Hyper 7 TQ2 .21 Can't fire it up.

[ChrisH]

Evening,

 

Hoping some knowledgeable person/persons can help me out.

 

Purchased my Hyper 7 .21 back in February.  Fired up on the second pull of the pull start and went through the first three tanks with no issue's.  Idle was perfect bar a few rises and drops in revs while tanks of fuel ran through it.  Engine temperature was measured with a IR heat gun frequently and with slight richening of the HSN, the temperature remained within the suggested range.

 

Came to the fourth tank and began the figure of 8 / slow driving.  Noticed it was driving itself when no throttle was applied so richened the LSN which sorted that but noticed the engine would 'hunt' for revs and became bit haratic.  Running out of daylight, I called it a day.  From the initial pull start onto this point was completed in one day.

 

On the second day I tried to start it but nothing, no burbling, nothing.  Fast forward 2 months into ownership, with only a few hours a week spare to try and get it going, I'm still stuck with a virtually non starting car.  

Iv'e watched a load of vids on YouTube, read a fair few guide's but can't get a basic setting dialled in to fire it up.  Factory settings are 1/2 turn out from flush on the LSN and 2 turns out from closed on the HSN.  The engine is being warmed upto between 190-200 degrees F.  

 

I'm using a Lipo glow ignitor with a nice strong glow on the Fastrax platinum medium glow plug.  Optifuel optimax RTR 25% nitro fuel and a carb gap of 1mm approx.

 

I have removed the fuel filter thinking that might be letting air into the system.  No difference.

 

I am unable to prime the engine by placing my finger over the exhaust and pulling the pull start.  The fuel just doesn't move through the line.  The only way I can get fuel from the tank to the carb is by blowing through the back pressure line.  I am getting air bubbles in the fuel line.

 

I have removed the tank, emptied the fuel and checked for leaks.  Appears to be fine.  Just got a feeling it's something more then just needle settings.

 

So that's where I'm at.  Running out of idea's but know it will be worth while when it does finally get up and running, possibly😀

[Stormbringer]

theres a silicone O ring that seals the filler cap

try pushing filler cap closed see if its just sticking and not alowing pressure to build up in tank as its this pressure that pushes fuel to carb when its running

if you think its loose fitting theres a little screw ion the inside of filler cap that expands or contracts the O ring so that its a tighter fit doesnt take much to go from loose to tight fitting

[ChrisH]

Adjusted the O ring, makes a slight 'pop' sound when the lid is lifted and fuel now enters the line and stays put.  There are some very tiny bubbles but guess that's because the fuel is just sat in the line.  Not starting yet, grumbles a bit like it wants to but nothing more.

[Stormbringer]

give it a little touch of throttle not a lot just a wee bit 

theres a knack to starting them whilst holding the transmitter tho lol

or you could up the throttle trim till it starts then return it to normal when started 

[Nitroholic]

When you prime......are you opening the throttle?

If you don;t fuel will not go through the carb and into the engine, where it needs to be if its gonna go bang.

 

Secondly...leave the LSN alone. Really, what you are doing at this stage is breaking hte motor in while running it very rich indeed. Excess fuel will build up, resulting in odd effects. Shut it down, let it cool...glowplug out, and tip out any fuel that may have built up.

 

Thirdly....if it's not idling, that is controlled by the idle screw. This is basically a throttle stop screw. To check it...with the engine off, but radio gear on....remove the air filter and look for the gap between the throttle slide and the side of the inlet. Should be about 1mm at the widest point. Then apply the brakes...and make sure it doesn;t close. The first check makes sure the idle will be right...the sceonf makes sure the setting is not becuase the servo is holding it open.

 

Your LSN controls mid range running....and is most noticable under acceleration and on coasting. You are not running it in areas that this would impact, and changing that setting when you haven;t dialled in teh HSN and idle is not going to help you any.

 

Also....you will always see tiny bubbles in the fuel line when priming. The system isn't under pressure.

[ChrisH]

Yeah kinda got used to holding the transmitter with a bit of trigger, while keeping the car on the ground and pulling the pull start😀

 

I'll give it proper go tomorrow and post an update, thanks so far👍

[ChrisH]

23 minutes ago, Nitroholic said:

When you prime......are you opening the throttle?

If you don;t fuel will not go through the carb and into the engine, where it needs to be if its gonna go bang.

 

No never done that, not even on my Carnage and that fires up no problem.  Something I can try thou thanks.

Edited April 29, 2021 by ChrisH

[ChrisH]

So just got back on it.  I'm back to being unable to prime via my finger of the exhaust and pulling the pull start.  Not even the slightest amount of fuel makes its way into the line.  Nothing has been touched or altered since last night.

 

Blowing down the back pressure line fills the fuel line with fuel right into the carb no problem.

 

Warmed the engine to 200 degree F approx, couple of pulls and it fired up, high revs then died 3 to 4 seconds later.   Now just gurgles on any repeated pulls.

[ChrisH]

Managed to spend a bit of time on the Hyper today and finally getting somewhere. I can pretty much start it within 2 or 3 pulls, when the temperature is within range. The idle is nice and steady for about 7-10 seconds then begins to drop off until it stalls. I try to pick the revs back up by opening the carb slide slightly manually but it eventually bogs down. I havn’t touched either of the LSN OR HSN, but have fettled with the idle screw to get it to where I am with it now. 
 

Can the LSN be leaned slightly to help with it bogging down or not ?

 

[Stormbringer]

if youve already touched the lsn then put it back to factory and try the hsn 1st 

youl only touch the lsn once its ran in and tuned with the hsn 

[ChrisH]

10 minutes ago, Stormbringer said:

if youve already touched the lsn then put it back to factory and try the hsn 1st 

youl only touch the lsn once its ran in and tuned with the hsn 

Thank you👍

[ChrisH]

Used some RTV instant gasket on both the carb, and the backplate just in case air leaks were causing an issue.  The following two vids are exactly the same time and setup, just split into two.  The revs still rocket even thou I barely use 1/4 throttle, just enough to keep it from stalling.

 

Any opinions would be great

https://youtu.be/wffo_Ol4VK8

https://youtu.be/ucxufUbkLxk

[hamradioguy]

the bottom video the crankcase was loaded up with fuel so try feathering/teasing the throttle untill it clears

the top video you can see the throttle/brake servo move which made it increase revs.

[ChrisH]

3 minutes ago, hamradioguy said:

the bottom video the crankcase was loaded up with fuel so try feathering/teasing the throttle untill it clears

the top video you can see the throttle/brake servo move which made it increase revs.

Yeah was having to feather the throttle in the top video, just it loaded up with revs at the end with out giving it any more throttle. Thanks for tips. 

[Nitroholic]

How much fuel has been put through the engine?

 

Because this looks like an engine that if free enough to start fairly easily.....but is not being allowed to run in the rev range it needs to. Every time it revs up...it runs like it should.

It's clearly suffering issues from over-fuelling, and from fuel build up in the crankcase making it run erratically.

 

According to your initial post you idles 3 tanks though it, then started gentle figure 8's.  You should be running it between 1/4 and 1/2 throttle under light loadings....but you still got the thing up on bricks trying to make it idle.
Idle is not a comfortable place for your motor. It's not getting cool air over the cyclinder, and it's going to fluff up.

 

Dont labour it....run it on a hard surface....but I would suggest you get it moving and use what throttle you need to get it moving.

 

Running a motor hard without proper break-in is bad for a motor.... but...equally...running it too 'soft' will bring it;s own problems

 

edit: Leave the LSN stock until you have completed break in, set idle and tuned the HSN. Even then...I have rarely needed to tweak LSN settings much

 

Edited May 3, 2021 by Nitroholic

[ChrisH]

21 minutes ago, Nitroholic said:

How much fuel has been put through the engine?

I would say around 4 - 4.5 tanks then it died on me and couldn't get it running up to now.

21 minutes ago, Nitroholic said:

 

Because this looks like an engine that if free enough to start fairly easily.....but is not being allowed to run in the rev range it needs to. Every time it revs up...it runs like it should.

It's clearly suffering issues from over-fuelling, and from fuel build up in the crankcase making it run erratically.

 

According to your initial post you idles 3 tanks though it, then started gentle figure 8's.  You should be running it between 1/4 and 1/2 throttle under light loadings....but you still got the thing up on bricks trying to make it idle.
Idle is not a comfortable place for your motor. It's not getting cool air over the cyclinder, and it's going to fluff up.

You are correct, it should be well Into the break in period but I couldn't even get it going before the weekend and since the initial 3 tanks and bit of slow driving with a 4th tank.

21 minutes ago, Nitroholic said:

 

Dont labour it....run it on a hard surface....but I would suggest you get it moving and use what throttle you need to get it moving.

 

Running a motor hard without proper break-in is bad for a motor.... but...equally...running it too 'soft' will bring it;s own problems

 

edit: Leave the LSN stock until you have completed break in, set idle and tuned the HSN. Even then...I have rarely needed to tweak LSN settings much

Ok, just with the revs being a bit twitchy I had fears of the thing taking off, guess I'm being to cautious!  I'm going to put a new plug in it and get it running on the ground.  Thanks for advice given👍

21 minutes ago, Nitroholic said:

 

 

[Nitroholic]

On the ground, you still have brakes if you need them.  Running it up on bricks with no resistance will make hte wheels spin up a whole lot faster, which looks dramatic....but they spin up a lot less fast on the ground with some resistance.

 

But a bit of caution and sensible precautions are always advisable....

[ChrisH]

6 hours ago, Nitroholic said:

On the ground, you still have brakes if you need them.  Running it up on bricks with no resistance will make hte wheels spin up a whole lot faster, which looks dramatic....but they spin up a lot less fast on the ground with some resistance.

 

But a bit of caution and sensible precautions are always advisable....

thanks again for the advice, really appreciate it👍