Ed Cregger
Posts: 7734
Joined: 1/31/2002
From: Ringgold,
GA, USA
Status: offline
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quote:
ORIGINAL: davidbegg
Yes know that, but have sealed everything with silicone and replaced the carb with one from an engine working perfectly. Everything has been checked and rechecked, removed, cleaned, refitted, tightened, inspected you name it. Lots of guys in the club have tried to fix it. Will get it right, goes really well for the remaineder of the flying session, but next time out flying, same problems , out of tune again, and stuffing around for hours trying to get it right. It is particularly bad in the transition from full, high power, to a lower power setting, cutting out, just stopping. Nearly every landing was a deadstick!!!.Tried different fuels, with nitro without nitro, tried a variety of different glow plugs, all failing to solve the problem. I have not replaced the bearings, don't know if they are easily obtainable in NZ, the engine is nearly new anyway so they should be OK. The engine feels smooth to turn over. I brought the engine through an email auction so can't return it to the shop. A guy in a hobbie shop here told me that most SC engines are fine, a few can be difficult to tune, but then are fine, but a very few engines will just not run properly reasons unknown. I decided that I have one of those engines, wondering if some parts tolerances are at either end of the tolerance scale and the differences in size of components is just to great for the engine to run correctly. As the engine was run in the problems got worse.
Do you want me to mail you over the engine to play with and get going?????. It is of no use to me. Surface mail can't be that expensive to Norway, not much further than the UK
It sounds to me like this engine isn't broken-in sufficiently to fly, that's all.
Mount it up on a test stand that is at least one meter up off the ground and run it for a while at high throttle with the needle backed off from peak by several hundred rpm. Run it for several minutes, then shut it down and let it cool off for twenty minutes. Then repeat, repeat, repeat until you can notice a difference in how the engine is handling when starting and tuning. Don't run this engine in a four-stroke, but run it in a rich two-stroke. Resist the temptation to over prop it. Run the smallest prop in the manufacturer's recommended range until it has twenty tanks of fuel through it. It's a two-stroke (I hope!). Let it rev. And OF COURSE you're running fuel with some castor oil in it. Right?
My apologies if you're an experienced modeler that knows all of this already. Sometimes the wrong piston ends up with the wrong liner. People make mistakes, but many times they will learn to live together sufficiently to give you a usable engine. Best of luck to you.
Ed Cregger
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Artisan
"Flying models since the Fifties - I'll get the hang of this yet!!!"
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RE: Club MAGNUM ! - 
