flyerme Posted February 9, 2012 Posted February 9, 2012 on the way home from picking the new super cat I encounted engine failure.whilst cruising for around 20 mins the engine started running rough then died. I made a restart, and as the engine still run rough I gave it full thottle and it ran fine again,when dropped back to cruise after a few minites it ran rough again ,full throttle applied and ran fine,so flew home at full revs (10 mins) and dropped revs for approch and ran fine landed no issues,but when broght the revs back up for taxing ran rough again. NOTE:noticed full leaking from air filter right before start up and when taking off noticed a slight miss , checked the float level,needle and seat,fuel tap removed inspected,plugs checked (brown) NOTE" float level sits about 4mil below bowl top., ran up the engine and runs fine when applying revs up slowly but always runs rough when pulling back the throttle ,push the throttle forward fast and cough and slutters.? thinking I may need to overhaul the carby (jets)? any ideas????????????? should mention was told after,that its happened before! and noticed it come with a spare(old)carbie.?
flyerme Posted February 9, 2012 Author Posted February 9, 2012 Update, suspect its the electric fuel pump ,over pressure! as the fuel tank is mounted high (up front under dash like an ag hopper) and gravity feeds to carby,plus has the mechanical fuel pump, we believe the electric pump (always left on) is over pressuring the float needle and seat. will run another test tomorrow with NO electric fuel pump turned on,keep you posted (no pressure reg fitted.
flyerme Posted February 9, 2012 Author Posted February 9, 2012 Nope not fuel pump!ran the same with no electric fuel pump, ran engine70% then switched off in that position and removed plugs,both ceramic,s light brown but 1 plug electrode black,will buy 2 plugs and see if not will pull down carbie and inspect and clean jets
JG3 Posted February 10, 2012 Posted February 10, 2012 Nope not fuel pump!ran the same with no electric fuel pump, ran engine70% then switched off in that position and removed plugs,both ceramic,s light brown but 1 plug electrode black,will buy 2 plugs and see if not will pull down carbie and inspect and clean jets I haven't used those carbies for some years so can't remember for sure, but that float level 4mm below top of bowl sounds very high..... Also fits the symptoms...... JG
flyerme Posted February 10, 2012 Author Posted February 10, 2012 I haven't used those carbies for some years so can't remember for sure, but that float level 4mm below top of bowl sounds very high..... Also fits the symptoms......JG adjusted float level to specs(with floats removed 1/2 inch from the top..) still the same (or getting worse..idles slightly rough constantly,and the same symtoms as prior,just replaced the plugs with the same as I removed ngk standered and noticed package recomends NOT to use in flying machines,,should I be useing the aridium equivalent? have not run yet as "the rains R ear",will do a run with new plugs if no different will pull down carbie (just a thought -might just fit the old carbie for comparrasen?) take it easy
JG3 Posted February 10, 2012 Posted February 10, 2012 adjusted float level to specs(with floats removed 1/2 inch from the top..) still the same (or getting worse..idles slightly rough constantly,and the same symtoms as prior,just replaced the plugs with the same as I removed ngk standered and noticed package recomends NOT to use in flying machines,,should I be useing the aridium equivalent? have not run yet as "the rains R ear",will do a run with new plugs if no different will pull down carbie (just a thought -might just fit the old carbie for comparrasen?)take it easy Regular NGK plugs are just fine. The only plug fowl in had in 1000hrs with a 447 was one of the fancy iridium ones..... Remove idle adjustment screw and blow out the idle circuit with compressed air. Check that the needle clip is secure in one of the middle slots. Check that the needle clip is under the nylon retainer, not on top.... Also check that the enricher valve is closing properly. That's all I can remember right now..... JG
fly_tornado Posted February 10, 2012 Posted February 10, 2012 I would be checking the fuel lines and the filter before pulling the carby to pieces, a blockage is not inconceivable.
flyerme Posted February 10, 2012 Author Posted February 10, 2012 I would be checking the fuel lines and the filter before pulling the carby to pieces, a blockage is not inconceivable. fuel lines clear replaced fuel filter first ,fuel flow to carbie is perfect.
flyerme Posted February 10, 2012 Author Posted February 10, 2012 Regular NGK plugs are just fine. The only plug fowl in had in 1000hrs with a 447 was one of the fancy iridium ones.....Remove idle adjustment screw and blow out the idle circuit with compressed air. Check that the needle clip is secure in one of the middle slots. Check that the needle clip is under the nylon retainer, not on top.... Also check that the enricher valve is closing properly. That's all I can remember right now..... JG ill do that in the mourning ,thank you
flyerme Posted February 10, 2012 Author Posted February 10, 2012 Regular NGK plugs are just fine. The only plug fowl in had in 1000hrs with a 447 was one of the fancy iridium ones.....Remove idle adjustment screw and blow out the idle circuit with compressed air. Check that the needle clip is secure in one of the middle slots. Check that the needle clip is under the nylon retainer, not on top.... Also check that the enricher valve is closing properly. That's all I can remember right now..... JG also wondering why the carbie was replaced? he did say after, that it had happened to him,I have a feeling he changed the carbie thinking he,d fixed it? wonder if its an electical break down,,hmmmm starting to get shy with this rotax..... maybe I should be putting my ever relyable robin in her? never skips a beat ,50 hp,I ll persavere with this piece of ,giving me a headache,so now I know why the low price....not happy Jan!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1:bash:
flyerme Posted February 10, 2012 Author Posted February 10, 2012 plugs, no difference,old carbie no good ,no choke plunger and other one doesn't fit,so cleaned the carbie thats fitted,pulled all jets etc..cleaned and blew out with compressed air re fitted,No improvement? So now really thinking electical break down - most likly coil? yep me really lovin the old robin... bloody Rotax....lol Take it easy
flyerme Posted February 10, 2012 Author Posted February 10, 2012 anyone have a set of rotax 447 coils?
flyerme Posted February 11, 2012 Author Posted February 11, 2012 JUST DID A COMPRESSION TEST AND BOTH CLYINDERS CAME UP AT 120 PSI. IS THIS ABOUT RIGHT?
fly_tornado Posted February 11, 2012 Posted February 11, 2012 aren't you supposed to put some oil in the cylinder and redo the test? then compare the results
skyfox1 Posted February 11, 2012 Posted February 11, 2012 Hi 120 psi is perfect same as my 503 l have just rebuilt
flyerme Posted February 11, 2012 Author Posted February 11, 2012 nope.not the choke,made no difference and seems to seat fine ,will not lower any more..,this afternoon will adjust the float level high(just an exsperament)as noticed after float reset(lower) constsnt running rough? more ideas please:scratching head: lol,ok better get back to Pa'injector pump, if man made it ,be sure as hell itll break,, take it easy P.S went up on the broom stick this mourning ..........ah really made me appreciate the supercats super handleing,, hanging to claw threw the air in her again.......
flyerme Posted February 12, 2012 Author Posted February 12, 2012 well ill be a monkeys............... AIR FILTER!!!!!!! just remove the air filter completly did a run up test and bingo,,,smooth at idle mid and high no engine fluctuation, tried my hardest to get her to run rough but she stayed true....................pushed and pulled from idle to full in a millie seconed and she just reved up beautifulll,,,,where to get an airfilter?lol will swap 1 with the thruster and see how she goes cheers
flyerme Posted February 12, 2012 Author Posted February 12, 2012 different air filter makes slight difference, without filter 98% notice very slight miss after idle,and still slight miss while decellerating,other than that she appears fine.so I believe its a air/fuel mix prob?' just wondering if the new carbie(being slightly different) is for the newer 447 and may need fine tunning?take it easy
skyfox1 Posted February 12, 2012 Posted February 12, 2012 Hi Good to see you are progressing check jet and needle size to see if they are for your alt as some differ
facthunter Posted February 12, 2012 Posted February 12, 2012 Have you got EGT's fitted? Don't run the thing lean, or you will ruin it. My method of checking mixtures is a bit dangerous as you are near the prop. Remove the air cleaner and as you progress the revs in stages, place your fingers PARTIALLY across the carb intake so that you obstruct the air a bit. The instant you do this the engine should run worse or else the motor is lean, (especially if it runs better straight away) Do you know how to tune slide carbs? It's not rocket science but you should know the principles. As you open the slide it goes. idle system needle adjustment for smooth idle with no faltering unless cold then slide cut out (more cut out is leaner). Then cut out and needle position and size. (needle lower is leaner) Then at full throttle the main jet controls the mixture. This is a brief expanation. Keep away from that Bloo** prop. Two strokes are killed stone dead if the mixture is lean. Rich mixture, they 8 stroke, smoke a lot and don't want to rev, but they don't wreck themselves. so be on the safe side . A 447 is an OK motor. Nothing special , but pretty popular in it's day...Nev
flyerme Posted February 12, 2012 Author Posted February 12, 2012 yeh all good! ,I'll stick to rotax specs check air screw .5(1/2 turn out) make sure needle set on 2,do an accurete messure of float level,.replace air filter.. ,noticed both egt and cht were running lil cold???..EGT running 700-800.,max is 1200 specs say 1000 -1100 ? and your method with your fingures!!!!! lol been doing that for years ....
flyerme Posted February 12, 2012 Author Posted February 12, 2012 UPDATE................. just went out to check the airscrew (as thats what I suspected )and descovered its all the way screwed in??????????????????????? I marked its position then went to turn it in(so I could bring it out to 1/2 a turn to specs) and lord behold it did not turn..so tunred it out 1/2 a turn and will test it in mourning but this would explain all the above symptoms, ,let you know how it goes and still hope to see you all fly in my lil strip.. .hey! its always good to get some short feild exsperiance under your belt? for the record the supercat at 50knts - no brakes was down and stopped by 150meters....still had 170meters spare
flyerme Posted February 22, 2012 Author Posted February 22, 2012 still not going? have someone bringing another carbie for a test next week, done a proper pitch adjustment as the poor lil thing only pulling 5800revs with the powerfin set at 10deg ,adjusted to 7deg and it increased revs to 6000 and engine starting to run warmer,but still to rich and cold cht=390 at 5400rev for 10mins and egt=1000 My savier also will be bringing the robin 50hp all ready to go in should needed,,ah a back up plan...bye the way every thing leans towards carbie being worn out!!! very old carbie throttle slide scored and has no resistence,float valve worn tip(I replaced this)idler jet 45 hole bigger than spare idle rjet 45..main jets I do not have so could not replace to see,so hence my maitance pro bringing me a 447 carbie off one of his students plane thats currently running fine,we will fit it and see what happens???can,t wait as im sure this will do the trick,,only thing is then ill need a carbie replacement? all good
flyerme Posted March 6, 2012 Author Posted March 6, 2012 Update: put the a new Tested carbie on and it made no difference still rough..,so then Jim Cuthill (CFI "Falcon hawk" benalla) adjusted the pitch from the origanal 10deg setting to 4 deg and she ran beautifull !!! we both ran a series of taxi tests, Jim doing some small skims,Unfortunatly twas blowin a gail,so no real flight test but engine didn,t skip a beat all temps now perfect no roughness at idle or when backing off and shes now pulling 6200rpm instead of the initial 5800rpm,..so will take her up in the next couple of days ..will sit around 2000 in my training area( just incase I can glide back to my strip...hopefully..lol) and keep her up for 1/2-1 hour in cruise and see hoe she goes?
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