Crankshaft

[Dago Fast]

Does anyone know how to properly index and press this back together?
2cyl tohatsu.

[Fast Fred]

yup,:cool: TDC on number 2 is 180deg off number one , set the fly wheel on it to line it up, then have it welded, mains and thorghs not a full weld thay need to flex make it look like this:cool: http://img143.imageshack.us/img143/6151/crank25wx.th.jpg (http://img143.imageshack.us/my.php?image=crank25wx.jpg):cool:

[Dago Fast]

Fred,

Do you use dial indicators or a lathe or jig to line up parts?
Do you make any alignment marks?

Thanks,
Jim

[Fast Fred]

what ya got? 25, 30hp, or 60, 70hp twin, best to just hand it over to the crank
guy, but ya can do it your self. i'll have a look at one and get back to ya, thares a 40hp too

[Dago Fast]

Fred,

It is a 40 hp

Jim

[will350]

I worked for the NW Kawasaki "crank" station in the 70s. Singles are easy,twins are a little more difficult, triples can be a real pain because of the indexing. Twins are always 180 off each other unless it's an "off the wall" set up to make it act like a single( I have seen this on a 305 honda twin 4 stroke where both pistons fired at the same time,it was sort of weird but went like stink)
To get them "straight and true" you need a couple of V-blocks and a good dial indicator. Set the ends of the crank in the V-blocks without the bearings set your indicator up and determine where the runout is and adjust it accordingly. If you've never done this before it can be really frustrating. It's not one of those "black art" things but it does require some thought as to what will happen when you move one throw vs the other end and where your high and low spots are overall.
The method I use to "adjust" them is a block of wood and a lead hammer.(lead because it won't damage the counter weight) Basically,you set one side of the counter weight on the block and give the other side a mighty whack( I'm still amazed at the amount of force it takes to move some of these) Then you set it back up in the V-blocks and check it again and so on.
Some instances require you to spread the counter weights apart or vice versa.
Assembly jigs really speed the job up if you have them but you can get it done without them although I wouldn't advise it with a triple.
If you've never done this....... Take it to you're local "crank man" and see if he'll let you "observe" the operation.If you can see it being done once,I'm fairly sure that the "light of understanding" will wash over you.This isn't "rocket science",it's mostly the "thoughtful" application of force (what's this piece going to do when you move that piece?)
Will


Fred,

Do you use dial indicators or a lathe or jig to line up parts?
Do you make any alignment marks?

Thanks,
Jim

[Dago Fast]

This engine fires on both cylinders at the same time but the pistons are 180 deg. apart.

Thanks for your instructions.

Dago Fast

[Ron Hill]

When Western Engine first imported the Tohatus's into the USA, and we started racing them...Western Engine would give the WARRANTEE motors to the RACERS for spare parts....Many were WARRANTEE because they'd been upside down and then not cleaned out... Some had the bottom crank pin rusted but the top one would be ok...

My dad, pressed the shafts apart, on several and used the top pins to fix the bottom pin..., When he went to WESTERN ENGINE TO ORDER SOME GASKET SETS...They looked at the crank pieces and laughed at him wanting gaskets sets...They said, "How you ever going to get those cranks back together?"

The OLD MAN, did like Will said, put them back together with some vee blocks, a 2 X 4, and a lead hammer.....After Western Engine saw that the OLD MAN had made about four engines out of about six busted ones.....They quit giving the motors away, and started having him rebuild their cranks....

I know for a fact, that I COULD NEVER take a crank apart...well, I might get it apart...BUT, I know I could never put them back together....But, I'd bet Chad could fix those cranks just like my dad....Some people CAN, some can talk about it!!!!

Will is one of those who CAN!!!!!

[will350]

As I recall it was a CB77, their "racey" version of the Dream that had tubular forks instead of leading link and dual carbs. At the time it was really fast and had a sound that was definitly "distinctive".
Will


That wouldn't happen to be the old Honda "Dream" your talking about, would it?

[Fast Fred]

knew a girl that ran a 305 Dream,
any who, it's not easy to get a press crank to .0005 of deflection, and thats ware ya need it to be. your not going to get the bearings off the crank , just the ends, leave them on, think your right on the fires boath cyl at the same time like my old hog.

to be an Expert said task must be performed a min of 2000 times:cool: :)

[Fast Fred]

bump:eek: :cool:

[2stroke4ever]

Wow:eek:

I have an Tohatsu 40 D.....

is the crankshaft so good? That i can turn the engine up to 8000 rpm?

[Roy Hodges]

those early Honda twins had both spark plugs firing at same time, they fired 180 degrees apart & then skipped one whole rev before it fired again. that's why they didn't shake & vibrate like the limey vertical twins . with the 180 crank , they were balanced , the English twins with a 360 degree crank couldn't have any decent balance .

[Fast Fred]

ow

I have an Tohatsu 40 D.....

is the crankshaft so good? That i can turn the engine up to 8000 rpm?
NO, 40C, is a twin.:cool:

[2stroke4ever]

i know... that the 40 C is a twin....

What is the limit of the crankshaft for my 40 D ? 6000 rpm or 6500 rpm?

THX for help!

[DonChichoJr.]

On Those Modular Cranks ( Tohatsu & Yammis ), What's The Maximum Tolerance, To Be Balance, Between The Center Bearing And The End Bearings ?

Any Trick To Be Easy That Work ??

Where Can I Get Info. ??

Thanks,
Don

[Fast Fred]

never did get one to holdup out side the revlimiter, on the Hot-Sue,
the yamaha was good till the 70hp carbs.

Hot-Sue pistons in your yamaha:eek:

120deg off number1 and so on, check it!:cool: .0005 of deflection, Tack, recheck deflection to.0005, you can get it that stright,
Done.:cool:

[Roy Hodges]

do you remember the Suzuki 750 triple two stroke motor sucker , er, murder cycle ? did it (the engine) have much in common with Suzuki outboard powerheads?

[Fast Fred]

had one of them thare bikes, from what i've seen gota say no, but kinda, but no.
yamahas and Hot-sues are updates of the 49 and 56 cuber. :eek:

[DonChichoJr.]

WHAT DO YOU MEAN WITH : 120 DEG. OFF # 1 .. .:rolleyes: ????

THANKS,
DON

[Fast Fred]

number one is keyed to the flywheel, at TDC the magnet on the fly wheel lines up, She fires, a 120 degrees later the magnet lines up again and fires, make sure
number two is on time, same for number 3.