Corvid
June 30th 20, 05:54 PM
On 06/30/2020 03:39 AM, Remi Dargis wrote:
> On Tuesday, June 30, 2020 at 12:01:55 AM UTC-4, Corvid wrote:
>> On 06/29/2020 03:09 PM, wrote:
>>> Hi everyone, i am new to ultralights (i was only flying skyhawks
>>> and warriors until now). i now own Fisher ultralight with Rotax
>>> 277. i never flew it, i never saw it flying and i do not know
>>> previous owner who actually flew it. when i got the airplane it
>>> had carb removed but everything else looks in good shape. i put
>>> carb back and was able to successfully start the engine. engine
>>> runs nice and smooth at 4000 rpm or above, but when it drops
>>> below 4000 it starts shaking badly. it runs stable but shakes to
>>> the point that some screws from the panel shook out. i have read
>>> that single cylinder 2 strokes shake a lot, but to me it looks
>>> too excessive. i took a prop off and it runs much smoother
>>> without it. i am thinking prop may be out of balance? the problem
>>> is that i do not have any experience or knowledge to tell how
>>> much vibration is too much on those engines. does anyone know
>>> how to determine if this vibration is normal?
>>
>> There's a link for tech support at https://fisherflying.com/
>>
>> The prop could be balanced perfectly, and have the flex or mass to
>> interact unfavorably with the engine, engine mount,
>> speed-reduction drive. Or anything else.
>
> my problem is that i don't know how much vibration is consider
> "normal". i am reading online that others are complaining about 277
> shaking, some say this is normal and just a nature of this motor. i
> don't want to start replacing things if this is normal. is there any
> criteria, anything to determine if this is normal? that shaking
> sounds like "compression vibration" - makes one bang on every stroke.
> or if you turn ignition off at higher rpm, when it starts to wind
> down below 4000 starts banging and does that till the last stroke
> when it stops.
4000 sure sounds high for banging and shaking. I know what I'd replace
if that's normal.
crossposted to rec.aviation.homebuilt , a once-bustling group which
still has lurkers waiting for questions like this.
> On Tuesday, June 30, 2020 at 12:01:55 AM UTC-4, Corvid wrote:
>> On 06/29/2020 03:09 PM, wrote:
>>> Hi everyone, i am new to ultralights (i was only flying skyhawks
>>> and warriors until now). i now own Fisher ultralight with Rotax
>>> 277. i never flew it, i never saw it flying and i do not know
>>> previous owner who actually flew it. when i got the airplane it
>>> had carb removed but everything else looks in good shape. i put
>>> carb back and was able to successfully start the engine. engine
>>> runs nice and smooth at 4000 rpm or above, but when it drops
>>> below 4000 it starts shaking badly. it runs stable but shakes to
>>> the point that some screws from the panel shook out. i have read
>>> that single cylinder 2 strokes shake a lot, but to me it looks
>>> too excessive. i took a prop off and it runs much smoother
>>> without it. i am thinking prop may be out of balance? the problem
>>> is that i do not have any experience or knowledge to tell how
>>> much vibration is too much on those engines. does anyone know
>>> how to determine if this vibration is normal?
>>
>> There's a link for tech support at https://fisherflying.com/
>>
>> The prop could be balanced perfectly, and have the flex or mass to
>> interact unfavorably with the engine, engine mount,
>> speed-reduction drive. Or anything else.
>
> my problem is that i don't know how much vibration is consider
> "normal". i am reading online that others are complaining about 277
> shaking, some say this is normal and just a nature of this motor. i
> don't want to start replacing things if this is normal. is there any
> criteria, anything to determine if this is normal? that shaking
> sounds like "compression vibration" - makes one bang on every stroke.
> or if you turn ignition off at higher rpm, when it starts to wind
> down below 4000 starts banging and does that till the last stroke
> when it stops.
4000 sure sounds high for banging and shaking. I know what I'd replace
if that's normal.
crossposted to rec.aviation.homebuilt , a once-bustling group which
still has lurkers waiting for questions like this.