at which rpm needle jet begin to raise? what are signs of clogged bypass holes?

by nicola di biase in 912 / 914 Technical Questions one month ago

I read a lot of informations on how the bing 64 works in general terms and details.

But i have never understood whether from idle to 3000 rpm (where there are always more or less marked roughnesses in rotax 912 engines) only the idle jet and the bypass holes are involved or if at these rpm the needle jet has already started to lift.

Many 912's are rought from 2000 to 3000. I suspect that in addtion of dirty idle jets, clogged bypass holes are the cause and a lot of people do not even know their existence!

In your experience what are the signs of clogged bypass holes?

thanks

Re: at which rpm needle jet begin to raise? what are signs of clogged bypass holes?

by Roger Lee » one month ago

Roger Lee

131 5.39k 5.47k

At every annual I weigh the floats and clean the idle jets. I have found 75 of the idle jets partially clogged or fully clogged. So no I just do it for my customers no matter what aircraft they fly. I'm teaching a Rotax class this weekend and these are two things I teach them. Since we use a real aircraft (a FD CTSW this time) they get to learn the easy way to pop the carbs out and then they all get to see how to weigh floats, look for clogged idle jets and how to clean an idle jet without damaging it. It's actually very easy and quick.

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

Report
Re: at which rpm needle jet begin to raise? what are signs of clogged bypass holes?

by Jeff B » one month ago

Jeff B

14 694 2.5k

Nicola,

Here is a great article by Brian Carpenter explaining the idle circuit and when the each fuel delivery route is in play. There are two more related articles (parts 1 & 2) which you can find with a search. I don’t impress easily, but I find most everything Brian publishes impressive.

https://electricmotorglider.com/wp-content/uploads/2017/04/CV-Carb-Part-3-web-1.pdf

Thank you said by: Sean Griffin

Report

You do not have permissions to reply to this topic.

Title	Category	Replies
Cruise RPM	912 / 914 Technical Questions	17
Sudden drop in RPM while changing fuel tank	912iS Technical Questions	3
RPM 914turbo	912 / 914 Technical Questions	8
Rotax 582 blue head Rise in RPM during Mag check	General Tech Discussion	0
RPM drop 912UL	912 / 914 Technical Questions	4

at which rpm needle jet begin to raise? what are signs of clogged bypass holes?

Safety First!

Recent Videos

Log In/Out

Login