Engine Q's

[Tarant]

Okay here it is, I have always ran my engine's on the cool side usully around 220-230 deg. So a few weeks ago I dicided to lean my OS .18tm out a bit and see where that gets me. I leaned it out by seeing the smoke and the sound and power output, no temp. So any way after being pleased I started to temp it and it was really low like around 230, and if I went any leaner there would be little to no smoke. However I am getting 16 minute run times telling me it is on the lean side. So after about 5 tanks of 20% I pulled the sleeve and piston and it looked bad.

I have never had any of my mill's look like this, so is this just normal or what? Also I have noticed small divits on the outer area of the piston, could dirt and debris be getting in there and messing this up. I am running a MS and after seeing the other post I am starting to wonder.

 

[Tarant]

anyone?

dont make me bust out the nOOb threats.

 

[TalonOne]

I am no expert ...but that looks normal to me.....I have seen a thread about buffing the piston to lean it up a bit.


My theory is if it runs good and I see smoke and its below 250 ish I am good.....I even run em hotter from time to time. Some dirt in ther is evevitable even when you are careful....too much of course wil ruin your compression............but I refoer back to my theaory....

TalonOut


PS missed you at the track last night we had a balst.....Need a ride???

 

[olds97_lss]

If that's bad, what do your engines look like normally?

If your getting pitting on the top of the piston (small divots), it's detonating too early. So you would need to run a cooler plug, lower nitro or possibly add a shim to the head.

From what I see, it looks fine. The castor oil in your fuel kind of caramelizes and creates a build up over time. That's what the brown is I believe. It is highly inadvisable to grind away at the piston, top or sides, to clean it up.

Now, when you see something like this, you really have problems...

That piston/con-rod was 3 or 4 gallons old. You can see the caramel color on the con-rod and near the top of the piston.

The gouge in the side was caused by a defective ball bearing in the rear crankshaft bearing. One of the balls split in half and went through the engine.

 

[Monkey Wrench]

Tarant, is that the OS that came on the Revo I sent ya?

Anyhow, that's pretty normal looking (as Olds states) but if it bothers you, you can get a little Mothers Metal Polish and GENTLY rub that caramel looking gunk out. You just want to be careful not to rub too hard (innuendos aside) so as not to take any metal out.

 

[bentover]

My .18TZ looks like the same in my CRT.5, and I tend to run it just a tad on the over lean side sometimes.
But I have a hot turbo plug in mine though.

 

[Tarant]

Yes Monkey that is the .18 you sent me.

My engines have never looked like this, just this one. But like I said it is th first engine I have ran lean, and it runs great and if you guys say it is normal I will go with it.

That is bad Olds, Thanks for the Detonating info I will go to a cooler plug.


I didnt make it to the track Talon, we closed at 6pm so I didnt have any time to get out there.

 

[joneser4u]

If that's bad, what do your engines look like normally?

If your getting pitting on the top of the piston (small divots), it's detonating too early. So you would need to run a cooler plug, lower nitro or possibly add a shim to the head.

From what I see, it looks fine. The castor oil in your fuel kind of caramelizes and creates a build up over time. That's what the brown is I believe. It is highly inadvisable to grind away at the piston, top or sides, to clean it up.

Now, when you see something like this, you really have problems...

That piston/con-rod was 3 or 4 gallons old. You can see the caramel color on the con-rod and near the top of the piston.

The gouge in the side was caused by a defective ball bearing in the rear crankshaft bearing. One of the balls split in half and went through the engine.

I know what mill that came out of,I just replaced that whole ass. in mine.p/s/r. Lord please dont let my bearing do this to me!



As for the os 18tm, I would replace that p/s if it has pits in the piston,next step is burining hole in piston and a bunch of aluminum goes all through the engine,ruining the entire mill,where right now its just a p/s. None of my mills look like that,I have several p/s I have pulled out to replace you would swear were brand new.They just didnt have pinch left.I dont own a temp gun?just own alot of 2 strokes,10 nitros 1 yamaha banshee 2 outboards. ohh I also work on them for a living.