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k&b wont run after removing glo ignitor

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k&b wont run after removing glo ignitor

Old 03-11-2023, 05:19 AM
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tbone4343
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Default k&b wont run after removing glo ignitor

I have a k&b 40 ringed motor with stock carb it starts and runs strong untill i remove the ignitor i changed plug and still the same im using os # 8 plug and 10% fuel cant figure it out any help would be great
Old 03-11-2023, 07:31 AM
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speedracerntrixie
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Sometimes you can have a bad plug right out of the package. If the engine dies right away I would look to the plug, if it sputters some then the mixture is possibly too rich.
Old 03-11-2023, 10:40 AM
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tbone4343
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i tried 2 new plugs and ran high speed needle in and out runs good untill i remove power to ignitor and it runs down and dies ?
Old 03-11-2023, 12:44 PM
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Have you adjusted the low speed needle?
Old 03-11-2023, 02:34 PM
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tbone4343
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i have not i dont have the instructions for the engine ill do some research and try that as that could be it to rich on low speed
Old 03-11-2023, 03:04 PM
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speedracerntrixie
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Keep in mind that engine depending on year produced could have come with any one of four different carburetors. Posting a picture of the engine would certainly help.
Old 03-11-2023, 05:46 PM
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tbone4343
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i am going to a perry carb i am familiar with these thanks for your help on deciding on carb issue
Old 05-02-2023, 01:45 AM
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tbone4343
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well i finally got the perry carb for this motor i posted it is a 40 k&b its a 35 with a ring and throttle lever is on opposite side . i can replumb it but i did some research and its running way rich . the air mixture screw was out 3 turns and i put a small pin in hole and it was pretty much closed so i backed it out so at least it was open some what maybe 1/2 open . i have not tried it yet as its been cold and raining. any input on this adjustment?
thanks
Old 08-05-2023, 03:55 PM
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LLRCFlyer
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Some suggestions: Make sure the fuel is fresh (no moisture) and has at least %5 nitromethane content (10% would be better). If it is a K&B .35, then it probably was made before 1975 and has cross-flow (loop scavenged) porting. If it does, the piston will have a baffle ridge across the top of the piston. Cross flow engines require idle bar glow plugs if they are to be used with a carburetor to make them idle. A standard plug can be used for full-throttle purposes such as control line and free-flight. Good luck finding an idle bar glow plug because Schnuerle porting made those obsolete years ago (MECOA might have some). If you have access to a power panel, try starting the engine and then slowly decrease the plug voltage until it just starts to run erratically and adjust the needle valve to make it run smooth. Repeat until it runs with the glow plug disconnected.

Good Luck
Old 08-05-2023, 07:53 PM
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And to initially set both high and low speeds, do the "pinch" test. You'll need a needle nose pliers, hemostat or some other way to pinch the fuel tubing to the carb while it is running, without taking off a finger or two.
Start the engine and warm it up for a minute or so. Bring it to whatever idle speed it will stay running at. Pinch closed the fuel line to the carb.
If it dies quickly - you are too lean on the idle setting.
If it runs for a few seconds, but then starts to speed up before quitting, you are too rich on the idle.
Aim for consistent, even running, before it dies.
If it was running a higher idle speed, adjust to idle slower, and repeat the test. Adjust rich/lean as needed at this new lower speed.
Repeat the pinch test for full open speed. Again, quitting quickly means too lean, running a few seconds, but picking up speed means too rich.

Having gotten it to a very close to ideal carb setting, that will be one less variable to deal with in dealing with the glow plug issue. You may find that it then just runs, with the ignitor off.

Note that this being a ringed engine, richen up the high speed a couple of clicks before actually flying. Also do a final "point the nose up" test to verify that it won't go lean in vertical situations.

If this is a never run engine, then all bets are off until you get a lot of fuel run through it, at a very rich setting, to break it in. You can hurt it a lot by peaking out the high end right away.
Old 08-06-2023, 08:53 AM
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Originally Posted by tedsander
And to initially set both high and low speeds, do the "pinch" test. You'll need a needle nose pliers, hemostat or some other way to pinch the fuel tubing to the carb while it is running, without taking off a finger or two.
Start the engine and warm it up for a minute or so. Bring it to whatever idle speed it will stay running at. Pinch closed the fuel line to the carb.
If it dies quickly - you are too lean on the idle setting.
If it runs for a few seconds, but then starts to speed up before quitting, you are too rich on the idle.
Aim for consistent, even running, before it dies.
If it was running a higher idle speed, adjust to idle slower, and repeat the test. Adjust rich/lean as needed at this new lower speed.
Repeat the pinch test for full open speed. Again, quitting quickly means too lean, running a few seconds, but picking up speed means too rich.

Having gotten it to a very close to ideal carb setting, that will be one less variable to deal with in dealing with the glow plug issue. You may find that it then just runs, with the ignitor off.

Note that this being a ringed engine, richen up the high speed a couple of clicks before actually flying. Also do a final "point the nose up" test to verify that it won't go lean in vertical situations.

If this is a never run engine, then all bets are off until you get a lot of fuel run through it, at a very rich setting, to break it in. You can hurt it a lot by peaking out the high end right away.

I've run into this a few times lately, usually with engines that have come from modelers that bought an engine, ran it once and then put it back in the box. They never got around to using it but it looks like a broken in engine when it isn't.
Old 08-07-2023, 09:48 AM
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tbone4343
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i thonk its the air bleed screw it was way in to closed i have been swamped at work and have not had time to try and test it and i did try and adjust high speed and could not lean it out so i think its the little screw air bleed / i dont have the manual or parts blow up so im not sure of the corret name
Old 08-07-2023, 11:48 AM
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A. J. Clark
 
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The idle air bleed hole won't have much effect on high speed tuning. If you can't tune high speed you have another problem.
Old 08-07-2023, 12:30 PM
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Umm.. you said you switched to a Perry carb, If it really is one, there is no "air bleed" screw. There is what they call an "idle speed screw". It can be used to prevent the carb from closing completely. Most of us just screw it out until the carb DOES close completely, so we can kill the engine from the radio. Don't take the screw all the way out, or the carb will come apart. Just back off until the barrel fully closes.
Adjust your radio so that at idle, the barrel is open a little. And so that at full throttle, the barrel is all the way open, but the servo is not straining trying to open it even more. Then you can use your trim, when at idle, to open/close the barrel a little to get the slowest, most dependable idle possible. Move the trim more, to kill the engine, when desired. Each brand/model of radio has slight differences in how to set these endpoints, and some have an option to make the trim only work when the stick is low. My super duper one allows me to set three low speed settings on a switch - one pretty high for starting, one medium for initial running and warming up, one for "as low as I can go without killing it".

The brass "knob" on the side adjusts the high speed mixture.

The brass disc, with the slot in it, adjusts low speed mixture. It usually only needs very small changes to find the correct setting.
Old 08-08-2023, 02:31 AM
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tbone4343
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i have the perry carb but did not install it as the throttle arm is on the opposite side and i would have to rerun the cable so i started looking at carb and thats when i found the air screw all the way in and i think thats why it was flooding every where,
Old 08-08-2023, 04:12 AM
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tedsander
 
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Originally Posted by tbone4343
i have the perry carb but did not install it as the throttle arm is on the opposite side and i would have to rerun the cable so i started looking at carb and thats when i found the air screw all the way in and i think thats why it was flooding every where,
Perhaps some with deeper history of K&B will respond, but in my experienced, and mild research on line:
1. Throttle arms were always on the right side (with the front facing forward). As they are with almost all glow engines. Your carb may have been installed backwards. Not that is should make much difference, as long as the fuel line inlet allows fuel line to attach without having to loop back.
2. K&B had many carbs, but I don't think they ever had one with an air bleed screw. Even the really early ones that used a coupled exhaust port valve. You may have some other brand carb that a previous owner used as a replacement.

Can you post a picture of yours as installed?
Old 08-10-2023, 12:25 PM
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jaka54
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All R/C carbs has the throttle arm on the left side (viewed from front of the engine). Picture below show an OS air bleed carb (You can see the small hole up front). The Perry carb you mentioned is not an air bleed cab, instead it has a disk on one side with a small slot inside the regulates the fuel at idle. On the other side is the high speed needle.


Picture below is an Kyosho .40 engine (Made by ASP ), it has a carb that is similar to nearly every R/C carb on the market for 3,5-15cc engines.
The small hole you see in the middle of the carb side is where you adjust the low speed (Idle speed) . On top of the carb is the small screw that holds the throttle drum. You adjust this screw so the drum can be full closed! You then set the opening of the drum with the radio so that the drum is open just 1,5-2mm at idle.


Last edited by jaka54; 08-10-2023 at 12:32 PM.

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