, which can likely mix with the leaking air and allow it to run. Then when the choke is closed the air still leaks, but the tiny pilot circuit can't supply fuel because it needs the air to flow thru the pilot air circuit to create the emulsion. Good luck to ya...

 

In many cases, carb spray+ compressed air will NOT clear a plugged idle jet. A thin steel wire of .010" diameter will clear any idle jet in the #40 range best.