saulk

Hi all,

My MT has been running fine but today it just kept on cutting out. I haven't changed any settings, it will start and tickover but when I accelerate it makes a really deep/bellowy sound then just dies, also happens if I come of the throttle and brake it just shuts off. I don't even know how to tune this engine, haven't a clue which screw does what. Thanks in advance.

Doohan

You shouldn't have to change the screws on the carby...sounds like a fouled spark plug to me.
When did you last change or check your plug?...pull it out and look at the tip, is it really wet and black?
Put a new one in and see what happens.
When did you last clean your air filter?...if its full of crap not enough air will be getting through.

saulk

Hi,

The engine has only had 3 tanks of fuel through it, spark plug seems OK, not wet at all, air filter is always clean.

Cheers

Doohan

Spark plugs can just die....put a new one in and try it again.
What ratio fuel/oil are you running?

saulk

Doohan,

All sorted now turned High screw out 1/16 turn and car runs fine. Oil/fuel mixture i'm running every litre of gas to 20ml of oil, is that ok
Cheers

Mad Wax

You need 1 part of oil to every 25 parts of petrol.

saulk

Mad Wax,

So you're saying I need to almost double the oil content that would then be around 40ml oil per litre of petrol.

Cheers

Saul

Mad Wax

I use the levels on the clear 2 stroke oil bottles - they have moulded lines on the side with various part mixes (25 and 50 to one I think, I use 25:1) use the correct oil mix, especially since the engine is new- a preset amount of oil from these marked bottles are usually 1 UK gallon of petrol. If my maths is correct you need 40ml of 2 stroke oil in every 1000ml.

You could have damaged the engine using a MUCH lower % of oil.

25ml of oil per litre is still wrong. 25:1 is not a percentage as you're thinking, it's a ratio. So for every 25ml of petrol, you need 1ml of oil.

Doohan

I hope you're putting in more than 20ml of oil per 1 litre!!!!
Thats way too lean and will kill your engine.
For run in and the first 10 tanks I ran 25:1
Now I run 35:1....seems to rev better and has less smoke now.

The easiest way to do it is this:
Put 100ml of oil in your container and decide what ratio you will run....you should be 25:1 if your truck is still new.
So just add 2.5 litres of petrol or 2500ml to the oil.
For 35:1 just add 3.5 litres to the 100ml of oil.

saulk

Mad Wax,

Changed above post I meant 40ml per litre, I was originally running 25:1 (40ml oil to 1 Litre petrol) but the guy at my local hobby store said it was too much and to run 50:1 I only ran half a tank like this, engine seems OK. I had a few litres of 25:1 mix left in a Jerry can and mixed in the 50:1 batch and only ran for a short while (half a tank) from now on i'll use a 25:1 mix. The guy at the hobby store seemed to know his stuff????? Hmmmmmm.

strong_material

My Feedback: (1)

it really depends on what kind of oil you are using. zenoah recommends a 25:1 mix with a 95 octane or more gasoline. this recommendation is based on their own Zenoah 2-cycle oil. I have been using AMSOIL Saber Professional 100:1 and breaking-in new engines at 64:1 and never had problems.

It may just be a foul plug or too lean H needle setting, which causes the engine to bog down when squeezing the throttle. bench-run it and give it bursts of full throttle. if it bogs down, richen the H needle a little bit.

badz

My Feedback: (1)

64:1? Wow what does your ring look like if theres any ring left?

Mad Wax

Clueless moron If his bad advice has damaged your engine I would seriously take it up with someone, since he's clearly a idiot. Perhaps he should give you a new piston liner and piston ring if it's damaged.

btw cut out could be carb problem, sounds similar to my Leopard engine.

saulk

Guys,

Thanks for your help.

Mad Wax,

Engine seems fine, have mixed a little more oil in now though, it was only run for a very short while.

strong_material,

Richened H needle by about 1/16 of a turn and that has now sorted it.

Cheers

Saul

Pigsmightfly

That's really not the sort of question one bloke should ask another