Spark Plug Burning Too Hot - Hole In Piston

[Mountainman]

If spark plug is replaced with one that burns much hotter can it burn a hole in the piston ? I was looking for a replacement plug for my Subaru 33cc and the gentleman working at a small engine repair shop did not have the exact plug - so he attempted to cross reference - nothing came up. He said that it would not be a good idea to just put any plug in my engine (even though it may look the same) if a plug burns to hot for said engine -- IT MAY BURN A HOLE IN PISTON. Well - I also worked in a small engine shop - for a short time - some 25 years ago - and don't remember any such problems. But - I am thinking - best - to get the correct plug. Happy Riding from - Mountainman

[Skyliner70cc]

Unlikely, that it will but your main problem will be preignition due to fact plug doesn't dissipate heat as well. Preignition/detonation can cause engine damage (you know, the pinging rattling sound you hear sometimes when you step on the gas in your car).

I'd use the plug but this is one of the rare times you may want to use a higher octane fuel.

[jesse8931]

actually it will i had an old suzuki 50cc dirtbike and replaced the junk spark plug with a ngk br8es and it put a huge hole in piston

[Mountainman]

Unlikely, that it will but your main problem will be preignition due to fact plug doesn't dissipate heat as well. Preignition/detonation can cause engine damage (you know, the pinging rattling sound you hear sometimes when you step on the gas in your car).

I'd use the plug but this is one of the rare times you may want to use a higher octane fuel.

Hi Skyliner -- I have noticed some of this going on - on the lower end of my revs - engine rattling.. Subaru said to use regular gas. Suffering from - slight loss of power and occasional missing - with carb air filter getting somewhat wet with gas ?? Mountainman

[Large Filipino]

What plug you need? I had a time searching for a plug and I found mine at my local Harley dealer. Under 2 bucks for a resistance plug with a 5 number.
Check out your local motorcycle shop. You might be surprised.
And it's a great conversation starter if you pull up on your bike.

[Skyliner70cc]

Hi Skyliner -- I have noticed some of this going on - on the lower end of my revs - engine rattling.. Subaru said to use regular gas. Suffering from - slight loss of power and occasional missing - with carb air filter getting somewhat wet with gas ?? Mountainman

Mountainman,
I'm assuming you have a 2 stroke? If so, its not unusual for differences in performance at certain rpms due to the fact that 2 stroke porting/timing is optimized for a certain rpm and desired engine characteristic. This means operation at all other speeds is compromised a slight degree.

It wouldn't hurt to try a new (colder heater range) plug or higher octane. If it works, then that is awesome. If it doesn't then try something else. I believe in ruling out the simple stuff first before looking for complex solutiosn to engine issues. Good luck w/ your ride.

Sky

PS As time goes by, carbon build up on a piston can cause preignition. This is why older cars often have "spark knock" when accelerating. Higher octane fuel or breaking the carbon loose by spraying water into intake are some options to try. Note: spraying water into intake on any engine is dangerous and risks engine failure and should only be done by someone mechanically experienced. Nothing worse than breaking a rode from hydrolocking an engine. Small engines would require nothing but a very thin and fine mist of water sprayed into the engine intake while it is revving very high. I have doen this dozens of times on my high mileage cars with no problems but it can be catastrophic if you don't do it right.

http://www.motorwatch.com/automotive...bonRemoval.pdf

[BigDaddyT]

Yeah a tablespoon or so of water down a carbureter while revving the engine on a car was fine. Wonder how much you could put into a little 2 stroke.

[Skyliner70cc]

BigdaddtT,
I would probably use a spray bottle that squirts a fine mist of water. When the water hits the piston, it instantly boils which is supposed to knock out the carbon. You can technically put gallons of water, total amount is not important, what is important is the rate of water going into the engine.

[BigDaddyT]

The way I was told was it explosively turns to steam and in doing so can remove carbon buildup.

[nsideus]

Couldn't the loose carbon score the cylinder? I use to decarbon the exhaust ports on my lawn equipment and was always very careful as not to let any slip back into the cylinder. I ran a crew for a lawn company and told the owner his exhaust ports were probably clogged he decided to clean them himself and scored the cylinders.