welding the crank

Yes im new here, just trieng to learn more. Ive had my KZ 650 for 13 years now never had to do anything but change oil and sprockets.... Why do you weld the crank?

On the 650 you do not weld the crank. It is a 1-piece design.

The 900/1000 engines have a totally different crank design - those cranks run caged roller bearings on a push together crank. Those are the cranks that get welded. The welding is to stop the crank components from twisting.

the only time you really have to get a 900 or 1000 crank welded is if your using a slick[drag racing] or doing major performance work like big bores or turbos or nitrous.strictly street driven stuff i wouldn't worry about so much.

timebomb33 wrote:

the only time you really have to get a 900 or 1000 crank welded is if your using a slick[drag racing] or doing major performance work like big bores or turbos or nitrous.strictly street driven stuff i wouldn't worry about so much.

Don't count on that.

only ever broke one on the street and it was because i didn't have my rev limiter installed.

The early 1981 J cranks were notorious about twisting - many of these early J motors were trashed and replaced at Kawasaki's expense.

A year or two ago, one of the forum members posted a picture of his engine - with 1 cylinder at TDC and it's pair about 1 inch down the bore...

In any moderate performance setup, it's worth doing

Maybe welding the crank is like buying insurance. You hope, you will never need it! But better safe then sorry. You can try all day to twist a crank and never do it, one small burn out on a GPZ1100 and I stroked it a 1/4" on one cylinder. Funny how that works!

Jeff.Saunders wrote:

A year or two ago, one of the forum members posted a picture of his engine - with 1 cylinder at TDC and it's pair about 1 inch down the bore...

The new Yamaha R1 is like that. They are calling it a new performance deal, when a lot of old Kawasakis have been running around like that.:laugh: :laugh:


Seriously, you can check your crank without removing anything. Use your TDC tool and degree wheel and find TDC on #1. Then move the TDC tool to #4 and check it. It should be the same as #1.

So u dont have any real power till your twisting it. Well im sure mine has gone all the way around, just ended up back in the same place. My bikes got soul built into it. And the Japanese dude that pressed mine had a passion for nice tight holes. I got one of good ones! Course if someone wants to tear it down I'll do the welding. Chuck (friend) has been r&d at case, various machine shops, pretty smart guy when he's got meth, (and no he doesn't work at any of these places anymore)told me practically spitting and gritting his teeth that if I welded the crank it would warp, no matter WHAT. I told him just a little bit and he grabbed ahold of my shirt at the shoulders and said It'll WARP! Coulda swore I saw gremlins swimming around in his eyeballs riding unicycles, juggling bent cranks. :huh: