Hobao ST hyper 21 engine tuning issued

[nareshpatel101]

I'm still trying to get this truggy going, so temperamental it either idles ok for 1min then less than 1/2 throttle and it could stall or on the other hand go wot and it stalls!!

 

I've got the hsn to flush and lsn is out 1mm from flush.

 

Also is it normal for so much oil/fuel to pour out the exhaust(see pic) that amount is with 2 1/2 tank of fuel.

 

Can anyone recommend the best suited glow plug for the hyper 21 3port engine please.

 

Thanks in advance.

 

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[Stormbringer]

are you running this engine in ?

if you are its normal for a fair amount of oil to come out exhaust as its running rich

have you checked the idle gap ? you can do this by taking off the air filter and looking into the carb there should be a 1mm gap with 0 throttle

[nareshpatel101]

are you running this engine in ?
if you are its normal for a fair amount of oil to come out exhaust as its running rich
have you checked the idle gap ? you can do this by taking off the air filter and looking into the carb there should be a 1mm gap with 0 throttle

It was a new engine, I built it in 2015 tried to get it to idle, used up 5 litres of fuel and gave up. Re started it whilst on lockdown and probably used up another 3 litres of fuel!!
Idle gap is set at 1mm.

Check these videos see if you can make any sense.

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[Stormbringer]

you do get a fair amount of smoke when you blip it 

it does seem to be puting oil out exhaust

sorry mate im not sure whats going on 

have you had it running and adjusted the hsn ?

you could try a full turn either way at 1/4 turn increments see if it improves it 

its been long time since i tuned a nitro engine

[nareshpatel101]

I've had it running just once but only ran 1/2 throttle as I wasn't sure of the engine was broken in, but after that once struggling to get it idling.

Does anyone know which other carb would fit on this hyper 21 3port, I know hpi 3.5 is too small. Thinking of trying a new carb even though this one was is a new hobao carb.

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[babylon]

Give this a watch.

 

 

[nareshpatel101]

Give this a watch.
 
 

Thanks Babylon seen this video already I'm no where near to that level.
I've spent weeks trying to get it just to idle properly. The problem is I start to lean the hsn maybe 3 - 4 turns at 1/8 increments, but then it keeps stalling randomly on less than 1/2 throttle or might stall on wot after that I struggle to get it started again. Eventually when it does fire up, it may just rev erratically.
I'm guessing I may have an issue with the hsn needle valve it does feel a lot more loose now.
I do have this spare carb but I don't know what make or model it is. It needs a new carb body as the thread is worn out where the hsn housing screws into. Any ideas on which one it is?

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[Lord Page]

I have the exact same problem with my .21 engine. Some times it's to lean and other times it's to rich. It will run great for a few runs then the tune goes all over the place. I have traced a very small air leak from the glow plug hole, try spraying some nitro cleaner or wd40 around the hole to see if yours is similar.

[nareshpatel101]

I have the exact same problem with my .21 engine. Some times it's to lean and other times it's to rich. It will run great for a few runs then the tune goes all over the place. I have traced a very small air leak from the glow plug hole, try spraying some nitro cleaner or wd40 around the hole to see if yours is similar.

Glad to hear I'm not the only one!! I've been pulling my hair out even though I'm a bald head[emoji16]
I did do a balloon test by placing one end on the carb and another on the crankshaft end and sprayed water mixed with washing up liquid but couldn't see any leaks any where.
So what you're saying is spray wd40 down the glow plug hole or when the glow plug is screwed on

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[nareshpatel101]

Also mate is your carb a hobao 30? If so what's your needles set at? Does your lsn stick out 1/2mm from the housing?

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[Lord Page]

With the glow plug in and the engine running, if possible the engine up to temperature. Mines is blowing a couple of very small bubbles around the plug, also the engine idle drops when I spray it with nitro cleaner. I have a defiantly have a leak around the plug.

 

As you can see in the video it idles fine but I never caught on video when it starts going rich and lean.

 

I am using the factory settings as a base, but I started leaning both hsn and lsn needles out a tad.

 

Lsn - flush with the side of the carb

Hsn - 2 turns out from closed

 

I am going to replace the head button, but I also think my carb has issues.

 

What fuel and plug are you using?

 

Cheers

 

 

Edited June 5, 2020 by Lord Page

[Stormbringer]

are you running an os8 plug ?

my son and i found those were best plugs for our engines

[Lord Page]

No I'm using an OS P5 plug. The OS 8 plugs do not fit my engine as mines has the turbo head.

 

I have a gut feeling that my midrange needle is out, but I have no idea how to test my theory or on the correct way to adjust it. 

Edited June 5, 2020 by Lord Page

[Stormbringer]

meaning to ask this 

why use a 21 in an st ?

st comes with a 28 as standard which you can upgrade to bigger engines

[nareshpatel101]

I'm using HPI R3 medium glow plug and 20% Optipower fuel.

My ST truggy came with a HPI 3.5 engine. I got hold of a used hyper 21 3port engine off Ebay which was a dud!! Then I had this crazy idea to rebuild the engine which I then realised would have been cheaper just to buy a new engine ready built. And so here I am 5 years later, still trying to get the bugger to run.

I've ordered a new hsn needle valve and casing, as mine seems to be fairly loose now. I'm trying to find out what carb the hyper 21 engine came with so I can try that carb too if I can get a new carb body.

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[nareshpatel101]

No I'm using an OS P5 plug. The OS 8 plugs do not fit my engine as mines has the turbo head.
 
I have a gut feeling that my midrange needle is out, but I have no idea how to test my theory or on the correct way to adjust it. 

Mate are you sure your head is a turbo head? Looking at your pic it seems to be the same as mine. I accidentally ordered turbo glow plugs and they definitely don't fit in my head.

I'll spray the nitro cleaner on 2mrw and see what happens that's if the bleeding thing gets going.

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[Lord Page]

Mines most definitely uses turbo plugs. 

[nareshpatel101]

I've just downloaded the hyper 21 info sheet you posted and yeah you're right you get turbo and standard burn plates.

This is the info sheet I've tried to work from, it has different needle settings to your one. I'll give your base settings ago see if get any joy out of that.http://cloud.tapatalk.com/s/5edb7a3348ae3/HB_Engine_settings_Hyper_21%20_3-Port.pdf

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[nareshpatel101]

Hi mate I tired spraying wd40 on the glow plug this is what happened

I also tired your base settings but no chance was it gonna fire up.

So I went with hsn - flush to edge
Lsn - 3 turns out from flush
Edge
And shockingly I got it to idle throughout the whole tank.

But then in the 2nd tank tried bleeping the throttle slightly and then it starts revving up and takes ages to settle to idle, whats the cause for this?

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[Koda ATL]

Hi, I dont know if youve already solved this issue. Its the needle tuning. Had same problem w my hoboa on road 1/8th scale. If the bottom end needle, the high end needle, and the idle need work hand in hand. You have to find a proper setting for all three. If you need someone to revv the engine to start the car, do that until you get better needle settings. Dont change glow plugs, or waste your time looking for leaks, people just want to type stupid things that wont help you. Its all in those three needles!