 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
Thom Riddle
Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)
|
 Posted: Sat Jul 21, 2007 10:13 am Post subject: Follow up to FS 1 prop pitch & lean mixture problem |
 |
|
Today, I flew a bit to see how the movement of the mixture clip down to riches position was doing and the EGTs were up to 1200+ again. Perhaps different atmospheric conditions was the cause. At any rate, I then increased the pitch of the prop but apparently a bit too much because I am getting about 6250 rpm WOT level flight. BUT the EGTs are down below 1100 during cruise and the CHTs are up a bit.
The bad news is that now the engine will not hold a particular rpm, especially below 5500 rpm. I've read about what causes this but can't remember where it was nor what to do about it. I have a big flight planned for tomorrow so I'm deferring the next step until after this flight.
I'll take the carb home after tomorrow's flight and check out all the jets etc to make sure they are the correct ones. I'm betting that the needle jet is leaner than it should be.
I don't plan to decrease the prop pitch until I find the real problem and fix it. If the jets are all the right number and the o-rings, seals, and float levels are good. I'm not sure what to do next. Any other ideas or resources for curing the rpm instability problem? I sure hope I can get this nearly new 447 to run as good as my old "worn out" 377.
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
|
_________________
Thom Riddle
Buffalo, NY (9G0)
Don't worry about old age... it doesn't last very long.
- Anonymous |
|
| Back to top |
|
 |
lucien
Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM
|
| Posted: Sat Jul 21, 2007 11:04 am Post subject: Re: Follow up to FS 1 prop pitch & lean mixture problem |
|
|
| Thom Riddle wrote: | Today, I flew a bit to see how the movement of the mixture clip down to riches position was doing and the EGTs were up to 1200+ again. Perhaps different atmospheric conditions was the cause. At any rate, I then increased the pitch of the prop but apparently a bit too much because I am getting about 6250 rpm WOT level flight. BUT the EGTs are down below 1100 during cruise and the CHTs are up a bit.
The bad news is that now the engine will not hold a particular rpm, especially below 5500 rpm. I've read about what causes this but can't remember where it was nor what to do about it. I have a big flight planned for tomorrow so I'm deferring the next step until after this flight.
I'll take the carb home after tomorrow's flight and check out all the jets etc to make sure they are the correct ones. I'm betting that the needle jet is leaner than it should be.
I don't plan to decrease the prop pitch until I find the real problem and fix it. If the jets are all the right number and the o-rings, seals, and float levels are good. I'm not sure what to do next. Any other ideas or resources for curing the rpm instability problem? I sure hope I can get this nearly new 447 to run as good as my old "worn out" 377. |
Did you say you raised the jet needle or lowered it? If you raised it, the midrange EGT's should have gone down, not up.
My 447 single carb on my trike always wandered a bit in the 4500 to 5500 rpm range and I never was able to really cure it. My carb had all the stock jets in it for sea level and my altitude was basically sea level as well. I did try raising the needle a notch on the guess that it was lean, but that actually caused it to 4-stroke intermittently so I was actually about right before then  .
My suggestion would be to reset everything back to the Rotax recommended jetting for your altitude/temp, reset your pitch for just bumping redline at WOT, straight and level. And then go from there.
That's what I had to do with my trike when I monkeyed with it and that pretty much got me back in the ballpark.
Then you can start suspecting the EGT gauges or looking for other problems... But I'd go back to baseline on the jetting/propping first... That's always worked for me...
Their jetting recommendations are virtually spot on for pretty much every condition you can think of. I moved my FS II from sea level to 7000' MSL. I did the jet calculations on the chart and installed the new ones (158 mains to 148) and it was spot on..... A little rich again now in the summer, but thats what the chart says as well (I need 145's right now really)....
LS
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
|
_________________
LS
Titan II SS |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
