MS660 needs your help!

[copcore]

I'm hoping someone might be able to give me a clue on this one.

 

My ms660 has done me proud for the last 3 years (just fine on friday!), however I lent it to my bro and his team today and It's come back dead!

 

They said it just conked out chogging up a few hours into the day.

 

First thing I noticed was a much stronger mix than I usually use in it, so I wondered whether they had clogged the carb. So checked plug was ok and put some fuel straight into the chamber-still didn't fire.

 

Dried everything off and tried again and fuel does seem to be getting into the chamber and wetting the plug, but it just won't fire. (Plug is def. sparking)

 

Any ideas? Can a rich mix (looked more like a 25:1 mix) really do damage?

 

Any help much appreciated guys.

[TREE-SURGEON-ESSEX]

Open the head check out pot and piston soon see if they wrecked your saw lend to no one i dont because no one looks after your gear

[geoff]

It can make them run lean,as less fuel to air ratio,the oil is not a fuel but a lubricant.

I hope this is not the cause in your case.

[Mesterh]

Does it feel like it has good compression?

[18 stoner]

It can make them run lean,as less fuel to air ratio,the oil is not a fuel but a lubricant.

I hope this is not the cause in your case.

 

25:1 instead of 50:1 gives less lubricant? How does that work out Geoff?

[stuartc44]

If you use a 25:1 mix there is less petrol in a given amount than in a 50:1 mix, therefore a saw will have less fuel, possibly run lean and could run hotter/cause damage.

[geoff]

25:1 instead of 50:1 gives less lubricant? How does that work out Geoff?

 

It won't give less lube,but less fuel,specificaly petrol,as there is less petrol in the mix,hence lean running.

I remember this from motocross 2 strokes.

It does sound A about F but none the less is relevent.

Also the mix is more viscous,so less will be passed through the fine jets in the carb for a given setting.

Hope this helps explain,as it is contrary to what people think.

[Big 'Ammer]

A mate who used to race carts told me about this years ago.

 

For example,

 

a 50:1 mix is 2%,

 

In 100ml of mix there will be 98ml petrol and 2ml two stroke oil.

 

a 25:1 mix is 4%,

 

So in 100ml of mix there is 96ml petrol and 4ml oil.

 

Therefore more oil means less petrol in any given volume, hence the mix being leaner of petrol.

 

This was very important to my carting mate, as they used to run mixs of between 12:1 and 18:1, so very easy to screw engines with the wrong set up.

[geoff]

A mate who used to race carts told me about this years ago.

 

For example' date='

 

a 50:1 mix is 2%,

 

In 100ml of mix there will be 98ml petrol and 2ml two stroke oil.

 

a 25:1 mix is 4%,

 

So in 100ml of mix there is 96ml petrol and 4ml oil.

 

Therefore more oil means less petrol in any given volume, hence the mix being leaner of petrol.

 

This was very important to my carting mate, as they used to run mixs of between 12:1 and 18:1, so very easy to screw engines with the wrong set up.[/quote']

 

About sums it up,the oil is not part of the combustion mix,petrol+oxygen are,more oil =less petrol=lesspetrol/air=lean running.

 

There is also the posibility,with way too much oil of affecting the mix viscosity,restricting the amount getting drawn through the jets to the venturi.

 

Try sucking honey through a straw,then shandy(if its your tipple).

[18 stoner]

It won't give less lube,but less fuel,specificaly petrol,as there is less petrol in the mix,hence lean running.

I remember this from motocross 2 strokes.

It does sound A about F but none the less is relevent.

Also the mix is more viscous,so less will be passed through the fine jets in the carb for a given setting.

Hope this helps explain,as it is contrary to what people think.

 

With you now Geoff, well explained:thumbup1:

 

I missread your comments:blushing: