1976 Kz 900 A4

Matt - to my eyes, those wristpins do indeed look galled.  Unfortunately, I don't know of an "easy" fix.  Back in the day, the right thing to do when prepping a (race) crank was to have the small ends of the rods bushed with a silicon bronze material.  This eliminates the potential for galling.  The downside is that the crank has to be disassembled in order to do this.  Falicon would do this as part of their stock rod prep/strengthening service.  I don't know if Falicon is still in business.  Maybe some other forum members can chime in with other suggestions.  Hope this helps!

Mike

 

Thanks Mike,

What I don’t know is, are the pins sacrificial and the rods might be ok. 

I wouldn't necessarily view the wristpins as being sacrificial.  The interface between the wristpin and rod bore is, in essence, a plain bearing.  So, they're always separated by that thin layer of oil and should never make contact with each other.  Because of the previous galling, there might be high spots (ridges) in that pin bore that would break through the oil layer on the next go around; putting you back to square one with more galling.  

If you can finely polish that wristpin bore to remove those peaks, without affecting the overall bore diameter, then you "might" be okay, beings that this is a street motor using stock pistons turning reasonable RPM levels and lubricated with good, modern-spec oil.   If you were building a race-spec motor slinging heavy pistons at high RPMs, then all bets would be off.

This is just my opinion and should be treated as such.  As mentioned before, there might be other forum members with more experience with rebuilding stock, street-type motors that could give their insights and opinions. 

Mike

Thanks Mike,

Anyone else have an opinion or procedure to share.

FWIW, I would agree with Dragbike Mike on all accounts.

Mike

You might want to think about another crankshaft.  Maybe the oinkster has one.  Or one of the members?  There are a few on ebay but who knows what condition?

wrote:

You might want to think about another crankshaft.  Maybe the oinkster has one.  Or one of the members?  There are a few on ebay but who knows what condition?

Ouch. Hope I’m not going there.

I would not use them that way.  Inspect the upper rod bearings those wrist pins cam out of very thoroughly before using them.

I found the specifications for the pin and rod small end. The pins are definitely trash. Worn down below spec. I don’t have any bore gauges to check small ends. The guy that is welding up my head is an engine machine shop, I’m going to run the crank over to him this week and have him spec it out. Fingers crossed! I did find two crankshaft specialist close, if it’s out of spec I’ll take it to them for ideas. 

Thanks all.

I was referred to these guys www.facebook.com/Gardnerracingconcepts as a good Kz crankshaft place. I wasn’t sure based on their FaceBook page. I messaged them and they replied. “ yes we can help we work on those daily and would love to work with you on your project” going to follow up with some phone conversations and see where it goes. Anyone know these guys?

wrote:

I was referred to these guys www.facebook.com/Gardnerracingconcepts as a good Kz crankshaft place.....   Anyone know these guys?.

I've never done business with them, but they are often the highest and most recommended place on this site when this question has been asked.  And most comments suggest that's it's one of the last crank shops that still does good work.

hstrial-gcranks.homestead.com/About-Us.html


 

wrote:

wrote:

I was referred to these guys www.facebook.com/Gardnerracingconcepts as a good Kz crankshaft place.....   Anyone know these guys?.

I've never done business with them, but they are often the highest and most recommended place on this site when this question has been asked.  And most comments suggest that's it's one of the last crank shops that still does good work.

hstrial-gcranks.homestead.com/About-Us.html



 

I don't have any personal experience with Gardner but they come highly recommended.  

This quote is from the GS Resources resident go-fast drag bike engine builder Ray Rains...

Quote rapidray:

For roller bearing cranks, the ONLY places I will send one is to John Pearson in Ohio, Stan Gardner in Maine, or Bob Mosher in Florida. I wouldn't ask Falicon what time of day it is!
Ray.