Kai Lyche

What "uninstall"? The lch' s are still sitting there! Very happy with them, save for the slight lubeoil spill past the rocker shaft orings ☺️

Guys: This is not going anywhere! All I did was asking for advice on how to properly seal my rocker shafts :-( Avocet; I can see from the picture of your installation that the bottom of your rocker boxes are perfectly dry without any oil spill- so what did you do? Thanks

Viton- yes, of course! I have a feeling the problem is not so much the orings: it´s more their installation. In order to seal properly they are made a VERY tight fit: so tight in fact that I think they get damaged during the installation process when the rocker shaft with the installed oring is inserted into the head. A little material is shaved off the oring surface. The manual says to install the shaft with "a twisting motion". Maybe I am not twisting enough :-(

I for one am one happy user of the LCH´s on my (previous broad finned head) mech lifter 2200A. From the production # it is evident that my heads were manufactured sometime in late 2013. I was forced to make a choice between new aircooled narrow finned Jab heads and LCH when I due to plain ignorance overheated my two rear heads during ground running and they went "plastic". Pricewise the LCH conversion kit from Rotec won hands down, as it turned out I would have to substitute my heads with the newer narrow finned ones. Another reason for making this swap was an intense desire to reduce the possibility of detonation. A "happy user" does not imply that everything was initially plain sailing with these heads. I went through the first ordeal when I test pressurized the cooling system: the connector banjo´s on top of the heads refused to seal properly. I am embarrassed to admit that it took a while before I discovered that I had installed the banjos upside down :-( Things perked up after this! Still with comparatively few hours on the LCHs (apprx 50), mainly due to dismal winter weather (I HATE those stories of beautidul flying weather that always seems to prevail both Down Under and in the US), the next issue was lubeoil leakage due to worn o-rings on the rocker shafts. It turns out that center groove for the 1/4" capscrew intended to lock the rocker shafts in place, is too deep: the shafts were oscillating along with the rockers and could not be kept still. Substituting the capscrews with others having an unthreaded part, solved this- but not the entire oil leak: the orings still wear out or flatten or soften up, or whatever. Presently the leak is just annoying and I have a program going trying to introduce some super sealant as well in the oring grooves. If that does not help I will substitute the shafts with 12mm diam close tolerance bolts, using bolt head and nut as a positive sealing surface. BUT the heads are cooling as advertized. Very seldom I have as much as 90C on the cooling liquid and 120C on the cht. A far cry indeed from the previous 170C on the aircooled heads.

Yes- I agreee: they should. Unfortunately, Jabiru in Bundy, their overseas distributorship, their service reps and what have you, have gone either deaf or mute or both. At least on me; I´m probably a pariah as far as they are concerned :-( Come to think of it, they actually have come out with some statements; their service bulletins suggest that we take an engine which has yet to turn the 200 hour mark, ship it to a workshop they approve and rebuild it with a new crankshaft and flywheel. This is so expensive that we are better off carefully cleaning the thing and using it as a fresh water boat anchor! Then our opinions correspond! We have already on another forum been through the mod developed in NZ, with the steel flywheel boss and crush plate. If nothing else turns up in a very short while, I´ll probably go down that road.

We were explained that the moment you put mogas in an unsealed container (your aircraft fuel tank), things start to happen. Lighter fractions (octane enhancing ethanol) start to evaporate, it draws moisture from the air, phase separation could start to set in quickly etc etc. Rather quickly the octane rating is not what it was :-(

If not an engine killer, at least it brings the planes down. I have 6 documented cases from 2014. No fatalities, just a few bent aeroplanes. The norwegian terrain is very rugged; mountainous and heavily wooded. Pilots are instructed to always plan their course in such a way that they could take the plane safely down when the engine stops. Because it will stop. Now, if you ask me how we cope in winter when all landable fields are covered in feet of snow, I will probably stare at my shoes and scrape them in the gravel :-( You just have not lived before you have experienced the plane overturning in a snow field on landing. Getting out of the plane is a question of motivation- and the smell of dripping mogas is a great motivator!

Yes, It´s a tight fit for sure. But should you in addition run your otherwise standard off the mill Jab on these "iridium" plugs, it really makes your day to see your Jab idle smoothly at 350 rpm: it will make you smile for days on end!

Buy your mogas from a high turnover pump station, use it immediatly, don´t leave it in the aircraft tanks or any other ventilated container for that matter subject to conditions that cannot be controlled.

Interesting! We in the NLF (Norwegian Airsports Society), where I am chairing the technical committee of the microlight section, specifically instruct our members to purchase their fuel exclusively from pumps with an above average (high) turnover. That way we hope to avoid fuel which is out of specs. I´ll be the first to admit that hoping just is not good enough, but I can´t see what else we could do. And I would like to emphasize that the fuel is not neccessarily dud after 6 weeks; the oil companies just say that they will not warrant the octane rating after that because long time pump tank/end user storage is beyond their control.

Not, not really- but just before x-mas he was unlucky enough to be the focus of one of my frustrated outbursts. That was when he mentioned he was working on a new flywheel hookup. However, he told me to keep it under wraps- to which I agreed. Overall, it would probably seem reasonable to assume that australian mogas is even lower on the quality scale than the stuff sold here. After all, in winter the whole car population could feeze up to an immecdiate standstill if there should be too much water in the fuel. Still, we are very carefull not to leave mogas in the tanks during winter periods of inactivity- the spectere of a lump of ice in the tanks is always with us. Up here EFI is seen as the solution to all our fuel related problems. There is one company specializing in this (Edgeperformance), and recently I was told some 90 kits had been sold worldwide; mine and around a dozen other Jabs among them. The rest is R912. Kits are very complete, but of course on the Jab the induction pipes have to be shipped to his shop for welding of the injector bosses (hardly worthwhile living in Aus) While there is a slight performance increase (not much), the engines run much smoother with even egt´s and no more fuel related problems.

Oscar, Anything is welcome! I am well aware of Ian´s plans concerning the flywheel attachment and I am sure it is going to be a good, solid, permanent fix. However, I am scared stiff our national CAA could act on the CASA paper any moment now. Should they start to investigate, no doubt both the flywheel and the through bolt issue will emerge and, reasoning like all other CAA´s in this world (flying is not neccessarily dangerous, but it could kill you), they are liable to stob Jab flying up here- 40 airplanes grounded! I just can´t have that; I can´t wait for Ian´s development to materialize and must be able to present a sound solution to the problem, preferably yesterday. We have a regional distributorship for Jab up here, and how I wish they would shoulder some responsibility, however, no go (what else is new!). Consequently this falls on little me :-( A bit kinder? As I write I have minus 15 centigrades right outside my window. The snow throwers are going full blast everywhere to keep mother nature at bay- in vain of course. Believe me; there is nothing kind about this. Our mogas, which we are presently forced to use because 100LL is rapidly disappearing, is a can of worms. We have summer fuel and winter fuel. Some northern areas are cold in the extreme (minus 42 centigrades the other day; yes- the kids STILL play outside), so they have a special fuel quality. Phase separation is a constant threat, we are running a neverending battle with at least 5 and often 10 % ethanol in the fuel, and the oil companies will only warrant their product´s octane rating for 6 weeks once it has left the distributor hubs (not the fuel pumps, mind you). But, it is comparatively water free (!) Common to all types is that the vapour point is nothing to boast about, and we were sorely plaged with vapour locks, lean running, detonation and what have you during the laughable short period we call summer. However, we saw this one coming and were somewhat prepared. As a curiosity, the Jab engines with their low mounted carby and lesser chance of heat soak, were far less affected than the R912 fraction (justice, for once!), which were really struggling. Many of these installations will only be able to solve the issue permanently by getting rid of the Bing things and hanging on some kind of EFI system. Something else to consider is that light aircraft flight instruction is solely carried out in flying clubs- the moment we go commercial the intensity of this activity would increase dramatically- then we would see the split crankcases! The broad finned heads were something else again. During maintenance and head bolt retorque compression ratios would habitually rise ever so slightly as the cylinder sealing surface slowly embedded into the now "plastic" heads. This, in combination with poorly understood princioles of air cooling by both aircraft manufacurers and individual builders (not the engine´s fault for sure), has forced quite a few head replacement issues. I am told the new narrow finned heads are a boon- but so expensive! The Rotec LCH´s seem to offer the best of both worlds- with some added complexity. Cheers Kai

Well, The CAMit generator has been on the engine for some 5 hours now; not nearly enough to draw any conclusions of course, but as they state on their website- the engine just feels different and I am full of hope. However, until winter releases its grip on this country (global heating is a great disappointment to me!), I will not be able to report on any development. Nevertheless, while I am happy, the others with this flywheel bolt issue are not, and with this rediculous thing from CASA hanging in the air and just waiting to hit the desks at our national CAA, I just cannot risk that one of the engines throw a flywheel (mysteriously, we have not had any through bolt issues). They will surely ground the rest of the fleet immediately. Just to emphasize; my only experience with this flywheel bolt thing is the 5/16" no dowel version. The others, i.e 5/16" with dowels, 3/8", 3/8" with dowels, 3/8" with dowels and starfish (when will we have the octopus?), I know nothing about. Let it be known, for the record, that in 2004 I visited Jabiru, Bundy. Phil Ainsworth was very kind to show me around, including the machine shop. That was before I had my 22A airborne. After the issues started to pop up: nothing, nada- niente! Apart of course a request to turn in the engine nameplate as it could no longer be considered to be a Jabiru. Surely, it is not a Jab any more, but before 2010 it was as standard as it could possibly be, and running itself to destruction. I will not deny that presently, with all my mods and power upgrade, I might be helping- but so far it is still in one piece. Imagine my complete surprise when I got in touch with Ian Brent at CAMit. They actually act like normal, communicative, socially trained humans in this company, responding politely and swiftly to queries and suggestions, helping to solve issues, keeping their promises; you know- like the rest of us. I am convinced they will be able to get this thing back on track, given some time. Kai

Greg, Thanks. Several of us are struggling with this issue now. Why now and not much earlier, is a mystery. The engines concerned must be 2003-2008 vintage or thereabouts, all fairly lightly loaded with well balanced wooden props and no prop extensions. Still, when failing, the engines are well below 500 hrs TT. Norway is very much Rotax country, so the total Jab population is fairly small- maybe some 40 engines. And with Sweden and Finland altogether 90 units. Not very much on which to base statistics. However, not many of us consider the Jab an inferior engine. True, it is overly sensitive to installation errors of all sorts and they have had their fair share of manufacturing deficiencies. The worst is probably total absence of anything from the lot at Bundy. On my own 4-banger I have installed liquid cooled heads, forged pistons, fuel injection, longer and stonger through bolts (!), the 40 Amps CAMit alternator plus plus, and I seem to have it licked save for that awful flywheel attachment joint that keeps on failing the bolts. Presently I know of four other engines in this country with the same issue. Unless you can tell me some horror story I am going to recommend the installation of your mod, which I believe should be fairly easy to manufacture locally, jus like you did. I see you used ARP bolts. Do you remember to what torque you set them? Regards Kai

Hm, You may know that there has been a lot of discussion on the Yahoo Jabiru engine group lately about the 5/16" no dowels flywheel bolt attachment. It seems that the rest of the world is finally catching up with the situation experienced in NZ a while back. So far the only promising solution I have seen, is the flywheel steel centre boss/crush plate you developed. The interesting thing for me right now is how is it holding up? Any more related problems? This particular solution was engineered for the 6-cyl: have any been installed on the 4-cyl as well? Any operational and/or maintenance experience? Thanks Kai

Yup, On the other side of the globe- Norway to be exact. Chairing the Technical Committee in the Norwegian Airsports Federation, I am keenly interested in the work some of your members has done on Jabiru engine mods- specifically the flywheel attachment to the crankshaft of older engines. Kai