Homemade carb sync tool questions

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wheels12

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Hey all I am wanting to build my own carb sync tool. I was wondering:

What kind of fluid is best? ATF or 2 stroke oil?

How small should the restrictors be and what do you use?

How high should I fill the columns? I tried with about 1ft of fluid but it seemed to get sucked out fast. Let me know what you guys think who have made them.

Thank you!
 
Hey thanks for the offer! I'm near Woodstock though. Hoping this will work once I get the levels and restrictors tweaked.
 
I considered making one for a while and experimented a bit but ultimately I ended up just purchasing one from Royal Distributing. I think it was around $80 if a remember correctly. I have synced a few bikes now well worth the investment.
 
Here you go: http://www.obairlann.net/reaper/motorcycle/manometer.html
This was pretty easy for my v-twin, just one long length of hose. If your bike is more than 2 cylinders it gets a bit more tricky to make the manometer and ensure there are no leaks at the fittings.
I used 2-stroke oil. No real reason other than the (possibly incorrect) belief that 2-stroke oil is designed to be burned so the properties may be less harmful to the motor than ATF in case the motor suck it in.
I put about 2 ft of oil in the tube (i.e. about 1 ft up each side of the base of the "U". My total hose length is something over 10 ft)
I didn't use restrictors, and my bike didn't suck in any oil (at least not that I could tell). The oil danced quite a bit, but it was pretty far out of balance to begin with, so despite the dancing I could easily determine that I brought the throttle bodies closer to balance.

I'd borrow that Motion Pro that rbjeepthing is offering if he's close to you.

Edit: You mentioned your bike sucked it in? How long is your hose? Sucked up one particular hose/side? Are you sure there were no air leaks on the other side? Even when the TB's are out of balance the vacuum from the cylinders should good enough to counteract each other enough to prevent sucking the oil in, unless your TB's are really out.
 
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Just go to princess auto, buy vacuum gauges, 1/4" ID tubing, and restrictors/regulators (adjustable regulators are better than restrictors so you can calibrate the gauges). Nail to a piece of wood or plastic and your done.
 
beverage said:
Here you go: http://www.obairlann.net/reaper/motorcycle/manometer.html
This was pretty easy for my v-twin, just one long length of hose. If your bike is more than 2 cylinders it gets a bit more tricky to make the manometer and ensure there are no leaks at the fittings.
I used 2-stroke oil. No real reason other than the (possibly incorrect) belief that 2-stroke oil is designed to be burned so the properties may be less harmful to the motor than ATF in case the motor suck it in.
I put about 2 ft of oil in the tube (i.e. about 1 ft up each side of the base of the "U". My total hose length is something over 10 ft)
I didn't use restrictors, and my bike didn't suck in any oil (at least not that I could tell). The oil danced quite a bit, but it was pretty far out of balance to begin with, so despite the dancing I could easily determine that I brought the throttle bodies closer to balance.

I'd borrow that Motion Pro that rbjeepthing is offering if he's close to you.

Edit: You mentioned your bike sucked it in? How long is your hose? Sucked up one particular hose/side? Are you sure there were no air leaks on the other side? Even when the TB's are out of balance the vacuum from the cylinders should good enough to counteract each other enough to prevent sucking the oil in, unless your TB's are really out.
Click to expand...

I'm thinking I must've had a leak somewhere. I have about 7ft of hose on each line I just put more fluid in so have about 2ft of fluid on each which should add some weight. I'll make sure the fittings are tight at the manifold. I agree it should counteract enough to not be way off and suck oil through. Idle is a little rough once its warmed up but not enough that is should be way out.

Thanks.
 
ATF will bounce more if you make your own... I used motor oil and it works fine.

Best thing to do though is buy a yard stick and zip tie the tube to either side so you have clear index markings.

Also, with the tubing make sure you run it away from any heat source when you're sync'ing your carbs - heat can shrink the tubes which gives you inaccurate readings. You can have the tubes as long as you like - the pressure will be the same.
 
I got a Morgan Carb tune...the best and it isn't that expensive.
No liquid, very accurate...

Don't forget, you are not going to use the thing only once...it is a procedure you will have to do over and over again.
Ideally every 1000kms or more often if needed.

And your bike runs like a swiss watch when the carbs are perfectly sync'd.
 
Spiider said:
I got a Morgan Carb tune...the best and it isn't that expensive.
No liquid, very accurate...

Don't forget, you are not going to use the thing only once...it is a procedure you will have to do over and over again.
Ideally every 1000kms or more often if needed.
Click to expand...
Yes, the CarbTune is nice, but you're still looking at over $100 to get it to your door. You can make a manometer for less than $10, and it'll work just fine.

I've never heard of balancing throttle bodies every 1000 kms. Pretty sure my manual indicates every 24,000 kms. At my pace that's about every 2 years. For me, a CarbTune is an expensive tool to have collecting that much dust, but the OP may feel otherwise.
 
thanks all, found some 6mm welding tips that worked for manifold connectors that had really small openings in them that acted as restrictors. Think that is where the leak was coming from. Tested it out this morning and it worked great it was really sensitive!
 
I used:

30ft of 1/4'' vinyl tubing at princess auto
4x 1/4'' Plastic T's at princess auto
12 electrical wire nail-downs (to hold tubing on wood platform) any hardware has these
4x 6mm Welding Tips (they had a very small hole through them that acted as a restrictor!)

I'd like to put some sort of valve in the bottom for draining or adjusting the fluid level in the tubes.
 
The manual may say one thing...but those of us with old carbs know better.

You warm it up thoroughly, then sync the carbs.
Get them within 1mm Hg of each other. (I have 4 to deal with.)
Blip the throttle, let them settle down again, check them several times like this.

Drive for about 500km, and they usually need to be tweaked again...not that they are out a mile from each other but they will be out.

Check them again when the bike feels "off"...often about every 1000km's.

Once you've rode the bike with perfectly sync'd carbs you'll know what it should feel and sound like and you'll know when it is time to get out the carb sync tool again.

Maybe your bike is really good at holding its settings...mine is 40 years old and often needs a bit of TLC.
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