Crank Pin oil Holes

[graeme]

I'm in need of a new crank pin and I have a question,
I have a 450 that has had a Honda XL500 rod for many years without any problems.
When the engine was built many years ago Ducati rod kits were hard to get so I used a Honda rod and bearing and had a stepped crank pin made.
It would seem that the pin hardening wasn't hard enough or deep enough and has recently failed. (with the usual hard face giong throught the engine.)
I am going to use another Honda rod and bearing and have another crank pin made. From a different source this time.
The Ducati pin has 2 oil holes to lubricate the roller bearing, but the Honda pin has only 1 hole. The pin that failed had 2 holes same as a Ducati pin.
As I'm using a Honda Rod and Bearing is there any advantage or disadvantage to having 1 or 2 oil feed holes?

The crank has been balanced to suit the Honda rod.

Graeme

[Jordan]

This would be a good question to ask at mc-engine@yahoogroups.com
There are knowledgeable and helpful people there (as here) who are particularly concerned with motorbike engine design issues.

Jordan

[joe46ho]

Hopefully Eldert sees this post and replies, if not you could p.m. him, that is the first person I would ask...

Joe

[DewCatTea-Bob]

By: graeme...
" The Ducati pin has 2 oil holes to lubricate the roller bearing, but the Honda pin has only 1 hole.
As I'm using a Honda Rod and Bearing is there any advantage or disadvantage to having 1 or 2 oil feed holes? "

____ I wonder how the Honda bearing-setup may differ at all from the original 450's ?
__ Anyhow, I'm no expert on such stuff but I'd think that at least two holes would be better because, it's not so much lubrication as it is heat-removal that the flow of oil is expected to perform, so as to save the bearing-setup from excessive/destructive heat build-up !
You didn't mention how the sizes of the original holes compare to the Honda's one hole, is it any larger ? _ Cuz if not, then your bearing-setup no-doubt didn't pass as much oil as stock.
__ Don't trust merely MY opinion alone but, I'd suggest three (equally spaced) holes that're slightly smaller than the original two. _ Or perhaps all three even being the SAME size if you 'race' your 450,, but in that case, a higher-volume oil-pump should then also be employed along-with.
____ I agree that Eldert would be good to consult about ALL this related stuff !


Hopeful-Cheers,
-Bob

[Eldert]

come on guys you give me to much credit

i am by no means a expert on this subject but i can share my experiences

i used a lot of Yamaha crankpins on cranks that where stroked or destroked . i used XT 500 and TT 600 pins
the TT 600 pin has a larger hole in it and is about 66 grams lighter . both have one 2 mm oilinghole in them

the placing of the oilinghole matters to . dont drill a oilinghole at the 12o clock position . the hole will be clogged in no time
due to the centrifugal forces flinging the sludge to the outside ( upperside ) of the pin . not all the sludge get cought by the
sludgetrap . the Yamaha pins have the oiling hole at the 9 or 3o clock position
never had any problems with both type of pins .

if i would have some pins made i would drill 2 oilingholes at 10 and 2o clock positions or 9 and 3o clock

Bob mentions getting the heath out . this could be done by giving the rod enough side clearance so the oil can get out easy
and get replaced by fresh oil . i use 0.4 mm as a minimum for sideclearance ( axial play )
if you have a stepped pin dont go overboard on the press to get the desired sideclerance . sometimes the radius in the flywheel is differend as the radius on the pin . if you keep on pressing thats a hell of a stressraiser , no square side on a Ducati crank . if there is to much stress in the pin it can break

Eldert

[graeme]

Thank you for answering my question.
The Honda pin has 1 large hole (2mm? I haven't measured it) It also gets fed from the end so the hole can go anywhere it is pressed into the crank.
The crank pin I had made had 2 holes at 3 and 9 o'clock same as the original Ducati pin.
I'll have the new pin made the same as the failed one, except with better hardening. I have the chance to have a second pin hardened at the same time and tested for hardness before the #1 pin is ground.
I'll take all your recomendations thank you all.
And a bigger capacity oil pump is on the way as the original is part of the carnage list.
Here's a couple of pictures,,,



Etc. Etc,,,,,,,,

Graeme

[DewCatTea-Bob]

By: Eldert...
"the placing of the oilinghole matters to . dont drill a oilinghole at the 12o clock position . the hole will be clogged in no time
due to the centrifugal forces flinging the sludge to the outside ( upperside ) of the pin . "

____ Now I wouldn't be surprised to get info like that from an "expert" in the field,
as I-myself wouldn't have had any expectations of a 2mm oil-hole ever getting plugged-up (under normally expected conditions), even on the centrifugally-forced side !
So that seems to me to be expert-advice.


" if i would have some pins made i would drill 2 oilingholes at 10 and 2o clock "

____ I still like the idea of three holes, and to make it sensibly MY-own idea, I'd suggest two 1.5mm holes (at 9:30 & 2:30 o'clock) with the third-hole being 2mm wide and located at 6-o'clock. - (Due to Eldert's point about the effect of centrifugal-force on the oil, I've now changed my thinking about the three holes being "equally spaced".)
The pair of 1.5mm holes are to be kept smaller so that the 2mm-hole (at 6-o'clock) gets a better chance to be of worthwhile use (as it would have centrifugal-force trying to starve it). _ I believe that the oil-hole located at 6-o'clock is possibly quite important to have, in the event that the other holes possibly become stuffed with sludge,, and this location is the least likely to ever become plugged-up (as centrifugal-force would draw-away any stuff that might plug it.)
The single 2mm & two 1.5mm oil-holes all combined, could provide a 6.25% increase in oil-flow capability (over a pair of 2mm-wide oil-holes).
__ I've put some good-thought into this, but still, I'd run it by a true-expert just to make sure that there's no cons which may go-along with all the pros I've considered.


" Bob mentions getting the heath out . this could be done by giving the rod enough side clearance so the oil can get out easy and get replaced by fresh oil . "

____ I don't know that that exrea-space measure would be necessary, (unless perhaps a larger oil-pump is employed), cuz I'd expect that the C-cuts on the sides of the rod's big-end should allow sufficient oil-flow, fairly well enough.
__ One thing that's of most importance though, is to keep the rod-bearings as cool as possible ! _ And I don't know of any other way to do that other than to make sure that a dense -(heavy weight) oil is kept flowing-past (by at-LEAST some minimum rate).

____ I hope & expect Eldert (or anyone else) to counter anything I've stated which is thought to possibly be incorrect thinking on my part here, (and hopefully actually agrees with most everything I've suggested & claimed here-above).


Dukaddy-DUKEs,
DCT-Bob

[double diamond]

That's a pretty wicked piston seizure. Forged piston with insufficient clearance? Possibly cause of big end failure? Matt

[graeme]

The other side of the piston (inlet side) looks like any normal piston skirt with just a few light marks from some hard face.
I think the big end shed hard face which lodged between the cylinder and piston skirt until it locked momentarily.
It didn't sound like a big end grumble, but more like a little end or a cracked ring noise up high in the cylinder.
From the postmortem the damage was done way before it started making a noise and letting me know something was wrong.
I know the moment it nipped up, I thought it had starved fuel from the old fuel taps at full throttle, backed off and it came good, but the noise was now constant. That's when it was shut down and van'd home. Still didn't sound like a big end.
The result is, I imagine, like adding 2 tablespoons of glass bead to your oil and riding 500 miles.
A magnet will somehow be added to the oil in future.
And the oil strainer only had half a dozen pieces of hard face on its outer surface. I would have removed at least a spoon full from inside the cases, and another spoon full from the crank and oil pump. Not including the spoon full from the sludge trap.
Graeme

[DewCatTea-Bob]

" The other side of the piston (inlet side) looks like any normal piston skirt with just a few light marks from some hard face.
I think the big end shed hard face which lodged between the cylinder and piston skirt until it locked momentarily.
From the postmortem the damage was done way before it started making a noise and letting me know something was wrong. "

____ Your photo didn't seem to reveal sufficient scoring-indication to have led to a solid/locked-up seizure, so I thought that perhaps most of the lighter scoring may have been due to some fuel-contaminated motor-oil.
However I've never had any experience with a crank-pin also being much damaged by thinned-out oil, (so it's probably indeed likely that the non-stock crank-pin was solely responsible for it's own short life).
__ Such similar piston-skirt scoring however, is fairly common due to fuel-diluted sump oil.
Did you ever check your 450's oil for any signs of fuel ?
__ Matt's short post seems to suggest that the metal scraped-off from the piston-skirt may've gotten into the oil and led to the failure of the crank-pin.
While I've never noted stock crank-pin failure due to any commonly contaminated motor/sump-oil, I suppose it's possible that YOUR crank-pin may not have been able to stand-up against such contamination.
So at this point, there's now some doubt of whether the piston-damage was root-caused by the failure of your non-stock c.pin, (as YOU've concluded),, OR if your c.pin went-bad possibly due to the piston-alloy having had become scraped-away, (as Matt has pondered).


Dukaddy-DUKEs,
DCT-Bob