1976 Kz 900 A4

Crank has been delivered.  Have you had a chance to inspect if yet?
 

It’s out of the box and up on the bench. Didn’t get any farther. Working on a set of carbs at the moment. Lol

While I had some down time waiting on parts to come back from vapor blaster, I checked out the crankshaft that tagged along on Wheelhops most excellent adventure. I don’t have V-block nor dial gauges, so I could only check rod the crank clearances and small end ID. Looks like we have a good one. Thank you to a couple of great members that have pushed me past my last big hurdle. I’d really like to find an index rod and check that as a last test before it goes in the cases. Anyone have a source for a 17mm index rod.
 

With the hurdle of needing a crankshaft is resolved for the most part, I’d still like to get an index rod and check that. I pulled out the other two I had and now I can make an objective determination on their conditions.


Without the pressure of needing one I figured I could look at them clear eyed and say yes or no if they are good or not. So the first one I checked again the small rod ends and they are out of spec. That measurement is .6713. The standard service dimension is .6694 to .6698. I found two rods out of spec and two rods out of the standard spec but below service limit. I’m going to recheck that crankshaft again one last time, everything else with crankshaft #1 is nice. The second crankshaft has good rods but the bearings were notchy and it also had a sheared off timing pin. I worked on the bearings and clean them out and they run smooth. I ran a quick check on the small ends of the rods again, all upper limit but within spec. So I worked on pulling out the timing pin. I was able to drill it out then tap it with a 3 mm tap, I then threaded in a round Machine screw and was able to pull the timing pin out.

 

 

So after my pat on the back session was over I got back to seriously looking over the second crank to make sure it was usable. I had noticed dirt and debris in the oil pump gear. Figured it was just gunk and it would clean out. Unfortunately it’s not, that dirt and debris is actually rust and it appears to have eaten through the top surface of several teeth in one section, as if that section of the crank was sitting in some wet cardboard or packaging. So here the question, it’s this a deal breaker and this crank can’t be used. See photos and feedback is appreciated.

 

Give the gear a good cleaning with a brass brush first and the crank is ready to use. 

wrote:

Give the gear a good cleaning with a brass brush first and the crank is ready to use. 

Wish it was that easy. The teeth of the gear have rusted through the hardened smooth surface. I’ll post additional photos.

Gotta say that is a top notch job pulling the broken timing pin!

Goiod Ridin'
slmjim & Z1BEBE

wrote:

Gotta say that is a top notch job pulling the broken timing pin!

Goiod Ridin'
slmjim & Z1BEBE

Thank you, it was sheared off flush. I center punched it. Drill it small and then up to the bit for the 3mm. I was hoping the tap would tighten up and start to move the pin but the force I was applying was making me sweet. I’ve broken taps off before and that was the last thing I wanted. I dug and found a 3mm machine screw, threaded it in, grabbed under the screw head with dykes (side cutters). The tip of the dykes were at the center of the crankshaft and created leverage and I was able to pull the pin without twisting it. 

slmjim, any thoughts on the crank oil gear?

Mikaw my opinion for what it's worth is that if this is the only issue it is worth saving. It is unlikely you will find a "perfect" 40 year old crank. Whilst this gears function is critical I don't think it is under huge stress. In the past I have recovered transmission gears with a tapered stone to dress and polish such damage which relieves stress points. What I have used is similar to the below (this is of course only my opinion)
 

wrote:

 Anyone have a source for a 17mm index rod.

 

Matt - 
If you're still in need, I should be able to help you out with that 17mm index rod.  I'll send you a PM.
Mike

Mikaw post=869997
slmjim, any thoughts on the crank oil gear?

Wookie58's suggestion to polish the teeth sounds pretty good.  Be very careful not to remove any sound material or change the profile of any tooth; just kind of 'kiss' the drive surface.  Or, perhaps start by using a small, fine, stainless high-speed wire wheel in a dremel-type tool.  (Wear eye pro!  Those tiny wire wheels sling bits of wire.)  You might find that doing so removes the surface pitting very effectively.  Too, wookie58 is correct that there's little load on that particular gear and, it's constantly bathed in oil.  It's likely to run for a lifetime without problems.

Good Ridin'
slmjim & Z1BEBE

We commonly touched up burrs on gears with an oilstone at the factory,  remarkable how much noise a small burr on the oilpump gear contacting the primary gear can make!  If the teeth are pitted the surface heat treatment is probably gone,  however I don't think that just a few teeth would be a cause of concern?  I don't understand the comments about just a little load on the gear, it is the PRIMARY gear along with being the oilpump gear.

Mike