Topic: Ready to sync

[fodzilla]

Guys,

I've had a busy day today, managed to finish setting float heights and dropped the carbs on with new boots.(heating them up made them much easier to fit).  I'm now ready to sync the carbs but wanted to check before I attempt for the first time.  This video shows similar looking carbs but he makes a statement about doing them in order; at around 3:20 in the video he says its important you do 1 & 2 then 3 & 4 then both sets together.   

However I only see 4 screws in the video and the same on my bike.  Do I make sense here or am I missing something? I'm a little confused by the statement??

Just incase it's needed, I have 627b carbs on my CB500 '73 and the video! haha

Thanks again!

[fodzilla]

Also, on a different note.  When I had the carbs off and came to bench syncing, I made the assumption that I didn't need to place a drill bit under the choke butterfly as there seems to be a brass pipe that completes this function. 

Is this correct? All butterfly's do move in time and open/close full together in sync.

Again, carbs are 627b's on a cb500 '73

[Deltarider]

Forget about that video. That guy doesn't know what he's talking about. I suspect him of showing of by demonstrating his toys. I mean what has his socketset to do with it. Besides RPM is way to high. Syncing is done between 1100 and 1500 rpm. Believe me, the man doesn't have a clue. At first I thought it was a joke (Iban Moto?).

[fodzilla]

Thanks Delta, but in term of the process is there a better video out there that someone followed?  I was about to use the example.

[harisuluv]

You can get the general idea from the video. 

There's no master on your carbs, so you don't really have to worry about syncing to a particular carb.  With that being said, you can look at the initial settings and decide which ones to adjust based on the others.  For example, if 1 and 4 are about the same, and 2 is a little over and 3 is a little under, well it would make sense to adjust 2 and 3.

There is no mechanism in which the left two and the right two can be changed simultaneously, as in syncing left and syncing right, then syncing the two sides together.  However what he might have meant (haven't watched the whole video) is that each pair is connected with a little stabilizer shim and so adjustment to one carb in a pair can affect the carb next to it.  For example, I can adjust #1 and since they are connected (loosely) by a shim, I can observe #2 also changing.

Don't overthink it, remember that the number they are pulling in vacuum is arbitrary, the only thing you're trying to do is getting them matching.  After that, you can adjust them all in unison as needed with the idle set screw.

[fodzilla]

Thanks harisuluv - That bowl you sorted me with was terrific btw.  Though it did result in me having to clean the remaining 3 bowls to the same standard to match!

Your advise makes sense and made me feel a little more confident about the situation.  Also, can I just ask the below questions while we on the carb subject?

1.
To confirm the float heights I have clear tube, but forgot to order the valves to connect it.  Is there a place and type I should buy?  I've google but can't find anything mentioned anywhere?

2.
When I had the carbs off and came to bench syncing, I made the assumption that I didn't need to place a drill bit under the choke butterfly as there seems to be a brass pipe that completes this function.  Was my assumption correct?

[harisuluv]

1.  Lots of different places you can get them, dealer, 4into1, partsnmore.  At the very least, stay away from cruzinimage stuff.

2.  The carb slides can be bench synced with a drill bit, the butterflies (choke) are not synced with a drill bit at all.  The brass tube is not related to the sync at all.  You can visually adjust the choke flaps to be opened or closed the same.  Perhaps more important than having them all perfectly closed is that when they are open, they are all open the same amount, so ou want to avoid #1 being at 90 degrees perfectly and the others at more or less than 90, which would inhibit optimal airflow.  Sometimes after taking them apart and putting them back together they might be all synced up when open, but when closed they can be slightly off, which is not as big a deal.  Choke is just a startup thing and doesn't have to necessarily be perfect, but you want it correct when it's open.

[fodzilla]

I think I'm going mad!  I can find the brass drain screws everywhere, but nothing to connect the clear tube to the float bowl?  Is that something that people use to check this?  I thought it would be a hollow screw or something.

[Deltarider]

I can understand that. Until now people fumble with tubes in the openings. I am amazed that nobody here produced a serie of small brass adapters that screw in temporarily (checking) replacing the drainplugs and that you can attach a tube to. For someone with machinery very easy to make and he will have a market here.

[fodzilla]

I know, I've searched online and can't find anything.  I'm interested to know how people get the tube on the float bowl still though if anyone has any advice?

[seanbarney41]

basically, anything you can jam in there tight enough to seal and connect the tube to...don't do this in the living room and if you spill a bowls worth of gas, no biggie, you won't burst into flame.  I use a vacuum nipple from my Mityvac set and just force thread it in there as the nipple is made of plastic.  Others have heated clear plastic hose with a cigarette lighter and screwed it in.  Clymer manual will tell you to get a spare drain screw, drill a hole in the middle and solder brass tubing into the hole.  I don't know what kind of resources you have available.  This is one of those situations where you will need resourcefulness and creativity...unfortunately not available on Amazon.com.

[fodzilla]

Thanks, I think I use the "lighter" and "jam it in" method until I have a chance to sit down and drill a hole though a screw for future checks.  Very surprised there isn't a tool for such a job already produced by members here.

Quite a requirement indeed it seems. 

[flatlander]

if you go into a petshop where they sell aquarium gear you can usually find little plastic connection pieces, straight ones and elbowed ones, that work for all sorts of stuff they were not intended for. also handy for draining fork oil etc.

[Deltarider]

Very surprised there isn't a tool for such a job already produced by members here.

Couldn't agree more.

if you go into a petshop where they sell aquarium gear you can usually find little plastic connection pieces, straight ones and elbowed ones, that work for all sorts of stuff they were not intended for. also handy for draining fork oil etc.

Right, that's how I made mine, but I'm well aware that that kind of plastic doesn't like gasoline.
What we need is a set of two little brass adapters (fine thread) that screw in far enough (not too far) and seal well when idling which is the best moment for checking.

[flatlander]

yes that's correct. the petshop stuff is an improvised work-around. it should not stay in contact with gasoline permanently but will last the time it takes for a vaccum sync. brass would be much more longer lived of course.