CyberJack posted an interesting fuel can (the photos of which I have attached) It says the Imperial runs a 80:1 mix
My best assumption is that lower compression (head spacer on the imperial) means less temperature, maybe meaning the cooling fins can take care of the cooling aspect more by themselves, leaving the oil more solely for lubrication.
Also, the imperials wouldn�t see use on heavy lawn or really heavy �jungle growth� that the rotarys were often subjected to. That means an easier life, and again less heat. Not being squashed against a mower base, with a fuel tank and big dress cowl covering the engine, probably also helped keep it cool. No governor means a reasonably constant speed for most of its life, like how an outboard is often used.
The lean ratio could probably also be associated by Victa identifying their target market as more discerning than the regular rotary buyer. I guess Victa figured their potential Imperial buyers might have been a bit perturbed by mowing accompanied by something of a smoke haze, and finishing mowing reeking of 2 stroke oil. As Victa was competing with 4 stroke Atco, Qualcast, Scott-Bonnar, etc, this was probably important to them. I supposed they already had a bit of a disadvantage with noise alone.
Hi Tyler, all the points you mention regarding cooling factors are things I never pondered before. I still think 80:1 is an extraordinary departure from 25:1!! I think I would be happy with 50:1 myself.
Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!
I was surprised with my 125 edger (not low comp, but a very open area around the motor), how cool the motor is after a reasonable run (1/2 throttle max) - I could literally hold the cylinder head 5-10 minutes after turning it off. I have always run it on 25:1 - as the sticker on the tank says. I thought it was strange it said (effectively) 30:1, once I worked out there was 20 fl oz in a UK pint (not 16) - making 1/3 pint in 1 UK gal = 25:1.
Next time I start it, I will use a infrared thermometer and compare temps to a fully cowled powertorque. Might be interesting.
I would be more happy with 50:1 as well - what oil do you use? I'm currently running Penrite semi synthetic 2 stroke oil - but I will probably go full synthetic next time i need to get oil.
G'day all ... and thanks Tyler for starting a new topic. AVB's comments on 100:1 mixes in modern engines is not surprising.
My best view is that this can is not a Victa factory can. I say that because Victa's association with BP simplified matters.
Victa BP Zoom (25:1) and BP Outboard Zoom (50:1) simplied things. Most Victas ran 25:1, but Victa primary documents show 50:1 was recommended for the Victa Lightweight, Twin, Supreme and Imperial models. I have not found a reference to an 80:1 mix for Imperials in any Victa document. [See post below: I'm an idiot].
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My best assumption is that lower compression (head spacer on the imperial) means less temperature, maybe meaning the cooling fins can take care of the cooling aspect more by themselves, leaving the oil more solely for lubrication.
Yes Tyler, I feel that is very much the case ... I think, as a general rule, a lower compression ratio means a cooler running engine. I guess a leaner fuel mix was required to prevent carbon deposits in 2-strokes.
Here's the problem though ... The First Victa catalogue covering the Imperial 2-strokes was the 1973 one (The 2-stroke Imperial was introduced in late 1972 for the 1973 range).
That Booklet said this about the Imperial engine: Amazing new 2-stroke engine Up till now most reel mowers have been powered by 4-stroke engines. But this year Victa is changing all that with the introduction of a great new low-compression 125 c.c. 2-stroke engine. This engine is designed to run smoother and last longer. It also runs cooler and needs less oil. (In fact Victa recom- mends BP Outboard Zoom for this engine: a mixture with less oil).
The devil is in the detail. That the engine ran cooler because of lower compression was a byproduct of the real reason - to make the engine smoother.
Why? Well, because of the small centrifugal clutch combined with strong 2-cycle power impulses from a mid-range rpm 2-stroke. It really was a compromise design.
It is generally accepted that reel lawnmowers require less hp than their equivalent rotary designs. This is because of the scissor action, and the limitations of what can be cut (about three-quarters of the reel diameter as a general rule).
Tyler, you point this out: reels do not suffer from spike-loading that rotaries certainly do suffer.
Reels mowers can't really turn grass into lawn. They can turn lawn into better lawn.
Cheers ----------------------- Jack
p.s. a very rewarding topic. Many thanks to all contributing members here.
No harm in being wrong � we�re all trying to piece together snippets of information on machines that haven�t been made for 40 years.
I thought 80:1 was strange (but slightly familiar) as well, and did a google search on it, that same news cutting link came up. We all forget stuff - I sometimes can�t remember what I did a week ago, let alone 7 months ago. I only just managed to find my soldering iron after 3 months (in a box of air filters and line trimmer cord no less).
Regarding the Imperial, seeing as how this requirement seems to have changed mid-way through Imperial production, maybe the lean mix was a marketing idea. As Victa was marketing their reel mower to �the fine lawn enthusiast,� maybe they were hoping this would bring them more in line with the 4 stroke offerings of other manufacturers.
80:1 not being available from the pump would (presumably) be more of an annoyance to owners of these machines � who may have been used to (with 4 strokes) just putting fuel in, checking the oil level occasionally and taking it to a mower shop for an oil change each year. Possibly their local BP servo would put a mix of BP zoom outboard and straight petrol (to make overall 80:1) in the mower can for Imperial owners.
I hadn�t considered the centrifugal clutch aspect � or the surging that might result. The engineers must have had a lot of problems to overcome with this project.
I have read many good things about reel mowers. I�ve got one as a project (pretty slow going) � from what I can tell, it�s a late 50�s or early 60s Qualcast Commodore � found it on the curbside collection. No rust fortunately.
No doubt I will be posting some questions when I get around to adjustments, and other things
Hi All, did anyone read this can or just look,yeah I'm just kidding.
This fuel can is obviously wrong.
It says BP Zoom outboard we know that is 50:1 or 100 ml : 5 litres
It says 80:1 but then says that is the equivalent of 57ml of oil with 5 litres of fuel but 80:1 is the equivalent of 62.5 ml of oil with 5 litres of fuel
If we used 57 ml of oil with 5 litres of fuel the ratio would be 87.71929825 : 1
The g4 carby was never used on the Imperial was it?
Just thinking out loud here, but maybe a g4 would be better than a sliding vane g3 when it comes to fuel (vaporisation?). EDIT - G3 was a butterfly carb, not a sliding vane - im thinking of the 3L, etc.
Maxwestern - you had me worried there for a second
I hadn't noticed that. Maybe whomever worked out the mixture on the can got a bit muddled up in the metric/imperial conversions Might stem from the fact one UK gallon is actually 4.54 L not 5 L
G'day folks, Yep, we've noticed the anomaly of the Imperial mower fuel mix ratio [as given on the cans] before, here at ODK.
My own thoughts were, that this was due to Victa doing a 'partial conversion' from Imperial to Metric units, with some rounding up involved.
Two fluid ounces [which is 56.6mL] of oil to one Imperial gallon [160 fl oz] of petrol would give an 80:1 mix ratio. As maxwestern has calculated, 57mL to 5L gives 87.7:1 mix, and 62.5mL would be needed for 80:1.
Maybe Victa had concluded that, given the accuracy of the measuring vessels likely to be used, any mix between 50:1 and ~90:1 would be OK!
Originally Posted by Tyler
80:1 not being available from the pump would (presumably) be more of an annoyance to owners of these machines � who may have been used to (with 4 strokes) just putting fuel in, checking the oil level occasionally and taking it to a mower shop for an oil change each year. Possibly their local BP servo would put a mix of BP zoom outboard and straight petrol (to make overall 80:1) in the mower can for Imperial owners.
I wouldn't think that any servo, even back then, would bother with such fiddling around. They'd just fill the can with Zoom Outboard - as it says on the tin!
Zoom Outboard was then dispensed either from a bowser, or by measuring jug [1 gallon size, or later on 5L] from a 200L tap drum - depending on the servo's sales volume of the product. Bowsers for Zoom 50 were common at boat marinas.
Mower/OPE shops in those days would only have Zoom 25 available as premixed fuel, but would have 2-stroke oils in stock. The 200L tap drum setup was what these shops used, and the fuel was mixed in the drum from Zoom Concentrate and regular petrol delivered from a tanker truck.
Cheers, Gadge
"ODK Mods can explain it to you, but they can't understand it for you..."
"Crazy can be medicated, ignorance can be educated - but there is no cure for stupid..."
I remember when we lived on the farm down in Gippsland and my parents bought a toecutter probably early sixties. My father got a 44 gal of petrol, added oil, rolled it around and that drum of fuel went through that toecutter over a couple of years as we had no other 2 stroke machine there. No ethanol problems back then.
Wow Norm sounds like you would have had use for all the mowers you've now got, back then. I used to be wary of loaning my collection to my father a decade ago because he would bring back the mower with worn out blades from hitting concrete and what not, now I wish he was still doing mowing jobs for people just to put them to use. Who cares about a pair of blades?
Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!
Hi maxwestern, That's impressive. Where do you get the kit from and how do you fill it up? I have always run my cars on gas. That motor should last longer and stay cleaner internally.
Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!
When it comes to 2 cycle equipment that I have use I have notice that the fuel oils have come a long way since I was a kid. When I start using chainsaw about 40+ years they ran on 16:1 mix and now days it is come the run at 50:1. Some the older saw actual used SAE30 weight motor oil in the fuel. Now with the synthetic oils those older saws that ran 16:1 are now running just fine at 50:1 mix ratio. A third of what I used 40+ yrs ago. I would not put to a test by trying at 100:1 on equipment that has today's spec of 50:1 but that may just me being overly cautious with my customer's equipment. It would take some nerves for me to try it even on my own equipment.
I just don't like tearing up good equipment just to experiment but I do have what I consider throwaways that I could experiment on and might try this Fall. Easy enough to mix at 100:1 as I buy the 1 gallon mix packages so I could put one pack into two gallons. 2.6 US ounces (5 tablespoons + 1 teaspoon) to 2 US gallons would 100:1. I actually use 5+2 as some oil always sticks to the measuring spoons or just used a premeasured package.
I have however seen where customer accidentally ran a 80:1 mix in his Stihl FS90 trimmer and it cooked the PNC the first day. He tried blaming it on me as I just installed a new carburetor on the trimmer but I knew it was properly tuned and had left the shop with the correct fuel mix. I empty his mix in one clear jar and put my 50:1 in another same jar. It stood out like a sore thumb that he had the wrong mix. Now of course Stihl always run rich on the fuel mixture so should have not cause it so quickly. I kinda suspected he straight fueled it and simply dump his mix in later trying to cover his skin.
It kinda strange using the new ratios as I remember I was continuously burning up PNCs back when I was using chainsaws and I know I carefully mix the fuel. I did however cut several pickup loads of firewood per day for most my Summer school vacation to heat the home and to sell. I usually got a about a month on one set, Matter the dealer parts department was getting pissed at me for doing so even though I was paying the new parts at whatever they were asking for the parts.
I run my line trimmers on 25:1 even though the sticker recommends 50:1,I use a cheap 2 stroke oil and retune the carb for 25:1 ,I think they last longer that way .
Hi Mowerfreak ,The mower is a total Bitsa ,I made it from rubbish,the gas lines are from old barbeques ,the four gas line connectors are from a car wreckers,the gas regulator was a air compressor regulator,I put the barbeque bottle in a car battery box with the gas tank mounting cradle made from old right angle steel from an old bed.
All up I did not spend over $10 for the complete mower with the gas conversion.
I have a forklift gas tank that I can fill at the service station and then I just transfer the gas from the larger tank into the smaller BBQ tank.
I think you're right Gadge � even back then the servo probably wouldn�t have stuffed around with trying to get an 80:1 mix.
I wonder how many Imperials were actually run on 80:1; I would think some owners would be uncomfortable running such a lean mix, and the others probably wouldn�t want to be mixing fuels � instead preferring to put in whatever they could get premixed.
Maxwestern � that mower is impressive. I have heard of trimmers in America being propane powered, hadn�t heard about mowers though (although I hadn�t really looked). How difficult was the conversion?
In the past 16-18 months, I have bought 2 line trimmers from the tip (Homelite half cranks admittedly) that looked brand new. Their owners obviously threw them out after trying to run them on straight � oil. Literally 1/2 tank of straight oil in each of them. The same tip usually has around 15 trimmers that have been straight fueled.
- at least in how the Imperial was introduced.
