small ends and the oil jets

gggGary

If not now, When?
Top Contributor
XS650.com Supporter
Messages
30,826
Reaction score
60,120
Points
813
Location
Baraboo, WI, USA
Pulled down a 11K mile 79 that had got a bit of water in a cylinder while sitting (never run after) and found the small ends looked like this.

rods 009.JPG

Then read this thread

you will note the RH small end looks like it got hot.

rods 013.JPG rods 012.JPG

The brass coating is gone and using an indicator through the oil hole using the smooth end of the wrist pin. I got about .0005" of wiggle. The left hand side had no measurable slop.



2many sez the racing manual has a small end oiling mod that I need to look up.

This engine shows some signs of "extended" oil changes, might have been run with low oil, hard to know about PO maint. This pic shows a fine wire stuck in the LH jet hole it seems to be angled slightly up, more or less at the back of the piston.

rods 012.JPG

rods 011.JPG

This shot is a different crank/cases

I wonder whether I should drill the RH to match? I will swap to a different crank with better small ends and it's getting new oversize pistons rings etc.

My informal survey seems to show the RH jug tends to go first from detonation. and other untimely deaths.

rod wrist pin loose wear oil jets gallery small end scoring heat distort
 

Attachments

  • rods 010.JPG
    rods 010.JPG
    175 KB · Views: 332
  • rods 014.JPG
    rods 014.JPG
    138.5 KB · Views: 314
Hey, gggGary, yep, this 'oiling' stuff is fun to ponder.
Route 1 is clean 'er up, use new parts, reassemble and go.
Route 2 is test, observe, measure, theorize, experiment, ...oops...

One thing we'd do in the shop is jam the solvent tank's nozzle into oil galleries and see if solvent would shoost outta the holes.

Could make an adapter to fit the upper case's entry, shoost a solvent/fluid in there, and using controlled pressure, see how much, how far the fluid shoots out the various jets.

Then it gets complicated. Involves flow rates and orifice sizes. Then deciding on how much and which way. I believe Steffi noted his squirter mods in his 533 crank redesign, on the xs cafe site.

On a similar vein, we used to do piston skirt knife edge and oil ring groove port mods on race engines back then, did the same on mine. One reason was to help wristpin oiling. And there's more. But, haven't found anything on if that's still practiced nowadays. Maybe somebody here remembers those. All I've found is the oil ring groove to wristpin oiling hole mod...
 
All I've found is the oil ring groove to wristpin oiling hole mod...

I've been looking for info on this mod and all I can find is the one drawing on the MMM site. Is it really just as simple as drilling a hole at a slight downward angle through the oil ring groove? "X" marks the spot? http://pjl.kotipolttoinen.com/random/oil_mod_maybe.jpg

The small ends of my rods are gone and I'd like the new ones to hold up as long as possible...

Thanks,

Pekka
 
Hey, pekka. I've been digging thru all my downloads, and I either can't find it or my old memories got cross-linked to other bikes again, maybe Honda, Triumph or Harley mods. Yes, it's drilling procedure, needs to be done carefully and precisely. Here's the mod offered by MMM, found on his site:

http://www.650central.com

WristPinOilMod.jpg
 
- - - you will note the RH small end looks like it got hot.

View attachment 59502 View attachment 59501

The brass coating is gone and using an indicator through the oil hole using the smooth end of the wrist pin. I got about .0005" of wiggle. The left hand side had no measurable slop. - - -

Hi Gary,
has anyone tried re-plating the wrist pin bores after the copper coating has worn off?
The crankshaft assembly could be suspended above the plating bath so just the wrist pin ends were submerged.
Ream the over-thick copper back to exact size afterwards.
 
Freddy-boy! That's egg-zackly the thinkin' I've been havin' over the past coupla years!

But, using electroless nickel.

Been doin' some research on this, it's an accepted practice for renewing bearing surfaces of expensive machine tooling. Not sure if it was done during your time, though. Don't think it was during mine.

The basic process would be to first finish hone the hole so it's cleaned-up and straight. Then measured and prep-cleaned. Based on target dimension and plating thickness, the end would be dipped into the bath for a specific amount of time (just minutes/seconds), then withdrawn and rinsed. According to the documented procedures, the plating thickness is so uniform that final sizing and finishing is NOT required, the plated surface matches the base metal surface, and is ready for use.

The hardness/durability factors are much better than copper, and nickel has a natural 'lubricity'. The main option is the choice of 'phosphorous/alloying' agents (for lack of the better term) in the bath...
 
Last edited:
Yes I was thinking about that. After a little searching this is not something that would be a practical DIY process, you would have to have a good plating shop do the work. Real copper plating solutions are a cyanide based brew, I don't think even a "Caswell kit" type plating solution would form a strong enough bond for this high stress use. The issue is the quality of the copper to steel bond. Then you get into the metal plated on, is it just copper or some sort of brass? Then a reamer and a fixture to get the reaming true or find a shop that could it for you. Wouldn't take long to get you to the cost of new rods, the mikesXS rods are supposed to be stronger also, $92 each with new bearing and crankshaft pin. Basically thinking out loud, opinions are invited.

cross post with 2many
 
Hi Gary, 2Many,
$92 each for new rods plus the hassle &/or expense of a full crankshaft teardown & rebuild.
Or a quick rod ends only dip in a Bro's plating bath on the nightshift.
Although not everyone has a "Bro with plating shop".
I do remember the nasty moment when the boss was touring VIPs around our company plating shop.
He had to lift 3 bus-bars to find an actual aero-engine part amongst all the teapots, car parts and childrens toys that were getting a chrome job in exchange for a pack of cigarettes.
Getting "foreigners" plated got to be real difficult for a while after that.
But yeah, electroless nickel was after my time.
And AFAIK you can only electroplate pure metals, and brass is a copper-zinc alloy.
 
Back
Top