Hyper ST non starter

[Harryp123]

Hi, I got this Hobao hyper ST a couple years ago now and it refuses to start. It will occasionally but after an hour of rotostarting, priming and heating with a hairdryer. When it does it cuts out pretty quickly. I put it to the side and forgot about it and only recently dug it out again. I think it might be that I cocked up the break-in process and definitely did not do it right. Also it is very hard to turn over with the pull start. When it did run I loved it and really want to get into nitro but it isnt making it easy. Any help would be greatly appreciated.

 

[olds97_lss]

Well, depending on the ambient temps, starting can be a bit annoying. If an engine becomes hydrolocked (full of fuel), you have to take the glowplug out, hold the vehicle upside down, the spin the starter or pull the starter cord quick a few times to get the fuel out of the engine.

When starting, it's typically best to adjust the trim on your transmitter so that your carb is open a little bit, then once it starts and warms up, you can adjust the trim back so it idles down properly. I see a lot of new guys pump the throttle with the engine off, like you would in an old car with a carb, which doesn't do anything on these engines.

These engines don't have a pump of any sort and rely solely on the venturi effect to suck fuel into the engine when it's turning over. So, you have to first prime the engine. Usually, plugging the exhaust tip with your finger, then turning the engine over via the roto or pull start a few times, you will see fuel flow through the line to the carb. Once it reaches the carb, stop priming. Put the adjust the radio trim to open the carb a bit, put the heater on the plug for 3-4 seconds before you try starting, then try starting it.

Once it's running, leave the heater on and blip the throttle a few times to make sure it's going to stay running, then remove the heater. Let it warm up a bit, and adjust the trim on the throttle so that it's idles back down.

 

[Harryp123]

I have tried that and it still doesn't work, not even the slightest noise from it. I have a bad feeling that I buggered it by not breaking it in properly if at all and being to young and stupid to realize. I feel like at this stage a new engine might be in order though of course I would love to get it working.

Also thanks a lot for replying.

 

[olds97_lss]

Just to be sure, have you taken the glow plug out and put it in the heater? The coil should glow a bright orange. Usually can't see it in the sunlight. If it doesn't, then either the plug is bad or the heater is dead.

If your using alkaline cells for the heater, they do not last long at all. Even good name brand ones.

 

[Harryp123]

My glow plug and glow starter are fine, thats why I'm stuck

 

[olds97_lss]

How old is the fuel? Where was it stored? Fuel doesn't last forever, especially once opened. Might need to take the carb apart, soak it in DA and clean it out really well with q-tips. If it sat for a long time, could just be gunked up. As well as the filter in the tank or in-line filter if it has one. You can try blowing back through the fuel line to see if air passes backwards in the tank easily. If not, then the stone/filter may be gunked up not letting enough fuel get to the engine.

 

[Harryp123]

Great will do that now, sorry for my newbieness but what is DA?

 

[jeffgnz]

When I've had trouble starting I try removing the air filter and putting a drop of fuel directly into the carb. If it fires and runs for a few seconds you know the glow plug is OK and you've got a fuel flow issue. If it doesn't fire up you know that its an issue within the engine itself.

 

[Harryp123]

When I've had trouble starting I try removing the air filter and putting a drop of fuel directly into the carb. If it fires and runs for a few seconds you know the glow plug is OK and you've got a fuel flow issue. If it doesn't fire up you know that its an issue within the engine itself.

I never thought of that, great idea i will gove it a crack. Many thanks!!

 

[olds97_lss]

Great will do that now, sorry for my newbieness but what is DA?

DA = Denatured Alcohol

Can be found in pretty much any hardware store near paint supplies in a 1qt can for around $4. A lot of guys use it in RC to clean stuff since it's a decent degreaser and it's fairly cheap. Put it in a cheap spray bottle and use it to clean the nitro oil off stuff before working on it so you don't end up covered in oil/grease.

 

[Harryp123]

DA = Denatured Alcohol

Can be found in pretty much any hardware store near paint supplies in a 1qt can for around $4. A lot of guys use it in RC to clean stuff since it's a decent degreaser and it's fairly cheap. Put it in a cheap spray bottle and use it to clean the nitro oil off stuff before working on it so you don't end up covered in oil/grease.

Ah ok I'll get some of that, thanks

 

[bobthebob]

I don't know if it is normal, but the k4.6 in my Savage never exactly starts easily. It does eventually start though, pretty reliably, and once running is very reliable. What has worked for me for some reason is basically over priming the engine it seems. Just getting it to the carb never seems to be enough. Basically my start procedure is like this: See fuel go to carb after initial prime, pull starter cord with glow plug lit like 10 times and nothing happens. Get frustrated, nearly flood the engine by pulling the cord another 2 or 3 times with full throttle and exhaust covered to more or less flood the engine. After this I will get a little "cough", and start feeling more resistance in the pull. The more it coughs and the harder it gets to pull, the closer it is to starting. Oh also I can only start it by giving it at least half throttle while I'm pulling the cord.

 

[olds97_lss]

I prime mine until I hear the fuel "squish" inside the carb. Much more than that and it's nearly hydrolocked, which is bad for pull-starts, one way bearings and conrods.