I got into gyros about 12 years ago and have been attending the major fly-ins at Mentone, Bensen Days and Wrens every year since then. I have never seen more 912 certificated engines than non-certificated. Any engine that is non-certificated is an alternative engine, be that what it may - Rotax included.
But let's lump those non-cert Rotax engines in with certified. Are we going to claim the Rotax 2-strokes are just as reliable and maintenance-free as the 4 strokes? I don't think so, the discussion is aiming at the 912 series and you draw the line with all Rotax 912/914 engines as being the premier choice and that there are far more of them than the other so-called alternatives.
Looking at all of the gyros at any major fly-in we do not count more Rotax 912/914 than alternative engines. The ratio is usually 8-to-1, if that.
You mentioned elsewhere you personally know of the an engine seizing and a Rotax C gearbox failure.
First, I am not aware of the seized motor you refer to, please elaborate as we would all like to understand this incident better. I have a question - or several - for you:
Did he have enough oil in the tank? Did he have the proper type of oil in the tank? Did he run the engine on pump gas - like it's supposed to run with synthetic oil - or did he run a lot of 100LL in it? How long did he go between oil changes? Who owned the engine before him? What kind of oil filter did he use? Did the oil filter fail get plugged up and stop oil flow? How many miles were on it in the sled before the engine was removed? Did the sled ever turn over, or get crashed? What kind of oil tank was he using, an after-market type or the stock one? Did he have the crankcase properly vented? Let's move on to cooling: What kind of radiator? What configuration was the cooling lines? Did he have the thermostat routed properly and did he use a suitable "T" fitting downline of it? Did the radiator have proper airflow? Pusher or tractor? Did he run it low on coolant?
Don't sell assumptions, sell facts - and have them all on the table before making claims such as that the "known" Yamaha failures you are aware of are a significant account of the percentage of flying examples.
Let's consider a REALLY HUGE difference in comparing any Rotax 912 series engines to the Yamaha alternatives. In your own opinion people buy them because they are cheaper. And not by a little, but by a whopping huge difference - as in you can buy two brand new 150HP Yamaha sleds and gut the engines from them for the price of a single new 115HP Rotax 914. But (again in your own words) people don't spend the money to buy new Yamahas. They have always - to date - bought used engines, most out of salvage shops with no license, no aircraft reputation whatsoever (except Mohawk and Skytrax engine sales).
Abid: how do you, or anyone else for that matter, quantify the reliability of an engine if you/we know absolutely nothing about its previous life in the snowmobile? Hey, guys crash those things, and hard - like into trees and other vehicles on the roads, and die. Those sleds get salvaged after being bought from insurance companies, etc. Impact damage can severely affect an engine. How about something much more mundane - like a guy turns over his sled on a steep sideways slope, rolls the thing over, and it sits there running inverted starving the top end of oil for several minutes. Suppose he quickly sells it to some unsuspecting shmuck, who guts it and sells the engine to a guy who puts it on an aircraft.
With a 912, its pretty easy to determine that the thing was used in an aircraft, and maintained as such. But no matter, in the used engine world it is always, "Buyer beware."
What I'm getting at here is that if you are going to compare a new Rotax to a used Rotax, which one are you going to consider more reliable?
If you are going to compare a used Rotax 914 to a brand new YG4i, are you still going to think the Rotax is the better choice?
Second, if you are going to cite gearbox problems, shouldn't we be quantifying that as a separate issue since there are MANY alternatives to the choice of what I, myself, consider to be a inferior gearbox for use on a 150HP Yamaha power plant - one which I have never used on one of my own Yamaha conversions? I sell adapters for them, and one customer has installed it with a Rotax C box simply because it fits under his cowl w/o modification. He did not do so on my recommendation.
Did this gearbox failure you refer to result in a forced landing? What other circumstances were involved in the failed gearbox - could it be that the gearbox was assembled incorrectly and that thrust washers were in the wrong place on the shaft? In other words, isn't it possible that this - again - was an installation issue, and not a problem with the mechanical reliability of the power plant?
Moving on, in my mind, there is more than one thing to consider when looking for an engine for whatever it is I am going to use it in: 1.) POWER. 2.) RELIABILITY. 3.) COST.
In that order. I am all about hotrodding whatever it is I am flying or driving. That's what I do, it has always been in my blood. Rotax doesn't fit my life-long agenda because it is too low on power, and once you do anything to it to make it produce more power it blows up too easily. Return on investment isn't there.
There isn't a single Silverlight, MTO, Cavalon, Magni, etc. that can come anywhere even close to the performance that comes with any Yamaha-powered gyrocopter, bar none. And if you think for one minute that simple engine, or even gearbox, failure is the only cause of gyroplane accidents, you can rethink your argument. We've all seen the video of the MTO trying desperately to take off with a passenger, only to crash shortly after takeoff obviously due to insufficient power. There are others. Somewhere on here there is posted a list of Rotax engine failures documented as engine failures, not installation mistakes. There are plenty enough to prove that Rotax is not any different than any other engine when it comes to failure.
If you really think think that the only reason people look to a Yamaha "alternative" because of cost, you are mistaken. This is obliviating the fact that STOL FW fliers are selling their ROTAX 912/914 engines left and right in favor of YAMAHA power. No Rotax can come close to the power advantage of any Yamaha, be it a YG3, YG4, or YG4i - and we are only just getting started. Pretty soon we are going to have blown Yammies flying the pants off of these aircraft at 200+ HP. We already have NOS tweaking the power 15% for STOL competitions - and these aircraft are regularly flown in the mountains, and from Idaho all the way to Oshkosh and back every year.
Where do any of you come off telling people on this forum that Yamaha power plants are unreliable, untested, unproven? Get your heads out of the sand, they have been flying for ten years and this is all you have to back up your claims that Rotax is more reliable than Yamaha - a gearbox that was found on ground inspection to have a burned bearing and some guy seized an engine in an otherwise undocumented incident that no one else in the world seems to know anything about?
Tell me you know of even one Rotax that makes 150HP reliably - all day long. Ain't gonna happen, dude.
People are turning away from low-powered Rotax engines, plain and simple. Not all, just the ones who don't agree that Rotax is the end-all to the conversation regarding choice.
Yamaha has proven to be every bit as reliable as Rotax while delivering incredibly more power, +50HP, at comparable weights and 1/2 the cost. You write of one engine seizure and then claim this is proof to substantiate some biased proclamation that Yamaha less reliable - even dangerous - as compared to Rotax?
Give me break, everything I've read here is far from any well-backed, expert opinion in any circle, at any time, regarding any choice.
You admit losing customers who don't want under-powered aircraft, Abid. Sounds just plain stubborn, perhaps you could re-think your strategy: Instead of considering a used Yamaha on one of your air sleds, why not consider a brand new one? You actually think this would cheapen your product line? I can't see how, and there are a LOT of people who will agree with that.
You would rather use a 300# Lycoming 150HP engine instead of a 165# 150HP engine on your new SBS because you're stuck in a mind set that refuses to let go of convention that is now outdated, and becoming more so every month Mohawk and Skytrax are in business.
This all boils down to opinion, as there are NO SUBSTANTIAL FACTS to back up any claims that Yamaha is less reliable than Rotax 912/14. Yamaha is without a doubt by now proven, by any standard. People here all opine, all go with what they think they know, and understand, and hearsay, from other folks. It is like any lie - tell it long enough and pretty soon it becomes the "truth".
OK, so no problem - leave the Yamaha market to the rest of us, we really don't mind. For every customer you turn away, Abid, who comes to you and wants to power the gyro to 150+HP at same weights as an anemic 100-115HP Rotax which is absolutely no more reliable and costs twice as much, we Yamaha guys get one more customer.
The future will tell the story, not the past and all of the Rotax engines ever sold combined since many decades ago. I look at it this way: OK, so yeah, Ford has outsold Porsche over the years. It's been in production far longer, too. But Porsche don't give a rat's ass. They still build and sell cars to the people with an eye to what they offer, still win races, and are every bit - if not MORE so - reliable. They don't sell as many cars, but ask them - and their customers - if that is what matters most.
