1530dean

Fuel ratio for 2 stroke

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Hi All,

Earlier this year I removed the automixing from my 40hp 2 stroke Tohatsu and have been very happy with the trouble free performance to date.

One of the issues that made me remove the automixing was the bogging down and poor idle and excessive oil fowling the spark plugs.

Regarding the aperture range of the original oil mixing setup the manual states and I quote "The gasoline/oil mixing ratio varies automatically between 50:1 (2% oil) and 120:1 (0.8% oil) according to throttle opening."

Now that I am pre-mixing my fuel and in order to avoid the same bogging down and idle issues I have been mixing my fuel at around 75:1 or 80:1.

I must add that I never take the engine up to WOT and at max would take it to 3/4 throttle only.

Also I must add that in the manual it states "engines to be operated with automixing system disabled require 50:1 gasoline/oil mixture (2% oil)."

Since the aperture setting at idle is set for 120:1 and only at WOT does it require 50:1 what risks if any are there at mixing at 75:1 or 80:1..?

I would be curious to know if anyone else is mixing at these slightly higher ratios..?

Thanks 

Dean

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oil is cheaper than engine parts use 50:1 replace spark plugs carry spares and plug spanner

racing two stroke motorbikes for 45 years and still have some i use 20:1 jet carby right its all good

how do you think all the older outboards got on they use 50:1

last thing you need is it nipping up because you guned it to get out of trouble 

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plus one with the boys..at 75/80 to one any load or revs would be a concern..there would be hardly any lubrication..if you looked at a chart of how the oil is fed into the motor from idle 120/1..thru to 50/1 it jumps to 50/1 by the time your doing 2000revs and stays at that for full rev range.....picking a halfway point between mix levels is suicide for that motor...im surprised it hasn't gone bang already...rick

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I have a Suzuki 15, and it is a pre mix at 100/1. Haven't had an issue.   ??????????   Howard. 

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Some small outboards are rated for 100:1. I think they have needle bearings which helps them cope with the lower oil. Though I have heard it said that this is more a marketing idea and a concession to the environment and if you want your motor to last run 50:1. This is what I do with my Suzuki 30 hp as I run at WOT quite a bit. I have never had any problems with oiled up plugs. 

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make sure you use good quality tcw3 oil not just any old 2sroke oil....for an extra couple of dollars of oil its better than rebuilding a motor...rick

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12 hours ago, rickmarlin62 said:

make sure you use good quality tcw3 oil not just any old 2sroke oil....for an extra couple of dollars of oil its better than rebuilding a motor...rick

Hi Rick ,so what's this tcw3 oil? I have a 15 HP Yamaha and run it on 100:1...had no problems (yet). Are you suggesting I should use maybe 80:1? BN

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41 minutes ago, big Neil said:

Hi Rick ,so what's this tcw3 oil? I have a 15 HP Yamaha and run it on 100:1...had no problems (yet). Are you suggesting I should use maybe 80:1? BN

Hi Neil,here's a article for you to read and make up your own mind.I run Yamalube in my engine with no I'll effect at 100:1 to date.

http://www.saltwatersportsman.com/two-stroke-engine-oil-for-fishing-boat

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hey neil  depends on manufacturers specs  older motors need heavier mix ...all good 'outboard oils' should have a rating of tcw3 written on bottle somewhere...its the international spec to comply with emissions and manufacturer warranty..rick

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21 hours ago, rickmarlin62 said:

make sure you use good quality tcw3 oil not just any old 2sroke oil....for an extra couple of dollars of oil its better than rebuilding a motor...rick

I use quicksilver is that ok?

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39 minutes ago, rickmarlin62 said:

all good luke  as I said good quality oil no probs...rick

Which ones should we stay away from?

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make sure they state two stroke outboard motor oil.tcw3 rating..not just two stroke oil  that is for mowers and brushcutters n chainsaws...tcw3 oil is cleaner burning  less emissions less oiling up of plugs...rick

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4 minutes ago, rickmarlin62 said:

make sure they state two stroke outboard motor oil.tcw3 rating..not just two stroke oil  that is for mowers and brushcutters n chainsaws...tcw3 oil is cleaner burning  less emissions less oiling up of plugs...rick

That was a disappointment.

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sorry not my job to name n shame rubbish oil brands  I don't want to get in trouble from mods......rick

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10 minutes ago, rickmarlin62 said:

sorry not my job to name n shame rubbish oil brands  I don't want to get in trouble from mods......rick

Can you pm me the bad ones?I'd be very interested to know for future reference.

Cheers.

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10 hours ago, rickmarlin62 said:

sorry not my job to name n shame rubbish oil brands  I don't want to get in trouble from mods......rick

All good - there are plenty of Australian brands of stuff that are poor quality too not just Asian stuff! I just bought a few things from China for transporting my art pencils etc and they are fantastic. Some other stuff have been rubbish.

Our rule refers to generalisation and picking on races of people. 

Why not be positive guys. Throw up some lists of GOOD QUALITY products. Many of you are experts with mechanical issues!

 

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Great stuff guys! Many thanks for the inside info. Oils ain't oils appears to be the case. The stuff I use has TC-W3. More concerned (now) about the petrol which has been unused for about 5 months. Cheers, BN

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30 minutes ago, big Neil said:

Great stuff guys! Many thanks for the inside info. Oils ain't oils appears to be the case. The stuff I use has TC-W3. More concerned (now) about the petrol which has been unused for about 5 months. Cheers, BN

Ive had pre/mix that old and just topped the tank up with fresh fuel/oil with no I'll effects .

49 minutes ago, mrsswordfisherman said:

All good - there are plenty of Australian brands of stuff that are poor quality too not just Asian stuff! I just bought a few things from China for transporting my art pencils etc and they are fantastic. Some other stuff have been rubbish.

Our rule refers to generalisation and picking on races of people. 

Why not be positive guys. Throw up some lists of GOOD QUALITY products. Many of you are experts with mechanical issues!

 

Agree Donna,I've noticed the quality of everything across the board has gone down hill from common household  everyday items to large things like cars, boats,houses etc. The problem is people would scoff at the price they would have to pay if those items were made from better materials.

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