I have never seen a bushed XL series engine myself. I own the XL.25, .28, .32 all ball bearing engines. My experience with the stock bearings is that their not so high on the quality list. Mine needed replacing after a season or two. The BOCA replacements I purchased have been working quite well.

           I use mine for speed limit combat. Starting is incredibly reliable as these engines are generally true ABC. We use OS LA .25's for speed limit due to the fact that stock as is,  the LA runs the time required without issue. The Magnum though needs to have it's venturi really choked down because it runs much faster using the same fuel and prop. The .28 seemed to be easier to tame but I haven't used it much. The .32 is as powerful as a FP.40. and I really noticed no difference on the same plane using a 9x4 which was the only prop that would allow the plane not to exceed 75mph. The XL.25 fuel consumption was slightly more than the LA. I use about 2.25 oz's for a 5 min plus flight on the stock LA and I had to slightly increase my bladder compartment for the XL even though the venturi was choked down. I use a adjustable venturi which has a nylon screw to block it off allowing me more power if needed.

           The .28 has been one I haven't used much but it seemed a little easier to tame than the .32 for my needs. The weight of the .25 is up vs a bushed .25. The XL .32 share the same bolting pattern and weight is very close. I give the engine line a big thumbs up. Easy to run, good power and good economy. The XL line I believe is a bit outdated and the XLS series took over offering even more power. I do have a new XLS.25 which is slated for a new wing I'm building. The New England crowd uses the ASP engines which are really the same engine. My XL series are all the older round cylinders where the newer XLS series is squarish. My only real complaint with the XL is that in the event of a ground strike, the drive washer which is locked onto the shaft via a collet is very difficult to remove. The only way I could remove it was disassemble cylinder and  use my arbor press and press the shaft out enough to get behind it. The removal would also be required if you need to change the stock  bearings which I can say will be needed at some point.

         One fellow in the club is using the .28  in a overweight Brodak Shark due to some sort of heavy armor covering. I believe he's using a Enya venturi and needle valve which the Enya Nylon venturi was a direct fit. It flies fast more than likely because he likes it that way and it makes for a great sport plane.

            I use Powermaster GMA 10%. These were designed for r/c and they typically use a bit more nitro like 15%. I have run as much as 35%. Boca has the bearings. When you enter the site they offer options as to your needs. They have a dropdown bar of hundreds of engines. I do like to measure the bearing and compare to the offering prior to ordering. They usually offer economy to high quality bearings and I just use the economy. Their cheapest bearing is better than the stock bearing and I haven't had any issues using them.

        GMA is 22% oil. The construction of this engine would allow for a lesser percentage. I certainly feel that 18% wouldn't do any harm. I personally would use no less than 20%. These engines don't require a lot of castor oil.  Keep the oil content like I mentioned in the 20% range and a 50/50 synthetic blend. I have also use Ro-Jett full synthetic in these from Powermaster ( No Longer available) which worked superb. They were designed to use modern hobby shop fuels. I just happen to use Powermaster GMA and I like what it does for the engine run. Don't prop these engines with wide blade props that are greater than a 5 pitch. I run a 8x4 on bladder pressure in combat and I use it with a 9x4 for stunt on suction. I have never had to use a 5 pitch prop and I would only think the results wouldn't be very rewarding. Let it rev and it will swing the 4 pitch all day long.

Is Anyone else out there running this engine? If so, for what use and what planes?

What size plane is/was the Stunt Trainer?  I can't find a picture of it any where.  Profile or full bodied?  Flaps, no flaps?

          Allen, the Brodak Shark was the plane my fellow club member was using it on. I feel all of your plane choices would be suitable. They weigh as much as the OS Fp engines. I think Steve nailed pretty much of what I was trying to convey. In addition, not a recommended practice, but my club member makes his own fuel and didn't add oil by mistake. I don't exactly recall why this happened, but he ran the engine for what I believe was 2 tankfuls  on nitro and methanol. The engine is still going strong. A careless mistake of course but it was interesting to see that it didn't destroy the engine.

I have not used this motor yet.  However, I am putting it on the DoodleStreak.  However, the seller recommends 25% castor fuel.  Could this be correct?  Would it be damaging to use the 25% or 29% or would that be safest for a short time?   

Ran an XL .25 in a Pat Johnston "Stunt Trainer" until the plane fell apart...with a bit of convincing. Nice engine. I used a 9-4 Taipan, but tried a 10-3 APC and a few other props. It wouldn't go fast enough with the 10-3. An APC 9.5 x 4.5 might work real well. The XL .28 is also a nice engine...I think it has a bigger bore and same crank, so it's lighter than the .25, if you have a choice.

Perhaps interestingly, the earlier (still PRC) Magnum instructions specified break-in fuel of 20% or more castor oil. More recently, they only specify 20% or more oil, recognizing that castor oil fuel is harder to get. I'm not opposed to synthetic oil at all, but also think some castor is a good thing, even if it comes from the drugstore. Decent fuel will make one of these last almost forever. I got my XLS .36 used from Mike Haverly and ran it for years and years. We estimated that it probably had 20 gallons of fuel run through it when I gave it to Tim, and it was still easy to get 1-flip starts at that point. I made several strings of 12 in a row, but the 13th always needed two flips. It also started twice without the battery connected, so...  Steve 

Ran an XL .25 in a Pat Johnston "Stunt Trainer" until the plane fell apart...with a bit of convincing. Nice engine. I used a 9-4 Taipan, but tried a 10-3 APC and a few other props. It wouldn't go fast enough with the 10-3. An APC 9.5 x 4.5 might work real well. The XL .28 is also a nice engine...I think it has a bigger bore and same crank, so it's lighter than the .25, if you have a choice.

I found the XLS 36 the best of the bunch.  I never did get the 32 to start forward consistently.  It would run slowly in a rich 4 cycle backwards quite nicely.  The 28-25 were fine engines, just smaller displacement and power.  The 36 has a characteristic of a lot of series sized engines built in basically one case.  The larger bore and displacement seem to just run more reliably, easy to set, usually don't change much in flight, hold a setting better.  The

Thanks for all the advice.  At least I'm not tied to 25% castor.  I will soon be running it.

First two flights on the Doodle Streak.  The first one too rich.  The second one, about there.  Biggest problem was not the motor.  With a weighted nose cone, it was way too nose heavy. But that can be fixed easily.  I uses Brodak 5% nitro, 11x11 castor/synthetic.  Should I up that to 10%?  At least it runs.

Sounds like your fuel tank is mounted on the inboard side of the nose? I've never done that, but Dirty Dan did some experiments with that setup and seemed to like it.

Are you using muffler pressure? I tend to like muffler pressure,  but if you tend to have leaky tanks, hoses, or mufflers coming loose or ends falling off, it's best to avoid it. When that stuff happens, the engine goes dead lean, which is never good.  Steve

No pressure