100:1 ratio

[rojac]

Looking at a 30hp yammie but it states a 100:1 ratio. It seems a bit light on. Would the downside of this be that the motor wears out quicker or wouldn't it make any difference??

Also can this motor be run on a normal 50:1 mix or would that cause problems??

Cheers

rojac

[bushbeachboy]

G'day Rojac,
A mate with a 30 Yammie was advised by the dealer to run not leaner than 50 - 1.

I've also been advised of that on this site.

[fishn-ads]

Yamaha has been 100-1 there 2stroke bikes for years they know what there doing with them maybe some cross over technology. But why you leaning the Yammie way?

[rojac]

Yamaha has been 100-1 there 2stroke bikes for years they know what there doing with them maybe some cross over technology. But why you leaning the Yammie way?

I've looked at tohatsu,merc, suzuki and yam.

Cost is a major consideration, which cuts out the suzi and merc. The yam is made in japan, all the gear that I've bought that has been made there has always been very good compared to other countries and I can get the services done at the local yam dealer 10 minutes away.

Having said that, I'm yet to commit.

cheers

rojac

[steveg1100]

Rojac

It sounds like a good reasoning to me for going with the yamaha.

I had my yamaha two strokes idling out of the water during flushing when another guy with a merc started flushing his motor. I have to say even though his two stroke looked like a much newer model than my yamahas I could not hear my motors over his. ( and he was about 6 metres away)

Yes the Japanese do make some good stuff.

Steve G

[ahoj]

My yamaha dealer told me 100:1 is fine but he consideres oil cheap and advised to go between 50-75 at this rate the spark plugs are as clean as using 100:1 so why not a bit more oil. Use TCW3 formula i believe its a synthetic oil.--I find no problem with my yamaha..

Ahoj

[fishn-ads]

Sounds like a good reason to me also.

I only asked because i recently got a new engine and found yamaha one of the more expensive, and that the majority of the feed back showed alot of independent (not sales men) people leaning away from the Yammy.

Aren't all those manufactured in Japan and offering 3 years warranty 30hp 2 strokes are bulletproof and don't need alot of servicing. I know that a month ago the Mercury looked to me the far best value in the 30hp market. I ended up going for a 40 Tohatsu though.

Just my opinion.

Ads

[rojac]

The yam has only a two year warranty unless you buy it in a "package deal" and then its three on the lot. The tohatsu and merc have three on everything and the suzi two.

I've been quoted $2900 for the tohhatsu and $3K for the yam (cv) but not as part of a pakage.

cheers

rojac

[billfisher]

50:1 has been proven over the years as the best ratio for premix 2 strokes if you want the motor to last. There is nothing at all different about Yamahas or other 100:1 motors which makes them run on less oil. It is just a marketing decision and a concession to the environment. Mechanics have told me after several years a motor run on 100:1 will show wear whereas a motor run on 50:1 will look almost like new inside.

[bushbeachboy]

Have a look at the 3 cyl 3 carb 2 stroke Yammy. Very smooth running, plenty of torque and economical. A mate is running his on a 4.15 Sea Jay Magnum and having been out in it a lot, I have found it to be a good combo.
Cheers

[borisdog]

I had twin 60Hp Yams on my Cat and always ran them at 100:1 with no probs. However the only bad thing that will happen if you run at 50:1 is a bit of extra cash and smoke. If it gives you piece of mind then go for it. A lot of the variable injection motors around now will run way, way leaner than 100:1 at low revs and richer than 50:1 at high revs. Everything's a compromise. :)

[MulletMan]

If you go messing about with the fuel/oil ratio, might be a good idea to check out the warranty details as some manufactureres void their warranty if you don't use the correct mix!

I'm of the opinion that the manufacturers tend to know a bit more than the local dealer does!

[billfisher]

The manufacturers don't care if your motor wears out after ten years, by then the warranty is long gone. Note that Tohatsu recommend 50:1 and they are not built differently from the so called 100:1 motors.

[fishn-ads]

I've been quoted $2900 for the tohhatsu and $3K for the yam (cv) but not as part of a pakage.

cheers

rojac


Rojac, Is it electric start and remote controlled? Short shaft? If it is ignore this. As I only have quotes for Long shaft, Tiller/Pull start.

If not Tohatsu price quoted to me was $2575.00 Motor only. As said a month ago Mercury was running them out about $200 cheaper. I paid $3407.00 for my M40c l.

PM if you want dealer details.

Ads

[Roo]

Have a look at the 3 cyl 3 carb 2 stroke Yammy. Very smooth running, plenty of torque and economical. A mate is running his on a 4.15 Sea Jay Magnum and having been out in it a lot, I have found it to be a good combo.
Cheers

Agree with bushbeachboy, The 3 cyl version has oil injection so you don't even have to worry about premixing :)
Pinkpanther is right too! manufacturer knows best. they'll also tell you to use Yamalube oil. I ran my 15 on 100:1 and 75:1 ratios. I didn't find any difference but for some extra smoke. The yamaha dealer said no reason why not 50:1 in the small motors but he said the larger sizes(30 up) need to be run at the correct stated ratio or fouling can be an issue.

cheers, roo.

PS. I liked the yamaha........but i love my zooki (4str)

[rojac]

Thanks for all the feed back, a decision has been made, put a deposit on a DT30 suzi ls tiller electric/zip start made in japan motor. 2 years recreation use warranty for $3300 only 10% more than the non electric start that I've been quoted on. Also runs 100:1 but dealer has recomended 50:1. Suppose the mix would come down to how long are you going to keep the boat.

Next boat and trailer

cheers

rojac

[Owen]

Just a bit of food for thought.
100:1 is probably driven mainly by environmental factors, however less oil = more horsepower.
Also as most motors are now injected, there is less chance of seizures from things like running out of fuel.
As for the wearing out of the motor not being of concern to the manufacturers, well the most dangerous period for a motor is when it is new. Everything is tight. SUrface imperfections have not yet worn off etc etc.
If the manufacturers thought 100:1 was in the danger zone, then they wouldn't recommend it for fear of seizures DURING the warranty period.
This is why they commonly recomend adding oil to the fuel even on injected motors during this period.
I'd be more converned about using a quality oil that supplies the required lubrication at the factory recommended level than dumping more oil in just because some mechanic thinks it may be better to run twice as much oil.
If for no other reason than it's the right thing to do for the environment.
Can't believe I said that ;D

cheers,
Owen

[winston]

Hello Rojak,
I have a CV30 Yamaha and run it at the recommended ratio of 100:1. it runs a little too rich on idle jet as it does foul the plugs after 5 minutes of trolling. The motor is four months old. I was hoping to run it this weeked and lean the idle a little.My point is even 100:1 is plenty of oil. I had a CV 40 for six years and also ran at the recommended 100:1 ratio, I did approximatley 350 hours . The head was remoned after five years and the mechanic said it still looked new. I am not a mechanic but trust the advice of Yamaha's world class engineers and designers. If they recommend 100:1 then this is best. Cheers Winston.

[Bowser]

Well I have run my 30hp 3 cylinder Yammie on 100:1 for most of the time I have had it. Of late I have bumped this up a bit because I have increased the weight and load on the motor and it is working a little harder and at higher revs. Originally the boat was a tiller steer and rarly did I get above half twist on the throtle. At this it was plenty fast enough for me. I have also always used Yammie lube and haven't had any sign of problems as yet.

Bear in mind that with fuel injected models the motor at times is running at 200:1 ratio. There are a lot of comments here that 50:1 is proven ratio, and it is on old motors. These do not have the technology of current motors and they are a bit like comparing an old holden red motor to the current crop of engines. The manufacrurer recomends the operation at 100:1 and they sell it into the US at that. Do you honestly believe they would do this in the litigation mad US if they felt that it was going to damage the motor at any time? If they did some yank would have them taken to the cleaners over it somewhere down the track, either alone or in a group action and US courts tend to pay out big time.

[billfisher]

Owen,

I don't quite understand your reasoning. I agree that the run in period is critical, but this is why the manufacturers stipulate a 25:1 ratio for the first ten hours, and 100:1 thereafter (or 50:1 in the case of Tohatsu).

Bowser, so what is different about the current crop of motors that makes them run on 100:1? And why does Tohatsu recommend 50:1. As far as I know Tohatsu has the same design with needle bearings.

[Owen]

Billfisher,
Don't feel bad about not understanding my reasoning. I just re-read it and neither do I. ;D
The point that I so clumsily tried to make was that the run-in period sets the standard for the life of the motor. Done incorrectly (regardless of oil/fuel ratio) the life of the motor and the wear rate suffer.

I'm not sure if Yamaha (the engine in question) actually does specify a higher oil/fuel ration during run-in. I did a search and can't find anything sayings so although other brands do.
However regardless of whether they do or don't, they wouldn't recommend 100:1 if it wasn't safe. The run-in is only a few hours. The warranty period is two or more years.
Engineers in this litigious (sp?) age tend to err on the safe side. They know joe public is just going to fill it up with fuel and go.

Newer engines are in fact quite different to older two strokes. Bore coating and ring technology have come a long way. So have quality oils.
The recomended ratio will have taken into account the properties of all of these factors. i.e I wouldn't do it on my Mercury, because at it's age I'm sure it has cast iron bores and chrome rings at best. We used to do it back in the 80's with our race bikes (using synthetic oils), but motor life wasn't of prime importance - horsepower was.

I would personally run more oil during run-in, but I'd be quite happy going 100:1 after that.


cheers,
Owen

[Mr__Bean]

The only time I would increase the oil would be if I felt my use of the motor was placing it under fairly constant high load conditions.

If your use of the engine is mainly low load applications, putting around with lures out, running around at part throttle, then I wouldn't contemplate more oil than the recommendation.

If however your motor is constantly run under a heavy load, then I would consider dropping back to 50 or 75 to one, based on your particular harsh operating conditions.

Additional oil at low speed/low load may end up doing more damage than good if you coke it up.

- Darren

[MyEscape]

Owen,

Just a point on the run-in for a 30hp Yamaha. I recently purchased one (a 30hpCV Yamaha), the dealer's advice was the first 2 tankfulls of fuel at 25:1 then thereafter at 100:1.

Beleive me 2 tankfulls (at 24 litres per tank = 48 litres through a little 30hp = quite a few hours of running) is a fairly good run-in period.

After that 100:1, and also because on a 4.15m tinny it's not working so hard(note Mr Bean's comment about working hard), would seem fine following the manufacturer's advice.

Steve

[billfisher]

So far no one can tell me why Tohatsu has a 50:1 ratio. I don't think they are behind the others in engine design.
The load the engine is under is an important consideration. As I drive around near full throttle most of the time I am more happy with a 50:1 ratio.
Obviously 100:1 will not rapidly destroy you engine, but it will (so I have been told) lead to more wear and shorter engine life. This will only manifest itself when the engine hours get high. No one will have any comeback with the manufacturer when their motor gives up after 8 or 10 years even in litigious US. The main worry over there for outboard makers is environmental concerns and this is why they have gone for 100:1.

[Owen]

Steve,
Was the 25:1 thing just the dealers advice?
Or was it factory mandated? i.e. Written in your owners manual.

Billfisher,
I don't really have an arguement that can be applied broadly against what you have said. In fact I'm not really trying to argue anything at all - just offering a different view I suppose.

However 100:1 will only reduce engine life if the oil in question does not produce adequate lubrication at that ratio. Any extra after that does nothing more than contribute to environmental concerns and wasteage. I can see your point regarding comeback on the manufacturer after many years of service, but on the other hand it would be commercial suicide to design an engine that in the eyes of the consumer had a limited service life. Engine manufacturers would be planning to be around selling engines longer than that IMHO.
If your motor says use 50:1 than do so. Mine does, and I do so. It May well be fine with less oil, but I'm not about to experiment or second guess the designer.
I just find it odd that fisho's claim to be friends of the environment on one hand and then on the other hand, think nothing of adding extra oil to our waterways for no other reason than the logic that if some is good, more must be better (unburnt oil is exhausted into the water).

cheers,
Owen

[billfisher]

Owen,

A premix motor will always waste some oil because you are stuck with a single ratio which has got to cover from idle to full throttle, ie the premix ratio is a compromise. Nearly all the larger (hence potentially more polluting) motors have variable oil ratios which only add the extra oil when its really needed, hence the ratio can vary from 50:1 to 200:1 according to the revs.

[rojac]

But how many engine hours are we talking about, 8-10 years for the motor, have to weight up if following manufacturers specs is going to seriously reduce the longevity of the motor given that its overall cost is not that great.

Would the quality of the oil ie synthetic make much difference ( they say it all comes out of the same tank ;))

cheers

rojac

[stunnedmullet]

Gidday Rojac
I purchased a 30hp cv yammy last year and although the manual states 100:1 , due to the high humidity and extreme conditions in Nth Qld it was recommended to run it on 50:1 My outboard mechanic(not associated with the dealer) agreed this was okay.
Initially I was told to run 2 tanks of 25:1 in it and then 50:1 after that. I have had no problem running a 4.2 m quintrex explorer with a full crew.
A cv 30hp yammy will idle rough at continuos low speeds because that is there nature. If you want something that runs smooth at idle for long periods then buy a 3cyl trible carby or a 4 stroke. Horse for courses. Should only be using TCW-3 rated oil for any premix outboard by the way. That is in any manual.
Good Luck with your purchase.
Damo

[billfisher]

The extra oil is a big plus when the motor is used infrequently too. You have twice as much left coating the cylinders and pistons with the 50:1 ratio.

[MyEscape]

Owen,

The handbook for the 30hp CV Yamaha states 25:1 for the first 10 hours, 100:1 thereafter.

Stated the same by the dealer, Reef Marine in Mackay, albeit more simply as first 2 tank fulls of fuel. Probably as a 30hp doesn't have an hour meter.



Steve

[timddo]

Just get a 4 stroke and you got no problems with oils, just pour in fuel and off you go. yamaha have oil injected motors for 30plus, so it mixes itself.