oil volume

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Manxman
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oil volume

Post by Manxman »

My mate and I are putting together B25 and a 441 trials bikes and we are wondering if we can reduce the size of the oil tanks, what would be the general thought for a minimum oil volume required .
thanks
eebtr7
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Re: oil volume

Post by eebtr7 »

I would not reduce the oil tank capacity...ever. The two quarts plus a little extra is just on the verge of being too little. If you wish to reduce the weight of the machine, try going on diet to lose about 25 pounds of blubber. Yes, I hear you...I'm trying to lose about 100 pounds, myself.
Manxman
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Re: oil volume

Post by Manxman »

Lol...thanks

I will make some streamlined tanks then,with the same volume ...if I lose 25lbs I wont be able to kick these buggers over...
Momus
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Re: oil volume

Post by Momus »

Manxman wrote: Mon Oct 21, 2019 6:58 pm My mate and I are putting together B25 and a 441 trials bikes and we are wondering if we can reduce the size of the oil tanks, what would be the general thought for a minimum oil volume required .
thanks
This topic is of interest to me as well.

I wonder if anyone has any experience of running their oil tanks low- deliberately or other wise- and if they suffered?

2 quarts plus- 1.9 litres - as recommended by eebtr7, with no reason or reference, in a little, low powered trials bike seems excessive and a good area to look at weight and tank bulk saving.

You would think that a litre properly managed would be plenty. On a commuter or trail bike that used a bit, 2 litres might be useful.

Some modern 250 four stroke MX bikes run well under a litre; 600 to 800 ml. 500 ml might be enough in a trials B25.
If you love it, lube it.
Jeff K
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Re: oil volume

Post by Jeff K »

Be careful that you also do not lose some cooling capacity . Less oil and smaller tank = less fluid to help cool the engine and less surface area. Trials bikes tend to go slow so they do not have the benefit of speed induced airflow across the engine.
Jeff
Mr Mike
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Re: oil volume

Post by Mr Mike »

Two considerations here, both of which have been touched on. (1) If the volume of oil is reduced to say 1/2 a quart, the contaminants generated in normal operation will degrade the oil at a significantly faster rate than with 2 quarts which means more oil changes. (2) the nice thing about dry sumps is the oil is stored out of the crankcase and cools much better. I have measured returning oil temp and all seems well even after strong runs. Of all the issues with these old bikes, I don't think the oil tank is one of them.

Mr Mike
beat
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Re: oil volume

Post by beat »

The Cheney fraim contents very little over 1 Liter only.

it is enough when engine is really healthy, - with some blow by and riding longer trips ( oil consumption 0.5 L / 1 000 km) it is definitely to small.

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Momus
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Re: oil volume

Post by Momus »

Mr Mike wrote: Fri May 01, 2020 1:54 pm Two considerations here, both of which have been touched on. (1) If the volume of oil is reduced to say 1/2 a quart, the contaminants generated in normal operation will degrade the oil at a significantly faster rate than with 2 quarts which means more oil changes. (2) the nice thing about dry sumps is the oil is stored out of the crankcase and cools much better. I have measured returning oil temp and all seems well even after strong runs. Of all the issues with these old bikes, I don't think the oil tank is one of them.

Mr Mike
We are talking about a trials bike here so very easy, short duty cycle. If 600 ml is satisfactory for a 40 plus hp MXer it should be ok in a trials bike.
As far as oil temps go really the only one that matters is the temp of the oil coming out of the engine before it is cooled?
If you love it, lube it.
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kommando
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Re: oil volume

Post by kommando »

The temp going back to the tank is useful but not the whole story.

http://www.nortons.dk/doc/lubricants.pdf

In summary if you have a hot spot in an engine such as next to the exhaust valve then oil that passes through this can be degraded quickly and it never recovers. This may be only a small amount but over a short time it could kill all your oil as more goes past the hot spot.
Mr Mike
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Re: oil volume

Post by Mr Mike »

For trials, MX and other special purpose bikes a smaller quantity of oil may be fine. For regular motor bikes I think the tanks holding around two liters are appropriate. I never liked the OIF concept. I wonder how much weight you add to the frame so it can carry oil when you compare it to a tin oil tank. Also did you ever try and clean the sludge out of an OIF? Another issue I have is with the radical weight reduction programs for special purpose bikes. I understand the benefit for rotating mass like wheels, cranks flywheels etc, but going to great pains to shed a few ounces of stationary mass is crazy...just skip that extra biscuit at breakfast or visit the restroom before you get on the bike.

Despite all the pros and cons of these old bikes and their lack of competitiveness with modern bikes, I still love'em and I can spend days and weeks on end tinkering and rebuilding them to make them as good as they can be. These old bikes are kinda like that first girl you ever got in the back seat of a car with.

Mr Mike
Momus
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Re: oil volume

Post by Momus »

Mr Mike wrote: Thu May 07, 2020 3:31 pm For trials, MX and other special purpose bikes a smaller quantity of oil may be fine. For regular motor bikes I think the tanks holding around two liters are appropriate. I never liked the OIF concept. I wonder how much weight you add to the frame so it can carry oil when you compare it to a tin oil tank. Also did you ever try and clean the sludge out of an OIF? Another issue I have is with the radical weight reduction programs for special purpose bikes. I understand the benefit for rotating mass like wheels, cranks flywheels etc, but going to great pains to shed a few ounces of stationary mass is crazy...just skip that extra biscuit at breakfast or visit the restroom before you get on the bike.

Despite all the pros and cons of these old bikes and their lack of competitiveness with modern bikes, I still love'em and I can spend days and weeks on end tinkering and rebuilding them to make them as good as they can be. These old bikes are kinda like that first girl you ever got in the back seat of a car with.

Mr Mike
I tend to agree that 2 litres in the tank or sump is about right for an air cooled motorbike that may have oil control issues.

The siren call for less oil in competition is akin to your backseat girl friend though. Less oil, smaller tank, more lighter packaging opportunities and a couple of pounds saved is not always easy. I've no love for BSA's version of OIF: it was designed by the cleaner after a night on the turps.
The concept of one component doing 2 jobs is sound; the whole thing could have been executed very cleanly by enlarging the front down tube.
If you love it, lube it.
Momus
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Re: oil volume

Post by Momus »

kommando wrote: Thu May 07, 2020 1:33 pm The temp going back to the tank is useful but not the whole story.

http://www.nortons.dk/doc/lubricants.pdf

In summary if you have a hot spot in an engine such as next to the exhaust valve then oil that passes through this can be degraded quickly and it never recovers. This may be only a small amount but over a short time it could kill all your oil as more goes past the hot spot.
Is there somewhere this local overheating happens on a B50?
If you love it, lube it.
Jeff K
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Re: oil volume

Post by Jeff K »

kommando wrote: Thu May 07, 2020 1:33 pm The temp going back to the tank is useful but not the whole story.

http://www.nortons.dk/doc/lubricants.pdf

In summary if you have a hot spot in an engine such as next to the exhaust valve then oil that passes through this can be degraded quickly and it never recovers. This may be only a small amount but over a short time it could kill all your oil as more goes past the hot spot.
This is why back in the day when I rode the bigger bikes hard. I used to go to the distributor and purchase a case or two of Pennzoil aircraft 50w, great for hot summer days and it was design for air cooled piston engines. I will show my age by adding that I still have a few "cans" of it on the shelf.
Jeff
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Re: oil volume

Post by twinshocker »

Momus wrote: Fri May 01, 2020 12:01 am .........
Some modern 250 four stroke MX bikes run well under a litre; 600 to 800 ml. 500 ml might be enough in a trials B25.
I don´t know if this is somethimg to compare. first the 250-fourstroke is watercooled which means the temperature is way better spread over the engine , not so much hot spots.

second, the oil circuit is different, These engines pump large amounts of oil into the cylinder head, while the B50 cylinderhead lubrication is a joke in my opinion. They learned over the years that the oil in the head is not only for lubrication but you can get also a significant amount of heat away from there via the oil.
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