fbpx

 

Hello

If Anyone could assist me I would Really appreciate it !!

When I do a mag test @ 3800 RPM their is no noticeable drop between the two on power up I get good RPM when reaching 1000 foot after take off i level off and come off the power to 4800 for the cruise or 5000 RPM the engine runs very rough not smooth @ all when i increase the RPM to 5250 5300 it then sounds better i first though i might be experiencing Carb icing but after 1 hour of flying it still stayed the same on the descent i brought it back to 3000 RPM sounded very smooth i landed checked that the choke on boath sides were up against the stops and they were i had just had the carbs balance about four flights ago because i notice it did the same at 4600 and at 5000 it was smooth now this problem is getting progresively worse so I have opted to stop flying untill it has been sorted out I also tried in flight to activate the fuel pump but to help any advice would be greatley appreciated Please.

Kind Regards
Charlie
  • Re: Rough Running between 4400 and 5100 RPM Rotax 80

    by » 12 years ago


    Hi Charlie,

    Did this problem start up out of the blue? Was there any maint. or changes done just prior to this popping up?
    Here are a couple of things to rule out.

    What rpm did you do your carb balance at? Do it at least 3500 rpm. The 2500 in the books is too low and too close to idle rpm. With the higher rpm sync you will get a better fuel/air flow. Pull the carb float bowls. You may have debris floating around that isn't a factor at low rpm and low fuel flow until you really demand more fuel flow at higher rpms then it gets pulled up into the jets. You may need to pull the carbs and clean them. I would probably do this myself for this problem if I new for sure the carbs are synced well at that 3500-4000 rpm. When you pull the bowls check to see if the fuel is equal in both and the floats are floating properly. Check the diaphragms. I don't suspect plugs right up front because you said the mag drop was fairly equal and unremarkable, but it may be worth a plug change if you don't find an issue with the carbs. If the carb cleaning and inspection doesn't reveal anything then it may be time to look at the gearbox and or prop balance.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


  • Re: Rough Running between 4400 and 5100 RPM Rotax 80

    by » 12 years ago


    Hi Rodger
    The local AP did the carb balance for me will check with him at what RPM he did it and will get him to pull float bowls as well the motor and box and brand new Kiev prop only have done 33 hours on it last maintenance was 25 hour oil change and he did the carb balance because I noticed @ 4600 their was a rough running but now it is progressively getting worse which is alarming me cant understand why not sure what the fuel pressure is as i do not have a fuel pressure gauge do u recommend i install one ? why do you think it may be the gear box .

    Kind Regards
    Charlie

  • Re: Rough Running between 4400 and 5100 RPM Rotax 80

    by » 12 years ago


    Hi Charlie,

    Since the engine is brand new with only 33 hrs. I would focus right now on just the carbs. Something could have settled in or changed. It could be a loose cable end, bad carb sync, air leak, carb debris, ect.. Focus on the carb / fuel delivery

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


  • Re: Rough Running between 4400 and 5100 RPM Rotax 80

    by » 12 years ago


    Hi Rodger
    Thank you so much for your help will do this tomorrow and let you know what the out come is
    Kind Regards
    Charlie

  • Re: Rough Running between 4400 and 5100 RPM Rotax 80

    by » 12 years ago


    Hi Rodger

    I just spoke with another pilot he said i should install a return pipe from the mechanical fuel pump with a constrictor and feed it back into the main inlet line to the pump this will alleviate the fuel pressure he seems to think the pump is creating to much pressure even when slowing down thus creating a richer mix making the RPM and engine sound rough which can make sense when they installed my engine they never installed the return into the manifold as my aircraft does not have a return line back to the main wing tanks.

    Your view on this would be appreciated nad very helpfull.
    Kind Regards
    Charlie

You do not have permissions to reply to this topic.