Carb Sync with bypassed Vboost

[tugla]

or just leave the vboost working while you have a stg 7 set up, i hear still works great. want to try, looking for a servo now

 

[VS Bullet]

I took the carbs off to clean them up, and mechanically balanced them by measuring the butterfly valves. Any wagers on how this turns out?

It will be a couple of days before I try it, still working on the coolant system.

 

[tugla]

should work out just about perfect, thats how i did mine just recently then used my weber and was real close, just slight change. eye method works good if you got a good set of peepers

 

[VS Bullet]

Thats good, I figured it wouldn't be too accurate. I used a rod and measured from the base of the carb to the highest point on the butterfly.

I also thought of something else. Since I have single carb K&N air filters, and two have the inlets on top for the crank case ventilation, I can attach the vacuum lines from the gauges to the filter inlets. I suppose the accuracy would be at the mercy of the filters, but I could test them on one carb to see if I get the same reading. I just bought these gauges and I want to use them!

 

[tugla]

not sure how that would work, worth a try. the carb tune hooks to a vacume port that pulls lots of air, ontop of the carb there is little draw while at idle. but as i said i never tried might work.

 

[VS Bullet]

Somebody was really twisting knobs on these carbs. 2 carbs had idle circuit screws turned 1/2 and 3/4 turn. I set them all back at 2.5 turns.

I have little faith that the air filter mounting will work, but I will try it. Untill I decide to buy more gauges, the measured settings may have to do.

 

[tugla]

the weber is not too much money and well worth it. and think you will get it close enough with a eye sync to get it to run and the rest you can tune by ear, if your use to that, thats how i did mine and then for ***** and giggles since i had the weber put it on and it was pretty dame perfect, you will know the sync is out when it running and you doing slight adjustments, should be able to guess which one to turn from doing the bench sync first.

 

[kinguk]

Re:

Hi,

 

[dwarf717]

Kinguk, start a new thread. My bike has been getting real ****** fuel mileage, and its been getting worse. I have noticed some driveability issues as well at around 3-4000 rpm. I tried to synch my V boostless carbs by ear with a stethoscope. They were pretty far out, but now sound pretty even. Havent really ridden the bike yet, but some test rips revealed some improvement. The bike seems to run smoother at lower rpms, and the usual powershift from 1st to second wheelie, is now a good tirespin, kick to the right, then wheelie.

 

[Rusty McNeil]

.

 

[sdt354]

I really don't want to buy another tool. Probably just do it by ear.

best of luck doing it by ear. Your better than most if successful at that. Slim chance it can be done. Best bet without the right tool is to set them up on the bench with a drill bit as a gauge to get all throttle plates in the same position.

 

[sdt354]

I took the carbs off to clean them up, and mechanically balanced them by measuring the butterfly valves. Any wagers on how this turns out?

It will be a couple of days before I try it, still working on the coolant system.

It can get you close.

 

[Rusty McNeil]

I took the carbs off to clean them up, and mechanically balanced them by measuring the butterfly valves. Any wagers on how this turns out?

It will be a couple of days before I try it, still working on the coolant system.

I have done the feeler gauge method (actually a small piece of stainless tie wire) many times to mechanically balance them. Without ever going back and synching then properly. This was before I had the motion pro.

I am gonna get flamed for this but i think if its synched well enough to fire all four cylinders at a very low idle its good enough.

Think about it; the delta range of synch adjustment is about 100% of throttle on the stop at idle. As you open the throttle further and further the range of adjustment become an increasingly smaller portion of total throttle opening, having a decreasing effect on how much the carbs are balanced. Synch matters most at idle, less and less as it continues to be opened further and least at WOT.

Therefore I think if its balanced enough to run all four cylinders when the blades are almost completely closed its fine.

 

[dwarf717]

best of luck doing it by ear. Your better than most if successful at that. Slim chance it can be done. Best bet without the right tool is to set them up on the bench with a drill bit as a gauge to get all throttle plates in the same position.

Well considering that one of my carbs seemed to not be working at all at idle, and now is, and the two banks of cylinders didn't even sound close, and now do tells me I made a step in the right direction. The bike fires quicker than instantly now, idles better, and rides easier at low speeds, so that tells me I'm closer than what it was. It really sucks that the v boost manifolds have been removed on this thing. I have carb gauges, but need to order that old webber style one to perfect the synch, and that will take a couple of weeks.

 

[vladthedog]

Well considering that one of my carbs seemed to not be working at all at idle, and now is, and the two banks of cylinders didn't even sound close, and now do tells me I made a step in the right direction. The bike fires quicker than instantly now, idles better, and rides easier at low speeds, so that tells me I'm closer than what it was. It really sucks that the v boost manifolds have been removed on this thing. I have carb gauges, but need to order that old webber style one to perfect the synch, and that will take a couple of weeks.

after buying the carbtune pro, I realized I'm in the same predicament. vboost was completely removed on my bike, so i just ordered a cheap weber one off amazon. we shall see.

 

[dwarf717]

Got my webber style guage last night, and adjusted the carbs. My tuning by ear wasn't all that far out. I got all four carbs to the same reading, and will check it out again this morning.

 

[Revv79]

Greetings, this is my first post/RE: I am curious, is bypassing the Vboost good or bad?:ummm:

 

[[email protected]]

Greetings, this is my first post/RE: I am curious, is bypassing the Vboost good or bad?:ummm:

Neither. Its just a preference.

Bypassing it means the guys are running vboost open at all times.
It makes your bike sound "meaner" at idle.
Throttle is a bit more sensitive to inputs at low speed.
Some say the bike runs slower with it open all the time.
Some say its faster with it open all the time.
Thought I saw dyno tests somewhere showing you lose a very small amount of HP in low end with it open.

I've run it both ways. I can't notice any loss in power except for maybe directly off of idle. Need to play around with the carbs a bit to dial it in just right. The only reason I have it full open is because I'm lacking a vboost controller. Still have the butterflies and tube. I wired in a switch to open and close it. Comes in handy while synching the carbs. If I'm stuck in traffic I will often close the boost but leave it open other than that.

I did buy a micro machines controller but haven't gotten around to installing it yet. I find the bike feels a bit smoother at low speed with it closed.

 

[D-Max2012]

Some have talked about best practices on syncing up carbs, on previous threads on this forum. Since the range of tune can vary as you roll on throttle, some have discussed not to be so concentrated on what the tune is at idle, since you normally don't get too far, at that RPM range :biglaugh:. I had this same question before buying my carb tuner.

Instead, increase the RPM till you're around your normal running RPM range and tune there. (I just adjusted the idle screw till I was there). On an avarage day, I'm normally between 4 and 5K in 5th gear. I picked up the Motion Pro and tuned it up around 4.5K. So far, its been great. I have a Lasko Fan/ Blower I put in front of the radiator, while tuning her up to keep things cool. Just food for thought.

 

[sdt354]

Greetings, this is my first post/RE: I am curious, is bypassing the Vboost good or bad?:ummm:

Welcome to the forum. Like Mike said, open v-boost is just preference. I'd wouldn't do it with stock exhaust. I to had an issue with my v-boost working and found the T boost to be the problem. I removed it yesterday and it's back to stock and working right. When I want the v-boost I'm usually in the upper rpm range anyway.
I got an Edelbrock sync tool for Christmas. They fit the top of the cabs nice, but aren't very sensitive at idle.
Steve