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Force E21-R26

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Old 10-25-2019, 12:06 AM
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Default Force E21-R26

Hi guys,


I recently acquired two Force E21-R26 engines. They are basically as same as RB Killer 10 & Ofna JL. There is one difference however, the bypass ports on the sleeve are merged with the transfer ports on Force but separate on RB & Ofna (see the picture below, interesting design tbh). Anyways, I've been getting a lot of headaches trying to dial this engine in. When you let the engine idle for 15 seconds it immediately starts to load up and I believe unburnt fuel/oil tries to enter combustion chamber from the bypass port and engine either stalls or starts popping violently causing glow plugs to foul. When I examine the glow plugs, I see that the thin wire gets broken due to added pressure during combustion after load up (only a very small break). I tried different carbs (picco carbs fit just fine) with smaller & larger venturis and although it seemed to help but did not solve the issue. I tried leaning the LSN but it gets to a point that engine starts bogging immediately due to very lean LSN. I tried OS P3 & Odonnel 77T & 97T plugs and the results were the same. It's also important to note that engine comes with three 0.2mm underhead shims whereas RB Killer comes with four. Compression might be too much during the load up (might need to add another 0.2 to decrease the pressure)


I read all the Ofna .21 JL thread along with RB Concept Engines thread and only found somewhat similar issues but no ones has talked about this specific issue.


The question is, is the sleeve design causing this issue? Or is there something else I need to look into.


It got to a point that it started to aggrevate my OCD and I need to solve this.





Force E21-R26 Sleeve




RB Concept Killer 10 Sleeve




Appreciate the help

Last edited by cansoykal; 10-25-2019 at 01:25 AM.
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Old 10-25-2019, 02:44 AM
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No, the sleeve design on the bypass port is not causing this. It seems a combination of fuel, plug and compression. Or it is just a wrong tuning.
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Old 10-25-2019, 06:29 AM
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Originally Posted by Roelof View Post
No, the sleeve design on the bypass port is not causing this. It seems a combination of fuel, plug and compression. Or it is just a wrong tuning.
I am using the same 25% fuel that I use with all my other engines. I'll add another 0.2mm shim and see if it helps.
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Old 10-25-2019, 08:38 AM
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When you let the engine idle for 15 seconds it immediately starts to load up and I believe unburnt fuel/oil tries to enter combustion chamber from the bypass port and engine either stalls or starts popping violently causing glow plugs to foul. When I examine the glow plugs, I see that the thin wire gets broken due to added pressure during combustion after load up (only a very small break).
I think you have to explain the "load up" and for sure you are making conclusions of stuf you do probably have no knowledge of.

The bypas is nothing more than a shortcut of the fuel flow into the transfer ports, it still comes from the same source as the normal flow so with or w/o there is no difference.
Plugs do break in a different way, with a wrong ignition timing that can be caused by a too high compression and/or too much nitro. You do use 25% so that should not be a problum unless you did change the head play.
What you did subscribe could be something of too rich on the LSN and with that you will go too lean on the HSN and that will damage the plug also.
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Old 10-25-2019, 04:48 PM
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Although I appreciate your input, your general attitude when replying just makes me sad. Ive been reading your comments throughout all the topics and all you do is look down on others with your so called knowledge. Just dont do this my friend. All we need is to share knowledge on this rc stuff not act like you've done rocket science.

Cheers.
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Old 10-26-2019, 11:22 AM
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Remember guys these are just rc car engines were talking about not politics. No need for rude responses or to have a rude opinion on, little kids read what we talk about and get a general idea of the people that race at the events close to them so no need to scare them off from wanting to learn something about there product. Letís keep it respectful in the replies and try to help and stay away from antagonizing.
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Old 10-26-2019, 12:14 PM
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Not to be rude but making own conclusions like these:

I believe unburnt fuel/oil tries to enter combustion chamber from the bypass port
does tell me you are looking into something you think you know. Saddly I have had too much discussions with people who think they know as also this:

I see that the thin wire gets broken due to added pressure during combustion after load up
No, that is not why the plug wire breaks, for sure not at idle when the engine is running full with mixture.. The harm of the plug was already done before that. And if the plug did realy break with idle then there is something serious worng like dirt inside the engine.
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Old 10-30-2019, 02:20 AM
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Update: Added 0.2mm shim to make it total of 4 shims just like the RB Killer 10. Temps went down significantly. Bogging and popping issues resolved. Engine runs just fine with no issues. ODonnell 97T plug seems to be working just fine. Plugs dont break anymore.

@Roelof: Plug used to broke the very moment you apply throttle after a long idle. Rich mixture & higher compression seem to break the plug. Would be easier to show you instead of typing but whatever I fixed it.

Last edited by cansoykal; 10-30-2019 at 05:49 AM.
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Old 10-30-2019, 03:15 AM
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When the engine runs the wire may break and the engine runs on w/o giving any notice of a broken wire. I even have seen engines run OK with most of the wire gone.

Where the wire did break from is pre-detonation. A too hot plug, a too much nitro content or a too high compression will shift the ignition to an early moment, if it is too early there is too much combustion heat damaging the plug and most of the time also the smooth surface of the piston and combustion chamber. The same occurs when the engine is too lean.

Plugs will stay perfect alive at high compressions when the moment of ignition is on the right side.
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