O.S PET 1.6cc info needed

Also will a standard bin silencer be ok or should I get an os pipe ? Or even not bother and run without !!!!

You can count the number of threads in the head and se what length of glow plug you can use. The OS#8 (medium reach) are fine and a long reach might be even better. The engines where cross-flow engines but there is a step on the piston (see picture below) rather that a protruding baffle, so there is no risk that a baffle would hit the glow plug.

The fuel should be all castor and plenty of it, i.e. 20-25%, and it looks like it has been fed castor before so that is promissing, here's where an ugly outside insures a pretty inside...

A muffler will need to have a strap around the cylinder, I can't see any screws in the case for holding a muffler (and I don't think I've ever had one either). It looks like you have an early version (perhaps a #II ?) and no-one bothered with mufflers at that time.

Here are two models with the later (#III) on the right hand side;

Hey kris yes it certainly has castor and plenty of it all over will check the plug threads in a mo so were thinking mk2 eh ? Have found a few pics in the net but none have the needle I have ? Maybe it's a bitsa ... Well so
Long as it runs that's ok with me interesting about piston being stepped think I will give it a nice long soak and clean and see what we have at the end I agree it probably never had a silencer as there doesn't appear to be any marks on fins or exhaust port so as u say was probably run as is am liking the look of your mk3's gonna have to get a plug and see how or if she runs doesn't appear to be any damage anywhere hopefully meaning a nice easy life are spares still available ? I see some of these had throttles which were basic choke design most I have seen seem to have these but I guess this was the basic model (which suits me) how does yours run ?

After 2 mins with the brake cleaner and a toothbrush it seems that someone has had it apart as one of the head bolts has been munched either wrong size screw driver or they are solid in the head don't know which am hoping that's all I find wrong with it !!!

Top one !!! " alt="" />

Workable but very annoying

Ok panic over the right size driver head and a little tap from timmy and all is well head off and the piston and sleeve look good usual gunk on top of the piston but liner nice and shiny with no gouges so that's good needle nice and straight so far so good
Oh and the head has four threads ( complete) so will the #8 still be ok kris ?

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OMG, that's some serious junk in there...

Be careful not to clean the piston (appart from the very top of it) and the liner, you do not want to loose the castor varnish on them, as that would remove the seal. I have never yet seen an engine, larger than a cox, that needed any devarnish done to the cylinder bore. On the contrary if the varnish is removed you may loose compression beyond repar.

The screws are a japanese Philips standard, so they are often ruined by the wrong tools.

4 threads should be fine with a medium or long reach plug, just stick a plug in there while the head is off and see what the combustion chamber looks like.

The guy said he found it in the bottom of an old tool box and as it had no plug in it am assuming that's where all the crud has come from as you say am gonna leave the lining alone just clean the top of the piston and get some muckite off it !!!! don't have any plugs to try as only have coxs nothing else but I must have one somewhere aaaaahhhhh I have a McCoy head for one of my coxs with a plug in it that might work have to find it and see so the machine screws are standard jap then that's good

After a little bit of research I think it's the mk 111 b as the mk11's had two screw heads / top end complete mk111's had separate head and four bolts the mk111 A had a smooth head and B's the finned head production of the 11's stopped in 61 and mk111's started in62 then mk Iv's then started in 63 so is somewhere between 62 and 63 this is going on some guys write up on Rc groups but seems quite comprehensive some also had integral tanks which looked quite cool mine has provision for this on back plate they were anodised red value of these apparently is barely nothing but that's ok as bought to use not to keep and appreciate in value
Anybody please correct me if anything I have said is incorrect this is not my research but someone else's

Ok so have spent a rather long time with degreaser and cotton buds trying to clean this engine up with not a great deal of progress
What would anyone reccomended to get the crud off
I have a tin of "gunk" which is a powerful degreaser meant for car engines haven't used it yet any better suggestions also does anyone have an explOded diagram of one of these as it didn't seem to have any gasket on the head should it or is it just mated together

Furniture stripper that contains methyl chloride will clean the outside and knock the crud off the piston top. Leave it at TDC so you don't remove the cylinder varnish, as Kris said. Wait a half hour, hit it with the brush, and wash off with lots of water. Oh, wear gloves and stand upwind! Methyl chloride eats lungs and skin.

I've got one of these engines somewhere... Gotta go see if I can find it.

Geoff

Getting there now just a bit more scrubbing couldn't find any remover Geoff but did find some degreaser a lot more work I know but u use what u have eh !! Seems like someone got epoxy on it at some stage ... Oh joy more cleaning and scraping had a moment of madness earlier and was gonna put it on the wire wheel ten seconds later with wheel spinning up to max thought "perhaps not " think that was a wise decision although I have a few tiny wheels brass they are if I can't get all the stubborn bits clean might try it or am I just gonna take layers of the engine here is what I have so far bottom nice and shiny but usual top still quite a bit of crud

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Ok about as clean as I'm gonna go for the minute it's no shelf queen but hopefully got rid of enough gunk to keep it a bit cooler when running stripped it down part by part and can say that either the con rod and Gudgeon pin have been replaced or this engine has very few hours on it as they are mint no play or wear at all perfect fit so as kris said earlier a dirty outside holds a good condition insides is a true phrase am pleased so far although will have to make some new gaskets am thinking normal gasket paper ? Time to clean internals only thing I won't be tinkering with is the needle valve as it looks thoroughly solid in the Venturi so might let it soak for a few days if I ever need to take it out have out an air line through it so it should be nice and clear

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Well, that's progress! Another option is a pot of warm automobile antifreeze. If you can find a used crock pot, it will simmer the crud off overnight. BTW, there's an engine cleaner on the market called Demon Clean that's nothing more than repackaged methyl chloride paint stripper.

Geoff

Well completely disassembled and looking good everything as it should be all nice and tight definitely not a sloppy jalopy !! The crankshaft opening was completely full of gunk !! Not one bit of fuel was getting through there can't believe how much was in there I'd be surprised if this engine has been run since the 60's looking at the crud in the crank oh we'll let's see if we can breath life into it again now to look at a suitable model to fit it into !!!

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Is your engine drilled and tapped for a centre bolt for a fuel tank? Mine is, but I have no tank.

BTW, do any of you know of a source for small needle valve assemblies? The whole thing is
missing on mine. (Also missing on two of my Cox .15s) OS no longer lists the Pet 099 in its
obsolete parts lists, so you know these are OLD! I would guess they are among the first post-
WWII engines that OS made.

While I'm at it, I also need a complete carb, OS part # 1181, for an OS Max .10 R/C. Anyone
have one for sale or trade?

Hey Geoff yes it is drilled and tapped for a rear tank I think they all were looking at the reference i have for these they were normally anodised red later ones natural finish or the other way around not sure only had enough for about a minute or so of running I think hence why most you see don't have the tanks on try putting your wanted bits in the for sale / wanted section someone might have one although to be honest these engines aren't rare and certainly not worth much I bought this one complete apart from glow plug for £6.50 !!! They are out there just have to look eBay is good if this runs well I might get a couple more as they seem quite solid
I imagine any needle valve from a .09 to .10 with same od of tube would be ok as they all perform the same way will see if I can somehow measure the jets so u can find something suitable I'll have a go

OS 701 muffler will fit the OS PET .099. I have one with the RC carb and the mullfer. I will get pics later tonight of mine. I find the best way to clean larger glow engines is with a crock pot and the real ethylene glycol antifreeze. Cook on low for 24 hours and it will break down all the baked on gunk. Just clean with a tooth brush under warm water. I have cooked dozens of engines to make them look new again.

The first OS Pet that I had came out in the mid fifties. It used two head bolts (front and back) and had no head fins. The next one had four head bolts. The front and back ones held the cylinder on (as before) and the side ones only held the head onto the cylinder. Still no head fins. I believe the next version had head fins. That may be the one shown. Next came the Pet-II which had head fins and, i think, a gray crankcase. The only ones I have today are the Pet-II and the newer ones with the drop-in cylinder. Unfortunately my Pet-II is a parts engine that someone "played" with.

I believe all used the step-down intake baffle. I don't remember using any special fuel for it, but that was before synthetics were used. My feeling is that 10%-15% nitro and ~20% castor should work well. I do remember giving mine a short break-in before peak running.

This is all from my experience so there may have been other iterations.

George

The OS website's history section shows the smooth head model produced in 1957, so ours must be 1958 or '59 models.
http://www.osengines.com/history/ostimeline02.html Note the original 099 in 1950, then the "new" version in 1954.
This engine has had lots of versions! Mine has the 1954 prop washer for some reason.

Here is mine





Need to turn the carb around yet and give it a bath in my crock pot.