Jump to content
IGNORED

If your carbs are out of sync, what symptoms?


Recommended Posts

Another symptom I noticed was noise. Because the power balance is off, at idle the engine shounds like the connecting rods are knocking. As the revs go up the engine can exhibit some nasty vibrations, some thing a V-Four shouldn't do.....

 

I also noticed the power curve was not very smooth. Low end torque was spotty, mid-range was a little better, and the high end seemed sluggish.

Link to comment
Share on other sites

OK - no hijack intended but what sync gauge is best? I know there are a couple - one from England (if it wasn't looted :bobby: last night) which is a bit pricey but probably worth the cost? And another domestic one a little cheaper. Thoughts???

Link to comment
Share on other sites

OK - no hijack intended but what sync gauge is best? I know there are a couple - one from England (if it wasn't looted :bobby: last night) which is a bit pricey but probably worth the cost? And another domestic one a little cheaper. Thoughts???

 

First off .... Most of them work quite well.

 

The Mogan Carbtune (the English one), was my first choice. It's not the cheapest, but it's decent and very highly regarded by many people.

 

I couldn't wait that long and I got a very good deal on a Motion Pro Manometer Style.

 

It works just fine.

 

The "gauge" style will be completely dependent on the quality of the gauges, and the good ones aren't cheap.

 

The electronic ones are expensive, presumably very good, but I'd consider that price to be overkill.

 

For what it's wort .... I have sync'd the V4 with a $25 vacuum gauge from Autozone. It's fiddly and time-consuming, but it can be done.

 

I have also used a homemade manometer, and very successfully.

 

Normal rules apply really .... Cheap tools can be useful, but can also be problematic.

 

I'd probably plump for the Morgans Carbtune, but I am quite happy with the Motion Pro unit.

Link to comment
Share on other sites

The main symptom is poor throttle response off idle. Also (as mentioned)--irratic idle / racing or stalling. I have a "Motion Pro" Mercury Tool that I've had for over 20 years. I paid $40 for it, but I think they are like $100 now. You definately want a tool that allows you to see all cylinders at once. One tip I could add is to shut the bike off and open the throttle wide a few times (then "drop" it closed) to properly seat the adjusters. I usually do this a few times during a sync. If you do this with the engine running you will get bubbles in the mercury tubes and will have to shut the engine off anyway.

Link to comment
Share on other sites

  • 1 month later...

When I noticed my carbs needed synced, I felt a roughness when cruising at highway speeds. I bought my sync gauge through a Goldwing website (Saber Cycle) that also sells them on eBay; it costs about $55 and comes with the 5mm and 6mm adapters for other bikes. It uses mercury and can do up to 4 carbs. It worked good for me.

Link to comment
Share on other sites

I noticed my out of sync condition most severely at idle...popping, unsteady idle, bogging off the line, generally running like crap.

 

If you think about it, idle is when you get the greatest relative difference in airflow through the carbs if something is out.

 

A small change at idle means a big percentage change relative to the other carbs.

 

That same small change at full throttle won't have nearly the effect.

Link to comment
Share on other sites

  • 4 weeks later...
The main symptom is poor throttle response off idle. Also (as mentioned)--irratic idle / racing or stalling. I have a "Motion Pro" Mercury Tool that I've had for over 20 years. I paid $40 for it, but I think they are like $100 now. You definately want a tool that allows you to see all cylinders at once. One tip I could add is to shut the bike off and open the throttle wide a few times (then "drop" it closed) to properly seat the adjusters. I usually do this a few times during a sync. If you do this with the engine running you will get bubbles in the mercury tubes and will have to shut the engine off anyway.

 

I made a homemade sync tool for my V-star 650, but it was just for two carbs. So my next thought was that I will make a 4 carb set-up for my RSTD. But I started reading the directions in this forum and realized that the proceedure is for balancing Carb 1-2 and then 3-4 and the final proceedure was 2-3 (this is to sync right to left).

 

So I gave it a try with my homemade job and it improved the way the bike was running (much smoother than the bike has ever been). I bought this bike about 2,500 miles ago and thought it was always just a little off.

 

It did take longer (extra 10 mins max) to move the hoses, but it seems to work.

 

It was really out of balance left to right. I'm glad I did not wait till I could get the extra time or money to get a 4 carb balancer.

 

It sure would be nice to have all 4 of them hooked up at once and I will likely make one.

 

But I guess the point is that if somone is one a tight budget or has access to a 2 carb tool then go for it.

 

It is important to note that the carbs that are not being measured need to be hooked back up :doh:.

When i went to 3-4 I forgot to hook up the vacuum line and plug on carbs 1-2. I wondered why it was idling so poorly. It was a lot easier once I hooked them back up. :hurts:

Link to comment
Share on other sites

Be sure to check your diaphragms for pin holes, I have the carbtune 11 and love it. it took about 10 minutes from setup to finish. the only problem it still ran like crap so I checked the diaphragms and sure enough they all had holes. I will recheck the synch after I get the new diaphragms.

Link to comment
Share on other sites

When I noticed my carbs needed synced, I felt a roughness when cruising at highway speeds. ----- .

Found this to be an interesting thread. Am intrigued by the range of symptoms reported. My experience is the same as for Heartbeat.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...