SonexBuilders.net

Hello All,
I just purchased a Onex Tri-Gear last month and have been looking over the aircraft and customizing to include a new paint job and scheme. Since this is my first experimental aircraft, I am being very cautious. I will need an hour or two in transition time in a Sonex and I am also concerned with the RevMaster 2300 engine in the aircraft due to the ease of the engine to misfire and/or foul plugs based on previous owners comments to me. Can someone describe start up, in flight and shut down procedures for this type of VW engine to include what I should expect as performance / reaction of the engine in balancing fuel/air mixture. Any tips for best performance would be helpful also. Would love to find someone that has a Sonex two place close to me willing to give me some transition time in their Sonex for a fee of course. I am so happy to have found a forum such as this to get real time information.
Thanks,
Dennis Wells
Ellijay, GA

Dennis. I am based near you at KLZU. Would be happy to show you my Sonex, give ride, etc.
Send email to buyeasy123@gmail.com.
Ron
Legacy Sonex 695, Aerovee

Dennis , I am helping a buddy with a rev master onex that burned a stator up. Long story short it appears he heavily fouled his plugs coming back from Oshkosh and in trying to start it over the course of 30 min of hard starting it finally took and he ran it at high idle to burn the fouling off. My suggestion would be to MAKE SURE you have to the two alternators on separate switches and only use one at any given time. Also if it becomes hard to start pull the s plugs and clean or replace if fouled. I would not continue to fly if it gets harder than normal to start without pulling plugs and I always keep a spare set in the plane for emergencies. My feeling on my buddies was that the fouled plug caused him to run his battery down and when he finally got it started both alternators were trying to dump their full capacity into the battery and it burned the stator up. Rev master recommended using only one alt at a time. We found this out after the fact

Thanks Ron for your offer to give me a ride in your Sonex. I will email you and hopefully we can talk..

Thanks Mark Whiddon for the information. The builder of my Onex told me he burned both stators up but he said it was due to excessive EGTs which I imagine could have been from fouling his plugs. He said that he thought it was from excessive climb rate at take off? I have a question into the builder if he had separated the alternators? I do know that he spoke with the Rev Master folks and they told him the same thing about separation. I have not yet got into the checking of systems as of today but hopefully start in the next week or two. I am very concerned with the plug fouling situation. I did notice that there is a metal shield that was wired to the top of the cylinder fins on both sides of the engine. This seems to me to prevent sufficient air to flow through all four cylinder heads to cool? What do you think Mark??
Thank You so much for your HELP!!!!
Dennis Wells
423-596-5752

Those metal shields are what I have on my Revmaster and are recommended by Revmaster in their engine manual. My CHT’s have never been a problem in climb or cruise.

David
N951X

David, do you have problems with plug fowling? The builder said to add an additive to the fuel to help with plug fowling. To me since I have always flown certified aircraft and had no problems with the Lycoming/Continental Engines, it seems the VW engine is just a bit like the 2 cycle ultralight engines where you have to monitor them constantly to keep them running. Or am I just making too much out of the engine characteristics.

Dennis

Dennis,

I have an AeroVee, but it's still a VW. In 400 hours of operation I have never once experienced plug fouling. You didn't say what type of fouling: carbon or lead? If it's carbon then your mixture is off, and probably running too rich. What are you running for a carburetor? If it's lead then you might try using TCP in the fuel. It's a lead scavenger. I have used it for my entire 400 hours and like I said I've never had lead issues anywhere in the engine. You add a ratio of 30ml of TCP for each 10 gallons of fuel. A single can lasts a long time, so it's not adding much to the hourly cost of running the engine.

Dennis, I’ve had no problems with plug fouling on my Revmaster 2300.

David

RE Rough running revmaster, we had a number of rough-running squawks with our Revmaster 2300. Below is my best recollection of them all, they may be nothing to do with your situation but it may give you some ideas.

Early on the engine always seemed hard to start and after first flight we had a good look at the engine as it seemed to be not running smoothly particularly at low RPM. We looked at plugs and they were OK. We eventually found that one of the 2 hall effect sensors was damaged when a magnet had come loose after a retaining wire broke on the little timing wheel. We had an early 2300 and Revmaster had redesigned the timing wheel with glue holding the magnet rather than wire and sent us the upgrade at no charge with a replacement hall effect sensor. No problem since with the timing wheel but that did not seem to actually cure the rough running or starting issue. A switch to 100LL seemed to help but not cure the problem.

It turned out to be timing advance..... The mark on our prop flange showing advance was not in the correct location causing the timing to be a bit too advanced. We determined and marked correct position on our prop flange when we took the plugs out to check for fouling as we could observe the motion of the pistons position with a plastic rod held through the spark plug hole while the prop was turned by hand. The Rough running and hard to start problem was resolved. It started fine ran much much better although I would add EGT was noticeably uneven in flight.

After 20 or so hours we experienced a new intermittent rough running issue on an away flight but we did make it back safely to the field. Before each flight with engine at idle we test earthing each of the 4 ignition circuits and sometimes that showed one of the redundant circuits was not working (engine rough running) which led to a return to the hangar and much head scratching. The revmaster 2300 electronic ignition is attached to the back of the engine by 4 machine screws. We sent the ignition box back to Joe at Revmaster a few times and he could find nothing wrong! We ended up connecting a big earth cable from the ignition box itself to bat negative as we suspected the machine screws were not a great electrical connection. This seemed to do the trick as the issue went away and several months of enjoyable flying were had. At this time we also put in a fuel/air ratio sensor and went for the ROTEC carb which has improved our EGT with almost no differential in EGT left and right. We are able to set the mixture exactly right in all modes of flight with the fuel air ratio sensor and this helps manage temps too.

After 120 hours or so we started experiencing intermittent rough running again very similar to the 20 hour issue. earth was good so we decided to go for the upgraded Revmaster printed circuit ignition. We found this new unit to skip at high power and individual circuits did not behave correctly when earthed so we sent the unit back to revmaster and they found a manufacturing fault where some connections were not made correctly. Although Revmaster fixed the problem we decided to go for the SDS ignition instead. A friend at our airfield has just done his first flight in his Revmaster 2300 Sonex with SDS ignition and we are impressed with the quality and programming capabilities with the SDS unit. A few lycoming powered RV-6 at our field have the SDS ignition. We feel that this critical bit of kit needs to be of the highest quality and reliability, given our history we just didnt want to play with the Revmaster ignition any more. We really like the engine mechanically, but we are not a fan of the standard ignition system.

Good luck with your Onex! Once you get the revmaster right its a great match to these airframes.

Szabo

I would like more information on the SDS ignition as used in the Onex or Sonex. Do you have access to pictures and installation information that you can share. I also have a Revmaster 2300 in a Onex with the electronic ignition plate back at Revmaster for evaluation. I would like to pursue a plan B if Revmaster cannot fix my problem. Thanks for your help.

Paul