Too rich on the low end

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Too rich on the low end

Postby RC_Flyer » Mon Feb 20, 2006 5:29 pm

Where would you start looking to fix a problem with a K.61 that runs too rich on the low end even with the low speed needle all the way closed? If I close it more the carb sticks on low speed. It is running OK on the top end with the high speed needle out about 1 ¼ turn. The center of the fuel tank is slightly lower than the center of the carb and I’m running muffler pressure.
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Postby MECOA » Wed Feb 22, 2006 10:00 pm

the end of the spraybar is bell mouthed so the idle needle goes in too far. I will post more on this when I get back on Mar 6.

Post a reminder for me arount march 7 or I may forget. Thanks.
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Postby RC_Flyer » Sun Feb 26, 2006 8:56 am

Thanks for the response. I understand that it would be possible to jam the low speed needle into the spray bar end and distort it (bell mouth). I expect this could happen when owners tighten the throttle arm retaining nut without holding the throttle barrel and jam the low speed needle into the spray bar. But I seem to have the opposite problem and after more break in time and tweaking it’s running much better.

I have three new RJL K.61s that have never been disassembled or messed with. I like to have spare backups for each type of engine I have! The down side of this is that often the warranty expires before they all can be used.

Two of them have throttle barrels that can stop before they can close all the way because the low speed needle bottoms out in the end of the spray bar. The solution is to turn the low speed needle out so it is just past the end of the throttle arm retaining nut (about .005 or less). I’ve only started one of these engines and I find the low speed setting is very sensitive, a very small amount of movement of the needle can go from too rich to too lean. There is a very fine line between having the throttle barrel close all the way for throttle kill, getting the low end lean enough and not having the low speed needle bottom out in the spray bar. But it is possible to have the barrel close all the way and be able to have the engine low end too lean so I know with a little adjusting it can be done.

With the third and newest of the three new engines, the throttle barrel will go way past the fully closed position with the low speed needle flush with the throttle arm retain nut? All of the engines came in the Blue RJL boxs. All of the carbs look identical from the outside. Here’s a picture of all three engines http://image.rcuniverse.com/forum/upfil ... d51526.jpg and the newest http://image.rcuniverse.com/forum/upfil ... j23208.jpg and the older ones http://image.rcuniverse.com/forum/upfil ... v67278.jpg and http://image.rcuniverse.com/forum/upfil ... r40678.jpg and http://image.rcuniverse.com/forum/upfil ... x68531.jpg

I like the K.61s very much and the carb design looks very, very good so I’m probably missing something simple. I have other engines with similar type carb function like my Webra 61s but have never run into a problem with the low speed needles bottoming out in the spray bar.

Any insight you can provide on how the low speed needle and throttle barrel movement should work would be greatly appreciated.
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Postby RC_Flyer » Sun Mar 05, 2006 4:47 pm

After working with the carb more I now have the low end set OK and the top end is OK but the mid range is too rich. And I still have an interaction between closing the throttle barrel all the way and the possibility of the low speed needle valve bottoming out in the spray bar.
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Postby MECOA » Wed Mar 08, 2006 7:29 pm

It actually takes a little bit of force to bell mouth the spraybar. I would be sure to have the low speed needle out to an extreamely rich setting and get the high speed adjusted right, then close the barrel and adjust the low speed.

follow the owners guide..

1> Start the engine and open the carburetor to the full open position, then adjust for peak R.P.M. with the main needle as previously described.

2> Close the carburetor barrel slowly until the lowest possible speed is reached without the engine stopping.

3> Go to full throttle after about 10 seconds of idling. If the engine gains speed slowly, the idle mixture is too rich. If the engine stops, the idle mixture is too lean. Turn the idle needle clockwise if mixture is too rich and counterclockwise if too lean.

The engine will accelerate from idle to full throttle smoothly and instantaneously when properly adjusted. The engine may not idle well at a low setting or accelerate as quickly until it is well broken in.

-------------

If the mid range is too rich usually the idle is still set too rich.
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Postby RC_Flyer » Thu Mar 09, 2006 1:03 pm

Thanks! I’ve tried the recommended adjustment procedures. I guess at this point I should replace the carb from one of my other NIB engines and see if that solves the problem.
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Postby RC_Flyer » Sat Jun 10, 2006 11:40 am

I finally got around to solving the mixture setting problem by putting the carb from the newest K.61 on the older engine of the three. All of the engines are new and all of the carbs look identical from the outside but as I discussed in my earlier post the latest carb allows the barrel to rotate further before the low speed needle bottoms out in the tube on the high speed side of the carb. The new carb solved the problem completely. Will RJL exchange the unused older carb for a new one that works correctly?
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Postby MECOA » Thu Jun 15, 2006 7:37 am

Send it in and let me look at it. The needle may be misaligned with the spray bar.
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Postby jezzicaz789 » Mon Mar 01, 2010 3:39 am

RC_Flyer wrote:Thanks for the response. I understand that it would be possible to jam the low speed needle into the spray bar end and distort it (bell mouth). I expect this could happen when owners tighten the throttle arm retaining nut without holding the throttle barrel and jam the low speed needle into the spray bar. But I seem to have the opposite problem and after more break in time and tweaking it’s running much better.

I have three new RJL K.61s that have never been disassembled or messed with. I like to have spare backups for each type of engine I have! The down side of this is that often the warranty expires before they all can be used.

Two of them have throttle barrels that can stop before they can close all the way because the low speed needle bottoms out in the end of the spray bar. The solution is to turn the low speed needle out so it is just past the end of the throttle arm retaining nut (about .005 or less). I’ve only started one of these engines and I find the low speed setting is very sensitive, a very small amount of movement of the needle can go from too rich to too lean. There is a very fine line between having the throttle barrel close all the way for throttle kill, getting the low end lean enough and not having the low speed needle bottom out in the spray bar. But it is possible to have the barrel close all the way and be able to have the engine low end too lean so I know with a little adjusting it can be done.

With the third and newest of the three new engines, the throttle barrel will go way past the fully closed position with the low speed needle flush with the throttle arm retain nut? All of the engines came in the Blue RJL boxs. All of the carbs look identical from the outside. Here’s a picture of all three engines http://image.rcuniverse.com/forum/upfil ... d51526.jpg and the newest http://image.rcuniverse.com/forum/upfil ... j23208.jpg and the older ones http://image.rcuniverse.com/forum/upfil ... v67278.jpg and http://image.rcuniverse.com/forum/upfil ... r40678.jpg and http://image.rcuniverse.com/forum/upfil ... x68531.jpg

I like the K.61s very much and the carb design looks very, very good so I’m probably missing something simple. I have other engines with similar type carb function like my Webra 61s but have never run into a problem with the low speed needles bottoming out in the spray bar.

Any insight you can provide on how the low speed needle and throttle barrel movement should work would be greatly appreciated.

Thank you for the post.
Hi guys, Im a newbie. Nice to join this forum.

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