KZ650 Sleeper Build (KZ1000 engine transplant)

Wookie58 wrote:

Something else you can "draw a line under" and move on 

Yes, now I am getting some parts together to bench test the piston to valve clearance. Usually I only check PTV on assembly when timing the cams, but I want to make sure the valve pockets are deep enough prior to assembly.

Checking with modeling clay will tell me if I am too tight. I have some unknowns with the cams I am using, the old school MTC pistons, and my modified head. The head has had both intake and exhaust seats sunk back but has also been skimmed so that makes it a bit more complicated. Currently my piston top at TDC with proper base gasket installed is .006" down from the top of the barrel which I am not allowing for and will be a bit of a safety margin.

I slotted my cam sprockets the same amount that aftermarket APE units are done, but I don't know how much adjustment room that gives. General knowledge says to set the cams at 108 LC for best overall performance.
 

I fabricated some fixturing parts to bench check piston to valve clearance.



Just some oak wood scraps but they should be up to the task. #2 piston will be bolted to the head with modeling clay laid down in valve pockets.

Before that happens I still need to find out what shims are required on the intake side. I also need to record installed height for intake and exhaust to check the installed spring pressure.

I am curious about how you will insure that the piston will be at the exact height relative to the combustion chamber and how you will insure that it is perfectly perpendicular and how you will prevent the piston from rotating on the dowel. To me, wood seems entirely too soft for the level of accuracy needed here.

I am interested to see how you simulate the piston location relevant to the gasket surface to get an accurate outcome (always looking to learn)

Wookie58 wrote:

I am interested to see how you simulate the piston location relevant to the gasket surface to get an accurate outcome (always looking to learn)
 

This is just to make sure I am in the ball park, it is not meant as a replacement for a solder wire PTV clearance check which would be done while timing the cams on the bike.

I traced the head gasket on some onion paper then measured the barrel to get the stud/bore locations (to within a few thousands) The wood is oak so its fairly hard, no issue with clamping it to the head. Easy enough to measure the piston pin height installed on the piston. Everything cut on my milling machine and lathe to with a few thousands. If I need to shim here or there its no big deal.

My head gasket is a .043" fiber one piece so I am going place some aluminum sheet/copper shims at that thickness on the flat piston land next to the dome. Those shims will keep the piston from rocking/moving when the valves are rotated.

The cams will be rotated by hand as the valve assemblies have light springs holding everything together. There is not much resistance but enough to mark the modeling clay. Testing like this will tell me right away if the valves will "lock" or have clearance to the pistons.

As stated before my piston is .006" down in the bore with the base gasket installed, which I am not including in these calculations.

Thanks, I'm a simple person so I'm trying to visualise in my mind the process   I guess the "danger zone" is approx 20 degrees either side of TDC (dependent on cam duration) at the end of the exhaust stroke when the piston is at the top of the bore and both valves are partially open

In the past I would have just assembled the engine and used some lead solder wire to check PTV while timing the cams. On some "unknown" components this usually backfires and you have to take the top end off to rework the pistons. I know this all too well from the development work that I put into my 650 drag bike.

I became a bit of a expert in making Bondo casts of piston tops and combustion chambers. I found that the even with very good aftermarket pistons (MTC/JE) the stock combustion chamber was lacking (too much dead space) so I decided to make a new combustion chamber shape that was exactly the same as the MTC piston top profile minus required squish. I made up a D tool with the profile required that was used to "scrape" the shape into the head once the valve seats were removed. This was all done using Bondo casts and a 10X comparitor at a tool shop I worked at many years ago.

This is the "D" tool :







The object to this was to get a 13:1 piston to act like a 16:1 piston to burn alcohol fuel for drag racing.

So I am not afraid to think out of the box and try some unconventional methods if it can get me close to my objectives.

I was able to get out in the garage today and bench shim both sides of the cylinder head. I also confirmed the installed spring heights so I can vice test what the seated spring pressure will be to see if any shims are required.





Funny to observe that this head has smaller valves than my 650 drag head. Same size valves in the head on my 1327 drag engine.

Tomorrow I will bench check piston to valve clearance using some clay and the fixture I made.

I got a chance to bolt up the piston to the head with my fixturing parts. I did need some thin shims on both sides of the piston but when I bolted it down it was rock solid.





I cut some thin gasket strips but only ended up using the longer ones for the sides of the piston, this was enough to keep it locked in place.

I bolted it together "dry" with no clay on the pockets. I rotated one cam at a time and was "locked" on both without being able to achieve the full lift of the lobe. A rough vernier measurement told me the tappet only moved down .340" on both sides.





I thought the cam might move down closer to full lift but that was not the case, having the chain hooked up to the sprockets makes a big difference. Pretty sure I will have to just bite the bullet and assemble it on the bike. One thing this setup will be good for is doing a quick Bondo cast of the combustion chamber and piston crown... maybe good for drag bike use.
 

We're the cams locking up because the valves we're contacting the piston?

Injected wrote:

I bolted it together "dry" with no clay on the pockets. I rotated one cam at a time and was "locked" on both without being able to achieve the full lift of the lobe. A rough vernier measurement told me the tappet only moved down .340" on both sides.

I thought the cam might move down closer to full lift but 



 

Am I missing something here (not trying to be a "smart arse") to the best of my knowledge there are very few stock motors (car or bike) that would be able to achieve full lift at TDC (which is why motors eat themselves if a timing belt breaks)
Are you able to measure how much cam rotation you get before the valve hits the piston (both sides of TDC) if you then double that number (cams turn at half crank speed) and divide it by 180  then multiply by 100 this will tell you the percentage of the "stroke" that this piston would have moved in normal operation. The stroke is a known value so the calculation is straight-forward - this will tell you how much additional clearance you have in normal operation when you take piston travel into account.

Wookie58 wrote:

Injected wrote:

I bolted it together "dry" with no clay on the pockets. I rotated one cam at a time and was "locked" on both without being able to achieve the full lift of the lobe. A rough vernier measurement told me the tappet only moved down .340" on both sides.

I thought the cam might move down closer to full lift but 





 

Am I missing something here (not trying to be a "smart arse") to the best of my knowledge there are very few stock motors (car or bike) that would be able to achieve full lift at TDC (which is why motors eat themselves if a timing belt breaks)
Are you able to measure how much cam rotation you get before the valve hits the piston (both sides of TDC) if you then double that number (cams turn at half crank speed) and divide it by 180  then multiply by 100 this will tell you the percentage of the "stroke" that this piston would have moved in normal operation. The stroke is a known value so the calculation is straight-forward - this will tell you how much additional clearance you have in normal operation when you take piston travel into account.

 

I guess I forgot to mention my little cam end degree wheel...



The cams are the same on both sides and they are both hitting the pistons by the same amount at TDC. I need to dig out my dial gauge and adapters to install it on the head yet (could not find yesterday) Again this is just a "experiment" and I am making this up as I go.

The real measurements will be done on the bike when fully assembled for those concerned.




Since the cams were NOS there was no timing card but I was able to find some info online.

In the RC catalog from 1980 they gave the following description :

Pro Stock special, full competition grind providing max HP and torque for the pro stock or super hot street class bike (drag racing at that time)

.425" lift IN/EX
Total duration 310 deg
108 LC
IN open 19.5 BTDC close 55.5 ABDC (EX opposite)

RC used "advertised duration" that was taken at .010-.020" to make it sound super aggressive (probably more like 280 @ .050")The measured lift on the lobes is .420" From that description I am not expecting them to "come on" till about 7K RPM, luckily I have the 1200cc bore so not worried about power.
My engine guy recommended not setting them up any lower than 108 LC or else it would run like a "tractor"

I believe they are somewhat of a rare cam these days, even my guy was unfamiliar with them but said the numbers sounded close to a Andrews 3X, and that is why he was concerned about the valve pockets. I believe he is just being very cautious and making sure to warn me of potential consequences especially since I am using them with those funky MTC pistons (most people use Wiseco)