I Feel Good!!!!!!

NEW222 Wed Jul 18, 2018 7:48 pm

Well, it is about time! Today I finally had a bit of free time to run up a couple of engines. I had not run anything up yet this year, until today. Mounted my test stands on my bench and had at it with a couple of engines, and tried a third. First up was a Golden Bee that I had to fix as only one tube was in the tank, so I had to repair and reinstall teh other. Fired up instantly. Ran about a minute then died. Took a bit to find its happy needle setting. Ran it overall about 8 - 10 tanks. Only one funny thing associated with it is that during one run, I was sitting a bit in front of it off to the side when I realized what was happening. It was running in reverse even while starting with a zero-drag spring starter... Anyways, off to number 2.

Number 2 was an engine I picked up a little bit ago, and gave a quick cleaning. Red horseshoe backplate with fine thread needle. Was missing the 'tapered' drive washer ( I had a thread about this, then I made one). Seems like this one will have to undergo a full cleaning as it feels like it has a good pinch at TDC. As well, I have to learn again how to start an engine with a fine thread needle. Got it to pop and sputter and that was about it. So, I left it there and went to number 3.

Number 3, now here is an engine..... Babe Bee that I hacked up a few years ago before I knew much about these things. Sandblasted the backplate, tank, and crankcase. Yep, you guessed it. I sandblasted both inside and out.....But, this gave me no noticiable problems. All surfaces mated and sealed good with no leaks. But the piston and cylinder had literally no compression, as I 'polished' them up, again before I knew what I was doing. I put polish in the cylinder and on the piston followed by a lot, and I mean a lot of turning the prop to polish it. Well, I polished the compression right away. However, it still ran, but very fussy starting and not very well. So last week I wanted to fix it. How you ask. Redneck style. I knew I had to expand the piston some and had a genius plan. I used one of my metal hollow hole punched in the rear of the piston (the size used was the one where the tapered part sat just inside the piston) and tapped it over and over till I felt the piston tight in the cylinder. Again, I overdid it. A little polish and chucked it up in the drill and ran it a bit. Still seemed a bit tight, but manageable. Put it on the stand, filled it up, and changed the head to a standard head (it originally had my first homemade standard plug head on it). It fired instantly, but did not run. A few minutes finding its happy place, and it appeard to run very well. Ran a few tanks through playing with the needle settings. Found that I need to richen it 1/2 turn to start, then lean it back out the 1/2 turn right after. I then put my homemade head back on it. It started again well, just sounded like a fair bit less power.

Overall, a good day and looking forward to another in the near future.

Ken Cook Thu Jul 19, 2018 4:37 am

Cox used a process to harden the pistons known as nitride hardening. This provides a very hard surface while leaving the material internally malleable. This process is also used for stabilization and the material doesn't distort. If your piston fit was compromised, first you needed to ascertain if the piston fit was the culprit. many times the glow head is not seating properly. Even brand new, they can leak and must be trued up. You shouldn't put polish in the cylinder with the piston in it. By bringing the piston to top dead center, you've essentially ruined the critical fit up top. If there's a need to do this which sometimes there is, you do it with the piston upside down and you stop the piston skirt approx 1/8" from the top. You should avoid up and down motion as well but rather a spinning up and down motion. Up and down scratches are just a pathway to lose compression. The real problem with polish is that you bed the polish microscopically into the porosity of the metal. This needs to be removed or when you run it, it will mix the fuel causing a lapping compound which will further remove material rendering it useless. It's very difficult to remove this from aluminum and a lot of hot water washing and scrubbing is necessary. In other words, if you don't want to buy new piston cylinders, I wouldn't make a habit of polishing them using the method you stated.

NEW222 Thu Jul 19, 2018 6:47 am

Oh yes Ken. You don't have to tell me twice! Shocked

Very good lesson learned here. I won't be re-performing this circus stunt!

getback Thu Jul 19, 2018 8:16 am

I am glad you got out there and had some fun , that means alot even if things didn't go accordly but still Nitro smell in the air !~! bounce

MauricioB Thu Jul 19, 2018 10:24 pm

Hello, good everything you tell here! ... some photos to share ???, it is good to see the engines running full of fuel screaming that they are alive! Thumbs Up