2 stroke running in

[yorkie_chris]

Not on 400E or YDS7.

So how can oil injected seperately into the intake tract affect the fuel air mix? Premix I understand, this I do not.

[Bibio]

it still ends up in the crankcase as mixed oil/fuel/air.

oil pumps are actually much better than premix as the pump controls the amount of oil according to the throttle position. where as with premix your stuck with a certain ratio no matter what the throttle position lets say 12-1. so at low revs its more than likely that with premix you will have to much oil in the fuel and at higher revs to little.

if the oil pump is set to 'run in' then the starting mix might be say 10-1 and mabee rising to 15-1 at full throttle where if set to normal the pump will output say 8-1 rising to 12-1.

Hmmm... still doesn't answer the question of how the "biggest killer of strokers is to much fekin 2 stroke oil" in an oil injected motor .

What are these ratios? air/fuel fuel/oil...?

[Bibio]

the ratios are an example (not exact) mix of oil to fuel..... e.g. 10-1 so for every 10 ltr of fuel it would use 1 ltr of oil

if not set up right the injector is squirting to much oil into the fuel/air mix.

which in turn ends up in the crankcase to much oil in the crank case cases gumming of the bearings. excess oil is also fed to the combustion chamber casing fouling of the plug and unburnt oil cases carbon spots to glow and burn holes in pistons.

Thanks

Not exact is an understatement... a normal premix ratio these days is 50:1 to cover the idle oil requirements and can be drastically reduced as revs rise. At 10-15:1, even allowing for it not being exact and regardless of whether it is injected or premixed, the motor would be fairly drowning in the stuff. No surprise there would be coking problems.

Thanks for the explanation. Never seen it myself. Closest would be gumming up my chainsaw or brushcutter from too many short runs.

BTB, your text highlighted in blood never constituted an explanation.

Cheers

[ogden]

Originally Posted by Alpinestarhero

In general, from what I've read about running in two-strokes, the idea is to not alow the revs to stay constant (i.e. always vary them, dont just sit at say 6000 rpm),

That applies to running in any engine two strokes or four.

[Doinitmyway]

Originally Posted by MattCo

Hmmm... still doesn't answer the question of how the "biggest killer of strokers is to much fekin 2 stroke oil" in an oil injected motor .

What are these ratios? air/fuel fuel/oil...?

Sorta simple really. Air and petrol burn best at 1 part petrol and 14parts air. Engines are mostly set to run just ever so much richer than this. This is because the incoming petrol also helps cool the piston crown.

To make it simple imagine a 150cc single cylinder two stroke engine. To get maximum power AT FULL THROTTLE, every time the cylinder/piston 'sucks' in it will draw in 140cc of air and 10cc of petrol and make nice power and stay at good temp.

If too much air gets in, say 145cc, then there isnt physically room for more petrol than 5cc. All the petrol will burn but not all of the air so fresh air gets into the exhaust (wonder why they're called O2 sensors ). Power will be down a bit and also because there is less petrol to cool piston crown it can overheat and sometimes melt

[if a two stroke runs too rich with oil then that oil will take the place of petrol in the mixture making the mixture leaner still]

If too much petrol gets in, say 15cc, then because only 135cc of air has been drawn in *there is not enough air to burn all the petrol* - this means no fresh air but some petrol will make its way into the exhaust. Power will be down and petrol can be smelt from exhaust.

This is theoretical and other factors do have to be taken into account (air density, temperature, volumetric efficiency etc etc) If you get your head round the fact that the engine size is a limit on the amount of mixture that gets drawn in then it gets easier.

Geek mode off...................................

[ogden]

Originally Posted by suzsv650

Use the BEST two stoke oil. This stuff is good
http://jestersmotorcycles.com/accessories/maint/P1%20TTS_2T.jpg

TTS is good - I use it in my RGV - but it doesn't smell as good as Putoline. And, lets face it, where stroker oil is concerned the smell is far more important than the lubrication.

Two stokes are awesome!

I feel sorry for these kids today, hopping onto sensible (and often restricted) bikes like SVs when they should be trying to kill themselves on souped-up strokers like in the good old days.

Originally Posted by Doinitmyway

...

Naught to do with quoted text in the context of the discussion, but thanks for the lesson anyway

Cheers

[ogden]

Originally Posted by MattCo

Naught to do with quoted text in the context of the discussion

Next to useless in the context really, given that we're talking about a fuel/oil mix, leaning the mixture even further.