Testing Z1 crank for twist

Last time we needed to check a crank for true a crusty ol' guy who used to run Top Gas had a local shop we would frequent & he let us use his length of drill rod. He & shop are long gone.

We need to check the crank in The Wounded Z for true. Need advice on what & where to buy (or borrow?) a straight & true rod to check a Z1 crank for twist.

Thanks
&
Good Ridin'
slmjim & Z1BEBE

I'd look for a piece of precision ground drill rod. Typically denoted air or oil hardening and sold in 36" lengths. Google has a number of sources. Finding a piece that's straight enough to use as a measuring gauge may be a little challenging though. The drill rod sold by McMaster Carr lists the straightness spec as .012" over 36" so that may not be good enough for your needs. I'm not sure about other sources.

I see $25.00 at Amazon. If you have a motor assembled and want to check for twisted crank, Set your TDC tool and degree wheel up on #1 and find TDC. Then put the TDC tool in #4 and check it. TDC should be exactly the same place on the wheel.

you can check the run out but................ best to have it taken apart and check the bearings etc these bike are over 40 now and did not have the best lives.

We appreciate the responses, everyone.

Nessim supplied the clue we needed to locate drill rod locally. Thanks for that.

We'll need to take a crank with us to the metals vendor(s) to make sure a 17mm. drill rod will fit, as the margin of error in the OD spec of the rod is on the borderline of the ID spec/service limit of the con rod small end(s). We just need a snug fit, not a press fit.

Unless we're not understanding something correctly, testing TDC on 1 & 4 will not identify an error in indexing (twist) of all four crank throws relative to each other.

There is a point in crank rotation where both crank pins for 1 & 4 are at 3 o'clock, for example, when viewed from the left (#1) side of the motor. That would place the crank pins for 2 & 3 exactly 180 degrees opposite at 9 o'clock. When the crank is in that precise position, the con rod small ends should all be in exactly the same axial plane if the crank is indexed correctly. This is where the expedient, quick & dirty field test that drag racers used back in the day comes into play; if there is any significant error in the indexing of crank throws relative to each other, a 17mm. straight rod will not align with all four small ends at once closely enough to allow it to pass through all four small ends at once. Note that this does not confirm that TDC for #'s 1/4 and #'s 2/3 is correct relative to their advancer timing marks. The method described by Big Jay is useful for that.

Axial and radial runout of the rod big ends and crank bearings are easily tested with dial gauges while the crank assembly is in V-blocks. No disassembly necessary.

If any issues are identified with this crank it's going to Falicon, unless someone recommends a better crank service vendor.

It's quite unlikely that there is any twist in this crank anyway. The motor is box stock so far, nothing we've seen to date indicates it or the bike was abused, and cranks don't generally become twisted in street use by stock motors anyway. One common symptom of abused Z1 motors is deformation of the aluminum in the dyno rotor, wherein the magnets will have shifted within the surrounding aluminum. There is no visible indication of that.

We'll post pics in this and/or The Wounded Z thread when we get a drill rod to test crank indexing.

Good Ridin'
slmjim & Z1BEBE

As Big Jay said (and I think he might know a thing or two about Kz engines ), I believe if 1 and 4 are indexed correctly, the odds of 2 and 3 being out are very low. If something slipped between 1 and 4, thus making 2 or 3 out of index, then 4 would no longer be indexed to 1. This is assuming the crank was built correctly in the first place.

I recall a post somewhere on KZR where someone showed why the rod test was not as good as checking TDC with motor assembled. (That's not a thing with 550's, so I didn't pay close attention).

You may want to consider Garner Racing Concepts in Maine for crank work. They have a good reputation. I would include thier web address, but evidently it has been hacked as I keep getting redirected to some Chinese site. They do have a functional FB page.
I am quite sure that Big Jay's method will identify a twisted crank, and may be more accurate. If the crank is twisted, the paired pistons will not reach TDC at the same time, or 1&4 will not TDC at exactly 180 degrees from 2&3.

In no particular order Crank experts
APE
Garner
Pearson
Falicon
I have only used Falicon , But that experience was over 30 years ago and was a good experience . They have since changed management
Dave

If you check the crank with the rod, and it is twisted, the rod will fit thru #1, 2 and 3, but not 4. If installed the other way it will fit thru 4, 3, and 2, but not 1.

Garner and Pearson are highly recommended by the racer guys over at GS Resources. According to one of the engine builder guys there Falcon is not the same as they used to be and can't be trusted with cranks these days.

Big Jay wrote: ... If you have a motor assembled and want to check for twisted crank, Set your TDC tool and degree wheel up on #1 and find TDC. Then put the TDC tool in #4 and check it. TDC should be exactly the same place on the wheel.

After clearing the atmosphere within slmjim's cranial cavity of the brain fart that was blocking his understanding, it's clear he (I) was wrong about this method being useful in identifying indexing errors relative to the other crank throws. Being so focused on checking with a straight rod masked the fact that Big Jay's method will positively identify the cumulative indexing error of all four throws combined.

At this point in the project we'd have to reassemble the pistons (sans rings) onto the con rods and drop the jugs onto the cases again in order to use Big Jay's method. Bottom end is still undisturbed and mounted in the frame. Hoping to be able to do sufficient inspection & cleaning of the case internals by simply removing the sump cover and not have to split the cases unless a problem is identified. We're particularly focusing on making sure shift forks are straight and the condition of the second gear dogs.

Good Ridin'
slmjim & Z1BEBE

Hey Jay A, remember Jimmie Mangus. If you Guys seen what the Hell We Beat cranks with to straighten and put bigs pins in the old Z1 cranks! You would crap :laugh:
Big ass lead mallet, pieces of hard round stock plus the hyd. press. Then we would take em down the street to "PUPPET" for that beautiful tig weld for the pins!
We had a Kawasaki Dealer in Tonawanda, NY, Owner Kal! he would warranty GPZ cranks, charge the factory big $$ for new ones, and labor. Then we would buy the cores for $50 bucks. Fix the slight imperfections and sell them back to him.
Those were the days! Almost primitive now!