How much 2 stroke oil

[kingsknight]

Alright chaps,

A friend of me asked if his '02 RS125 is drinking to much 2 stroke oil. He said it drinks about 1L of 2-stroke oill every 200-250miles. Sounds a little much to me?
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TS50 (sold) NS125F (sold) NSR125R-K (write off after 2 crashes) CG125 (nicked) XR125L-3 (Sold )-: ) DR125SM '11 (sold yay) XL125V '12 (In love with this bike) XT600E '04 (fun on the dirt)

[cb1rocket]

My mate's old rs125 wasn't far off that mark. They do smoke like hell too!

[kingsknight]

yeah his does smoke a lot. also burns engine oil he said! It had an engine rebuild not so long ago as well. about 3000 miles or so ago. He has owned it for about 5 years and said it's always been the same!

2 strokes are not cheap to run lol
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TS50 (sold) NS125F (sold) NSR125R-K (write off after 2 crashes) CG125 (nicked) XR125L-3 (Sold )-: ) DR125SM '11 (sold yay) XL125V '12 (In love with this bike) XT600E '04 (fun on the dirt)

[truslack]

250 miles, 30mpg (though that's possibly a bit low for an RS125?) gives 8.3 gallons or 37.7 litres of petrol.

1 litre of oil to 37.7 petrol is obviously a 38(ish):1 ratio (obviously dropping a bit if you lower its fuel consumption). This should average out about right.

Please feel free to correct me if I'm wrong, but it doesn't seem to be far off to me.
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Current: Suzuki RG 125 Gamma, Honda H100, Triumph Tiger 800XC, Suzuki SV650 (minitwin)

[kingsknight]

oh it does drink fuel! He said the best he has ever got is around 40mpg and that was riding very carefully!
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TS50 (sold) NS125F (sold) NSR125R-K (write off after 2 crashes) CG125 (nicked) XR125L-3 (Sold )-: ) DR125SM '11 (sold yay) XL125V '12 (In love with this bike) XT600E '04 (fun on the dirt)

[truslack]

If you use the average as 35mpg then, it works out at roughly a 32:1 oil ratio, again, not too far off normal as far as I'm aware.
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Current: Suzuki RG 125 Gamma, Honda H100, Triumph Tiger 800XC, Suzuki SV650 (minitwin)

[cb1rocket]

commuter 2 strokers are fine and good on fuel and oil, its these highly tuned sports rep that break your wallet.

I went to the isle of wright with my mate while I was on my SV650 and he had to fill up 3 times while I did the whole trip on 1 and a half tanks of fuel!

We were constantly pulling over/stopping cos there was problems non stop! And more just filling up and putting oil in!

[herulach]

[cb1rocket]

[Kickstart]

Hi

That sounds pretty hideous. Not sure on the RS (never measured it) but it's not bad on oil (old early AF1 was great on oil, and had a 1.8 litre oil tank). The manual lists the oil mix as between 0.9% and 2%.

I would also expect way more than 40mpg. When I measured and recorded mine it averaged about 55mpg over quite a few thousand miles, but that is mainly when used out of town (but a fair bit of flat out riding). Ridden with great care during the fuel strikes it managed 74.5mpg (but it really was horrible to ride like that).

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[truslack]

[Kickstart]

Hi

50:1 isn't unusual, and having a pump it can run leaner when not required (hence down to over 100:1).

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[truslack]

I run my H100 at 20ish:1
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Current: Suzuki RG 125 Gamma, Honda H100, Triumph Tiger 800XC, Suzuki SV650 (minitwin)

[Kickstart]

Hi

Wouldn't expect it to need anything like that rich a mix of 2 squeak oil.

Honda manual says to use between 25:1 and 50:1 premix to run the engine when bleeding the oil pump. At 1300rpm idle speed the oil pump gives a maximum of 0.364cc per minute. Assuming that the amount rises directly in relation to rpm then that is 134cc an hour at 8000rpm. Assume 90mpg on petrol at 8k and 60mph (not exact but close enough) and that is 3 litres of fuel used in an hour. Based on that the Honda pump gives 22:1 at the very most (shut the throttle and the oil delivery drops by about 80%).

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Teflon-Mike]

for 'pre-mix' the rough reckoner was that low-tuned motors like strimmers or lawn-mowers would run a thicker mix, down around 25:1 or lower, becouse they dont suck fuel in so fast, you need to put more oil in it so that the bearings get enough lube.
On higher perfromance engines, they are using a lot more petrol, so they dont need as much oil in it, and thinner mixes up in the region of around 50:1 or thinner are more common.
35:1 is a rough-reckoner starting point for a 'typical' air-cooled road-going two-stroke, like a YB100.

Auto-lube is a different matter, and can get complicated. Pump meters the oil into the engine, but there's a meter-valve worked by the throttle cable.

Often this actually DECREASES oil-flow, rather than increases it.

Pump delivers measured volume of oil per revolution, and geared to the crank, that means so much per rev or cycle.

And the throttle adjustment will lean off the oil-feed as loads increase, to compensate for the fact that the pump is probably geared to over-oil at low revs when there's little flow through the crank-cases to wash lube into bearings.

Ie, giving the thicker effective mix of a low-speed engine an part throttle and lower speeds, the thiner mix a higher output engine needs at higher rpm.

So..... if the cable has never been adjusted and has gone slack...... likely its not leaning off the oil feed as much for wider throttle openings.......
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[Kickstart]

Hi

Not sure on leaning off the oil (although might) but likely not richening it up at anything like the rate the fuel supply increases as the throttle is opened wide.

The Honda H100 workshop manual unusually has a graph of oil supply to control lever angle (ie, the lever on the pump) at 1300rpm. With the lever angle of zero it passes 0.065~0.073cc per minute. This increases at a constant rate up to 0.338~0.364cc per minute at 39 degrees of control lever angle. After that the amount doesn't increase any more.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Teflon-Mike]

[truslack]

I knew 20:1 was rich, but I don't like oil pumps and i'd rather it ran too oily.

I did however think a higher tuned bike would need a higher ratio of oil, so thanks for explaining that.
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Current: Suzuki RG 125 Gamma, Honda H100, Triumph Tiger 800XC, Suzuki SV650 (minitwin)

[Kickstart]

[Cheeseybeaner]

[HD]

Err.

My bike is very oily so I slackened off the cable a bit. Would it be better to actually tighten it then?

EDIT: I didnt actually slacken it I more pulled it out more so there was less cable actually pulling so I sort of did if you get me
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Rusty '02 Vito Camper + CBR600F3

[Cheeseybeaner]

[cagiva gezzer]

I used to reckon 1L per 1,000km. As above, oil consumption will depend heavily on how open the throttle is, not the revs.
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"because one stroke isnt enough and four strokes waste two"