Jump to content
Buckaroo

Rumbling idle this morning?

Recommended Posts

2 minutes ago, Ed Cesnalis said:

In that RPM range mine is not very smooth.  

This rumble coming down is some  what unusual from my past experience. Maybe I’m just being extra sensitive. 

Ive never had my EGT go yellow once in 150 hours. Any ideas?

Share this post


Link to post
Share on other sites

I know yesterday when I cleaned to jets I noticed the large air intake tube had a very loose righting clamp. ?? Of course I tightened that.

Share this post


Link to post
Share on other sites

I would check 2 things.

First check the vent tube to make sure both are still attached at the carbs and airbox. Also check where it goes through the airbox to make sure the vents are not exposed.

If that checks out OK, then take the 3" hose off the back of the carb and reach in with a finger and lift the piston up. It should move up and down freely. I have seen a couple sticky before, and it keeps the carbs from staying balanced in transition.

That EGT split is pretty big. You definitely have something going on.

Share this post


Link to post
Share on other sites
17 minutes ago, Tom Baker said:

I would check 2 things.

First check the vent tube to make sure both are still attached at the carbs and airbox. Also check where it goes through the airbox to make sure the vents are not exposed.

If that checks out OK, then take the 3" hose off the back of the carb and reach in with a finger and lift the piston up. It should move up and down freely. I have seen a couple sticky before, and it keeps the carbs from staying balanced in transition.

That EGT split is pretty big. You definitely have something going on.

Bingo! Yesterday wrestling with the left carb I must of twisted her so much the vent hose pulled out of the carb. It had a tight zip tie squeezing around the tube. Is there a better clamp method? 

A huge thanks Tom! 

C16C14B6-871C-464C-91EE-9983C6D63694.jpeg

Share this post


Link to post
Share on other sites

You can put on a hose clamp if you wanted. Zip ties are enough though.

Share this post


Link to post
Share on other sites

Can someone enlighten me how the carb vent lines to the air filter function with regard to mixture etc?

 Thanks!??

 

Share this post


Link to post
Share on other sites
1 hour ago, Anticept said:

You can put on a hode clamp if you wanted. Zip ties are enough though.

I love hode clamps!??

Share this post


Link to post
Share on other sites

The vent tube provides a static source of air to compare to the air in the carb. The pressure differential raises or lowers the piston and needle, varying fuel and air for the carb. By having the hose unhooked the two carbs were getting different pressures to compare. This causes them to have different amounts of air and fuel going to each side of the engine. This makes one side of the engine produce more power than the other causing roughness.

Share this post


Link to post
Share on other sites

Tom,

The piston balance pressure is dictated by an ovalish air inlet hole at the top of the carb inlet flange.

The tube balances the pressure on the fuel in the bowl. The issue is that typically cowling pressures are different for inlet air, and air moving through the carb is subject to Bernoulli's principle and pressure would change with throttle settings. The tubes are put in place to run to an area of relatively stable, slower moving air in the air intake source, past the filter.

Fuel level in the bowl has quite an effect on richness in a CV carb, so sampling a stable air pressure source is quite important.

We don't see this on other carb designs because the mixture is manually set, and the fuel bowl level has less of an effect as a result.

Share this post


Link to post
Share on other sites
2 hours ago, Tom Baker said:

The vent tube provides a static source of air to compare to the air in the carb. The pressure differential raises or lowers the piston and needle, varying fuel and air for the carb. By having the hose unhooked the two carbs were getting different pressures to compare. This causes them to have different amounts of air and fuel going to each side of the engine. This makes one side of the engine produce more power than the other causing roughness.

Thanks! Who thinks this stuff up!

This forum has gotten me unstuck twice in two days!?????

Mom really appreciative!

Share this post


Link to post
Share on other sites
10 hours ago, Buckaroo said:

Joe from Lockwood told me to never use a wire to clean the holes. He said it would trash it.?

Are you sure Joe wasn't referring to aviation safety wire?

Big, big difference in what Roger is recommending.

Share this post


Link to post
Share on other sites
1 hour ago, WmInce said:

Are you sure Joe wasn't referring to aviation safety wire?

Big, big difference in what Roger is recommending.

He didn’t elaborate! He just told me to use Napa red can electric spray cleaner with the red tube and pressure spray the jet holes. 

Im sure Roger knows how to insert objects that will not disrupt the jets and not ruin the jets. Joe’s talking to Montana me who he knows nothing about this shit just to keep me from having increasing problems! 

Its all good and tomorrow I can fly thanks to you all!

Share this post


Link to post
Share on other sites
1 hour ago, Buckaroo said:

He didn’t elaborate! He just told me to use Napa red can electric spray cleaner with the red tube and pressure spray the jet holes. 

Im sure Roger knows how to insert objects that will not disrupt the jets and not ruin the jets. Joe’s talking to Montana me who he knows nothing about this shit just to keep me from having increasing problems! 

Its all good and tomorrow I can fly thanks to you all!

Buckaroo,

You need to meet us in Page, this October.

Share this post


Link to post
Share on other sites

A thin strand or 16 ga. wire will not hurt the opening in the idle jet and I challenge anyone who says it does to show ANY kind of proof. You are not drill or applying great pressure. Just allowing the wire to remove any fuel build up. You slide it back and forth some while turning the jet on the wire. This absolutely positively WILL NOT damage the idle jet in any way. The wire is so thin that a little too much pressure and it breaks or pulls out of the insulation where it is peeled back to.

 

Share this post


Link to post
Share on other sites

Copper is softer than brass, so it's true, you're not going to damage the opening. Brass is over twice as hard as copper.

It's even softer than aluminium.

Share this post


Link to post
Share on other sites
8 hours ago, WmInce said:

Buckaroo,

You need to meet us in Page, this October.

I’d like to very much. I am flying to Oshkosh. Never been at Osh and really looking forward to it!

Share this post


Link to post
Share on other sites

You're not trying to drill and scrape a groove through the idle jet, just sweep away any old fuel deposits.

Share this post


Link to post
Share on other sites

One thing I’ve noticed about the Rotax! Everything is tiny. My big ham hands struggle to get anywhere in the engine area. It’s like a miniature world under the hood! Darn thing sure performs though!?

Share this post


Link to post
Share on other sites
8 hours ago, Buckaroo said:

I’d like to very much. I am flying to Oshkosh. Never been at Osh and really looking forward to it!

Make sure to read and understand the NOTAM for Oshkosh, and it will be a breeze.  It's very rewarding to land at the show.  Just don't hose up the landing, all of aviation is watching!  :o

Share this post


Link to post
Share on other sites

The NOTAM should start with "You shouldn't really come and land during the show but if you really , really want to and can really handle it, here is how you should go about it ... "

I get sweaty hands just watching youtube videos ...

Share this post


Link to post
Share on other sites
5 hours ago, Warmi said:

The NOTAM should start with "You shouldn't really come and land during the show but if you really , really want to and can really handle it, here is how you should go about it ... "

I get sweaty hands just watching youtube videos ...

I disagree, landing at Oshkosh ranks in one of my top few aviation experiences.  It felt like a real rite of passage.  When I did it I had less than 300 hours total.  It’s not a hard procedure, you just need to do as you’re told and keep your head on a swivel.

The one thing to watch is the weather; it’s pretty unpredictable that time of year and there are often pop up storms and sometimes strong winds.  If the weather makes you uncomfortable you should consider diverting to Appleton or Font du Lac and waiting for more favorable conditions.

Share this post


Link to post
Share on other sites

I have to agree with Andy. I have flown in several times. Follow the procedure, listen for instructions, and don't run over anybody in front of you. You need to be able to hit your spot for landing. If everyone else does the same there are no problems. The thing that scares me the most are those who do not read the NOTAM, or follow the instructions. I have witnessed people who force their way into the middle of the line instead of entering where they are supposed to.

To be honest flying into a busy local fly in breakfast is far more dangerous. The worst I have experienced was flying into a flight instructor renewal clinic that the state of Illinois used to put on. As far as following pattern procedures those instructors were the worst. That was the only time I have really been scared in the traffic pattern. 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×