An interesting thought

[funkymoped]

I was emailed this picture the other day asking is this right as the engine had done only 270 miles.



Now I have been told that the cause of this is lack of oil in the petrol also I learned that modern synthethic oild burn quicker and therefore lets the petrol get hot and consiquently burns a hole in the piston.

So my dear friends 30-1 on synthetic oil is a no no and I have now found a supplier of classic oils in the classic cans. 20-1 mineral oil mix and SAE 40 in the gearbox, I am assured also that 10-40 tesco oil will eventually fail.

Oh and who told me this a guy that has been building two stroke race engines for Yamaha for 30 years.

[pertheswede]

Very interesting TC, I also of the belief that most of the aftermarket pistons are made of inferior grade metal composition to the original YAMAHA ones, making them less heat resistant too

How much are these old style mineral oils and where can we get them from? You or?

[funkymoped]

I have ordered some from my local bike shop today I will update when I know
what it is but you can buy a cheapo one in your local garage.

[Charlie]

Oh dear, that piston looks to me as though we are suffering a weak mixture, ie not enough fuel or lubricant, you will get the same result on mineral oil at 20:1 ratio if it runs lean, the worst thing you can have on a premix 2 stroke engine is a weak mixture cos this generates heat and that leads to pre combustion, generating more heat and a cheap alloy piston has a much lower melting point than a cast iron barrel
Modern synthetic oil is designed for modern engines which run much tighter tolerances than old strokers from the seventies, i always use Castol TT 2 stroke oil in my bikes, thrash em to death and not once have i had a problem in nearly 30 years
and when i say old strokers from the seventies, i mean bikes not you TC

[jobby]

can you still get castrol tt? it seems to have been replaced with tts at most places

[Charlie]

Yeh still available at most decent bike shops, i get it from autojumbles, try online

[funkymoped]

I have ordered a load from my local bike shop should be in this week.