Creaking Saito

The gudgeon pin is out at last. The pin had some dark marks on it and fortunately, the bore in the con rod was OK. Cleaned the marks off the pin with fine Scotchbrite, cleaned the bores with WD 40 on a cotton bud. The pin was an easy fit in the piston but was impossible to push into the con rod by fingers alone. It appears that the seized con rod is a common fault with Saito engines, the usual failure being at the big end of the con rod. Re-fitting the pin to the con rod took a while. I mounted the pin on a long bolt secured with a nut. Holding the bolt in the chuck of a battery powered drill and using plenty of oil, turning the pin at low speed finally enabled the con rod to go on to the pin, it was extremely tight and the con rod heated up very quickly.It took about half an hour to get the pin turning freely. Now the pin can be pushed into the con rod, its firm but shows no sign of sticking. A lot of oil was used, it turned black after a couple of minutes, blotting up the blackened oil with kitchen paper and adding fresh oil kept it from getting stuck again. Now I have to re seat the valves, I poured some oil into the cylinder and overnight it has all drained out.

You have probably succeeded by now with the piston pin.

I would've suggested warming the con-rod in an oven or much to my wife's disgust a saucepan of oil at high temp and placing pin in a fridge or cool area for a while. Then insert. A common method (rather than force pushing it in) to heat up car and bike pistons to assist with removing the gudgeon pin, albiet these are also held in place with circlips too. Reverse to refit.

I know what you mean Phil, but the method is more suited to fitting bearings. The pin has to be free to move in the con rod, there's a cross hole in the top of the rod, it must be there to allow oil to reach the pin.

For info Brian

your namesake from down under, engine master "Winch" has written many articles about Saito motors including the Gas units. He has made reference to several suitable 2 - stroke oils, in particular
www.deluxematerials.co.uk/gb/rc-modellin...t-5060243901484.html
Because your motor uses several plain bearings, i think you should be using ITRO 20:1 mix.

After sorting the seized gudgeon pin, I took out the valves as they didn't seal properly. The inlet valve had a patch of rust that left the seating face badly pitted. There was a flake of rust stuck to the seating face in the cylinder head, I got this off with a bamboo skewer and WD40. HobbyPlastic stocked the valves, they come in pairs. Order placed Monday morning, valves delivered Tuesday morning. After a final check of everything I could think of, I reassembled the engine. It had its first run on Tuesday afternoon, it was reluctant to start at first, probably due to the generous amounts of oil sloshing around. Reset the carburettor to the info on the Saito website. Now starts easily and throttles quite well considering that it isn't run in yet. During my search for Saito information, I came across this thread, its the most informative easy to understand piece I've come across. Anyone who still has a Saito engine might find it a useful read.
www.rcuniverse.com/forum/glow-engines-11...es-bill-robison.html
During the running in process, there was a lot of oil coming from the crankcase breather. I copied the OS system and routed the breather tube so that the exit was pointing into the carburettor intake. Doesn't seem to affect the running, and now all the gunge comes out of the exhaust instead of over the test rig, and the engine gets some extra lube and the garden fence gets a coating of used oil.I still haven't managed to convince my wife of the weatherproofing benefits of old engine oil on garden fences.

Brian, this is hardy relevant to the Saito, I should have posted it on your Hannibal topic, so will probably earn a rebuke and go into negative Karma but now I'm here congrats on getting your letter published in the latest RCM&E!