1976 Kz 900 A4

wrote:

Have you posted pics of the rod small ends? You may not need it.
Steve

Steve I didn’t get any pictures before it was boxed up. John Pearson mentioned the wrist pin is lubricated two ways. Mostly by oil scraped off the cylinder walls by the oil control rings and it gets forced into holes drilled into the piston under the oil rings. The second is oil slung up off the crank. Upon disassembly of this engine I found a windage tray bolted to the crank main support. It’s number 3 rod and pin that are the worst. The scrapper did its job. It kept oil off the crank, thus off the cylinder walls and the wrist pin. I’d say that windage tray/scrapper is no good on a street engine. Might be ok on a drag bike that gets tore down on a regular basis. That windage tray/scrapper just became a wall hanger. 

 

The oil is coming out of the crank bearings also. It's slung up toward the pistons and the wrist pins. Like I said my piston seized in #1 bore and was trashed. The wrist pin was also but the rod was not. It had a little scuffing but cleaned up nice with 320 paper. I tried a new pin and it fit as well as the others so I installed the stock KZ 1000 pistons and barrels I bought and ran them until I could get a new piston set. That was with my Z2 750 crank. I'll get a clip of the crank and pins today.
Steve
 

You may be able to use the one you have.
Steve

wrote:

wrote:

Have you posted pics of the rod small ends? You may not need it.
Steve

Steve I didn’t get any pictures before it was boxed up. John Pearson mentioned the wrist pin is lubricated two ways. Mostly by oil scraped off the cylinder walls by the oil control rings and it gets forced into holes drilled into the piston under the oil rings. The second is oil slung up off the crank. Upon disassembly of this engine I found a windage tray bolted to the crank main support. It’s number 3 rod and pin that are the worst. The scrapper did its job. It kept oil off the crank, thus off the cylinder walls and the wrist pin. I’d say that windage tray/scrapper is no good on a street engine. Might be ok on a drag bike that gets tore down on a regular basis. That windage tray/scrapper just became a wall hanger. 

 

Interesting mod!  It looks to be integral with the center bearing cap.  
 

Thanks Steve. I only have a digital caliper similar to your. When I check the ID I get a minimum 17.08 to 17.12. Out of spec is 17.05. Not sure how accurate my caliper is. 

 

HRM, here is a stock photo I pulled fron the net. It cover the center main support cap and held in place with the 4 cap bolts

 

No eBay APP ID and/or Cert ID defined in Kunena configurationHave you ever seen this type of bore gauge?

www.harborfreight.com/6-piece-telescoping-gauge-set-5649.html

You would need a decent 1" micrometer to go with it.  The standard range for the small end works out to a difference of 0.0004".  Calipers are not accurate enough.  A micrometer can read to 0.0001", but may not be accurate to that value.  But I do think you could get a good idea of where you're at with those telescoping gauges and a micrometer.  Anyone you could borrow a micrometer from.



I used the same setup to measure the cylinder bore on a kz1000, and I was able to get consistent readings.

DOHC are the telescoping gauge referred to as snap gauges. The engine builder welding up my fins said he wouldn’t trust them. 

Thanks for the photo.  I was thinking it was a solid piece and you would have to find a new center block.

I agree on the mic.  You need a good vernier micrometer.  I started with 1 inch, then bought a 2 inch and then bought a 3 inch.  There should be a few for sale on facebook.  My only warning is to avoid anything made in China.

You would be surprised how accurate a good telescoping gauge is if you use them often enough to get familiar with them. They are not something you use once and get an accurate reading with. As with many measuring tools you have to develop a "feel" for them and do multiple measurements. I might do as many as 10 comparison measurements and take the average of them to get what I want. It isn't uncommon for two people to measure them same thing and come up with slightly different results. There is a method for using telescoping gauges that can yield better and more accurate results, but it is a learned technique. There are some good videos on the internet about using measuring tools. If the reading is important enough I may even use two mics to verify what I am looking at. Gauge blocks are your friend for keeping your mics in check.

Rick H.

I have never heard of a windage tray causing a lubrication problem . 
It is a race oriented  part . , but it wont hurt a motor to have one . Stock or Modified
It's like saying putting a gate in your oil pan is going to cause oil starvation . Not a have to have , but sure is nice 
Both these mods are very cheap too
Dave

RickH is 100% right. Those telescoping gauges are difficult to use but once you master them it is quite easy and quick to get repeatable results. a steep learning curve for sure. If you are serious about motorcycles or machining/fabrication in general good measuring tools are almost always a good investment IMHO. There are some high quality Chinese tools, like anything you get what you pay for. Alternatively there are more expensive types of tools for measuring bores that will be easier to use.

Stay the hell away from any precision measuring tool from HF. I bought those telescoping gauges from HF to save a few bucks and they are near worthless. the effort it takes to lock the arms fudges your measurement. I was never able to get repeatable results. I got a set of used Starett  on ebay and they are a million times better. the single floating arm is better than two - less to go wrong. I used them to achieve tolerances of +/- 0.00025" on some parts recently

Testing with gauge blocks will help you get a feel of what a good measurement feels like, most micrometers come with a basic gauge block. Remember .0001" is VERY small, a tiny amount of pressure difference can change a measurement by a couple tenths easy. it all comes down to the operator at that point.