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Getting ready for a trip out west when the weather breaks here in PA in the spring. Already flushed clutch master cyl and front and rearbrake master cyls and refilled with valvoline syn., replaced a bad rear rotor and all 3 sets of shoes, cleaned and lubed calipers, replaced timing belts and tensioners, new iridium plugs and oil change with Rotella T full syn., 2 new michlin pilot gt's with dyna beads.

I'd like to check the carb sync. Is this a big deal? very techy, or a waste of time? Bike not running bad, just like to have it great for this trip. Thanks in advance. Gary;)
 

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Hi Wingdancer,

Simple anwer is do it, no it is not a very techy job, well worth the time and effort in my mind.

With the 1500 having only 2 carbs you only have one adjustment screw, so get a gauge, connect up, adjust and job done, it normally takes longer to get acess than to do the job.

Nick

welsh winger
 

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If you have the time and equipment then checking carb sinc is a great idea. I also would check the altenator. A few members here have had problems when traveling with the altenator pooching out. Tony
 

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Welcome to this forum.

It is not really too technical.

Might as well, give you something to do til spring. Go buy a cheap Harbour Freight Fuel Vacuum gauge for ~$10.

Sync only affect engine performance at idle. It basicallybalancing the manifold pressure on each side of the engine by slightly adjusting the carb's closed throttle plate at idlewith that sync adjusting screw.
 

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Hi ya Wingdancer:waving:Welcome to the forum. I've been thinking about doing the same with mine but have no idea how it's done. So maybe I'll learn something from you making this post.

How bout updating your profile as to your location, we may be neighbors. I took my very first trip out west this past June, hope yours is just as great as mine was.
 

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Think about it this way (How and Why).

A two or four barrel carb has a solid shaft connecting the throttle plate(s);therefore, they have no sync adjustment.

One carb on an engine can not be synced. Only adjustment would be idle and mixture.

Two or more independent carbs haveto be mechanical linked.

Sync will fine tunes these linked carbs. The 1500 carb is actually two independent carbs. Sure, they have a base, but they have the throttle linkages.

At idle, these throttle plate(s) are relatively closed, but they are slightly opened due to the idle screw. The closed plate with engine running creates a low pressure vacuum.

So, the sync makes an attempt to balance the air flow by measuring the vacuum pressure and changing the position of the other plate. If the same amount of air is mixed with the appropriate amount of fuel, both sides would also produce the same amount of power at idle.

Also, the idle speed screws and idle mixture screw needs to be adjusted too while the engine is running to fine tune.
 

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Foosman(5) wrote:
Think about it this way (How and Why).

A two or four barrel carb has a solid shaft connecting the throttle plate(s);therefore, they have no sync adjustment.

One carb on an engine can not be synced. Only adjustment would be idle and mixture.

Two or more independent carbs haveto be mechanical linked.

Sync will fine tunes these linked carbs. The 1500 carb is actually two independent carbs. Sure, they have a base, but they have the throttle linkages.

At idle, these throttle plate(s) are relatively closed, but they are slightly opened due to the idle screw. The closed plate with engine running creates a low pressure vacuum.

So, the sync makes an attempt to balance the air flow by measuring the vacuum pressure and changing the position of the other plate. If the same amount of air is mixed with the appropriate amount of fuel, both sides would also produce the same amount of power at idle.

Also, the idle speed screws and idle mixture screw needs to be adjusted too while the engine is running to fine tune.
Nice simple terms,,,,,,,,,,,, thats the way I like it:grinner:. Thanks Foosman. Now I just need to figure out what to get as far as gauges.
 

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Much easier to use 2 guages, IMO, the adjusting of one carb,slightly affects the other carb, so with one guage, you gotta go back and forth.With 2 guages, you can watch them both at the same time.jimsjinx
 

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I was wondering about that,,,,,,,,,, so would 2 of those gauges work for me? Or is there a better tool?
 

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If I had a video I would put it up and show you. Basically you need a set up of two or more gauges. You will use two. You can have up to a six gauge set up for a Valk or something , but you need a minimum of two. (the 1500 has two carbs)

You can buy several vacuum gauges (or a carb tune) and fasten them to a scrap section of plywood, and go by lowes and get some surgical tubing or plastic tubing .

When you assemble the gauges to the board, you then cut the tubing to the exact same length for each one. Naturally use tubing small enough to slip over the vacuum port on the gauge.

Next you will need restricters of some kind. Again it is important to have them the very same(I do not like aquarium valves as it is hard to adjust them the same.) You can make restricters out of anything that will slip up in the tubing, and simply drill a 1/16th inch diameter or smaller hole in the restrictions. This evens out the pull to the gauges and allows them to read and not jump excessively. If the gauges are jumping too much, you need smaller restrictions.

You then simply warm the bike up, best to do this after the motor is up to operating temps, you simply connect one gauge to one vacuum port on one carb, and the other to the other carb. You then with the sync screw simply balance the carbs so that both gauges read the same. Or as close as you can get them. Work the throttle a time or two and check it again, may have to do this a couple times, but does not take long.

It is not a hard job and very simple actually. You can do it.

Go to places like You tube and look for Carb sync, watch what they do, you will catch onto it very quickly. Basically just hook up a gauge to each carb, and balance them so both gauges read the same, not much to it really.

Kit
 

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Your making it sound easyer all the time Kit. I'm not new at pulling wrenches, but I never did play with carbs much, except lawnmowers and snowmobiles.

I'm not sure Iunderstand what you mean by "restricters" though. Sounds like your saying to put some sort of "plug" up in the tubing,,,,,, with a small hole drilled through the plug?

Does that sound right???

And Thank you for the help. The bike is running great. But if it's something I can check (and learn to do) it's always a plus.

Hope to shake hands in the Rockies:waving:
 

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Winger77 wrote:
Your making it sound easyer all the time Kit. I'm not new at pulling wrenches, but I never did play with carbs much, except lawnmowers and snowmobiles.

I'm not sure Iunderstand what you mean by "restricters" though. Sounds like your saying to put some sort of "plug" up in the tubing,,,,,, with a small hole drilled through the plug?

Does that sound right???

And Thank you for the help. The bike is running great. But if it's something I can check (and learn to do) it's always a plus.

Hope to shake hands in the Rockies:waving:
Yes the restrictions you can make and insert into the tubing. Or you can go buy some inline aquarium valves and use them so you can adjust them for different bikes. I suppose I am too picky sometimes. They will work fine. What you do is insert one end of those valves into the tubing, and then cut another six inch section of tubing and insert the other end on the valve leaving now another open end. Then you connect the tubing to the bike either at the vacuum ports or with adapters depending on the bike.
It is very easy, not a lot to it. Once you do it one time, you will see, not much to it.

Kit
 

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Ok,,,,,all sounds easy. BUT,,,,,, (yep, another but), what is the reason for restriction?? Why can't the tubes be direct from the gauge to the carb??

Sorry if I'm asking so much, I just want to make sure I understand what I'm doing.

I won't be doing it till later this winter when I do the timing belts and other stuff.
 

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Winger77 wrote:
Ok,,,,,all sounds easy. BUT,,,,,, (yep, another but), what is the reason for restriction?? Why can't the tubes be direct from the gauge to the carb??

Sorry if I'm asking so much, I just want to make sure I understand what I'm doing.

I won't be doing it till later this winter when I do the timing belts and other stuff.
The restrictions allow you to cut down the total vacuum created by the engine, if you do not restrict the vacuum to the gauges it will overpower them and also cause them to fluctuate too much. So you have to have them.
On the 1500 you will need one adapter on the right side. On the left side you simply pull off the green vacuum hose and slide the tube from one of the gauges unto it. on the right side you have to take the screw(manifold plug ) out and install an adapter and then slide the tube from the other gauge unto it.
What I do not know for sure is the size of the adapter, I use a carb tune tool and it has a whole bag of adapters so I just pick one that fits. Would be a 5 or 6 mm but really do not know which.

Kit
 

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Kit,,,,,, Thank You for your patients and replies. You really cleared it up for me.
 

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I use only one gauge. I have only used ita few times. I talk about it more than I use it. Great conversational piece like here on the forum.

Two would be nice, but I am still saving up my money to get the second. Every time I almost have the money, I buy something else, ha. It is less useful than a tire gauge. At least the box keeps the dust off the glass.

The vacuumgauge can get pretty sensitive. The actual needle fluctuations can also be used to diagnosevalve train operation.There are manygauge illustrations in reference books.Sort ofsimilar to reading aspark plug illustrations..

The el-cheapo gauges have restrictors.
 

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And boy do they dance . I found myself increasing the rpm to calm down those needles. Finally I said that's enough, got my big prybar, opened the wallet and dropped a "C" note on the Motion Pro Carb Sync tool. Unless you've seen the restrictors, you'll never understand. Picture a conical metal plug with 2 holes @ ten thousandths of an inch. With the adapters that screw in to each vacuum port, it's worth every penny. If you wanna do the gauges, you need to understand how much vacuum you need to restrict. I didn't. That's why I bought the correct tool for the job. Being and Aircraft Mechanic, I'm kinda anal.
 

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Did some looking around and this one was posted here awhile ago so I saved it. It looks like it makes the job easy and accurate. What are your thoughts about it? Anyone have experiance with these?

TecMate CarbMate Carburetor Tester

And the price is right compared to others.

PS. I was also wondering if this would work on snowmobiles with Mikuni carbs??
 
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