Jabiru cold start kit

[Old Koreelah]

Some good news for people using Jabiru engines. This kit is inexpensive and it doesn't take long to install

 

I just found out how good it is. I always hand-turn the donk at least ten blades to get the oil flowing and check compressions. To save weight I use a tiny battery (Deka 120 CCA). It's getting old and weak and this morning could barely turn the engine over, so after the first couple of laboured rotations it looked like we were going nowhere. I made a forlorn 2nd attempt and she fired up. What a great improvement!

 

As Molly used to say: Do yourself a favour...

 

 

[Keenaviator]

I've put a cold start kit on my NOS 2200A because it has the early lower power black starter motor which used to really struggle in cool weather. It certainly works.

 

 

[billwoodmason]

I installed a cold start kit in my j230 9 months ago after having some starting difficulties. It made an immediate difference. It has started first go on every start since instillation.

 

 

[Paul davenport]

Yes same here starts well on Lh and cranks for some time on rh before starting . Now for something completely different has any one wired 2 cht probes to the one guage Lh/rh rear cylinder through a switch ?

 

 

[Jabiru Phil]

I repeat a reply to this cold start problem.

 

Over two years now and using NO choke, coldest temps not a problem by drilling out the choke jet size to 1.2 mm

 

She fires up after 6 to 8 revs.

 

I admit that I haven't seen the cold start kit in any aircraft.

 

Just saying that, this simple mod fixed my problem, no more hot water over the carb etc.

 

Happy chappie!

 

PHIL

 

 

[jetboy]

Yes same here starts well on Lh and cranks for some time on rh before starting . Now for something completely different has any one wired 2 cht probes to the one guage Lh/rh rear cylinder through a switch ?

I've wired 5 cht probes to one gauge

but you have to be specific about this

 

depends on the type of gauge

 

is it floating - with respect to airframe electrically?

 

or are the probes floating (electrically insulated)?

 

is the gauge powered / amplified or energised directly by the current from the thermocouple?

 

The switch must select both wires - from each of the probes

 

The switch must be a suitable low resistance type if the non-powered gauge type is used.

 

Seeing its a Jabiru we are talking about, dont have to worry too much about the cold junction, or the accuracy of the probes

 

 

[hyundai]

Some good news for people using Jabiru engines. This kit is inexpensive and it doesn't take long to installI just found out how good it is. I always hand-turn the donk at least ten blades to get the oil flowing and check compressions. To save weight I use a tiny battery (Deka 120 CCA). It's getting old and weak and this morning could barely turn the engine over, so after the first couple of laboured rotations it looked like we were going nowhere. I made a forlorn 2nd attempt and she fired up. What a great improvement!

As Molly used to say: Do yourself a favour...

Hi Old koree

I was thinking about cold start kit but the other day in the morning the batty was on the way out, I had forgotten to remove the intake foam plug. I hit the starter it struggled one turn then started boy did it run rich. Then after I thought if the engine has to turn at 300 rpm to create a spark how then did it start on just one to 2 turns.

 

Another thought the coils come off a Honda motor they don't have to spin a 2 two 3 hundred RPM.

 

I did drill the choke jet out to 1.2 and made a difference, so I am thinking is it not enough fuel or spark.

 

.????

 

 

[frank marriott]

Then after I thought if the engine has to turn at 300 rpm to create a spark how then did it start on just one to 2 turns.

Think rate of turn, i.e. speed of the magnet passing the coil, induced voltage, not RPM.

 

 

[Old Koreelah]

Interesting experience, Hyundai. I was told that the original Jab coils wouldn't fire unless the engine exceeded 270 rpm, but I reckon Frank is right: even one rotation should be enough, as long as the rotor passes the stator fast enough to trigger a spark. Seems like lots of people have had success with drilling out the choke to about 1.5mm.

 

Slightly related: recently I had Ignition (once active on this forum) dynamically balance my prop. During the process he noticed the poor idling. This had often resulted in the engine cutting out on late final. At his suggestion I replaced the plugs and reset the idle jet 1.25 turns out. It now starts more easily and idle is smooth down to 800rpm. No more swapping hands to restart the engine after touchdown.

 

 

[hyundai]

Think rate of turn, i.e. speed of the magnet passing the coil, induced voltage, not RPM.

I would hav to disagree so what your saying at 100 rpm it may have spark at 300 rpm it would have no spark.

 

Because when cold the jab won't start at 300 rpm. So what your saying cold 300 rpm jab won't start so put a half dead battery it will start. Next time cold morning a good batterie won't start I will try choking the inlet and see what happens. I will keep the forum posted on what happens. Cheers

 

 

[hyundai]

Interesting experience, Hyundai. I was told that the original Jab coils wouldn't fire unless the engine exceeded 270 rpm, but I reckon Frank is right: even one rotation should be enough, as long as the rotor passes the stator fast enough to trigger a spark. Seems like lots of people have had success with drilling out the choke to about 1.5mm.Slightly related: recently I had Ignition (once active on this forum) dynamically balance my prop. During the process he noticed the poor idling. This had often resulted in the engine cutting out on late final. At his suggestion I replaced the plugs and reset the idle jet 1.25 turns out. It now starts more easily and idle is smooth down to 800rpm. No more swapping hands to restart the engine after touchdown.

We must all agree jabs start excellent when hot.

 

 

[frank marriott]

I would hav to disagree so what your saying at 100 rpm it may have spark at 300 rpm it would have no spark.Because when cold the jab won't start at 300 rpm. So what your saying cold 300 rpm jab won't start so put a half dead battery it will start. Next time cold morning a good batterie won't start I will try choking the inlet and see what happens. I will keep the forum posted on what happens. Cheers

By all means disagree but it might be of interest for you to read up on how a magnet induces voltage into a coil - has nothing to do with temperatures although they do effect how an engine starts - simple AC theory - but whatever you're happy with. (Hint, has nothing to do with battery voltage only the speed of the magnet)

 

 

[JohnC]

When I bought my J400 (3300 engine) a few years ago I could never get the engine to start at anything below 5C (38F) without preheating the carb with a hair drier - tried every “old trick in the book” for starting cold engines to no avail.

 

Fitted the Jab cold start kit and problem solved, the engine always starts immediately within 1-2 revolutions regardless of ambient / engine temperature..

 

I also have a small (mains powered) 80W frost heater fitted under the cowl with an insulated blanket on top of the cowl during the winter, this makes for perfect starting with or without choke, and (more importantly) eliminates any chance of condensation forming inside / outside of the engine when in the hanger.

 

Bad starting “hammers” the flywheel bolts, and any condensation will eventually destroy the Jab engine internals especially if not regularly flown.

 

 

[hyundai]

When I bought my J400 (3300 engine) a few years ago I could never get the engine to start at anything below 5C (38F) without preheating the carb with a hair drier - tried every “old trick in the book” for starting cold engines to no avail.Fitted the Jab cold start kit and problem solved, the engine always starts immediately within 1-2 revolutions regardless of ambient / engine temperature..

 

I also have a small (mains powered) 80W frost heater fitted under the cowl with an insulated blanket on top of the cowl during the winter, this makes for perfect starting with or without choke, and (more importantly) eliminates any chance of condensation forming inside / outside of the engine when in the hanger.

 

Bad starting “hammers” the flywheel bolts, and any condensation will eventually destroy the Jab engine internals especially if not regularly flown.

Hi john

 

It would sound yours was spark problem we read all the stories of spark or fuel in my case it was lake of fuel.

 

The jab has the carb under engine so it has problem getting fuel up to the heads and the choke is a bypass jet.

 

Works great on a motor bike carb is right at the intake port. Jab say it must spin at 300 rpm to start is that to draw the fuel up to the heads or to creat a spark.

 

 

[facthunter]

You have two issues. getting fuel and having a strong enough spark. The "bypass" type choke atomises fairly well but works best with the throttle closed, and when richened up even more, does it better Since when one cylinder fires it will rotate the engine fairly well momentarily and the engine will usually catch and keep running the main thing is to have the RATE of rotation at just before TDC enough to cause a spark. When you crank a motor it doesn't turn at a constant rate. Under the effect of compression it slows up. The stronger the starter motor or the free er the engine the better this works. You could pull the motor through 1/2 a revolution at the right speed to "fire" a spark in theory. It's the rate it moves at the critical "phase" of rotation where the spark actually fires that matters. It's done by using "impulse" magnetos where they are fitted, and why they are so dangerous, as they will fire at almost zero RPM and when the prop moves a tiny amount, if it's in the right place. Nev

 

 

[JohnC]

Hi johnIt would sound yours was spark problem we read all the stories of spark or fuel in my case it was lake of fuel.

The jab has the carb under engine so it has problem getting fuel up to the heads and the choke is a bypass jet.

 

Works great on a motor bike carb is right at the intake port. Jab say it must spin at 300 rpm to start is that to draw the fuel up to the heads or to creat a spark.

Hi Hundia, before the cold start kit was fitted I increased the bypass jet, fitted new coils, experimented with the coil / flywheel gap, fitted new plugs, rotors, caps etc, however the cold starting was still unacceptably bad and especially worrying when away from my home airfield with a "stone cold" engine, the aforementioned did improve things however the engine still took several attempts with worryingly long cranking times stressing the flywheel bolts.

 

The Bing carb is standard fare on old "kick start" BMW boxers with a conventional ignition set-up and the crank speed is more important for a good spark rather than fuel draw. The cold start kit uses a secondary coil to induce voltage from the battery regardless of engine speed; you could "hand prop start" the Jab engine if the cold start coil had a live feed (Jab use the live from the starter solenoid secondary circuit) and if you were brave enough - i;m not.

 

Jab definitely got it right with the cold start kit as this eliminated the problem, and this is a common problem in the UK with Jab engines in the winter especially the 6 cylinder.

 

4 Jab engines at our airfield have the cold start kit fitted with no starting problems, 2 don't have the kit and these 2 are often difficult to start in the winter.

 

Only last week it was reported via the LAA that a 2200 engine suffered a failure of the starter ring gear shearing the bolts and detaching from the flywheel, this almost confirms my suspicions that the flywheel to crank bolt problem can be traced to bad starting.

 

 

[jetjr]

CAE were saying this for a while.