4-star -> Unleaded conversion?

[YT2095]

I`m in charge of several 2 stroke engines for agricultural use, once upon a time 2 stroke fuel was available then we had to use 4-star fuel and add 2 stroke oil to it and mix.

NOW! the 4-star fuel is no longer available in the UK and so in addition to adding 2 stroke oil, we have to buy Unleaded fuel and mix yet another compound with it!

 

apparently with some cars this happens too, the cars that ran on 4-star fuel have to either add this new addative (like Redex) or get the engine converted.

 

I`m wondering if I can convert these engines to run on Unleaded alone without all the faffing about like an A` Lev chem exam!

 

I don`t mind adding the 2 stroke oil, but without this new stuff it`ll burn the cylinders out as it`s too "HOT".

I Beleive it`ll require a carb adjustment (fuel/Air mix).

 

I`de like a second INFORMED opinion please

[RICHARDBATTY]

Does the lead replacement fuel not work the same in a two stroke? EDIT lead replacement is getting limited.

[RICHARDBATTY]

The lead helped valve wear in four strokes. It was part of the process of producing higher octane fuels which was then utilised by the engine as a side benefit. The higher octane helped prevent knock (unstable compounds igniting when it shouldn't). This was not required after advances in fuel production and engine valves and designs. The octane of leaded was 97 ron unleaded is 95 this will cause pinking and can mean a timing adjustment on four strokes. The addative is to help the valves and boost octane so you don't have to make changes. Two strokes have no valves so a higher octane super unleaded should be good. Only guessing but a very slight increase in oil might be good.

[YT2095]

well the Castrol product does mention it containing kerosene (parafin for us Brits), I`m sure there`s other stuff in there too.

 

so you`de Reccomend Super Unleaded then? Funny you should say that as I was told there are 2 types of unleaded, denoted by a Green symbol (I can`t say I`ve paid all that much attn in all honesty though).

 

I know the 2 stroke oil is a Must, no escaping that requirement, but the conversion...

I`m not so sure about, the only thing is, other than the carb, and maybe back-Pressure at the manifold, there`s not a whole hell of a lot to alter

 

I guess I`m going to have to phone a Hire Shop and see what they do, they must have the same problem/irritation as myself.

[RICHARDBATTY]

Well what I failed to get across was you have no valves so no need for lead. You just need a higher octain than 95 ron to be as you were. So if you can get 97 ron unleaded you should be ok. Too hot may just mean too lean. Have you got dirty fuel. Have you got leaks in induction system. Those sticky out carbs on inlet dont help if they get knocked.

[YT2095]

it`s the "Too Hot" part that`s the danger, I don`t want to "Weld" the piston rings to the bore

 

I considered altering the F/A ratio to make the mix fuel rich, I just needed confirmation. btw I found out what that "Exhaust restrictor" was that this other guy mentioned, he actualy meant a catalytic convertor, LOL!

I don`t think I`ll bother

[RICHARDBATTY]

Often exhaust restriction in small 2s motors is just something daft like a washer welded in the pipe to reduce its diameter. Have you thought of adding fan blades to the output shaft, to aid cooling in summer. When the person pushing is hot they don't push fast enough for air cooling. Weld a ring on with a few holes for removable blades and you can cultivate a cooler relationship with your machines Lawn mower air flow from the grass box could be partialy diverted to blow past the head. That sort of thing.

[drizzt]

or you could just build a liquid coolant system with an old heater core some form of a pump (mechanical or electrical not sure on the app)and a aluminum heat sink wouldent have to be very big either