Manometer 3/16 hose clamps.

hotrdd

hotrdd

XS650 Junkie
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So built the majority of my Manometer last night with some 3/16 ID clear tubing and then bought some brake bleeder screws and re-threaded them to M6 1.0. Now I have two questions.

1) Where did you guys find clamps small enough for 5/16 OD hose?
2) How did you go about making the ends removable so that you could thread them into the carbs?
 
Not following you, probably because I haven't made a manometer.

If I need a hose clamp for something like that I usually use a small zip tie instead. Use pliers to pull it tight.
 
Any hardware supplier should have spring clamps in that size and smaller.
The one time I did sync off the carb I removed the plugs and replaced them
It is easier if the intakes have the barbs installed but before vacuum petcocks you used the plugs on the side of the carbs.
Unless your are porting them off the bottom of the head then you leave the barbs in and cap them when not in use?
 
I have the BS38 Carbs and they do not have barbs. They have a screw that comes out and you need to tap into that. Maybe I'm doing it wrong?

Am I correct that any leak in my manometer line could cause a huge reading issue?
 
I put an o-ring on the nipple to seal it in the hole. I don't use any clamps on the hoses, just push them on the nipples. My nipples are probably better than a brake bleed nipple though .....

BS38MixScrews.jpg


You don't leave the nipples in place, you take them out and replace the screw when done syncing.
 
What RPM should I do this at. When I dialed this in last week it changed if I did it at 1500 RPM or at 3000 RPM. Also how close do I need to be, is a 1 inch difference on a 3/16 line acceptable?

If I move onto the dead cylinder tuning should I keep the Manometer on and adjust it again and again as I go?
 
Theoretically, with the linkage, sync set at idle should be good throughout the RPM range. I use an ancient store-bought Carb Stix that has mercury in it. With that heavier liquid, it's possible to get the columns dead even with each other. I hear the homemade versions with the lighter liquid are hard to get even and bounce around more. Still, I'd try to get the columns as even as possible. As for the different readings at different RPMs, I'd split the difference I guess.

Get the sync close then set the mix screws, then check/set the sync again.
 
I'm hoping that doing the rest of the sync work will help me get everything dialed in perfect. Right now each change affects the other changes this just goes round and round. The next dial in will be to set the mix screws using the dead cylinder method.
 
When you set the mix screws, that can change the idle speeds slightly so they don't match one another any more. When the idle speeds are not matched, the sync is off. That's why you need to re-check it after dialing in the mix screws. It usually won't change things much but sometimes a minor tweak to the sync is needed.
 
I'll leave the manometer hooked up while I dial everything else in. I never thought something could be so tedious, frustrating and rewarding at the same time.
 
The homemade manometers are very sensitive.. Just get them as close as you can at a couple of different RPMs and split the difference and call it good.
 
Set the sync at idle. On my homemade manometer the levels bounce about 3/4 inch. When one side is on the intake stroke the fluid gets pulled that way, when the other side is on intake it gets pulled the other.
As you watch the levels, set the sync so the high spots match each other and the low spots will to. Even a tiny turn of the sync screw changes the levels alot. 1/32 to 1/16 turn might be three inches difference in the level. Get it as close as you can.
On the grease fittings save the ball and springs. They fit the side pull choke detents on the 80-81 carbs.
Leo
 
I used some brake bleeders instead and just re-threaded them. The small hole in the end helps keep the fluid from bouncing around. I have the levels pretty close now but will keep the manometer on while I dial the rest of the Carbs in with the dead cylinder method.
 
I have access to a big-ass 48" long Dwyer U-Tube Manometer that will measure up to 18" w.g.

Can I use this manometer to measure vacuum via fittings (like 5twins shared an image of) to sync my BS38 carbs ('76/C)?
 

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Great!!!

Now, how do I hook it up? There are 2 tubing connectors at the top of the manometer. Do I simply connect tubing from each connector to the vacuum fittings on each carb and adjust for any level difference in the red fluid?

Is there just one adjustment screw for balancing? What's the name of that screw and where is it located?
 
Yes, hook one tube to each carb. I hook left tube to left carb and right tube to right carb so the reading is not confusing. There is a sync adjusting screw on the carb linkage between the 2 carbs. It controls the right butterfly position. Adjust it until it matches the left one. If idle speed goes too high or low during that adjustment, reset using the idle speed screw on the left carb. The idle speed screw on the left carb controls the idle speed on both carbs simultaneously because they are connected through the linkage .....

Adjust Screws.jpg
 
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