TaxiDriver Posted September 29, 2012 Report Share Posted September 29, 2012 (edited) I've bought meself a petrol brushcutter/strimmer and assembled it, and now find it needs a 40 : 1 two stroke mix ?? Ive probably been over thinking this, but how do I calculate the amount of oil to petrol ? Oil = 1/40th of the volume of petrol ? It has a 500cm3 fuel tank if that helps ?? (Isn't cm3 a volume rather liquid measure - confused) The other thing, being Two Stroke, the oil in the fuel is for lubrication I presume ? Does this mean the engine doesn't have a sump/reserve of oil ? I can't find any mention of engine oil in the destructions nor can I find a means of adding any engine oil anywhere Edited September 29, 2012 by TaxiDriver Quote Link to comment Share on other sites More sharing options...
apache Posted September 29, 2012 Report Share Posted September 29, 2012 Buy a 5L fuel can, fill it with petrol. Write "2 stroke" on the side. Add 125ml to that. You can buy pre-measured aliquots. http://www.ebay.co.uk/itm/3x-125ml-CASTROL-HORTICULTURAL-ONE-SHOT-2-STROKE-ENGINE-OIL-3x-125ml-BOTTLES-/251003790559 Don't mix it in the tank. Quote Link to comment Share on other sites More sharing options...
keg Posted September 29, 2012 Report Share Posted September 29, 2012 Correct in that there is no sump, the engine gets its lubrication from oil in the mix. Do as apache says or you can also buy a 2 stroke mixing bottle which allows you to mix a litre at a time and also allows you to measure different mixes such as 50:1 Quote Link to comment Share on other sites More sharing options...
TaxiDriver Posted September 29, 2012 Author Report Share Posted September 29, 2012 Thanks Very Much Gentlemen Quote Link to comment Share on other sites More sharing options...
Davie_M Posted September 29, 2012 Report Share Posted September 29, 2012 Dont mix more than you need as it wont keep Quote Link to comment Share on other sites More sharing options...
gixer1 Posted September 29, 2012 Report Share Posted September 29, 2012 Just take the amount of petrol and divide it by the ratio you want, so in this case you'll have 5 litres (5000ml) so 5000/40=125ml Regards, Gixer Quote Link to comment Share on other sites More sharing options...
apache Posted September 29, 2012 Report Share Posted September 29, 2012 Dont mix more than you need as it wont keep I get through a can full every 6 months and it seems to last fine. Quote Link to comment Share on other sites More sharing options...
station Posted September 30, 2012 Report Share Posted September 30, 2012 Dont mix more than you need as it wont keep Didn't know that - how long is OK then ? And why ? Quote Link to comment Share on other sites More sharing options...
39TDS Posted September 30, 2012 Report Share Posted September 30, 2012 Mine keeps for months without any issues. Quote Link to comment Share on other sites More sharing options...
guss109 Posted September 30, 2012 Report Share Posted September 30, 2012 The petrol breaks down as it goes stale and the two stroke separates from the fuel so it doesnt lube the piston and it will sieze the engine Quote Link to comment Share on other sites More sharing options...
TaxiDriver Posted September 30, 2012 Author Report Share Posted September 30, 2012 Thanks Folks, been out today and bought a gallon of petrol and a litre of 2stroke oil and a simple mixing bottle. The mixing bottle takes 1litre of petrol and then you top up with oil to the requesite mark depending on the required ratio. that way I only mix up as much as I need at a time Quote Link to comment Share on other sites More sharing options...
craftycarper Posted September 30, 2012 Report Share Posted September 30, 2012 I thought it went something like 20:1 = litre of petrol add 20ml of oil and so on, use within a month as said Quote Link to comment Share on other sites More sharing options...
Davie_M Posted September 30, 2012 Report Share Posted September 30, 2012 The petrol breaks down as it goes stale and the two stroke separates from the fuel so it doesnt lube the piston and it will sieze the engine Been there done that Didn't know that - how long is OK then ? And why ? Mix as you use it Quote Link to comment Share on other sites More sharing options...
Davie_M Posted September 30, 2012 Report Share Posted September 30, 2012 Mine keeps for months without any issues. thats what i thought till a very expensive enigine rebuild on a crosser to see the state of the piston and cylinder you would never think there was any 2 stroke in the petrol also nackerd he crank Quote Link to comment Share on other sites More sharing options...
Highlandladdie Posted October 2, 2012 Report Share Posted October 2, 2012 It is a good habit to always give the can a shake before you fuel up. This will make sure everything is thoroughly mixed. Petrol, as has been said does go 'off'. For hp engines its best not keeping a large stash, up to 2 weeks is probs ok. Our mx bikes are supposed to run 40:1, however we run them at 36:1 due to hard use. Good oil is a must for longevity, most people scrimp here and end up paying big time later. Quote Link to comment Share on other sites More sharing options...
PhilR Posted October 2, 2012 Report Share Posted October 2, 2012 Back in the 60's I used to use Castrol R or Bardhal (sp) oil in my 2 stroke bikes and learnt after one or two seizes to up the oil to petrol mix, just in case. Upside of the R was the exhaust smell, all the oldies will remember it in an instant. Quote Link to comment Share on other sites More sharing options...
Highlandladdie Posted October 2, 2012 Report Share Posted October 2, 2012 Absolutely bootiful smell! We currently use silkolene pro 2 sx. Does the job nicely and smells brilliant too. Quote Link to comment Share on other sites More sharing options...
Catweazle Posted October 2, 2012 Report Share Posted October 2, 2012 Absolutely bootiful smell! We currently use silkolene pro 2 sx. Does the job nicely and smells brilliant too. Silkolene Comp2 or Pro2 always worked well for me, as well as Belray. For chainsaws / brushcutters then cheap oil is fine, mix it at the recommended ratio because adding extra oil thickens the fuel and makes the engine run lean, actually increasing the chance of engine damage. Try to get a bright red oil, this shows up well and avoids that niggling worry that you might have forgotten the oil. Quote Link to comment Share on other sites More sharing options...
ajb403 Posted October 2, 2012 Report Share Posted October 2, 2012 I thought it went something like 20:1 = litre of petrol add 20ml of oil and so on, use within a month as said Your maths is out there mate, if you want 20 parts petrol to 1 part oil and you have 1 litre of petrol then divide 1 litre (1000 ml) by 20 to find out what 1 part is ie. 1000ml divide by 20 = 50 ml of oil. Quote Link to comment Share on other sites More sharing options...
clakk Posted October 2, 2012 Report Share Posted October 2, 2012 drain it b4 u put it away,used to get many customers with none starting chainsaws n strimmers cos they left em fuelled over winter ,the petrol seperates and the oily goo blocked the little jets in the carburettors so theyd come in swearing about this piece of c,,, that wont start but its just their fault for being lazy , Quote Link to comment Share on other sites More sharing options...
AVB Posted October 2, 2012 Report Share Posted October 2, 2012 I used to race karts in my youth. They had 100cc two stroke, rotary valve engines that used to rev up to about 18,000 rpm. Ah the smell of Castrol R. Very addictive. Mind you they didn't half make a mess when they 'let go'. If you were lucky it would just be a seizure that would require a rebore and new piston. I had a con rod snap when flat out once. Not a pretty sight. Quote Link to comment Share on other sites More sharing options...
Highlandladdie Posted October 2, 2012 Report Share Posted October 2, 2012 drain it b4 u put it away,used to get many customers with none starting chainsaws n strimmers cos they left em fuelled over winter ,the petrol seperates and the oily goo blocked the little jets in the carburettors so theyd come in swearing about this piece of c,,, that wont start but its just their fault for being lazy , Bang on, good advice Quote Link to comment Share on other sites More sharing options...
Catweazle Posted October 2, 2012 Report Share Posted October 2, 2012 I used to race karts in my youth. They had 100cc two stroke, rotary valve engines that used to rev up to about 18,000 rpm. Ah the smell of Castrol R. Very addictive. Mind you they didn't half make a mess when they 'let go'. If you were lucky it would just be a seizure that would require a rebore and new piston. I had a con rod snap when flat out once. Not a pretty sight. 100 Nationals at Hoddesdon ? Quote Link to comment Share on other sites More sharing options...
AVB Posted October 3, 2012 Report Share Posted October 3, 2012 100 Nationals at Hoddesdon ? Yes. Would have been 1977 in Juniors through to about 1984 in nationals. Also did Tilbury and Nuthampsted and one place in Norfolk that I can't remember. Quote Link to comment Share on other sites More sharing options...
Catweazle Posted October 3, 2012 Report Share Posted October 3, 2012 Yes. Would have been 1977 in Juniors through to about 1984 in nationals. Also did Tilbury and Nuthampsted and one place in Norfolk that I can't remember. I know Tilbury, horrible place in the middle of a marsh. I broke my collar bone and both arms on the motocross track next to the kart track. I seem to remember Hoddesdon had a shallow drainage ditch in the centre, Nasty. You might have known my mate Brian C, the Ginger Ninja, he was racing 100 nationals there at about that time. Quote Link to comment Share on other sites More sharing options...
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