Sluggish Acceleration after Carb rebuild

[Tieftoener]

So, finally finished my carb rebuild and reassembly onto the bike. A few too many explicatives resulted from trying to get the throttle cables back on.

 

With the help of all the resources here, I was able to work my way through removing, disassembling, cleaning, inspecting, replacing a few parts, reassembling, and reattaching to the bike.

 

Yesterday, I picked up some vacuum line and a 5-port junction to check the sync tool I have. It was originally designed for my dad's old Honda CB750 with some unique attachments and a bunch of indicators on the gauges, rather than actual numerical vacuum levels. With the junction, I hooked up all four gauges to #1 port and they were all right on. So, proceeded to hooking up to all four cylinders.

 

I spent a good 20 minutes with a fan on the bike, getting things adjusted. Things fell into place a lot faster after I opened up the 4 idle adjustment screws another half turn - they were originally all open 2 1/2 turns during reassembly. They were all over the map when I started, but got all 4 lined up very well. I initially set it right around 1000 rpm, and then checked and tweaked things around 2000 and then again at 3000 rpm. They remain well synced at all three levels now. Granted, this is not the same fuel flow/load as actual riding conditions.

 

On my test ride, I noticed that things were more sluggish than usual, and it doesn't seem to have the same level of "snot" that it used to. It's slow to respond to medium or hard acceleration. It doesn't ever "bog down," so to speak, but just not as responsive as it should be.

 

Does anyone have any suggestions?

 

I'm a little disappointed with myself that it was more responsive with 1 main jet completely plugged and 2 others about 20% plugged

 

Thanks much in advance!

[joboo]

I am assuming that you are talking about the multiple gauges rather than tube type of sync tool. I suspect that some of the unique attachments may be valves to control needle bounce as well as the ability to use the gauges for other things. Not sure about your multiport attachment and what interaction with the other attachments. I am also a little confused about your idle adjustments. In my experience ( which is not all that great) the starting point is about 2 1/2 turns but I have never had all of them be the same when finished. Turning them out another half turn each in all likelyhood won't give you the smoothest idle, they will all be slightly different. The other thing I wasn't clear on, you talk about the idle adjustments in the same sentence as the sync, don't want to be insulting but if the pilot circuit (idle) is off from the beginning, meaning that you opened the pilot circuit to set the idle instead of using the main idle adjustment, then your sync adjustment is going to be off. This should show up on your gauges as carb #1 is fixed and the others are synced to it. You indicate that it did well at the higher RPM settings which use different jets at different RPMs. You may be getting a false indication when you are between idle and main jet draw because of the idle settings, especially if the gauge attachment is slowing the vacuum response. What are the readings at idle? If you start at 1000 RPM to sync, you will never get it right. the throttle response comes from the low end which you are leaving out. I have to assume some of these things from your descriptions, like things fell into place after speeding up idle and checking beginning at 1000 RPM, suspecting it was done because of needle bounce or lack of it because it was too damped.

[Tieftoener]

I am assuming that you are talking about the multiple gauges rather than tube type of sync tool.

Yes... not a mercury style.

 

I suspect that some of the unique attachments may be valves to control needle bounce as well as the ability to use the gauges for other things.

Yes, they were not helpful, causing more problems than solving. The valves were leaking, causing errors. I was having a lot of difficulty with them; they are very cheap and imprecise plastic molded pieces, and the needles would go from "wild" to cut off in the slightest of movements on the valve screws. So, I just removed them and averaged things out with my eyes.

 

Not sure about your multiport attachment and what interaction with the other attachments.

 

I used the multiport junction to plug all 4 gauge tubes into and the 5th junction connected a hose to the #1 vacuum port. I read that this was a good method to verify that the 4 gauges/tubes on the sync meter were calibrated and even. It was just used to check this. Afterwards, I plugged into all 4 vacuum ports on each intake.

 

I am also a little confused about your idle adjustments. In my experience ( which is not all that great) the starting point is about 2 1/2 turns but I have never had all of them be the same when finished. Turning them out another half turn each in all likelyhood won't give you the smoothest idle, they will all be slightly different. The other thing I wasn't clear on, you talk about the idle adjustments in the same sentence as the sync, don't want to be insulting but if the pilot circuit (idle) is off from the beginning, meaning that you opened the pilot circuit to set the idle instead of using the main idle adjustment, then your sync adjustment is going to be off. This should show up on your gauges as carb #1 is fixed and the others are synced to it.

 

I used the main idle knob/screw to adjust RPM for the normal 1000rpm setting. I continued to use it as I synced the carbs... as I used the balance adjustment screws, rpm would change quite a bit, and I'd have to bring it back up or down using the main idle knob.

 

After lots of messing around, I could not get things close enough with the sync, so I decided to try opening up all 4 pilot idle adjustments another half turn. I originally opened them 2 1/2 turns when I reassembled things. All I can say is that after opening them up another half turn, getting the carbs synced up was a lot easier. Things settled right in and evened out within just a few minutes of tweaking.

 

I always used the main idle knob to adjust idle RPM.

 

I'm not insulted at all - I'm learning as I go here, and appreciate the input!

 

How do I correctly adjust each of the 4 pilot idle screws so they're at the right flow? Is there another sync procedure for those?

 

You indicate that it did well at the higher RPM settings which use different jets at different RPMs. You may be getting a false indication when you are between idle and main jet draw because of the idle settings, especially if the gauge attachment is slowing the vacuum response. What are the readings at idle? If you start at 1000 RPM to sync, you will never get it right. the throttle response comes from the low end which you are leaving out. I have to assume some of these things from your descriptions, like things fell into place after speeding up idle and checking beginning at 1000 RPM, suspecting it was done because of needle bounce or lack of it because it was too damped.

 

I first set it at 1000 rpm. I had read that others recommended to also check how well things were synced at 2000 rpm. So, I did that. The sync at 1000 rpm showed good sync at 2000rpm and 3000rpm. I adjusted things just a smidge to be good at both 1000 and 2000rpm. The primary focus was on the 1000rpm idle sync. Things happened to look good up to 3000 rpm; I was just noting this, thinking it was a good sign.

 

Needle bounce was a bit tricky to get used to, but I just averaged things out, using the middle of the bounce range as the target. I got things adjusted so that all four needles were averaged at the same spot and bouncing the same range.

 

Thanks very much for the input. Any insight to the error of my ways is greatly appreciated! This was my first sync, and I'm sure I'm probably missing a few things.

[joboo]

Yes... not a mercury style.

 

 

Yes, they were not helpful, causing more problems than solving. The valves were leaking, causing errors. I was having a lot of difficulty with them; they are very cheap and imprecise plastic molded pieces, and the needles would go from "wild" to cut off in the slightest of movements on the valve screws. So, I just removed them and averaged things out with my eyes.

 

 

 

I used the multiport junction to plug all 4 gauge tubes into and the 5th junction connected a hose to the #1 vacuum port. I read that this was a good method to verify that the 4 gauges/tubes on the sync meter were calibrated and even. It was just used to check this. Afterwards, I plugged into all 4 vacuum ports on each intake.

 

 

 

I used the main idle knob/screw to adjust RPM for the normal 1000rpm setting. I continued to use it as I synced the carbs... as I used the balance adjustment screws, rpm would change quite a bit, and I'd have to bring it back up or down using the main idle knob.

 

After lots of messing around, I could not get things close enough with the sync, so I decided to try opening up all 4 pilot idle adjustments another half turn. I originally opened them 2 1/2 turns when I reassembled things. All I can say is that after opening them up another half turn, getting the carbs synced up was a lot easier. Things settled right in and evened out within just a few minutes of tweaking.

 

** Leave these alone to begin with and come back to them later..LOL...CV carbs are like 4 Marines, they all have different personalities, but you can train them to work as one unit, eventually.

 

I always used the main idle knob to adjust idle RPM.

 

*** This will get you in the ballpark, but once there do not adjust idle in the middle of adjusting sync screws. The idle will go up as you get them all into working together, once they are all together then you turn the idle down. Remember, Carb #1 is fixed, you are adjusting #2 to #1, then adjusting #3 to #4 and then adjusting 3&4 to 1&2. If when you are done, and adjust the idle, the gauge "range" on all of them will decrease the same. The fluid on my board hardly moves at all. Think about it like this: the butterfly valve on each carb, is connected to the next except for #1 which is connected to the idle screw, set #1 with the idle screw, then each one in line, since they are all chained up, changing the idle screw affects them all, so changing it during requires starting from the beginning. A little more complicated than that because you are actually changing the metering per cylinder but you get the idea.

 

I'm not insulted at all - I'm learning as I go here, and appreciate the input!

 

How do I correctly adjust each of the 4 pilot idle screws so they're at the right flow? Is there another sync procedure for those?

 

**** There is a tool, and I am sure someone here has a procedure for it, or at least a better way to do it than I do. Me personally, I don't have the tool, so I use the 2 1/2 turn method to get to a starting place ( if you forgot to note exactly where they were when you started) I turn them out another 1/4 and then hold a plate about an inch from each exhaust and check the feedback by listening, it produces a popping sound when lean, so the pilot screws can be adjusted up or down to get the desired tone, takes a little practice but you will see what i mean, helps to have someone hold the plate for you while you adjust. I am sure it also will make a difference if you have a 4 into 2 exhaust, which I don't. Remove the plate, twist the throttle and make sure decel is smooth, loud popping at this point indicates too rich. I always check sync again after any pilot adjustments.

 

 

 

I first set it at 1000 rpm. I had read that others recommended to also check how well things were synced at 2000 rpm. So, I did that. The sync at 1000 rpm showed good sync at 2000rpm and 3000rpm. I adjusted things just a smidge to be good at both 1000 and 2000rpm. The primary focus was on the 1000rpm idle sync. Things happened to look good up to 3000 rpm; I was just noting this, thinking it was a good sign.

 

Needle bounce was a bit tricky to get used to, but I just averaged things out, using the middle of the bounce range as the target. I got things adjusted so that all four needles were averaged at the same spot and bouncing the same range.

 

* OK I have a set of these and personally was never able to use them with any accuracy at all, the "range" was terrible. I bought a few dollars worth of tubing that I board mounted and it is great, just posted a picture of it recently on a post "pacific northwest".

 

Thanks very much for the input. Any insight to the error of my ways is greatly appreciated! This was my first sync, and I'm sure I'm probably missing a few things.

 

I also have to warn you that there are other things it could be other than your procedure for sync. I did have an experience similar to what you are describing and after tearing the carbs off again found 2 problems, I found some pin holes in one of the diaphragms and that I had accidently bent one of the floats, turning over the carbs without the float bowl attached. Don't really know which thing it was.

 

Well, I'm sure the guys here are having a good chuckle at my attempt to help on a subject that has been beaten to death on the tech pages, but what the heck, we all had to learn at some point! AND I make no apologies for the USMC joke!

[Tieftoener]

You may be getting a false indication when you are between idle and main jet draw because of the idle settings, especially if the gauge attachment is slowing the vacuum response. What are the readings at idle? If you start at 1000 RPM to sync, you will never get it right. the throttle response comes from the low end which you are leaving out. I have to assume some of these things from your descriptions, like things fell into place after speeding up idle and checking beginning at 1000 RPM, suspecting it was done because of needle bounce or lack of it because it was too damped.

After re-reading your first response, I'm confused. Isn't idle speed 1000rpm? I will gladly re-sync at whatever is recommended. That's what was recommended in the sync instructions in the Tech section, so that's what I went with.

 

Is there a place I can get some replacement "de-bouncer" valves that would actually work?

[joboo]

Sorry man, I agree with your confusion, what I tried to clarify in the followup was, yes initial setting 1000RPM ... this will change as you get it adjusted and then bring it back down. What I read was you made several adjustments to idle as your sync adjustments were being made..hence the procedure to clarify. The asterisks denote order of response. Freebird just posted his procedure link again today for another guy with pictures and all. Works for the ventures and is very similar to the royals, the royals don't have the ais, the carbs are smaller and more touchy and the RPM has a range that seems to be a little lower. The 1k is also a starting point for the RPM but it does have a range that spans over 100. These things all have their "sweet spots" tempered by personal preference. Attempting to set them all to a factory standard nets average results. I wish some of these other guys would throw their 2 cents at this so you could get direct help on your exact model.

[Venturous Randy]

In doing the sync, what are you calling the "pilot idle adjustment screws"? Are you adjusting on the screws just below the diaphragm covers? This the only thing I can think of when you are referencing 2 1/2 turns.

RandyA

[Tieftoener]

In doing the sync, what are you calling the "pilot idle adjustment screws"? Are you adjusting on the screws just below the diaphragm covers? This the only thing I can think of when you are referencing 2 1/2 turns.

RandyA

 

Yes, sir, those are the ones.

 

I don't have an EGA or CO sniffer, so not really sure how I can get those in the right place. All I've seen is that stock position is 2 to 2 1/2 turns out from bottom. Is there an EGA circulating on loan for forum members like the valve adjustment kit?