Vac Carb Sync Issue I need a little help !

[DLS951]

1985
16500 mi
170-180 Compression
TOTAL carb rebuild
Carb joint boots replaced


Tried to sync (Motion Pro tool) carbs, gets close to balance, blip throttle reading changes, repeat, blip repeat, different readings every blip.

Hooked up a Vac gage, needle swings wildly, cant get a steady read.
All cylinders do the same thing.
starter fluid sprayed at all connections=No RPM (change I'm sealed)

Check Vboost valves, I'm within spec.

Bike starts right up, with 1/2 choke, runs with no choke in 30 sec.
Idle is smooth at 1000 rpm. WOT is strong.
Rev produces a hesitation on the upside, and a slite back fire on the down side of rev.

I cant get Carbs to sync.

Any ideas?

 

[DLS951]

PS
Floats are wet set on bike at 16mm

 

[maleko89]

Do you have inline restrictors for each sync tool hose? Did you spray around the manifold?

 

[SpecOps13]

Motion Pro initially calibrated on cylinder 2 with the 4-1 adapter ???

A/F Screws adjusted first ???

I can't think of anything else off hand that may help....:ummm: Mark already touched on the restrictors...

 

[DLS951]

Restrictors in place
A/F=2 turns
Manifold and carb boot sprayed

 

[jfeagins]

Are all your carb-to-carb throttle springs installed properly & none missing for loose connections between carbs?

 

[jfeagins]

Not sure how the condition of the coasting enrichener diaphrams might affect the idle IF they were in bad shape and/or leaking air.

 

[jfeagins]

I get a little bit of that kind of variation while synching with my old mercury style guages, but usually find that one of the tubes has inhaled an air bubble along the way. Not sure how the Motion pro tool works though.

 

[DLS951]

carb-to-carb throttle springs installed properly.
enrichener and carb piston diaphrams gaskets o-rings are brand new. (complete rebuild)

All cylinders Vac gage, needle swings wildly

 

[jfeagins]

Can you borrow another tool from someone and see if it is just your gauge?

 

[DLS951]

Tried my gauge on my Rhino, Gauge works correctly.
Googled "Erratic Vacuum gauge readings" and found this cool Diagnostic site
http://www.secondchancegarage.com/public/186.cfm
According to my gauge, and this site, I may need valve springs?
at 16k miles?
Grrr *@/?^% !!!

 

[alorio1]

Vboost closed ?

 

[sdt354]

Tried my gauge on my Rhino, Gauge works correctly.
Googled "Erratic Vacuum gauge readings" and found this cool Diagnostic site
http://www.secondchancegarage.com/public/186.cfm
According to my gauge, and this site, I may need valve springs?
at 16k miles?
Grrr *@/?^% !!!

16k? it is not probable to need springs for a long time yet. Is the carb rack properly seated all the way, the air box seated. All clamps tight? I'd start there. They will run with carbs not seated, not very well though. +1 on the vboost not closed at idle Joe-check.Let us know.
Steve-o

 

[bobbybob]

1985
16500 mi
170-180 Compression
TOTAL carb rebuild
Carb joint boots replaced


Tried to sync (Motion Pro tool) carbs, gets close to balance, blip throttle reading changes, repeat, blip repeat, different readings every blip.

Hooked up a Vac gage, needle swings wildly, cant get a steady read.
All cylinders do the same thing.
starter fluid sprayed at all connections=No RPM (change I'm sealed)

Check Vboost valves, I'm within spec.

Bike starts right up, with 1/2 choke, runs with no choke in 30 sec.
Idle is smooth at 1000 rpm. WOT is strong.
Rev produces a hesitation on the upside, and a slite back fire on the down side of rev.

I cant get Carbs to sync.

Any ideas?

Sounds like it could be the enrichment (secondary) diaphrams.The small ones mounted on the sides of the carbs.Could be sticking,or possibly have a hole in them.

 

[Rhoy Carter]

What type of sync tool are you using?

 

[DLS951]

tested on another motor, gauge is good.

 

[DLS951]

enrichment (secondary) diaphrams= new diaphrams, springs, both carb side and cover side circuts are clean.
Carb are seated properly on new boots. (yes they have a maniflod side and a smooth carb side)

 

[Rhoy Carter]

I dont think the vac gauge readings on the link you posted will apply to the vmax due to the fact that you are checking the vec on each cylinder seperately, on the car motor you are checking vac on all cylinders ay once.

 

[tugla]

i would take the rack off, hold it up to the light and set the sync by eye, it gets it about 90% or better and then put it back on the bike hook up our tool. seems lately lots of issue with the motion pro, the morgan carbtune seems to be flawless. but do a visual sync, set them all to carb 2 and once on the bike will only have to turn up thumb screw to get idle right.

 

[DLS951]

visual sync?
What are the steps?