Doesn't sound good.
What are you running for the ignition? Spark plug? Gap distance?
Do you have a hole in the firewall behind the carb?
Do you run or have you considered running a line from the carb vent into the fuselage?

Prop size shouldn't make any difference.

yea,the burbleing sound bad but i am not going to worry about it too much if mine starts to do that,i think the most important thing is that the engine performs and not quit in flight,i can deal with the burble just fine,i know it may be anoing but as long as my plane remains in the air and comes home in one pice with out any mishaps,im happy,anyway i finaly got some lawn boy oil,they had it at the true value store about 4 miles from home,i never even thought about cheking there till i spoke to a good friend of mine,

so i guess ill lay off the briggs and stratton and go with lawn boy,i am just going to break in the engine in the air,will take real easy on the first three gallons of fuel,i just have to wait for an oportunity,they're having a flying at the fiel this weekend so no chance to fly till maybe the following weekend after that,so we'll see how it goes,Geppino your plane is well seasoned at 100 flights,you may be due for a new one, maybe a christein eagle,that would be nice,well once i get serious with this plane,i will be geting an extra 260,that would be great for me,i wouldnt want to get too oversize since i dont want to have to buy a trailer to haul it,my pickup truck will do just fine foe a 25% to a 33% plane

Don't agree. An engine running poor has great effect on the plane's flight performance. Forget about hovering or stable harriers. There are some simple rules to get an engine to run superb. I'll make a video this weekend, weather allowing.

Simply run it on the ground for 2 hours @2500rpm, 2 hours 3500-4500rpm on a 22x8 prop. Adjust needles before you put the cowling on. Now you'll still have over 2 gallons of fuel left and can fly the plane how you like it, except for endless hovers or nose up flights. Use a 23x8 after the 3 gallons and switch to synthetic, readjust engine after the first tank.

Some of you may have read my accounts of my rebuild of my DL 50. To bring anybody who may be interested up-to-date, I crashed my plane a few weeks ago. I rebuilt a replacement plane, but after a couple of flights I noticed black "gook" coming out of the front bearing. Initially I thought it was a destroyed font bearing and maybe a bent crank case. I ordered the parts from DL USA and proceeded to disassemble the engine to have it ready for the new parts. But then I couldn't extract the woodruff key from the crankshaft, so I ground it off thinking I could extract the remains after removing the crankshaft from the case. But now I doubt this will be possible, so I ended up ordering a new crank shaft assembly too (with con rod installed).

In the mean time Scott from dlenginesaustralia kindly posted pics and thorough instructions for disassembling and assembling the DL 50 (on page 114 of this thread). The instructions and pics have proven to be invaluable.

So all my parts have arrived and I got my Loctite 620 Bearing Mount today. So right after work I rushed home to begin assembly of my baby so I could put it back into my other baby!

But before assembly, I took Scotts instructions/notes and wrote them in chronological order in a way that I could understand a little better. I also took a few pics that might be of interest.

Scotts instructions were right on, but I have a few things to add about my particular re assembly;

1. The rear bearing did not require a pipe to tap it onto the crankshaft - mine slid right into position. Same when installing the rear bearing/crank assy into the case/front bearing assy - dropped right in.
2. I also put the front bearing and crank in the freezer, thus shrinking them for easier assembly.
3. The assembly process went perfectly fine and I had no problems - well, maybe the woodruff key was a bit of a problem - but just a bit. Mine fit rather tightly into the slot in the crank. Also, you want to install it so it is slightly angled toward the front of the crank shaft. This way the heated prop hub will slide into position a little easier.
4. In my pics you can see the hub holder tool I made from 1/4" ply. This worked well for disasembly and assembly. You can use your prop drill jig (or a prop) to make your own. You'll just have to open up the hole in the middle to accommodate your deep - well socket. (I got my deep well socket from Sears. I was worried if they would have one or not, but when I got to the tool dept. they had a whole wall full of sockets - many deep well of which there were quite a few that would have worked. Both 13mm or 1/2" work fine.)

Lastly, although I ordered a new front/rear case assy, after disassembly I noticed how short/stout the case is, so I'm quite certain the case is not bent from the crash, so I didn't use my new one. Therefore, I have a case assy. for sale if anybody wants to make me an offer - brand new in the bag.

One more thing; when preparing for assembly, I would refer back to the photos in dlenginesaustralia's pics back on page 114. Well, here are my revised instructions followed by a few assembly pics just in case anybody is interested in what the inside of a DL 50 looks like.


I. Preparation/Assembly Notes:
Loctite 620 Bearing Mount (High Temp) is required to securely mate the bearings to the crank shaft and to the crank case (and other parts as instructed). Bearing Mount can be purchased or ordered in small quantities (5ml – 15ml) for as little as $5.00 - $15.00 from ball bearing retailers.
Protect your workbench and engine parts by working over a sheet of cardboard or other relatively soft barrier.
Clean all parts thoroughly for easier assembly and best adhesion of Bearing Mount.
Do not use excessive Bearing Mount. Do not apply until ready to fit the parts. As you proceed, remove excess Bearing Mount with cloth.
Keep all tools within reach so you can work quickly while parts are still hot.
Wear clean, leather gardening gloves when handling heated parts.

II. Crank Installation
1. Place front crank case half, rear bearing and propeller hub into oven heated to 280F.
2. After about ten minutes, working quickly, remove case from oven, apply Bearing Mount to case and outer race of front bearing. Install front bearing into case.
3. Replace front case/bearing assembly in oven to re heat for installation of crank shaft/rear bearing assy.
4. Working quickly again, remove rear bearing from oven, apply Bearing Mount to inner race of rear bearing and crank shaft. Tap bearing onto crank shaft with 15 – 16mm I.D. pipe applying pressure only to inner race of bearing—do not apply pressure to bearings, seal or outer race.
5. Install aluminum bearing spacer onto crankshaft.
6. Working quickly once more, remove front case/front bearing assy. from oven. Apply Bearing Mount to outer race of rear bearing and in case for rear bearing. Install crank/rear bearing assy. into case. Allow to cool.

III. Hub Installation
1. Apply Bearing Mount to woodruff key and crank shaft. Install key into crank shaft.
2. Remove propeller hub from oven. Turn off oven. Proceed immediately to the next step.
3. Working quickly and supporting center of crank assy. with hardwood dowel or similar (so as to keep force centered on crank shaft—not on con rod/counterbalance), lightly tap heated hub onto crank assy. just far enough to expose crank threads so prop shaft can be fitted.
4. If necessary, apply more heat to hub (using heat gun), then use a tool to hold hub while tightening prop shaft drawing hub the rest of the way down.

IV. Final Assembly
1. Install bearing, piston, wristpin and wristpin clips to con. rod. Be certain wrist pin clips are fully seated and the “tails� of the clips do not have any nicks in them which could cause them to break off inside the engine.
Note: The arrow stamped into the top of the piston points toward the exhaust. The anti-rotation pin in the ring groove is located opposite the exhaust.
2. Join the case halves using a thin film of gasket sealer or the Loctite Bearing Mount used for bearing installation (which is thin, fuel proof and normally sufficient—if desired, Loctite 518 or 573/4 could also be used, but usually not necessary due to the good fit of the case halves).
3. Apply a drop of blue Loctite to the case bolts. Tighten evenly in a standard chris-cross pattern.
4. Lightly oil all parts including the piston ring and cylinder walls—the two-cycle premix oil you have been running your engine with is suitable.
5. Compress the piston ring with your fingers while sliding the piston into the cylinder.
6. Tighten the cylinder to the case halves with blue Loctite on the bolts.

Thanks to Scott at dlenginesaustralia!

Thanks for the info, first let me say that on that video the end cap from the muffler may have been blown out, first the exhaust pipe then the end cap. I cant be sure when the end cap blew off, because I did not notice until the end of the next day's flying. The exhaust may be venting to atmosphere, no muffler to speak of. I have now bought a Bison Pitts style muffler, it wont be so loud.

I have an NGK M6 spark plug, gapped at 18 thou.
I have a carb vent into the fuselage tube, but no canister on the end.

My ignition is running at approx 4 volts, one of things I have been meaning to try, is to install a two cell LiPo and a regulator, this would bring my voltage to 5.2. but I do not believe this is my problem it ran good with this same set up. However, one never knows until it’s tried.

I do not have a hole in the firewall and I do not relish the thought of doing so, as the fuselage would end up with fuel spit. The carb is 15/16 away from the firewall; it should be breathing OK, as I get a good static RPM of 7240.

The High Speed needle is set to Max RPM and backed out 100 RPM. The Low needle is set so lean, I need to warm up the engine for about 30 sec, in order to accelerate it without dying. Once warmed up the DL50 has never quit in the air.

One more thing I need to look at is the order of the gaskets on the carb, as I did take it apart to clean the filters etc... after the bad landing and cracking the 23x8 prop. It had a lot of dirt and grass around the carb area. There is a possibility I may have reassembled them wrong.

Unfortunately I did a couple of things including changing props at the same time, so I will need to back track to see which one changed the DL for the worse. It was such a nice week up here that I just wanted to fly. Even as bad as it sounds with very little of the muffler that remained, it's never let me down and can pull that 20 lbs Pitts like there is no tomorrow.

The original muffler is something to be desired, I have gone through two of them..... Hope the Bison last longer.

Geppino

I have been using a Bisson Pitts on my DL all summer with no problems with it at all.

Wonderful job Tim, well done, it's better than lot of manuals I have read. [sm=thumbup.gif]

Thanks for taking the time. [sm=thumbup.gif]
Geppino

BOUND_4_HELL you said "The High Speed needle is set to Max RPM and backed out 100 RPM." Once you have the new muffler, and if the burbling is still noticeable, you might want to set the engine at max rpm and not back out the hs needle for the rpm drop. I switched to 50:1 on my second DL50 today and retuned the engine. There was a noticeable decrease in the burbling with the hs needle set at max rpm. No problem with vertical uplines either, well almost done...the 17lb WH Edge just kept climbing and climbing until it was a dot. It flat spun for what seemed like forever coming back down. Let us know if you do reset the max rpm and what the results were for you.

Chuck

That's possible cause #1 of the problem.
Try a 2-cell 1100mah A123. Put a 1N5003 (or 1N5004 etc) diode (Radio Shack) in series with the positive wire between either the switch and ignition cutoff or switch and ignition if you don't have a cutoff. The diode will bring the voltage down from 5.7 (full throttle) to 5.9 (idle) volts and can handle up to 3 Amps.

http://tweakshop.net/DL50-install/1.jpg
If you solder the battery pack yourself, you could use servo wire and use the yellow/orange wire as balancing wire. This way you can balance charge the battery through a switch with charge jack. http://tweakshop.net/DL50-install/2.jpg

Edit: Same setup applies for the Rx battery. http://tweakshop.net/DL50-install/6.jpg

If the ignition voltage fix doesn't work, I guarantee the problem is related to air pressure changes around the carb intake. Imagine the air pressure changes heavily during different throttle positions and positions and speed of your plane. Adding the volume of the fuselage to the engine box results in a much more consistent air pressure because it's leveled out over a larger volume. Simply add a thin coat of alcohol thinned epoxy to the inside of the engine box.

Great work Tim !

And your right about not needing pipe to tap on Crank bearing if you have bearing hot enough/crank cold enough it will normally just slip on.

that must of took alot of time to post Tim,thanks for doing it,you never know i might need this information in the future,but ill keep my fingers croses,the removal and instalation of the bearings is right on,i've done alot of bearing replacement and the way i doit is by heating the parts up where need be and freezing also where need be,it is so easy to pop them out and pop them in that way,no problems but you do have to be quick or the part accepting the bearing might shink too soon and you'll have to start over with the heat to re-remove the bearing again and go through the prosess all over,anyway good info,i wish you luck on the project,

question for the forum,does everyone make a loop on the fuel supply hose that goes to the carb?i ask this because i did since i wouldnt want my engine to quit in case in on a vertical downline because my tank is very close to the carb on the pitts special,a friend sugested this when i told him how close the tank was to the firewall,seems like the way to go,i have seen a few exposed tanks on diferent planes that show a loop around the top of the fuel tank,i gotta say though,i had the hardest time on mine because the tanks cap goes through the back of the firewall but it worked fine

I forgot to ask a question in my last post....

You know that spring that goes inside the spark plug cap on the end of the ignition module? I'm tired of seeing it laying on my workbench next to my plane or on the floor after I've had the cap off when working on my model for whatever reason. It always falls out. Then I have to remove the spinner, prop and cowl so I can pry the cap off the spark plug to put the spring back in big hassle.

So, is anybody running their DL without this spring? I asked this once before and got only one answer from Bob Pastorello who said I have to use it. He's the DL "guru" on this forum, but I was wondering if anybody has actually run their engines without the spring.

I'll hang up and listen for your answer.

same question here

I have never tried it without the spring.

Thanks to those who appreciate my comments.....
Regards the spring... properly installed (smaller end TO the plug), it provides an additional grounding path to the top shoulder of the metal base/body of the plug. Personally, I think it is handy to keep.

Also, FYI - I am no longer following this thread as I have sold my DL's. If anyone needs any info, however, I would be happy to help.

Tim - absolutely outstanding documenting of the service assembly. Well done. And thanks!
See ya'll around other threads.

Hey, thanks for checking in Bob.

I'll be missing your expertise on this thread.

Do check in every now-and-then.

Be well!

Tim

Bob,
What's the reason for selling the DL's? New planes or moving on to different engines?

Guys I have run my dl50 without the spring sence new dont know who is right or wrong but I have had no concerns. But they give them to us for a reason. p.s. they give us two..Thanks The Runner

Hi Tim,

Like you, I also think the spring is a pain in the butt, so I do not use it. Instead I soldered a wire to the metal cap and crimped an eyelet on the other end of the wire. Drilled a hole in one of the fins and attached it with a screw and nut.

If for some reason the metal cap looses contact with the spark plug because it has no spring, an electrical return ground path is still there. Electricity will flow from the spark plug through the aluminums head, through the wire attached to the fin and back to the cap, then continues to the ignition module as previously with the spring.

Geppino

Once everything is setup correctly, the spark plug needs replacement only once a season at most, so why bother taking the spring off, drilling holes etc?

For whatever reasons, occasions arise when I have to remove the spark plug cap (a while ago I changed the spark plug, recently I just rebuilt my engine, and some other time I decided to check the tightness of the spark plug, whatever).

So I don't purposely take the spring off. What I was trying to say is that when I take off the spark plug cap, that's when the spring falls out and I never notice until I see it laying on the floor after I've already put my cowl back on. It's not a big deal, just a bit of a hassle (because, to remove the spark plug cap to put the spring back in, I remove my cowl (and spinner and propeller) so I don't tear it up - I have my cowl cut pretty close to the spark plug cap and wire).

I ran mine for most of a couple of gallons before I knew that I didn't have the spring on mine. The only reason I found I didn't have it was I started getting a glitch that we were tracking down and found the spring was not there. BTW it wasn't glitching because of the lack of a spring, it was because I had a bad regulator feeding back to the rx through my jomar kill switch. Replaced the regulator and problem went away.

Well, all is right with the world (okay, MY world).

I got my Extra out after work today and got in three good flights with my newly-rebuilt DL. Started right up and purred like a kitten - on the ground. In the air it's running perfectly and roars like a tiger (is that gay?) .

I ran it without that aforementioned spark plug cap spring too. Won't make a habit of it I guess and will replace it next time I take the cowl off, but didn't have any problems without it.

All I have to do tonight is cook some brats for my wife and step-daughter and look at my airplanes!

I'll take 2 brats with onions and mustard Tim. A cold beer wouldnt hurt either. Now thats not gay.

I have a situation where I would like to move the exhaust port to the opposite side. Can this be done? Would it work if I just rotate the cylinder, the cylinder head and the piston ? Would the ports line up ? Tks