deadstickpilot

I grabbed my old sure start, along with a new one, and decided to do some experimenting...

I grabbed the old Cylinder and piston (nothing wrong with them just used) and polished both pieces on the inside and outside. I mounted it on the new crank case, the old case is a bit worn, and I was shocked to see how smooth it was. It still had all the compression, except is was SMOOTH!!


I can't wait to try her out![8D]

flyinrog

My Feedback: (1)

Dont know what you "polished" it with but I would gamble you just luckily ended up with a good fit....btw ,,exactly what does smooth mean?..higher rpm?..less noise?...got a tach reading?...did you gain 1k rpm or did it just start easier?...Rog

combatpigg

My Feedback: (3)

I was taught to never touch the piston / liner with anything more agressive than a plastic bore brush and 3M green pad.
Polishing those parts with a fine enough compound might not harm the compression seal, it would take an experimenter to see what happens.
What was the baseline power output before this experiment?
Polishing could actually harm oil retention in the hot environment of the upper cylinder. Intolerance to lean screaming runs would point that out, plus signs of scuffing.
If polishing works, it would be good to have a baseline to be able to judge how well. No 2 Surestarts run exactly the same.

deadstickpilot

By polishing I just cleaned the little guy up .



This motor has always leaked, (the previous owner ran it BACKWARDS and LEAN).



Sooooo.




















(the darn thing won't stay started)




Which is why I decided to do experimenting on it...

combatpigg

My Feedback: (3)

I used to make a weekly ritual out of cleaning my combat TDs back when TDs were King of the Hill. The idea was to get 1 flip starts for contests. A few gun cleaning tools make quick work of it.
Some Surestarts have surprisingly good power.
If a wet piston doesn't hold a compression seal for at least 5 seconds after bringing it to TDC, it's junk. Time to put it away in your "possibles" cigar box.

lfinney

My Feedback: (44)

from my experience, CP has nailed it, from my conversations with cox developers, they advised using hoppes'no.9 gun cleaning solvent to de-varnish sleeves, and many free flighters and C/L ers' used some in their fuel, by cleaning your sleeve you de-varnished it, and as a result got a better run and less friction as well. be advised that hoppes no.9 cleaning solvent is some nasty stuff, so use with caution, its got carcinogens galore in it, and thats why it works so well! such as benzine and toulene , its still good stuff to clean with[>:]

BMatthews

I'm going to run counter to CP's claim about holding compression for 5 seconds. By far my fastest runners were and are the loosest of the lot. Now this doesn't mean scored, galled and generally abused. I'm talking about well run cylinder and piston pairs that have had many hours of running clean to develop a wholesome partnership. When wet with fresh glow fuel I could apply about 2 oz of torque to the prop tip and it would leak its way merrily up and over the top and back to an open exhaust port in about 3 to 5 seconds. Any "worse" than this and they were near impossible to start. Even at this amount I pretty much needed to use the old style spring starter to get it running. But OH BOY! DID THEY RUN WELL!

But it was a thin line between high powered Nirvana and a leaker that wouldn't start to save your life....

When it's reached this level of gap you can start a dry piston into a dry cylinder and the piston will easily fall right through. Then when oiled and in the engine with a good glow head seal I look for the amount of leakage with the numbers mentioned above being about as short a time as I like. The 5 second leakers would hand start pretty easily. The 3 second leakers need the spring.

EX Model Engines

Another huge problem I have had with the surestarts are the glow head gaskets. Some are good, some not.

Lost Glider

It may not be the gaskets, but the heads themselves. I have been running my heads over a flat file very, very, very gently, do not apply any pressure. I have run more than 50 heads over the file, and had no problems with them sealing.

Randy

gcb

"Back in the day" Hoppes #9 contained nitro benzine, a known carcinogen. I believe Hoppes stopped using it about fifteen years ago. At the time, many used to de-varnish with that method, or add some Hoppes to fuel which also cleaned out the varnish. Still others would tear down the engine and de-varnish with a wet Brillo pad, or Scotch-Brite.

These are only applicable if you use all-castor lube. A small percentage of synthetic lube will keep varnish out of your engine.

That's my story, and I'm stickin' to it...

George

Andrew

[link=http://www.hoppes.com/msds/904_MSDS.pdf]Hoppes #9 MSDS[/link]

andrew

Mr Cox

So there is neither Touluene or Chlorobenzene in there...
Mainly Kerosene and ethanol so it could work as fuel too then, with citronella cent and everything...

EX Model Engines

Good point, and I have found that in some extent. I find I can get around the problem easier is to use one of my own, noncompressed gaskets for the head.

lildiesel

You will probably want to shoot me, but I recently worked on a early Baby Bee cylinder and piston set that would not move through TDC for anything in spite of days of sitting in a warmed bath of power steering fluid. I finally ran a wet wad of #00 steel wool through it just like cleaning a gun barrel. After soaking/cleaning it again the piston moved better but not through TDC. A second pull of the wad did the trick because after cleaning the piston moved through TDC smoothly. I don't have any before and after numbers since there was no before. All I can say is that it now takes a Lil' Wizard around on 42' lines smartly and without loosing tension until I was going for near 90° wingovers.

BTW, relearning all this old C/L stuff is a heck of a lot of fun, especially since I've got a kid with which to pass it on.