Zenoah G320 Seized?

[Dp400]

Hi All,
I ran my 2nd hand (but new to me) 30DNT with a Zenoah G320cc for the first time on Saturday and during a run it just died. Im new to RC and especially to 2 stroks so still learning the ropes but I think it may be seized, the pull start would not pull once it died. Ive removed the engine and tried to move the flywheel but it wont budge at all and I don't know what to do next. Any help anyone can give will be much appreciated. My fuel mix was 25/1 by the way.
Thanks in advance to anyone who can help or offer any advice.

 

[Shad0man]

The best advice I can give is to relax. If it is seized know that it has happened to most of us.

Others better qualified to walk you through the steps will chime in. Regardless, rebuilding a top end, if needed, is not a big job during which you will learn much.

Enjoy the process.

 

[smokinwheel]

Well if it is locked up it is an easy fix even if you need to put a top end kit on it.

Now the real question is why?
You say it is at 25:1 mix, well that's good. Let's assume it is with a good name brand oil.
Did it have a lean condition? Mixture too lean or maybe something clogged a jet or passage in the carb causing it to go lean?
How about heat? This is a question because is that grass, I see packed in the fins of the recoil assembly? Lack of air flow is not good.

Pull off the exhaust and have a look in the exhaust port. That piston should give you a clue by the way it looks.

 

[Dp400]

Well if it is locked up it is an easy fix even if you need to put a top end kit on it.

Now the real question is why?
You say it is at 25:1 mix, well that's good. Let's assume it is with a good name brand oil.
Did it have a lean condition? Mixture too lean or maybe something clogged a jet or passage in the carb causing it to go lean?
How about heat? This is a question because is that grass, I see packed in the fins of the recoil assembly? Lack of air flow is not good.

Pull off the exhaust and have a look in the exhaust port. That piston should give you a clue by the way it looks.

What looks like grass on the right of the photo is the outerwear cover

 

[smokinwheel]

What looks like grass on the right of the photo is the outerwear cover

Got it , sorry it's early.
Coffee not working yet.

 

[Seandonato73]

Without tearing into it and posting good pictures any advice given is speculation at best. I can assure you of 2 things right now. 1 yes it's seized, and it didn't have jack to do with the oil ratio. Piston pics through the exhaust, best to get the top end pulled off and post pics of that.

 

[jeepfreak1972]

Hi All,
I ran my 2nd hand (but new to me) 30DNT with a Zenoah G320cc for the first time on Saturday and during a run it just died. Im new to RC and especially to 2 stroks so still learning the ropes but I think it may be seized, the pull start would not pull once it died. Ive removed the engine and tried to move the flywheel but it wont budge at all and I don't know what to do next. Any help anyone can give will be much appreciated. My fuel mix was 25/1 by the way.
Thanks in advance to anyone who can help or offer any advice.

View attachment 92888

Sounds like you had a seizure from being tuned to lean. On 2 strokrs there are two ratios to deal with, oil mix ratio and air / fuel. No amount of oil will protect an engine with too lean of an air/fuel ratio / tune.

 

[zxb466]

Do you know what your engine temp was when you were running it? Do you have a video of it running?

 

[Rep732]

@zxb466 temperature isn't necessarily going to seize the engine, when you lean it out too much your also taking away the oil needed to lubricate the engine.

 

[zxb466]

@zxb466 temperature isn't necessarily going to seize the engine, when you lean it out too much your also taking away the oil needed to lubricate the engine.

Yeah just thought maybe if he had that info it would help point us in the right direction with what went wrong

 

[Rep732]

@zxb466 it was too lean, it's honestly that simple. If he can take pictures of the piston it will likely tell us it got too lean. Even a picture of the spark plug will help.

 

[Dp400]

Here are some pictures of the piston showing scratches on the exhaust side and the carburettor side…

 

[Shad0man]

Yep…. you stuck a piston.

As many have shared, lean is a death nail for a two stroke.

Unlike a 4 stroke, the gas and oil produce lubrication and combustion and then exhaust. There is no secondary lubrication.

To be safe error on the side of a rich mixture however, the greatest power is when on the edge of to lean.

It can be a delicate balancing act often dictated by one’s wallet.

As I shared, most if not all have and likely with stuck a piston.

Fortunately, it’s an easy, inexpensive repair.

Thank you for sharing your experience.

Repair it and enjoy !!!

 

[jeepfreak1972]

Yep…. you stuck a piston.

As many have shared, lean is a death nail for a two stroke.

Unlike a 4 stroke, the gas and oil produce lubrication and combustion and then exhaust. There is no secondary lubrication.

To be safe error on the side of a rich mixture however, the greatest power is when on the edge of to lean.

It can be a delicate balancing act often dictated by one’s wallet.

As I shared, most if not all have and likely with stuck a piston.

Fortunately, it’s an easy, inexpensive repair.

Thank you for sharing your experience.

Repair it and enjoy !!!

And an opportunity for a performance upgrade.