Carb Sync Equipment

[GrassStripFlyBoy]

I'm at point of wanting to check pneumatic carb sync, and will need to invest into a gauge set up.  I see Spruce sells electronic "Carbmate", and a twin dial gage.  Rotax Forum video showed a dual needle dial gage, I kind of like that one.  Also, don't see LEAF selling anything in these offerings.  So, what's the preferred tool for the job here.  Looking for the right / best selection, not the cheapest way out.  Thanks, Darrell

[Tip]

If you don’t want to spend a bunch, eBay has dual units for motorcycles. Make sure that you put isolator valves in line. I pegged my first set and ruined them.

[GrassStripFlyBoy]

I trolled eBay and had noticed them, and I don't need a case / brackets / and unnecessary bits.  Have enough oddball hoses I could set up rig with just buying the gauges and valves.  Are you happy with how they've worked?  

[Jacques]

Darrel

 

you can have a look at this

I have good result with mine

https://www.leadingedgeairfoils.com/carbmate-carburetor-fuel-injection-throttle-body-synchronizer.html

 

 

 

[Tom Baker]

I like my dual gauges, but have never tried a Carbmate. 

[Warmi]

I have been using CarbMate as well. It is easy to hook up and use but it is hard to figure out which side is out of synch and what needs adjusting.

[Tom Baker]

35 minutes ago, Warmi said:

I have been using CarbMate as well. It is easy to hook up and use but it is hard to figure out which side is out of synch and what needs adjusting.

That is why I like my gauges. At a glance I can tell which carb I want to speed up or slow down, and a quick idea of how much change needs to be made.

[DHeal]

I use the twin-gauges style on my 912 ULS and find it easy to use and decipher.   Another possibility is to find an old but accurate twin-engine aircraft manifold pressure gauge.

[ct9000]

I use a Carbmate and find it easy to get very accurate results but it is probably better to do the mechanical balance first and then fine tune with the Carbmate. They are not that cheap but well worth the money.

[ibjet]

I bought just the duel gauges from Lockwood Aviation. When I figured out that you have to restrict the airflow volume to the gauges (with the little 90 degree on/off valves) then it worked fine and easy (before that the gauges were swinging wildly). I made a little bracket that I could clamp to the flange on my air cleaner box and that holds the gauges up where I can see them from inside the cockpit. I just took a picture of it in the box. Thought I had a picture of it all hooked up. I just looked on the Lockwood site and they do not show any hoses. Hmmm, I'd call I guess.  

[Tip]

This works just fine. You do need some poly tubing to adapt to the crossover tube.

https://www.ebay.com/itm/2-Gauges-Carburetor-Synchronizer-Carb-Vacuum-Sync-Tuner-Tool-Fit-For-Motorcycle/174211886130?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D225074%26meid%3Da8fec906e27a431a8b431f3f3d6a959a%26pid%3D100667%26rk%3D1%26rkt%3D8%26mehot%3Dnone%26sd%3D174211886130%26itm%3D174211886130%26pmt%3D1%26noa%3D1%26pg%3D2334524%26brand%3DUnbranded&_trksid=p2334524.c100667.m2042

 

[GrassStripFlyBoy]

I'll go the twin gauge set up with something off eBay, thanks fella's.

Was out yesterday and engine ran normal, but when throttling back slowly between 5k down to 3.5k or so I thought it might be tiny bit rougher than normal.  One of those moments where you question is it always like this or did something change, very slight - but thought I need to get balancer anyways and might as well check it out.  

[FlyingMonkey]

I use a Carbmate, takes about ten minutes to do a sync.

[GrassStripFlyBoy]

Curious what is the interval you go between checking balance?  I suppose with plenty of hours behind a Rotax one learns to recognize this.  Until I get to that level of understanding I'll confirm with test from time to time, but wonder how often this is performed as a general guideline.

[FlyingMonkey]

41 minutes ago, GrassStripFlyBoy said:

Curious what is the interval you go between checking balance?  I suppose with plenty of hours behind a Rotax one learns to recognize this.  Until I get to that level of understanding I'll confirm with test from time to time, but wonder how often this is performed as a general guideline.

I usually check it in the spring and fall, and re-check if I sense any roughness.  That has worked for me for a few years.

As an aside, the last two times I checked it required no adjustments.  Sync usually won't change if nothing is disturbed.

[Tip]

2 hours ago, GrassStripFlyBoy said:

I'll go the twin gauge set up with something off eBay, thanks fella's.

Was out yesterday and engine ran normal, but when throttling back slowly between 5k down to 3.5k or so I thought it might be tiny bit rougher than normal.  One of those moments where you question is it always like this or did something change, very slight - but thought I need to get balancer anyways and might as well check it out.  

Make sure that the holes in your balance tube are inside the air filter box.

[FlyingMonkey]

9 minutes ago, Tip said:

Make sure that the holes in your balance tube are inside the air filter box.

Yes!  I wrapped a bit of bolus tape on each tube to catch the airbox grommets and keep the holes where they belong.

[Tom Baker]

I would check mine anytime I wanted to adjust idle speed, or if it felt a little rough. One indicator that I like to use is the throttle lever. If you are out of balance it will develop a resonant vibration. As far as doing the balance on a CT I do them by myself. I set the parking brake, and stand outside the airplane and reach in to the controls. Sometimes a lot of starting and stopping the engine, but if it is not far off or checks okay it goes pretty quick. I just pull the top cowling, but I secure the bottom with a bungee cord connected to the front 2 cowling fastener sockets then wrapped around the gearbox. This keeps the bottom cowling secure. With practice you will know which carb to adjust based on desired idle speed and readings on the gauges. 

[GrassStripFlyBoy]

Appreciate the inputs, will be checking out things shortly.  Regarding idle RPM I think mine is near 2200.  I saw on Rotax forum that higher RPM is advisable for preventing gear box wear issues, but also wonder if dropping it down a bit might be nice for less trust during taxi & landings, I can always feed in throttle for higher RPM at warm up time and bump up as needed.  Thoughts here?

[Tom Baker]

I always try to set idle speed at 1750 to 1800. Some even say that is to high. When most of the CTSW's were new they were delivered with the idle speed set in the range you are talking about. 

[Tip]

1800 RPM for idle. You can almost hear the difference in gearbox rattle from 1790 to 1800.....

[GrassStripFlyBoy]

Went over the whole plane with a "nut & bolt" routine.  Balance tube secure and centered.  Noticed one exhaust had both the nuts securing the flange to head a little loose, could wiggle the header pipe a bit by hand and saw the flange moving too, so torqued them down back snug, probably not enough looseness to amount to anything - but nice to inspect and confirm.  Also noticed when throttle is full idle position, the right side carb is full closed to stop screw, but the left carb has slight gap.  Swapped out that control cover I recently made with my panel project, the factory cover was the same result - so nothing to that.  Plan to adjust the RPM to 1800, correctly adjust the stop screws, and check balance when the sync kit arrives.  Appreciate the inputs from everyone, having fun tinkering and learning the Rotax.  It sure is a treat to pull the cowl and not be looking at a crudy, leaking oil, 50 year old Continental.  Wiped down and waxed the belly, that was the worst job on my old Cessna, cleaning grime off the belly.   

[Tom Baker]

When I did my initial Rotax training 13 years ago I was taught to not use the idle stop screw, but rather the airframe idle stop. The standard Rotax idle screw is attached to a flimsy metal bracket, and if you try and use the screw it will likely bend the bracket. When balancing the carbs back the idle screw off, and when done tighten it back down using a .004 feeler gauge to set the gap for a secondary back up stop.

[mchou83]

these are two toy we use to do the carburetors sync.

 

[Tom Baker]

10 hours ago, WmInce said:

Ideally, at the desired idle RPM, the idle stop screws should "bottom out" at the same point as the throttle lever, against the aft console cover stop point.

If the stop screws are bottomed out, but there is more travel left with aft movement of the throttle lever, then that's where damage (bending) can occur at the carb stop plate. Not ideal.

Bill, I was taught that when the lever was against the stop in the cabin that you wanted .004 of an inch clearance, or the thickness of a business card from the throttle arm at the carb to the idle stop. That would be almost touching, but not quite. I remember one mechanic that you know that back in the day if the carbs were balanced, but the idle needed to be adjusted down he would file the slot in the cabin so the throttle lever could come back a little further. You do have to back the idle screws off before you start making adjustments, then reset the gap when you are done.