Splitting N600 crankshaft yourself ?

[lyletrudell]

I own a machine shop, and have been around very precise machining since I was 17.
I have rebuilt many racing pressed together 2 stroke cranks for my Karting/motorcycle hobbies, they run 14,000+ RPM's. The problem with any part run on a production line is it has a tolerance. When you check a crank half, the centerline distance from the main shaft to the rod shaft is not the same. They can vary .002" or more!!
There is no way to align a split crank that is not matched from selecting the best matched rod/main distance, period!
I have gone thru a pile of 20 halves to get them to be within .0005".
We know the Honda crank is made "cheap", and the spline design is not good for accurately locating the 2 halves.
But, high RPM and HP was not the goal.
The mismatched crank halves are aligned by "bending/wedging" the assembly to get it "close".
The best motor I ever built was .0002" total indicator runout, from one end to the other.
Remember:
.001" is one thousands of an inch.
.0001" is one ten thousands of an inch, this is beyond most shops without a temperature controled clean room.
A 6,000 rpm Honda 600 motor would be happy with .001"-.0015" and be very reliable.
But, you can't just press them together and say it's OK.
You need a precision ground matched V-block fixture or bench centers and a good .0001" indicator. Then you need to wedge the crank throws apart, re-check, wedge......until the best possible runout is achieved.
Not something you can do at home.
Lyle
I'm pulling my Coupe motor out tomorrow, maybe, I should try aligning a Honda 600 crank......8,000RPM's would be fun : )

--- In
2cylinderhondas@yahoogroups.com
, "jpro8071" wrote:
> It isn't always that simple. We sent a disassembled crank to Falacon.
> Minimum was like 10 or 12 connecting rods to get anything done. And it wasn't cheap. I'm sure it was quality - don't get me wrong, they are experts in the area. But finding off-the-shelf parts isn't always that easy.
> --- In
2cylinderhondas@yahoogroups.com
, "Zay J. Speed" wrote:
> > Hi Crank shaft splitters
> > Check with "Falacon" crank shaft rebuilders of Florida, also "Hot Rod" connecting rods. and Wisco Pistons they have lots of rods & pistons & bearings big & small
> > crank shaft rebuilding at home WOW what's the world coming to!

[lyletrudell]

Check out this crank!
http://www.twostrokeshop.com/RZRD350_Ba ... tm#9058SKF
Will check to see if they have any parts that might adapt to our cranks.
Lyle

[Marshall]

Lyle, Seems as though our careers have followed similar paths !
Your experiences given by you are going to be of great help & guidance. I have access to equipment & tooling which gives me a fighting chance. Many thanks for the information you have given.

--- In
2cylinderhondas@yahoogroups.com
, "lyletrudell" wrote:
> I own a machine shop, and have been around very precise machining since I was 17.
> I have rebuilt many racing pressed together 2 stroke cranks for my Karting/motorcycle hobbies, they run 14,000+ RPM's. The problem with any part run on a production line is it has a tolerance. When you check a crank half, the centerline distance from the main shaft to the rod shaft is not the same. They can vary .002" or more!!
> There is no way to align a split crank that is not matched from selecting the best matched rod/main distance, period!
> I have gone thru a pile of 20 halves to get them to be within .0005".
> We know the Honda crank is made "cheap", and the spline design is not good for accurately locating the 2 halves.
> But, high RPM and HP was not the goal.
> The mismatched crank halves are aligned by "bending/wedging" the assembly to get it "close".
> The best motor I ever built was .0002" total indicator runout, from one end to the other.
> Remember:
> .001" is one thousands of an inch.
> .0001" is one ten thousands of an inch, this is beyond most shops without a temperature controled clean room.
> A 6,000 rpm Honda 600 motor would be happy with .001"-.0015" and be very reliable.
> But, you can't just press them together and say it's OK.
> You need a precision ground matched V-block fixture or bench centers and a good .0001" indicator. Then you need to wedge the crank throws apart, re-check, wedge......until the best possible runout is achieved.
> Not something you can do at home.
> Lyle
> I'm pulling my Coupe motor out tomorrow, maybe, I should try aligning a Honda 600 crank......8,000RPM's would be fun : )
> --- In
2cylinderhondas@yahoogroups.com
, "jpro8071" wrote:
> > It isn't always that simple. We sent a disassembled crank to Falacon.
> > Minimum was like 10 or 12 connecting rods to get anything done. And it wasn't cheap. I'm sure it was quality - don't get me wrong, they are experts in the area. But finding off-the-shelf parts isn't always that easy.
> > --- In
2cylinderhondas@yahoogroups.com
, "Zay J. Speed" wrote:
> > > Hi Crank shaft splitters
> > > Check with "Falacon" crank shaft rebuilders of Florida, also "Hot Rod" connecting rods. and Wisco Pistons they have lots of rods & pistons & bearings big & small
> > > crank shaft rebuilding at home WOW what's the world coming to!

[Marshall]

Lyle, Seems as though our careers have followed similar paths !
Your experiences given by you are going to be of great help & guidance. I have access to equipment & tooling which gives me a fighting chance. Many thanks for the information you have given.

--- In
2cylinderhondas@yahoogroups.com
, "lyletrudell" wrote:
> I own a machine shop, and have been around very precise machining since I was 17.
> I have rebuilt many racing pressed together 2 stroke cranks for my Karting/motorcycle hobbies, they run 14,000+ RPM's. The problem with any part run on a production line is it has a tolerance. When you check a crank half, the centerline distance from the main shaft to the rod shaft is not the same. They can vary .002" or more!!
> There is no way to align a split crank that is not matched from selecting the best matched rod/main distance, period!
> I have gone thru a pile of 20 halves to get them to be within .0005".
> We know the Honda crank is made "cheap", and the spline design is not good for accurately locating the 2 halves.
> But, high RPM and HP was not the goal.
> The mismatched crank halves are aligned by "bending/wedging" the assembly to get it "close".
> The best motor I ever built was .0002" total indicator runout, from one end to the other.
> Remember:
> .001" is one thousands of an inch.
> .0001" is one ten thousands of an inch, this is beyond most shops without a temperature controled clean room.
> A 6,000 rpm Honda 600 motor would be happy with .001"-.0015" and be very reliable.
> But, you can't just press them together and say it's OK.
> You need a precision ground matched V-block fixture or bench centers and a good .0001" indicator. Then you need to wedge the crank throws apart, re-check, wedge......until the best possible runout is achieved.
> Not something you can do at home.
> Lyle
> I'm pulling my Coupe motor out tomorrow, maybe, I should try aligning a Honda 600 crank......8,000RPM's would be fun : )
> --- In
2cylinderhondas@yahoogroups.com
, "jpro8071" wrote:
> > It isn't always that simple. We sent a disassembled crank to Falacon.
> > Minimum was like 10 or 12 connecting rods to get anything done. And it wasn't cheap. I'm sure it was quality - don't get me wrong, they are experts in the area. But finding off-the-shelf parts isn't always that easy.
> > --- In
2cylinderhondas@yahoogroups.com
, "Zay J. Speed" wrote:
> > > Hi Crank shaft splitters
> > > Check with "Falacon" crank shaft rebuilders of Florida, also "Hot Rod" connecting rods. and Wisco Pistons they have lots of rods & pistons & bearings big & small
> > > crank shaft rebuilding at home WOW what's the world coming to!

[Zay J. Speed]

600 Crank Shaft
     You got it ! that's why I threw that out there. I have been rebuilding cranks since 1976 and thought have em check out what it can cost and take, this is not an at home project.
Falacon started way back for drag bike cranks and oh yes are they big money, I thought that they might have specs or info for the A / Z fans as well as now understanding that this form of mechanics is for a select few that can see and under stand multi cylinder cranks and all the measurements of this repair, and how high the bill can get . I never did rebuild a an A / Z crank there was plenty of motors up until  the late 90's & easy to just get a different one.
I did 2 & 3 cylinder 2 stroke crank shafts Kawasaki , very difficult ! The other area to investigate on this is your Snow Machine specialty shops. These people do some nice 2 & 3 cylinder cranks, and they are becoming 4 stroke mostly but still pressed and they do some high  R.P.M. & Torque .

[jpro8071]

Thank you for sharing this wealth of information! Always appreciate when it comes from experience versus the theory and conjecture so often tossed around.

--- In
2cylinderhondas@yahoogroups.com
, "lyletrudell" wrote:
> I own a machine shop, and have been around very precise machining since I was 17.
> I have rebuilt many racing pressed together 2 stroke cranks for my Karting/motorcycle hobbies, they run 14,000+ RPM's. The problem with any part run on a production line is it has a tolerance. When you check a crank half, the centerline distance from the main shaft to the rod shaft is not the same. They can vary .002" or more!!

[lyletrudell]

Hi Jpro, thanks for the compliment. I don't claim to be an expert in anything. If we get imput from a diverse group of people we might figure these cars out, learn something new, meet some intersting people and keep our Honda's on the road.
Now we need to come up with a list of people that can do all the services our Honda's need.
Lyle

--- In
2cylinderhondas@yahoogroups.com
, "jpro8071" wrote:
> Thank you for sharing this wealth of information! Always appreciate when it comes from experience versus the theory and conjecture so often tossed around.
> --- In
2cylinderhondas@yahoogroups.com
, "lyletrudell" wrote:
> > I own a machine shop, and have been around very precise machining since I was 17.
> > I have rebuilt many racing pressed together 2 stroke cranks for my Karting/motorcycle hobbies, they run 14,000+ RPM's. The problem with any part run on a production line is it has a tolerance. When you check a crank half, the centerline distance from the main shaft to the rod shaft is not the same. They can vary .002" or more!!