I just ordered a Magnum 25 and was wondering if there is any mods needed to get a reliable engine, I'm not looking to get top rpm just a trusty engine. I know there 15 need things like fuel tubing on the needle valve and things like that but does the 25 need anything. This is going on a JK Aerotek FW190 to start into combat this weekend and combat is pretty new at my club and we keep all planes with a 25 that's why I did not get the 28 so we can keep things a little more even.


Thanx for any help guys
Dauntae

Yeah, you want to do almost the exact same things to the .25 carb as you do with the .15 carb. The design is actually very simular, just a little bigger. But the low speed and high speed needles look almost exactly the same. (I haven't tried swapping them, but they look awfully close).

I also just finished going through all my Mag .25 and .28's and drilling out and tapping the carb mounting screws to 6-32 instead of the stock 3mm. I only had to do that after nearly 3 years of running them hard. Just be sure to use a good application of locktite on the carb mounting screws, and you should be fine for quite a while. But if you do strip them out, the tapping operation is really easy, and a 6-32 x 1/4" long socket head screw is really an improvement. Oh, last year, I also found that the Ace hardware store near me stocked 3mm philips head screws that were better quality than the stock screws and were easier to get in and out and get tightend down nicely.

Thanx for the responce and I do have one question, What I heard about the 15 I only heard and don't really know what is needed to be done to it. I just got the engine today and plan to fly it Friday along with some break-in time to be ready for our funfly Sunday.

Thanx again
Dauntae

I have a write up on my website at www.midatlanticcombat.com. The engine pictured is a .15, but it should be easy to see how it applies.

There are a couple of other options and ideas that I picked up from other guys that I haven't managed documented and posted yet, but what's on the site is what I do. (not to imply that I came up with the techniques shown on my website, they were all taken from other sources as well).

Kirk,
Any suggestions on how to fix a stock muffler which has stripped the threads used to hold the muffler to the motor itself. There is not enough room on the back side of the muffler to thread a nut into the the bolt, so I think my only choice would be to drill out and re-tap to a larger diamater thread, or purchase a new muffler. Figure with your experience with combat you have probably faced this issue before. Believe the muffler bolts for the OS 32SX are 3mm. If I go to the next larger sized thread and re-tap, any idea where I can purchase the 4mm bolts? BTW, only one of of the threads are stripped. Appreciate any advice you might be able to provide.
Sincerely,
Gary Murdock

Believe it or not, I haven't had this happen to me. Of course, I have mousse cans on all my B and 2610 engines, and they use 4-40 bolts. I also am a big fan of locktite on the smaller engines.

That said, I know guys routinely drill out and re-tap their muffler bolts to a larger size. Guys use 4-40 bolts on the .15 engines that use the 2.5mm and 2.6mm bots. And I think they use 6-32 on the engines that come with 3mm.

Oh, while I haven't had it happen on the muffler, I've now re-tapped all my Magnum carb mount bolts to 6-32, after I had a couple of the 3mm ones strip. I just had a carb party one night, tore down and re-did 5 carbs, including tapping for 6-32 and drilling the crankcase mount.

I'd use 6-32 because the corse thread gives more metal in the threads. I know that in theory fine threads are better for high-vibration envrionments, but when you have a metal as soft as the cast aluminum used in many of our engines, it makes sense to get as much metal surface involved as possible, and 6-32 seems to work well.

So, if it was me, I'd tap to 6-32. You can get good quality 6-32 taps and drill bits at your local hardware store, and by all means, use quality socket head cap screws and locktite so you can get that thing torqued down so it never comes off until you want it to.

You can also clean out the stripped thread hole really well and put a glob of JB Weld in there and screw the bolt in and let it set up that way. Then remove the bolt and chase the thread with a tap and you should be OK. Otherwise, It's a great excuse to buy a Mousse Can Muffler

You know, I've heard of guys doing things like that, using JB Weld to make threads, and it's never worked for me, the JBweld always strips out easily. I must be doing something wrong, since it seems to work well for other guys.

I haven't tried this with JB Weld, but with other filled epoxies, I've allowed the epoxy to partly set up and then warmed the epoxy and the metal I'm trying bond to with a heat gun just enough to see the epoxy start to liquify. This has let me attach counterweights to spinning rotors in test where I couldn't use bolts or screws to hold them on. I've spun as much as 4 ounces on a 9" rotor as much as 4500 RPM without anything flying loose in the course of a 48 hour cycle test where the rotor is brought to a given speed, held for a period of time, then raapidly stopped.
Make sure you thoroughly clean any oil out of the thread holes with a detergent or alcohol. Oil residue not only can keep the epoxy from sticking, but can also keep the epoxy from properly setting.

Stripped out muffler is a good reason to throw it in the parts box and get a Macs tuned pipe for the Mag .25 XL.
All I run is Magnun .15 and .25 engines, the fuel tubing on the needle valve is my first modification

Larry