Hobao hyper 7 wont run unless super rich

[jamesd90]

Hi all,

I have a Hobao hyper 7 tq sport .21 that has been in storage for 5 yrs+. But worked fine before going in.

I thought I'd bring it back out, before starting changed the glow plug (os 8)
Fresh fuel and also fitted an electric starter

Tried to turn over by hand and think it was possibly seized. Continued to turn it over on the flywheel by hand and it freed off.

Went to start it - no good, not even a kick
Carb Settings were how they were left when it last run. Disassembled the carb, cleaned everything and reassembled

So, thought back to basics, reset the carb to factory (both ends flush, idle at 1mm gap and main needle 3 turns out) still no start

To get it to run, I have to have the STNV OUT approx 2mm from flush, it runs very rich and there is plenty of unburnt fuel coming from the exhaust. When in this state it starts and idles no problem. After it gets warm, I trying to throttle it obviously bogs and cuts out. So I lean off the STNV and it drives OK and will continue to start afterwords. BUT as soon as it cools down, it then won't start with the STNV left in it's lean position, I have to wind it back out to rich?

Also have a split/missing throttle boot but believe this just to be a dust cover?

So, 2 trains of thought, something of concern inside the motor after it potentially seized or an air leak/carb issue?

Any thoughts or theory's would be appreciated

Thanks

James

 

[CertifiedMike]

Is your fuel also 5 years old?
What fuel is it? What brand and %?
Is the OS 08 plug actually correct for this motor? I don't know.
Did you source the plug from a reputable dealer? Fake plugs are a real thing I guess.
Air leaks usually cause a lean condition, not rich. It might be an issue but logic tells me follow other things right now.

Is your air cleaner clean, fresh oiled, assembled and breathing as intended?

Not likely the issue but are your fuel lines clear, not cracked from sitting, age...?

Is your exhaust all tight, no leaks?

All stuff that can throw your tune off.

 

[jamesd90]

Is your fuel also 5 years old?
What fuel is it? What brand and %?
Is the OS 08 plug actually correct for this motor? I don't know.
Did you source the plug from a reputable dealer? Fake plugs are a real thing I guess.
Air leaks usually cause a lean condition, not rich. It might be an issue but logic tells me follow other things right now.

Is your air cleaner clean, fresh oiled, assembled and breathing as intended?

Not likely the issue but are your fuel lines clear, not cracked from sitting, age...?

Is your exhaust all tight, no leaks?

All stuff that can throw your tune off.

Thanks for the reply!

Fuel is new off the shelf 25% from Alpha fire (it actually has model technics on the back!) but I've also tried 20% a friend has with same results

The glow plug is off of Amazon, but I also have 2 other plugs that all glow OK outside of the motor

The air leak idea was that there so much "unmetered" air entering thats why I have to have the mixture so rich to match the air intake?

Air filter foam is new also!

Fuel lines are clear and updated to silicone. I can blow through them no problem and it reaches the inside of the carb

Exhaust is mounted to an intact rubber gasket at the motor, with retaining spring in place

 

[CertifiedMike]

Thanks for the reply!

Fuel is new off the shelf 25% from Alpha fire (it actually has model technics on the back!) but I've also tried 20% a friend has with same results

The glow plug is off of Amazon, but I also have 2 other plugs that all glow OK outside of the motor

The air leak idea was that there so much "unmetered" air entering thats why I have to have the mixture so rich to match the air intake?

Air filter foam is new also!

Fuel lines are clear and updated to silicone. I can blow through them no problem and it reaches the inside of the carb

Exhaust is mounted to an intact rubber gasket at the motor, with retaining spring in place

Assuming all those things are correct, good... I would be looking at orings at this point too I think.
Don't forget to use green slime on the rings!!!
Its not a bad idea to check them off the list.

I understand what you mean by overrichen the carb to compensate and it makes sense.

 

[Suburban_Hooligan]

a lot of that sounds like what my old HPI engine did 20+ years ago. that turned out to be a vacuum leak. in my case the backing plate had come loose and there was a metal gasket in there that got jacked up, so even after i tightened the backing plate it still leaked. so check for vacuum leaks.

 

[jamesd90]

a lot of that sounds like what my old HPI engine did 20+ years ago. that turned out to be a vacuum leak. in my case the backing plate had come loose and there was a metal gasket in there that got jacked up, so even after i tightened the backing plate it still leaked. so check for vacuum leaks.

Is there a certain way to do this, or just a visual inspection?

 

[CertifiedMike]

Is there a certain way to do this, or just a visual inspection?

This forum used to be called RC NITRO TALK.COM...
I can't sem to find the how to reseal article that I KNOW used to be here...

This one seems pretty good and should help you out.

https://www.hpisavageforum.com/threads/nitro-engine-sealing.15150/

 

[zeus r/c]

Is your fuel also 5 years old?
What fuel is it? What brand and %?
Is the OS 08 plug actually correct for this motor? I don't know.
Did you source the plug from a reputable dealer? Fake plugs are a real thing I guess.
Air leaks usually cause a lean condition, not rich. It might be an issue but logic tells me follow other things right now.

Is your air cleaner clean, fresh oiled, assembled and breathing as intended?

Not likely the issue but are your fuel lines clear, not cracked from sitting, age...?

Is your exhaust all tight, no leaks?

All stuff that can throw your tune off.

I have to agree with buggy maybe check and tighten every screw could be something in the engine causeing it as well id take the entire engine apart soak clean and re assemble set to factory and go from there also try tyning it while its running both needles on either end should not be flush i have a few of these csrbs myself and i dont even run then flush to the ends ill takes pics and post how mine are set maybe that will help as well ill post them in a couple hrs when i get back home

 

[zeus r/c]

I have to agree with buggy maybe check and tighten every screw could be something in the engine causeing it as well id take the entire engine apart soak clean and re assemble set to factory and go from there also try tyning it while its running both needles on either end should not be flush i have a few of these csrbs myself and i dont even run then flush to the ends ill takes pics and post how mine are set maybe that will help as well ill post them in a couple hrs when i get back home

So heres a few pics of how i have my low mid high needles and my idle needles i hope this will help brother