Anything that increases crankcase volume is counterproductive, power wise.


Ed Cregger

DON'T listen to any of the naysayers.......go for it!!
get your Dremel out and cut, grind, polish and glue every piece of this technilogical marvel.
drill lightening holes in the piston, rod and heck even the drive washer. may as well port the head into a double bubble setup while your at it.
replace the carb with a BIGGER one and use a pump to feed it.............i'm betting you'll get at least 200 rpm more out of all this fine and tedius work
only draw back will be the stock rod..................probably grenade itself in the first flight.
man i can't wait to see your rpm figures, this is gonna be a goer, even if for a short while

Thanks - I think....

I'm not going nuts with it. I had some down time as I waited on the bearings to get here so I just put a radius on the ports and smoothed out a few things. I didn't do much so I'm not expecting much but I have learned a few things in this thread so keep the sarcasm, comments, questions and snide remarks flowing! I'm surprised Dar hasn't chimed in. He loves beating on me!

One of the biggest problem we have seen out of the evo engines is the crank pin breaking.

PROP we get 17,800-18,000 on APC 9x8 props for the OS 46's on jett mufflers
PROP we get 14,500-14,900 on APC 11x7 props on the OS 55's with jett mufflers
PROP we get 17,300 on 9x8 APC for the OS 37 with jett mufflers


For your 60NX check exhaust timing and get it to 180. If it isnt there then put a 15 degree upwards angle on it till get to 177, this with the upward angle will get you to 180. As cox said make sure compression is correct for the fuel you use. As a reference my Jett 60 LX only spins a APC 9x8 at 18,400 on the ground.

Put it back together and ran it. I didn't see much difference. Maybe 300-400RPM. It is hot as hell here - right at 90 degrees and hovering around 70% humidity. The last time I checked the RPM on an APC 10x8 in this weather I think it was around 14,500-14,600 and I'm geting 14,800-14900. Not worth the trouble to do what little I did to mine. I have a Super Tigre G-51 with a ring that I plane to play with the exhaust timing on. Where can one get a degree wheel for these small motors? i didn't take any pics but my ports look a lot like iflyglow's earlier in the thread.

Unfortunately not all engines respond the same but you did find 400 free RPM. You may need to open up or at least polish the carb throat to gain enough flow to compliment your port mods , that and the exhaust may be restricting it also.
I will take any free 400 rpm I can get any day.
So tell me, does it run "better"? More responsive? Crispy, like we used to say at the dragstrip?

convert it to Spark ignition......that'll make some serious RPM's

Yes but I had changed a couple of things. I had been having flame outs while advancing the throttle from mid to WOT and today I got the low end about as lean as I could get it without it dying but I was having lots of trouble with the Merlin HD2003 (long reach heavy duty hot plug) plug I had put in it. the 60NX did not like this plug - AT ALL. My first hint was when it started to run in a way I have never seen a plane motor "run" before. I start this engine with a chicken stick and after I primed it, closed the throttle to just above idle, I flipped it once. It hit, bounced off the compression stroke and went backwards, bounced off the compression stroke and went forward and it stayed "running" like this for a good 50-60 iterations as I looked on in bewilderment. So I guess it was a 1.5 stroke engine at that time. I flipped it again and it hit hard against the stick. Another flip and it started backwards and as I closed the throttle it started running forward nicely but as soon as I took the glow starter off it died. Started it again and ran it up and it stayed running but obviously didn't like the plug. I stopped it and put in a Merlin HD2002 (long reach medium heavy duty) and the motor was transformed. Very snappy response with no mid range sag during throttle advance. With a 10x8, this motor has near instant throttle response any way before and after the mods but I was digging the way this thing was running. I just love this engine. The stock muffler is absolute, 100% garbage so you have to spend the extra cash to get a better exhaust but with a Macs pipe or the EVO/Jett muffler it is a hoss. Not bad for the $124 I paid for it. I'll get another one soon to put it on a little Rookie club racer I have a 46AX on currently.

By the way, I was running 15% Omega Aero with 18% castor/syn oil.


Thanks again. Your wisdom is much appreciated but why convert it when you can just buy one here - The new Magnum Gas XLS-52.

was funnin' with ya.......that's why i added the smiley.
this was actually a good experience for you, as you found out how little the work actually did.
i've beat many a Free Flight competitor because they did mods on their engines that caused reliability issues.

ThumbSkull gave you solid advice as to why you don't want to mess with the transfer ports....atomization of the fuel is affected and causes more harm than good.

timing, carb bore, and head clearance is the easiet way to gain.
you can pack the crank for a smoother transfer, but stay away from the radical grinding as you lose reliability there too.

buy a Jett, and see how it's built.

If I bought a Jett, I'd be too afraid to take it apart to see how it is built! I will have one day though - a 60LX in a Sundowner!

What's wrong with 300-400 r.p.m. increase for about an hours work?!!?

Some of you guys make me laugh...

I notice that it's the ones that don't have the confidence in their abilities that protest the most... These sort of threads bring out the same nay-sayers every time.

It's a (relatively ) cheap Chinese engine...not a collectors item...

Some people like to tinker...some people are just scared to try anything different.

SpinnerRow...the above comments are not directed at you...300-400 r.p.m. is a decent increase for what little you did...IMO you should be proud and happy with the results...

it'll be a 56LX.
don't need to take it apart, but a look in from the rear with the BP off will astound you.
the Rod is a work of art.

but you won't find any unnecessary porting and polishing. course with production engines you'd end up with too many variables if the maker design them with hand crafted port and polish

I don't know where that came from (?) but I don't think it is true, people with first hand experience gave good advice here and those who choose not to trust it can simply try for them selves...

I consider the work that I do to my engines as personalizing...

I'd love to have a Jett .56 LX but spending that kind of dough is cost prohibitive at the time. How much are they...350.00 or so?

I have several Nelsons of various sizes...dozens of K&B 6.5's and 7.5's and over a dozen Super Tigre X.40's, X .45's, and X .60's so just speaking for myself, I know what a well designed engine looks like and specs out to...

If you can take an 80 dollar engine like a TT .46 or Evo and get to within 85 - 90 percent the top r.p.m. of an engine that cost 3 times as much, and it is still tractable, then the time spent modifying it is time well spent, IMO.

no need for a degre wheel. Just use the crank pin as your timing mark. At TDC the pin is at the top. At BDC the pin is at the bottom which is 180 degrees. pretty simple.

If it doesn't apply to you, then don't worry about it... It's just that whenever a guy posts a question about modding an engine, there will be people who pipe up and tell him not to....it's the attempt to stifle creativity that bugs me...

This work might make sense if you were racing in a class that everyone had to start with the same engine and these mods were allowed.
For me I'll just buy the right engine in the first place. Jett, BVM, Nelson and the like have this figured out pretty well.

If you are into making cheaper engines try to perform at high RPM's then it just makes sense to me to start with an engine that's built for revs.
If I wanted cheap speed type performance, I'd start with a DF engine. At least the rod will hold up to the revs.

Just like any other engine, there really is no replacement for displacement. Just buy a bigger cheap engine.

I was in the 2-stroke motorcycle racing business in the 80's and it's a real science getting the port timing better than the factory did.
The best mods in 2-strokes were light flywheels, reed valves, matching the C/R to the fuel, and the biggest was in the exhaust system.
A properly tuned pipe felt like it doubled the power.

A Nelson Ultra Thrust or Jett Stream (Jettstream? ) muffler are a great bang for the buck, no doubt about it...and they are without the hassles of a full length tuned pipe. My modded Webra .50 runs better than great w/ one.


Put a Tower/Aquacraft (same as GMS ) muffler that cost 15 bucks on your TT or O.S. or Evo / Magnum .46 or .52 / .55 and you'll get a nice gain, and still have throttlability...even better bang for the buck, for those engines.


The way I look at it...work with what you already have...try an experiment or two...no big deal...if you mess it up, you're not out several hundred dollars, and you learned something in the process.
If you did it right, there's the satisfaction in knowing that you did it yourself, and it's hard to put a price on that.

The Evo .60 is new...we will see if the crank pins hold up...
We had 2 Evo .52's in our clubs loose theirs...sheared off flush...
We will see if the metalurgy has been improved, aye!

Like I said, the way I look at it...it's a cheap (relatively ) Chinese engine...not an irreplacable, not to be seen again collectors item...

I had started making the mods before I started this thread and I just thought I would share. I generally don't listen to nay sayers. Like what was said above - "I like to personalize my stuff". I have one 60NX with a bearing swap and one with port work and a bearing swap. I'm happy!

You can't buy a bigger 40 sized engine without shelling out the bucks which I don't have enough of. If this thing spits a rod, I'll buy replacement parts or a new one and probably mod that one even more! I'm a tinkerer from way back. I've been porting heads and building race car engines for 20 years - as a hobby. Even my daily driver with cold A/C is modded! I don't have anything that is stock. Most ARFs I buy, get changed some way before their maiden flight.

I learned a few things and I plan to play with the timing on my Super Tigre G-51 to see what I can get out of that thing. It would be cool if that engine would turn what the 60NX will turn being that it cost me $69 new!

Will the rod break on these 60NX if I keep it around 15K or less? Cause that is about all I ask out of them. I'm not going to put a 9x6 on these things and spin them to the moon.

SR...it's not the rod...it's the crank pin that MIGHT be "iffy"...
You can be the "Beta tester" for us, aye!
We will find out as more and more people start flying the .60NX, if they have the bugs out of their crankshaft metalurgy.
When Horizon starts selling their Phoenix 7 ARF and the .60NX that they recommend for it...there will be a bunch more of 'em out there.

The Evo .52's and early Magnum .52's (virtually identical internally ) had over-hardened crank pins...I recall reading of several of them breaking.

My early Magnum .52 had seen well over 15K when I had it in my Kaos .40
I fly it now with a 12.25x3.75 APC however, on 15% and the revs are down to a little under 14K. (it's still running great )

I've never seen so many guys miss the point over and over. It's a hobby he wants to rework a motor for the enjoyment of it. It's a hobby.

Denis

You forgot - "and share my findings with others of like interests".

Its all good. Seeing some of these old geezers get their tighty whities in a bunch is amusing as well...

For the record (hope I don't confuse anyone):[ul][*] I don't "need" more power. [*] The engine is powerful enough in stock form.[*] The mods weren't worth the HP increase but were worth the time I spent doing them.[*] I don't like salt on my watermelon - what's the point in eating something sweet if you are going to dump a bunch of salt on it?? Eeeewwwweee!
[/ul]

Bugs? I'll bet they are using the same alloy as the rest of the engine line and the limit of strength has been reached here. To use a more expensive alloy would certainly raise the price of the engine.
This being a chinese engine built to a price point, I doubt they will bother to make a better crankshaft for it. I think it more lkely that a chinese engine running on the edge of failure would more likely be detuned by the mfgr to keep them from failing and having to pay warranty claims.

Just my opinion......

The tone this thread is taking is disturbing because member participation is being ridiculed. Everyone, even the beginner, should feel free to contribute, ask, or comment. There are probably 100 beginners reading for every post by an 'expert'. Keep this in mind when posting. Keep it friendly. This is a good thread so far.

This is the first crankpin story I've heard. I've run a .52 and have seen it run hard. I like the OS .50SX and I think the Evo beat it by a lot. Also, I think the engine was targeted to the upper end of the Chinese market. I would place Evolution quality as being better than OS.

Also, there was an interesting thread some 3 or 4 years ago if anyone wants to search for it (post the link here if you do.) I think the project took place in Europe, but someone tried to lighten a Saito engine as far as possible. He posted the results of each lightening effort. Not quite the same as porting, but still related as far as modding the internals.

And unless you added some oil to your Omega it is only 17% oil according to their website.