hello all,
backround iam a 30 year old mechanic,(20 years XP on engines) being sent mad by this tiny little engine. i can understand the basics of my slide carb, but ive had trouble getting the initial set up for my engine to run (Cyclon evo 4wd) 3.5 ccm Jamara).this was bought second hand so i have no paper work for it. the problem.

I can get it to run prety fast for about 10-15 mins not always full thottle, and then it will sooner or later cut out (i beleave due to heat) so i allow it to cool and then try to restart, mostly it will start, with some effort and run at tick over UNTILL i remove the glow starter, then it simply cuts out this happens almost all of the time ie it will cut out within a second of the glow starter being removed, ive removed and comparred the glow plugs to new and unused plugs and there seems to be no difference but a new plug will normally get me running again (ive gone through about 10 glow plugs inside a week.

any help or hints and tips would be greatly acepted

Can you answer some questions?

1. How much smoke is coming out of the pipe? Alot, a little, or none? Any change when you give it throttle? More smoke comes out?

2. How hot is the engine after the 10 or 15mins of running? If you spit on the head, does it sizzle right off, boil away after a few seconds, or just sit there?

3. What type of glow plug are you using?

Alot of things could be the problem, because as a used engine, you cant be sure how worn out it is. These things are very easy to damage if not run right. If the previous owner ran it too hot, he could have worn it out, and when the engine gets hot...the piston sleeve expands and creates blow by.

It sounds worn out, this happened to my buddys Picco 21 when it was tired, he could only get maybe 10 minutes out of it then it would have to sit and cool before he could run it again. Obviesley loosing alot of compresion when shes hot

oops

I agree, it sounds like this motor is toast. Try this when its cold. Rotate to crank to TDC and see how fast the air gets by the seal between the sleave and the piston and try to get a feel for how much resistance there is. When these engines are new, its barely possible to turn the engine over because this seal is so tight. When an engine is on its last legs, there is almost no resistance moving from BTC to TDC. Also, find someone with a temp gun and take the temp at the glowplug sometime after 6 or 7 minutes of running or right after it cuts out. I'm betting that the temp will be somewhere around 320 degress because of the ineficient cooling due to lack of compression and possibly an engine running too lean.

It does sound like he is too lean. He went through 10 plugs inside a week!! That's way too lean or he is running the wrong plug for that motor. Take the whole unit to your local hobby store and let the guys there tune it for you. Once you get an good tune on the motor think of it as a starting point. Everyday and sometimes more than once a day you will have to make small changes to the High Speed Needle to compensate for the relative humidity or outside air temp.

Just stick with it and it will all make sense soon. Your at the right spot for getting information / help in this hobby .
And forget about trying to compare these motors to full size 4 stroke gasoline engines.

I forgot to add, to compare glow plugs, you have to look at it when it is connected to the glow ignitor.
Pull the plug from the motor, put it into the ignitor and look at the coil...Is it glowing red evenly? Are all the coils glowing? if the first coil (closest to the outside) is not glowing it is probably bad.

Look at the pic below to get some good info on plugs.

firstly thanks for all the feedback. although its not the news i wanted to hear ;( looking at my engine and the points you have all mentioned it looks like ive bought a duff old engine. but i was warned that this was not a cheap hobby,
once again thanks all