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Hyper 21 - 3 port


JohnE

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Can anyone give me any help with returning this engine to factory settings on the slow mid range needle please. I have stripped the carb because I thought that it had a blocked jet.

 

Main needle ok at 3 turns

Fuel supply nozzle flush with body

Idle screw not been altered

 

The factory sheet says the following for the slow mid range needle

 

With the adjustment screw in place (is this the idle speed screw) close off the throttle body against the screw. Gently screw in the needle valve until it closes off the supply fuel nozzle and is prevented from re-opening by the entry of the needle valve into the central hole of the fuel nozzle, work with great care with this one we are only looking for minimal frictional contact between the two parts. Re-open valve 3.5 turns

 

I am confused by all of this so any ideas as to what next or can this only be done with the carb attached to the engine and servo arm

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Why do you want to know some setting that your engine/plug/fuel/altitude/temperature will not run best at?

I can give you rich settings for a new engine...I can give you a wide range of settings that it will run best at...not every engine will be the same (even when it is the same type of engine/carb)..

Start from rich and adjust down....HSN first..

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Hi, its not the setting that I am after its the method of reinstalling and setting up the mid range needle first. I have removed it from the carb and the setting up from scratch instruction is not clear. It appears not to be just a case of screwing in the needle and then winding it out by 3.5 turns because it is aligned to the main needle and jet

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Ok.

LSN- black screw where throttle linkage connects- 0.5mm proud of flush is plenty rich. (manual=STNV).

Spraybar/midrange- gold screw opposite LSN (manual=SFN) should be flush.

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if you take the high speed needle out you will see there is a hole in the mid needle every quarter turn. Get it flush then look down and align the the mid so you can see the hole

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so two questions

 

Is the setting of the LSN done with the throttle attached to the servo or before

 

and

 

There are no holes in the low/mid range jet and in fact its not a jet its a needle valve that sits into the end of the fuel entry jet. The only jet that I can see on this carb is the fuel entry which should sit flush with the carb body. Both of the other adjustments are needle valve

 

High speed and low/mid speed

 

The only other adjustment appears to be idle with what must be a stop screw.

 

If I need to line up holes then this could affect the position of the fuel entry jet/nozzle

 

I think

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John, read these posts again

Ok.

LSN- black screw where throttle linkage connects- 0.5mm proud of flush is plenty rich. (manual=STNV).

Spraybar/midrange- gold screw opposite LSN (manual=SFN) should be flush.

 

 

if you take the high speed needle out you will see there is a hole in the mid needle every quarter turn. Get it flush then look down and align the the mid so you can see the hole

 

Black screw where throttle linkage connects is the LSN....if you set it how I suggest then it does not matter if linkage is connected or not....if the head of the screw is 0.5mm from proud it will be plenty rich.

 

The gold screw on the opposite end of the carb. to the LSN should be flush...and as Jizwizard pointed out there is a way to ensure that it is in the correct position (flush can feel flush but lining up the hole is the check).

 

Here is a bad picture of where to look to line up the hole...

 

DSC00866_zps5ce86ab2.jpg

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ok gents thank you for your help. I have followed your advice and the engine now starts and idles nicely however it is as rough as a pair of old boots from the initial throttle opening and sounds as though its misfiring and is not at all clean, plenty of blue smoke but it sounds sort of crackley if that makes sense. I suspect that its running very rich now on the LSN needle and so I will try to weaken this off at an eighth of a turn at a time

 

It is most certainly not singing at a high note which it used to do and it used to pull away very cleanly indeed, but at the moment it is not revving at all, maybe I should treat it to a couple of new glow plugs. By the way the fuel is the same stuff that I ran it in on and that is 20% which I bought from Modelsport UK

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Yes, now you have a rich mixture....gurgling...poor performance...lots of smoke.

Read the tuning guide...grab a screwdriver and give it a go. :)

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Thank you all, its now running really sweet. Had to take the low speed needle in by around 1.5 turns but it seems ok. When I more time I will run it again but just screw this in an eigth at a time until it bogs down at pick up

Thanks again gents, really appreciate your help

Edited by JohnE
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