SC53 problems

[Paul Sutton]

Hi,

Am fairly new to hobby, althugh taking my A test soon, so have some experience. I've recently purchased an almost new SC53 fitted to an Acrowot Trainer. I have flown both several times and are in very good condition, however there seems to be a problem with the engine (I've had an SC46 on an Arising Star and had no problems)...the engine seems to take a few seconds to 'engage' when powering up to full throttle..it is definately lagging..something which the 46 didnt do..today it cut out twice while trying to power up on an aborted landing. The previous owner replaced the carb, and this seems to have been fitted ok.

..was wondering if anyone could help on this?

Many thanks

Paul

[Bruce Richards]

Paul sounds like the low end needle is too rich or it may be too lean. Try turning the low end needle 1/4 of a turn anticlockwise if the problem gets worse try a 1/4 turn back plus another 1/4 turn clockwise. I am assuming that the top end is set up correctly. You should be able to tune it so that it will throttle cleanly from tickover to full power. Let us know if this helps. There are lots of more detailed explanations of setting up engines on this and other forums so if you need more detail search around the Internet a bit.

[simon barr]

Hello Paul, and welcome,

The motor could be labouring due to the prop being too big..what size prop is it?

[Andy Gates]

I have had the same with mine too.

Mine is the remote needle valve version.

Eventually after a lot of work, it came down to a too rich idle mixture and a slightly weak spring not pushing the throttle barrel over hard enough, which meant a quickish opening of the throttle lead to the mixture going too lean.

I tried stretching the spring which has helped, although for the longer term I may be replacing the carb with one from another engine manufacturer.

I hope this helps.

[Paul Sutton]

Thanks for the replies.

will get someone at club to look at mixture set-up, although they have done this several times, so i'm thinking it could be something else also..

Prop size..think its a 11x8 although dont hold me to it!..i shall have to check

.Also Andy...strangely enough didnt mention but mine is also the remote needle version (?)..

...and without sounding er thick (!)..where is the spring located and is it easy to stretch?

Thanks

Paul

[Andy Gates]

The spring is located in the carb between the barrel and the body at the fuel nipple end.

To get access to it, wind out the barrel retaining / throttle stop screw so the barrel will slide out towards the throttle lever.

Once removed, the spring will be found either still in the carb housing or on the end of the barrel.

I stretched mine so that it was about 1 1/2 times its origional relaxed length before refitting it.

For referance my motor runs on an APC 12 x 6 sport prop and I can get 50mins of gentleish flight out of a 10oz tank of Contest 10 fuel.

I also run it on a slightly hotter plug, an OS A3 plug

I hope this helps

[Paul Sutton]

,,thanks Andy i shall give that a try later.

Not sure what prop i've got on there, but will purchase an APC as our club tends to use these.

Thanks

Paul

[Andy Green]

Just engines (http://www.justengines.unseen.org/)sell replacement carbs. Andy PS had to post he link as all the format buttons are missing.