Help needed in central london please - hyper 7 engine settings / tunning…

[Rickyo007]

I have got a brand new Hobao Hyper 7 TQ 21 Black Edition and ran it in gently and progressively using 20% Byron fuel with 15-20 minutes breaks between each tank. Car starts first time.

However I had a problem whereby it suddenly kept cutting out when I applied the brakes or came to an idle so I tried a few high / low end adjustments and now the car is just screaming when I fire her up so I am desperately trying to reset everything to the manufacturers settings and get it up and running again. I have got the manual with all settings listed.

Thank you

 

[ohsnap]

Ricky - You asked this question in another thread in this forum and Metalhead and SavageXL gave you some good information.

From your description, the issue is not going to be solved by messing with your HSN or LSN settings. Concerning these, you need to get them back to what they were before you noticed the problem and messed with them.
If you reset to factory settings (especially the HSN), you'll be too rich to run.

With the motor not running, pull the air filter off and turn the transmitter and receiver on.
Look down the barrel of the carb and hit the brakes.
From your description of the initial issue I'll bet that the throttle moved/closed further.
That is the root of your problem and which is why your engine kept cutting out.
At idle, it should not move.

If your engine is now screaming - your idle gap needs to be smaller.

You have a couple of things that you can adjust.
One is the idle screw - which in your case needs to be set so that the idle gap remains open enough so that the engine has enough air and fuel to idle (and not die).

Another thing that you can mess with is (like SavageXLmentioned) is your transmitters throttle/brake sub trim. Set it to zero / neutral. Refer to your manual as how to do that.

The third option is your linkage - sometimes you have to refine that.
The linkage is what pushes the slide closed.
The idle set screw is what keeps it from closing too far.
Ideally, with your finger off the trigger, you want your carbs slide to return to the idle setting and not close any further when you hit the brake.

The idle setting should have a gap sufficient so that the engine will idle without trying to move forward. That gap is typically 1mm+/-. If it's idling so high that it's moving forward at idle, you're burning your clutch shoes.

Just take some time and observe what changes when you make each change and you'll get it dialed in.

 

[Rickyo007]

Update...

Hi TGL,

Firstly thank you for taking the time to send me detailed instructions. I have just finished working on the car. Thanks to everybody else also.

I have removed the air filter tube and adjusted the throttle linkage arm and put a bit more tension on it via moving the colletts a little. Now there is a 1mm gap in the carb and when I brake it remains the same and does not move. Unfortunately I have had to put the car on charge as my battery has just died so cannot test it just yet, not sure if this will work.

I have reset my Main Needle Valve (HSN I think it's called) I screwed it down until resistance was met and re opened it 2.5 full turns. I can adjust this as required when the car is running. I have done the same with the LSN, I screwed this down and reopened it 3.5 full turns as per instructions.

*I have not touched the Mid Range screw at all as I was told to leave this at all times*

I was wondering if you would be kind enough to have a quick look at this CML Link below; which shows you the set up sheet for my engine (Hyper 21 3 Port) as I really want to make sure that I have the correct terms for the engine screws because they use slightly different terms as there is a diagram on page 3...

Main Needle Valve (MNV) - I believe this is HSN High Speed?
Supply Fuel Nozzle (SFN) - I believe this is the Mid Range?
Thorttle Adjustment Screw (TAS) - I believe this is the Idle Screw?
Sub Throttle Needle Valve (STNV) - I believe this is the LSN Low Speed?

http://www.cmldistribution.co.uk/cml_product.php?range=RACING&productId=0000003472

I'm hoping this will work with a few 'running' adjustments as required.

Thanks again for your time.

Ricky

 

[Rickyo007]

I have just tried starting it...and what a suprise the car wants to climb the walls and is still revving like mad. I have tried adjusting the idle screw and the LSN and no joy. When the metal inside the carb closes after I press and release the throttle on my transmitter it seems to struggle / close slowly for the last 20% of the way say, again I tried adjusting the throttle arm and no joy...
This is so frustrating!

 

[ohsnap]

Hey Ricky,
A nitro engine can be frustrating, but don't give up.
You have the right terms
Main Needle Valve (MNV) = HSN
Sub Throttle Needle Valve (STNV) = LSN
Thorttle Adjustment Screw (TAS) = Idle Screw
Supply Fuel Nozzle (SFN) = Mid Range
Strange that they use the standard terms on page 2

With a 1mm gap, it shouldn't be reving high.
Undo your last changes to the LSN.
You may have an air leak which gives a lean condition and high idle.
If it gets to this point, search on the site and you'll see some threads that discuss sealing your engine. The base of the carb as well as the engine backplate are the usual suspects.
Do you have a video of it running / maybe a picture of the idle gap?

You mention that it struggles / closes slowly for the last 20% of the way.
That shouldn't happen it should be smooth the whole way opening and closing.
I would disconnect the throttle linkage from the servo and try sliding it by hand to see if it binds.
If it is binding figure out why.
You may have to pull the slide from the carb body and see if there is some unwelcome material like flashing.

While I doubt this is the cause, sometimes the angle that the carb body sits compared to the servo also impacts whether it'll open/close smoothly.