ET: Engine (Twin) oil holes in Crank pin?

[Vincent Brake]

Anyway, back to pin holes!! or is it a hole in a pin...

How would a Harley crank do that positioning?
or a KTM, (if they have roller cages?)

some one out here? in the know?

 

[Speedtwin]

I believe the earlier harley oil way is at 30 degrees before TDC, S and S use a slightly different set up maybe worth checking that they seem to know what they are at....

 

[oexing]

There is a good reason to have the TWO oil holes per conrod at 90 degrees past TDC, but I don´t see the idea to have them at 30 degrees, before or after TDC. Anyway, the oil enters the crankpin at the timing side end and when you got one hole each at exactly TDC it will be centrifuged out at the nearest hole, at the t.s. conrod hole. So I say the d.s. conrod bearing will get less oil then.
Simple correction is to have the holes at 90 degrees past TDC, well, before TDC would work too. But I like the theory that when revving/accelerating the engine up the oil level in the crankpin will shift a bit for the 90 degree past TDC position, so you get another extra cc into the bearings - not so with holes at 90 degrees before TDC. And when having the holes at 90 degrees the bore in the crankpin will fill up at half diameter till it can reach the holes to exit into the bearings. So centrifugal forces will have the oil in the crankpin form a perfect level all along in there and lubrication will be same for both conrods from this effect.
In my engines I do TWO oil holes per conrod, positioned just outside of roller or needle tracks, left and right. So with a 20 mm bearing you drill them at 9mm from center line, no factor when having holes at 90 degrees past TDC at highest load positions as needle tracks don´t reach holes.
I did central holes in my crankpins about 14 or 16mm i.d. and finally plugged to hold press fits in the crankshaft assembly , 40 mm pin in high tensile crank webs from 1.6580 30CrNiMo8. I have never found case hardened cranks , only high tensile, and provided all is well you don´t need to add hardened washers at both sides of conrods as basically there is no side load from bearings - well, when all bearing faces are machined perfectly parallel, no taper acceptable here and 0.01mm play within bearings minimum !

Vic

 

[DucATIRadeon]

ktm 690 and Yamaha raptor (700cc), and JAWA 889 engines have the holes at 90degrees from TDC in the advance of TDC so the oil gets there before the combustion pressure exerts its force onto the rods.
I do agree with the philosophy at 90 degrees there is an oil bath and indeed all the holes get pretty much the same quantity of oil.
the Ducati bevels had the oil holes just past TDC to oil them on the actual power stroke. and the holes were in the middle of the bearing track(s).

note: I mentioned 30 degrees before as an example, not actual degrees! my bad if that put you off!

what I do miss, tbh, is a conversion to plain bearing bigends like the older Royal Enfield had them (and the latest KTM 690R and smaller 390 engines!); I suppose until there is a proper oil pump that generates sufficient pressure (more than flow!) that's out of the question, as then it doesn't really matter where the oil holes would be (aquaplaning effect so no contact between the running surfaces).

the crankshaft in above picture has mainshafts and webs from 1 piece? if so that's superior to the existing design and stiffer too! ducati bevels (singel and twins) and modern 4T single bangers with needle bearings have this too and a lot simpler to align/true during/after pressing together.
just my opinion...

 

[Vincent Brake]

so holes in the PIN.:
upon questions put elswhere, they came up with + 45 degree from 12H. seen from timing side. Thanx KTM
Further a Very good remark to put 2 holes to the side of the needles (easy as INA has 16mm wide, and cage20mm) thanx VIC.
Next to devide the oil evenly over the pin, i made a central drill of 3,2 mm, and a 45 degree drill 3,2mmfacing outwards centrally towards a axial drill 3,2mm placed 8 mm under the 4x 1,0mm oil drills to the bearing.
the central drill stops under the middle big washer of 7 mm wide, (plugged).
So the oil is now evenly over both bearings. many Thanx to Peter!!! for the idea.

Picture ahum, downside up.....

 

[oexing]

Vincent,
that looks like a laborious job, small drillings at that length. But should work certainly as we do not expect to have a lot of debris in there with paper filter fitted.
My idea was roughly inspired by the Earles BMW twins, just a big blind hole in the pin, ending ca. 10mm from the other end, diameter ca. 14-16 mm and finally plugged with hardened threaded plug. I place the 4 drillings at 90 degrees past TDC, so late after crank rotation past TDC. My theory is when you accelerate the engine, oil will be pushed towards the holes from a levelled position in constant speed. Normal level at constant engine speed should be exactly up to the 4 drillings, even when the oil feed into the crankpin is from one side. Imagine the crank at 4000 rpm, feed from one side will NOT produce an uneven oil level higher on the feed side , seen along the total length of the 14 mm bore. So my belief is oil will feed into the two needle bearings evenly with holes at 90 degrees past TDC. - And easy to machine as well, cleaning later could be done but who will ?
Look at my first photo, you see the feed hole at bottom left side and 4 small holes ca. 1.5mm at top , 90 degrees past TDC. So looking at the crank with fitted pin the rotation would be clockwise seen from timing side end.
Four holes at 45 degrees should work as well but with a big central hole of 14-16 mm you´d have more oil in it filling up to the 4 holes in operation when they are positioned at 90 degrees past TDC. Effectively you´d have a centrifugal oil filter in there too - until debris has filled up to the 4 small holes after some time of road use. From then oil will enter conrods unfiltered nevertheless.
Same cannot be done with standard crankpins exactly like here as the central hole has to be less than 14 mm , maybe just 6 - 8 mm ? But basically the 90 degrees position is possible as well, just less reservoir inside the crankpin.
Now I am waiting for comments about my theories - or criticisms ?

Vic

 

[DucATIRadeon]

Now I am waiting for comments about my theories - or criticisms ?

Vic
View attachment 59707

View attachment 59708

bloody brilliant looking kit you have there, Vic!
ticks all the boxes I have in mind: one-piece crankpin and web (much improved strength and easier to align when pressing together), modern row needle in cage bigend bearing, are those billet aluminium conrods, I hope with a hardened sleeve?

still interested to see if anyone with an extra crankshaft and conrods is willing to play with plain bearing (floating bush) bigends like the Royal Enfield Bullets had with feeble oil pumps...they lasted almost forever.

 

[oexing]

Nooo, no alu conrods ! They are very high tensile case hardening steel, no extra bearing bush pressed in. I know about Enfield rotating conrod bush but prefer the needle bearings, I like the nice precision jobs - well, a professional defect possibly, toolmaker, you know . . .
They are a bit Carillo, a bit Manx inspired, funnily same weight like Vincent standard within 5 gr. Honestly, I did not calculate this, would not have the brains for this . . .

Vic

 

[DucATIRadeon]

you wouldn't need to calculate the weight, just press a button...

but coming back to the pin holes: in the drawing there are 4 holes of 1,2mm dia to "spread" the oil evenly to both bigends.
lets define the engine as running.
the 2 inner holes will get the most oil (closes to the central feed hole), and what's left, or can't get through fast enough, will eventually go to the sides.
if possible: mechanically speaking there is no difference as the hole(s) are there anyway, would the M4 grub screws in the oil gallery be placed much closer to the outer 2 holes the oil goes "quicker" to the sides, AND you eliminate a potential (unintended) sludge trap.
another thing: the 1,2mm holes are rather small, especially if the oil is "cold". perhaps the centrifugal force will assist in pushing it through the hole(s).

another thought for simpler machining:
you have a machining arsenal at your disposal: make the central gallery as you have it there upto the the outer most hole, and drill the 4 holes radially such that they coincide at your 45degree position. you will need to make a small spotface (or center point) first to avoid the drill bending away on round surface, and there is ample space to do that from your description.
the hole furthest away from the oil feed (or at the end of the central oil gallery) will need to the smallest, the hole closest to the feed the largest.
just an idea...
flow characteristics

 

[Vincent Brake]

Thnx Mr Ducati and Vic.

Now motogiro time.
Look it up on my pc later.