Vernon Hadley Posted March 15, 2011 Share Posted March 15, 2011 Having purchased an ASP 70 4 stroke at a local swop meet , when using it for the first time the said engine will not accept full throttle. I already have an OS 70S 4 stroke plus OS52 4 stroke along with an SC52 4 stroke all of which I have been using for some time and have not come across this situation before. There was not a manual with the ASP, the engine starts easily however it requires three full turns of fuel and throttle response from tick over to 3/4 throttle is very good. However, as already stated once the last quarter of stick is applied the engine just dies. Opening up the needle a further quarter to half turn makes no difference. The prop in use is a gliders g sonic 13-8. Can anyone offer advice on this problem. Regards Vernon Quote Link to comment Share on other sites More sharing options...
Andy Green Posted March 15, 2011 Share Posted March 15, 2011 Sounds like a blockage in the carb. Also are you able to check the tappit's gap. I have one of these in a SIG Rascal and its brill. Never a days problem in 2 years. A Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted March 15, 2011 Share Posted March 15, 2011 Agreed.....my ASP70 has been a great motor....I currently run an APC 13x6 on mine..... It must be a fuel restriction....might the clunk be partially blocked? I came across one recently with a very small hole in it....the plating had all but blocked the hole up!!! Odd as the last quarter opening of the barrel often doesn't doo much!!!. Quote Link to comment Share on other sites More sharing options...
Vernon Hadley Posted March 16, 2011 Author Share Posted March 16, 2011 Many thanks to ANDY and STEVE for your prompt replies i will look into your suggestions , Can you adivse on the valve clearances Regards Vernon Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted March 16, 2011 Share Posted March 16, 2011 Valve clearances should be set with a cold motor. Set the piston to TDC on the firing stoke & check the clearances with a feeler gauge. They should be 0.1mm or 4 thousands of an inch in English Personally I doubt this is the problem......incorrect valve clearances will cause poor running but not cutting out..... Do you have any inline filters? (Bin them & filter fuel as it goes into the tank!!!) If you need three full turns on the main needle there is definitely a restriction somewhere......my ASP runs at about 1.25 turns open.....I doubt it would even start at 3 turns!!! If you'd like a pdf copy of the ASP instructions PM me your email address & they're yours!!! Quote Link to comment Share on other sites More sharing options...
Ian Skeldon 1 Posted March 16, 2011 Share Posted March 16, 2011 Check the idle adjustment jet, I would turn that out by half a turn and try again. I know that in theory that should only effect the tickover into mid range but experience proves that sometimes if this is screwed in too lean it causes the effect you mention. Your main jet being turned out by 3 full turns might also indicate this as the problem. If altering the idle jet cures that particular issue, you will need to start screwing in the main needle valve again as that will now be too rich. HTH, Ian Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted March 27, 2011 Share Posted March 27, 2011 Hello Vernon . Does the engine look as if it may have been stripped? I bought a Magnum 120 FS a couple of years ago that would tick over all day but would only rev up to about3/4 throttle then cut. I tried eveything then checked the valve timing . It was one tooth retarded . Easy to check. renmove the cam cover set engine on TDC (inbetween compression) with the valves on the rock ( Exhaust just about to close and inlet just about to open ) If this doesnt occur at TDC then thats the problem . If you cant decide then set the motor as described and look in the at the camshaft . When at TDC you should be able to see a dot stamped on the cam pointing to the center of the cam follower . If all of the above is correct then you know its just a fuel problem . RegardsEdited By Engine Doctor on 27/03/2011 11:25:35 Quote Link to comment Share on other sites More sharing options...
JC Posted July 8, 2011 Share Posted July 8, 2011 I would have to agree with Ian on this one. I'm no expert but I have just spent weeks trying to get an SC 70fs to run (same engine as ASP). Three turns out on an engine that has been run in is too much. The fact that it won't transition from idle to full throttle indicates mixture problem. The factory setting for the low speed needle on this engine is acheived by screwing out the idle needle completely and then turning it back in 4 turns. this will give you the starting point. i know this thread is quite old now but mabey this post will help someone else. I hope yours is now sorted vernon. JC Quote Link to comment Share on other sites More sharing options...
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