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Cheap alternative to carb sync adapters?

  • Thread starter Thread starter Killer2600
  • Start date Start date
K

Killer2600

Guest
Hey guys, I plan on building a homemade manometer to do the much needed tuning and sync to my carbs. Does anyone know if there is a cheap alternative to buying the 5mm adapters (which costs way too much for what they are)? I've found a place online that has them for $1.50 each but for 4 of em and shipping I'd be looking at $20 which seems to be the average total cost I'm seeing online. A dealer wouldn't happen to have these cheaper than $20 for 4 would they?
 
How about drilling a hole through the center of some soft screws?
 
I have vacuum gauges I bought off ebay that came with cracked ones. Im curious as well where to find them cheap. I was just thinkin though what it would take to make some. Be nice if mig welder tip would screw right in there but the threads are probably different.
 
Killer2600 said:
Hey guys, I plan on building a homemade manometer to do the much needed tuning and sync to my carbs. Does anyone know if there is a cheap alternative to buying the 5mm adapters (which costs way too much for what they are)? I've found a place online that has them for $1.50 each but for 4 of em and shipping I'd be looking at $20 which seems to be the average total cost I'm seeing online. A dealer wouldn't happen to have these cheaper than $20 for 4 would they?
Click to expand...

So the shipping and handling is $3.50 each? Where did you find them?

Tom
 
Don't forget to lightly grind the head of the bolts and scuff the nipples before applying the epoxy.
 
$20.00 to have those adapters in hand sounds like a lot but when you consider your time AND getting all 4 to have a similar flow, it's pretty darn cheap! I got stuck for some adapters years ago and made 4 from M5 x 40 (0.8mm pitch) hext head 8.8 cap screws. This required CAREFUL centerpunching, jigging and drilling down the center of each (what'd you say your time was worth?). Then the heads were cut off and chamferred and the hole deburred each end. A nut was run up the threads (which are about 16mm long on partially threaded bolts of this length), and a small o-ring rolled up to the bottom of the nut - and that made each adapter.

Remember that the REASON you're making the adapters is to synch more than one carb.....and for this reason EACH adapter, hose and gauge has to cause an equal reading with an equal vacuum applied....to enable timely, predictable adjustment of the carb airflow. A quality gauge set has a means to calibrate each gauge to one, to achieve this purpose and you don't want to be working to make that happen with one or more oddly flowing adapters or hoses etc.

Nothing like tinkering though to cause understanding ;) Best of luck!
 
adapters

adapters

I made one of those home made manometers. I used some fittings that I had from a MityVac. Just shoved them in - worked fine.
I was never really trusting of the sync job, so eventually got a mercury one. Hooked it up and the home made one that cost me about $2.00 pretty much had it right on.
The mercury was easier to read as the oil I used took time to settle and bounced around a bit, but the home made ones work just fine
 
In my experience, water with food coloring works well with clear tubes.

If using a u tube style manometer, you need about 10-15 feet or ceiling height, which means about 30' of hose per cylinder, unless you have a pit or basement or other way of getting the water reservoir below the bike tires.

I tried to create a vacuum tight chamber, so it would pull against a small air pocket, but due to my half a$$ed approach had trouble getting it to seal. I might try it again with better results.
 
spchips said:
If using a u tube style manometer, you need about 10-15 feet or ceiling height, which means about 30' of hose per cylinder, unless you have a pit or basement or other way of getting the water reservoir below the bike tires.
Click to expand...

Where I read about it, the author had used cheap wood yard sticks, and found those to be long enough. He recommended transmission fluid as being inexpensive, low viscosity, easy to see, and not a terrible problem if it got sucked into the engine. How much vacuum do these things pull? One atmosphere is about 30 feet of water, so are you saying that these things pull more than 5 psi vacuum?

30' of hose per cylinder is making buying gauges sound pretty reasonable.

Tom
 
themess said:
Where I read about it, the author had used cheap wood yard sticks, and found those to be long enough. He recommended transmission fluid as being inexpensive, low viscosity, easy to see, and not a terrible problem if it got sucked into the engine. How much vacuum do these things pull? One atmosphere is about 30 feet of water, so are you saying that these things pull more than 5 psi vacuum?

30' of hose per cylinder is making buying gauges sound pretty reasonable.

Tom
Click to expand...


Sometime this fall or winter, I'm probably going to try and browbeat some of the Indy-area riders into chipping in on a Morgan Carbtune. I played with one yesterday, and me likey.

In the meantime, you're welcome to use my mercury sticks if you can make it 45 minutes down the road!
 
12" of mercury is 12' of water, and yes, they pull that much vacuum. on the one I had with pods (lower vacuum), it was no problem to do, but the other two I ran out of space in my 12' garage.
 
If you are using a single U-Tube, connect cylinder 3 to one end and then the other cylinder to the other. There will be no displacement if the two carbs are in sync. You could use a four-way valve from a fish store for carbs 1,2, and 4 so you don't have to shut the engine off each time (or just put a valve on the #3 side while switching carbs.
 
pricey toy

pricey toy

bwringer said:
Sometime this fall or winter, I'm probably going to try and browbeat some of the Indy-area riders into chipping in on a Morgan Carbtune. I played with one yesterday, and me likey.

In the meantime, you're welcome to use my mercury sticks if you can make it 45 minutes down the road!
Click to expand...

I synchronized my 81 GS1100G last night with the 'Carbtune Pro' It was a little more expensive than I was hoping, but it works great. The old beast is actually idling and makes smooth power just off idle. I still think the old mercury sticks are better and Motion Pro makes a new version that uses a 'non-mercury' fluid. http://www.motionpro.com/motorcycle/tools/syncpro/
Unfortunately, they've upped the price. I just missed a brand new old stock nercury version on ebay last month (went for 61!).
 
themess said:
Thanks, Killer.

Has anyone tried this kind of meter? It is electronic and only compares the readings of two cylinders at a time and shows the difference.

http://www.casporttouring.com/store/merchant.mvc?store_code=CST&screen=PROD&product_code=24002

It costs $75.
Click to expand...

I have had this tool for a couple of years now... it's great... but the adaptors I received with it, as I found out yesterday, MAY not fit the carbs on my 77 GS400. I say MAY because they're damn difficult to turn in by hand. I am going to Dremel a slot in the ends so I can use a screwdriver to turn them. When I do get around to it I'll post the results.

I was amazed I even found the adapters... I don't need them at all on the Bing's on the BMW.

It has, for the record, made syncing the carbs on the airhead very easy. Engine is smooth as glass after.
 
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