Fuel oil ratio on 2 stroke from 50:1 to 100 :1

two stroke mick · 22 July 2019, 13:37

I have an old 15 hp Johnston, I believe that this is a 200/2001 engine (J15RVLSIC). This engine has a fuel to oil premix ratio of 50:1. I use this engine for angling on the lakes and spend considerable amount of time trolling. The smell of two stroke is not great the kids sometimes say it gives them headaches). I am thinking of running a second tank with 100:1 mix for trolling and low speed work.

I am aware that at some stage in the past these engines were ran at 100:1 but that was subsequently modified to 50:1.

I Leroy's ramblings on this engine (very good post and instruction guide) He makes reference to using 100:1 mix for trolling on syn oil. He makes a big point on using syn oil.

Thoughts on using two tanks, 50:1 tank for higher speed work and 100:1 for trolling and low speed work.

Aside: I find this to be a very good engine but at 35 kg I would not want a heavier one as it is just about doable

Regards

TSM

Poly · 22 July 2019, 17:56

Quote:

Originally Posted by two stroke mick

Thoughts on using two tanks, 50:1 tank for higher speed work and 100:1 for trolling and low speed work.

Given the number of times I’ve forgotten to open the tank breather I wouldn’t trust myself to always switch back (that said for occasional spells it probably wouldn’t matter). I don’t troll for fish but is it feasible to do it into the wind? Are you sure it’s the exhaust giving them a headache - not sun exposure, petrol fumes or boredom?

Locozodiac · 22 July 2019, 18:12

Any motor designed to run 50:1 ratio is for running at their max wot rpm range factory stated. Autolube motors uses way less fuel/oil ratio when running at idle or fast idle rpm. You could run a motor while trolling with a 100:1 ratio at min rpm, just don't open the throttle to max wot range when not trolling.

Happy Boating

jeffstevens763@g · 22 July 2019, 20:39

TSM I've had the same engine stinks like chuff but 50-1 is what it says on the tin IMO leave it at that and up tide and drift keeping trolling to a minimum

willk · 22 July 2019, 20:54

Thinking outside the box....

How fast can yer wains paddle the sib?

jwalker · 22 July 2019, 22:38

I'd have no issue using 100:1 when trolling. One of the issues with premix 2 stroke is the build up of excess oil in the crankcase when they are run slowly for extended periods. That's why they turn smokey. If fact, in many older engines the oil build up was so great that they would refuse to idle for extended periods of time and blipping the throttle was required to keep them running.

two stroke mick · 29 July 2019, 07:39

Update

Yesterday I ran the engine on Dr 100 as I have an etec. Big improvement in the smoke and smell no grumbles from kids. The mix was 50:1. A big surprise which was not expected was that the engine seemed to be quiter

Tsm

two stroke mick · 29 July 2019, 17:07

Woody the oil was Dr 100 not dr100 eyesight is not improving with age

Pikey Dave · 29 July 2019, 21:09

Quote:

Originally Posted by two stroke mick

Woody the oil was Dr 100 not dr100 eyesight is not improving with age

Do you mean XD100 ?

willk · 30 July 2019, 07:17

Quote:

Originally Posted by Pikey Dave

Do you mean XD100 ?

Woody it that it were so simple.

two stroke mick · 30 July 2019, 17:30

XD 100 is correct

Poly · 31 July 2019, 14:06

Quote:

Originally Posted by two stroke mick

XD 100 is correct

I’m confused. You said in the OP this was for a premix two stroke 15hp. Then you mentioned an Etec and XD100. XD100 is not intended to be premixed - it is for direct injection.

two stroke mick · 01 August 2019, 07:06

I understand that xd100 exceeds tcw3

Roflhat · 02 August 2019, 07:41

Quite a few of the thundercat racers run XD100 in premix, seems to do the trick, engine internals still look good