MK4 engine choice?

[LCB 0]

I’m new to the group. Sorry if this is redundant. I’m buying an Avid Flyer Mk4. It has a Jabiru engine that is bad. Looking for options. Can the airframe handle 115 hp? Having built an RV-9A, I’m aware of common sense limitations. 
thank you!

[ChrisBolkan 130]

Try and fix the Jabiru?

Go to a 912?

[1avidflyer 1983]

What is the issue with the Jabiru engine?  I put about 600 hrs on a Jabiru engine in my Avid MK IV.  What serial number is your engine?  I've seen these engines used on sale for $4000-5000 occasionally lately.  The Jabiru would be the simplest fix most likely.  912 will give better performance, but hard to find a mount, and it does move the CG forward on an already nose heavy design.

[derekbfly 0]

Are you looking at the one listed on Barnstormers for 15K

It says....

Engine is a Jabiru 2200a Serial number #165 with about 650 hours since new. The engine runs great, but we had a bad leak down test. The engine will at least need one new head. (Very hard to find)

[LCB 0]

That is the one

[1avidflyer 1983]

The very early Jabiru engine had cooling issues.  Rotec in Australia (not Rotax)  makes liquid cooled heads for the Jabiru engine and that seems to be a good remedy.  Not cheap though, about $3000 for the 4 cylinder engine.  Are you sure what is causing the loss of compression?  

[derekbfly 0]

I enquired about the plane and he said someone is coming to look at it and he thinks they will buy it

I saw 2 Jab engines on Barnstormers one is the 2200A for 4K and the other is the 3300 gen 1 for $3400

 

 

 

[dholly 718]

Flown a Legend Cub on straight floats with a 3300. It would be too much even on a stretched Mk4, IMO.

[derekbfly 0]

Ive seen a couple of 912's on craigslist for good price

[1avidflyer 1983]

912 has lots of power for an Avid.  Harder to find an engine mount for it though.  Also, requires about 10 lbs of weight in the tail for CG purposes.  Those that have them like them.   JImChuk

[ChrisBolkan 130]

They do require 10LB min in the tail with 912! Could be tools or battery though so doesn't have to be dead weight. I even have 10LB in my Fat Avid tail with the 912. That said I have no complaints whatsoever with the 912 once I put a slipper clutch and high torque starter on it. Before that I was plagued with issues, but I have an older S model engine. After the slipper clutch and high torque starter the engine has been a dream.

[AvidJack 26]

The easiest way to go would be another 2200.  You can pull the service manual off of the Jab web site, and at the very end it will tell you what the changes were by serial number.  You have an early serial number, which would be the old J-head cylinders.  Good news, they didn't overheat as much as the later models- mostly due to the fact that they didn't make the (advertised) power, coming in at around 55 HP, according to the certification of the engine in Australia.  SN165 had a checkered past, but the really bad issues with the early engines were taken care of- the aluminum rods and early crank were replaced, along with the early block.  It still retained the old heads, and the smaller carb. Those heads are hard to come by, but not totally impossible.  Note that the prop was sized for the lower power engine, you'll need to replace it with a repower. 80 hp would make a *really* nice mk IV.

If you do go with an earlier jab (2200a), get a serial number as close to upper limit before they went to the hydraulic lifters, as per that service manual, or try a gen 4 model. It shouldn't be too hard to switch to a 912 series, the cowling would have been stretched to fit the jabiru,, but measurements would tell the tale.  I wouldn't be surprised to find a bit of weight back by the tailwheel to counteract the jab installation. Plumbing in a radiator would probably necessitate removing any fairing work under the gear..

Jack  Austin, TX

[Philip 0]

Jabiru, Australia has a good supply of parts. I just bought new barrels for my A Series 2200.

I run Rotec water-cooled heads which I love but it does require fitting pumps and a radiator which is a big job.

Were I to do it all again I would purchase a brand new Jabiru as they have alloy barrels that cure many ills and the price is amazing compared to a Rotax.