|Diamond Geezer||11/08/2013 11:32:27|
|334 forum posts|
still trying to get this sc 46 run in problem is wont fire all I have is fuel coming straight out of the exhaust for some reason it dont seem to be going into the engine checked for air leaks etc any ideas
|Steve Hargreaves - Moderator||11/08/2013 12:15:56|
6744 forum posts
Sounds like its too rich DG......any unburnt fuel will pass out the exhaust port & into the muffler.....very common on start up but when its running the unburnt fuel will get blown out & all will be well....
How far open is the needle...? I recall that SC instructions suggest about 5 turns which is crazy.....2 turns max!!
So lets start from the beginning.......I would suggest an 11" prop for that engine to start with.....a larger prop will help it start as it has more "flywheel" effect... glow start well charged?? OK...first remove the plug & give the engine a good spin on the starter....this should blow out all the fuel from the crankcase.....watch your eyes...don't get the fuel mist in them!!! Now replace the plug...
Close the needle right down......open it 1.5 - 2 turns...set the throttle to 1/4 to 1/3 open & try & start it.....it should fire & run......let it run at this setting for a minute or two & then stop the engine & let it cool. Repeat & run it like this for 5 mins or so....stop it & let it cool.....start it again & run it about 3/4 throttle for 5 mins whilst varying the throttle setting from mid to full. Stop it & let it cool.....repeat twice.....& let it cool each time.
The idea for an ABC engine is to get it hot quickly so the liner expands to the correct running tolerance...running it too rich will mean its running too cool & the liner won't expand properly.....the short runs stop it getting too hot!!
Then tune for max power.....If during this process the engine shows signs of distress (like slowing down) then open the needle a turn or so & do a little bit more running in. When the engine will hold full power & you can get a reasonable idle out of it...go & fly it!!!
I have a copy of the ASP instructions (same engine different badge!!) written by the late Paul Landels of Just Engines fame....PM me your email address if you'd like a copy....
Hope that helps...
283 forum posts
Change the plug. The ones supplied are not normally very good. I had an SC70 FS that I could not get to run for love or money. After several weeks of fiddling with both needles checking and rechecking the fuel lines someone at the patch said 'have you tried a new plug?'. It then started first time and is now my most reliable engine by far.
|Mark a||16/08/2013 12:51:38|
|321 forum posts|
I run all my 2 stroke engines both SC and Irvine with OS no8 plugs and Westons liquid gold 5% fuel.
|the unmagnificent man||17/08/2013 19:02:15|
425 forum posts
DG. I agree with all that Steve said but would also like to know if you decided to adjust the low end needle in an attempt to start it? If so then it could well be that it is open too much. I think I'm right in saying that before you get the top end needle right that you need to get the low end needle somewhere near its correct position. Then repeat what Steve suggested.
so, low end at factory setting then high end in then out 1.5 to 2 turns.
That should see it at least fire.
reasons for it not firing at that setting could be no compression for some reason,a bad plug, a battery that doesn't give enough to glow the plug, a bad connection somewhere. If all that's good at that setting it'll fire.
sounds to me as if the plug is being drowned.
Hope this helped let us know how you got on. UMM
Please login to post a reply.
Want the latest issue of RCM&E? Use our magazine locator link to find your nearest stockist!