Crank rebuild steps? Post pictures, part #s, and directions!

[imquattro]

Hey guys!
We need a write up on this procedure!! (or just point me to one?)
Should be "generally" the same for the 3 cylinder 2-strokes and could be adapted to the 2 cyls...

[Suzsmokeyallan]

This topic has not been touched simply because many persons do not have the types of tools in their home shop, and even if they did you will still need a helper and a fair bit of experience on the type of work involved.
The main problem for one person with crank rebuilding is weight, as the cranks increase in cylinders the weight factor becomes too much for one person to deal with in the press. One slip and you can be hurt badly by falling weight usually on your arms and feet where it can be painful.
The basic tools used are a large vertical hydraulic press of around 20 tons, various pressing blocks and plates etc, which will get a crank apart quite quickly.

A single is relatively easy to do, Ive done so many of these over the years that I've lost count.
A twin is not so bad, but a little heavier and of course the pin locations per cylinder relative to each other now become part of the procedure, along with some added weight.
A triple such as the GT750 is just way too much heft for a single person to deal with, its easily upwards of 40 lbs, so you need a helper for the disassembly and reassembly.
For the reassembly on a multi cylinder crank, its a lot more technical than a single as now the cylinder timing and of course total crankwheel alignment is involved. Therefore you must have the V block set, a perfectly straight and level table, preferably a steel plate one, and dial gauges set up to check and correct where the runout is.
For the amount of time and effort needed on a twin and triple with a novice doing it, places like Bill Bune do an excellent job and their price is very reasonable when you consider what it takes to do the longer cranks.

[imquattro]

Well put.
But those obstacles shouldn't prohibit someone from posting a walkthrough.
I've seen & read many a complex documetary and I feel there has got to be members here who have sucessfully accomplished this procedure vibration free.
Some of us have the tools, equipment, & help to do the job, but are intimidated by having no instructions or walkthroughs to follow.
And I only have one spare crank to practice on... and I don't have a spare $300 to send it out to be done.

[imquattro]

At least THIS shows some steps and tooling:
http://www.kawtriple.com/mraxl/files/crankrebuild.pdf

[geck0]

At least THIS shows some steps and tooling:

WoW. no wonder I send my cranks out for repair.

[two-stroke-brit]

its money well spent.
its probably the single most vitale part of the whole build.
bill bune has done two for me ,and i am an engineer/machinist of 35 years .
you can save the money on paint or something else.
my 2 cents
good luck

[greasemonkey]

I use this site to research my parts:
http://www.cmsnl.com/suzuki-gt500-1976- ... 81570.html" onclick="window.open(this.href);return false;

[Suzsmokeyallan]

I can understand your query on this, but its not something to be taken lightly. You cannot just gain the skill and know how by reading and then going and doing a crank rebuild.
There are so many things to be aware of and how they directly will affect the parts. In other words for example, one "miss press action" and you can ruin a seal by crushing it.
The same applies for lower rod bearings and thrust washers which are easily damaged as well.
An interference fit such as used on a con-rod big end pin or a main journal does not move easily, they tend to move in jumps, you need to have the skill with the parameters of what and how much effort to use on the jack handle if not you can damage the parts in between the crankwheels
Similar to what Mark said about being in the field for 35 years, but unlike him I've got a bit more years under my belt and done lots of single cranks and I would do a Buffalo crank, but I'd need to have an experienced helper for such a job.
For such a rebuild, just orienting the crankwheels and their related parts at the right spot, and the initial pressing of the parts as you build up the crank which is fast becoming larger and heavier are of absolute importance.
You need someone there thats not only watching what you are doing but is is another set of skilled eyes to follow along.
If you want a walk through typed out it can become a long process of essay writing and that will only give you an idea of procedure, not what will actually take place to a 100% value.

[imquattro]

The more I see what's entailed, the more I agree with everyone...
Definitely a send-out job.
Thanks for your instruction and wisdom...

[geck0]

This showed up years ago from a member named kickstart. I at one time considered this but then realized that splitting the crank is intense enough let-alone getting it back together to spec or better
http://www.ozebook.com/compendium/t500_files/crank.htm

[Suzsmokeyallan]

With that setup its possible to split the centre of the crank apart leaving the lower ends intact on each side. Then you would simply replace the seals and o-rings on the centre bearing and press it back together.
What would be required next is removing the circlips and replacing the outer seals on the outboard bearings to get the finished seal and o-ring job done.
However this 'easier way out' also means you didn't inspect the lower ends unless you plan to disassemble it further.

[tz375]

If the big ends are clean and no signs of rust, that might be a reasonable compromise.

[Suzsmokeyallan]

Not always, since you cannot see the inner surface of the big ends. I thought my T500 big ends were decent from all of my visual assembled inspections and how the engine sounded, but when Bill Bune pulled them down they were beginning to pit around the edges of the conrods.
Had I used them, after a while they would have eventually gotten worse as the pits got deeper and larger.

[tz375]

And therein lies the rub. Once you look, you have to change them and if they feel fine and don't strip the crank, they will probably last another 10, 20 thousand miles. There is no argument what the "right" thing to do is, but I suspect that there are lots of bikes running fine with pitted bearings.

Every Honda crank we have stripped has pits and that's game over for a race bike and the ones we fitted without stripping them lasted years with no apparent side effects. Were they pitted too? Who knows. That will have to remain a mystery, but my guess is that they all have some pitting.

It's that old philosophical question - if you can't see the pits, are they really there.

[greasemonkey]

I never rebuild an engine without doing the crank.
fresh oilseals don't only keep the oil out of the case but also keer pressure were it belongs.
the thing is: If you got some experience with engines and you feel good about doing it, go ahead.
if you have doubts about yourself: let somebody do it for you.
I plan on doing the crank of my gt500 myself but i have some plans with it so seals are not needed in my case.
the right tools, a burner and a freezer is all I need.