[dirtrack650]

I've had a 700 in my garage for several years with a blown balancer and cracked case. I've read several of the posts here concerning balancer issues, warnings about availability, and the PITA to replace them.

My Q is, how does the balancer work? What fails on them?
Some people say the bolt backs out?

Thanks,
D

 

[Spockster]

I've had a 700 in my garage for several years with a blown balancer and cracked case. I've read several of the posts here concerning balancer issues, warnings about availability, and the PITA to replace them.

My Q is, how does the balancer work? What fails on them?
Some people say the bolt backs out?

Thanks,
D

The bolt should never back out, it's left-handed threads and is supposed to get Loctite then torqued to (a bunch). Though there's been cases of the bolt coming out.

There's a damper that's weighted on both ends of the balance shaft. The spinning weight cancels out vibration.

What fails is the rubber composite bushings on left side damper gear. You can find chunks of the bushings in the oil screen as they begin to fall apart.

 

[dirtrack650]

I borrowed the pic from davionics post, thanks! Excellent detail.

Why the need for the bushings? You'd think it was a simple counter balance weight. Almost $100 for six.

@ Spockster - I researched some of your posts from 2016ish. How would the balancer work if it were welded solid without the bumpers?

 

[dirtrack650]

Unfortunately, the older posts don't show the pics. 😞

 

[O' Darkness]

Unfortunately, the older posts don't show the pics. 😞

I don't know jack squat about the balancer or the bushings, but if I were on a gameshow and had to guess, I'd say that it's because internal combustion engines are inherently inconsistent and unstable, thus requiring a certain variability in the balancer?

If I somehow got this right on accident, I fully expect a participation trophy.

 

[Spockster]

I borrowed the pic from davionics post, thanks! Excellent detail.

Why the need for the bushings? You'd think it was a simple counter balance weight. Almost $100 for six.

@ Spockster - I researched some of your posts from 2016ish. How would the balancer work if it were welded solid without the bumpers?

View attachment 55872

Welding it would probably increase harmonic vibration, but the damper weight would probably still provide some reduction in rotational vibration.

The bushings isolate the gear from the weight.

I've been trying to restore my pics when I find them missing, I'll see if I locate the posts. You might've seen the posts about me installing the damper gear out of phase... Wish I had a video, the vibration was unreal, supernatural even. ...or paranormal?

I always thought the bushings could be made from Delrin, or some other synthetic material.

Half the bushings are smooth on the outside edge and half are sawtooth, don't understand why they're different.

 

[dirtrack650]

I read your posts about Delrin. The OEM bushings are available now, but at a price. Even my 77 KZ has a balancer, I don't think my 77 XS does, never looked.

 

[Jason Pittenger]

I don't know jack squat about the balancer or the bushings, but if I were on a gameshow and had to guess, I'd say that it's because internal combustion engines are inherently inconsistent and unstable, thus requiring a certain variability in the balancer?

If I somehow got this right on accident, I fully expect a participation trophy.

I will grant you one!

But I think you're right. The rotational speed of the engine varies quite a bit per rotation.
An engine only speeds up for 1/2 a rotation and spends 3/2s of a rotation slowing down.
Most of the slowdown happens on compression, just before it's 1/2 rotation of the power stroke.
Being a V-Twin, it's a little more steady than a single, but still lots of instantaneous changes in speed throughout each rotation.
The rubber provides some elasticity to this to smoothly reduce this rotational vibration.
Essentially, a harmonic balancer.

https://en.wikipedia.org/wiki/Harmonic_damper

If you've ever taken apart the rear wheel assembly, there's a giant rubber piece inside that couples the rear drive to the wheel.
Part #92075 2005 Kawasaki VULCAN 750 (VN750-A21) Rear Wheel/Chain | Kawasaki Parts Warehouse
This reduces the rotational vibration/shock on the driveline. This also can help prolong tire life by not forcing harsh power pulses on it.

 

[OleDirtyDoc]

The

I read your posts about Delrin. The OEM bushings are available now, but at a price. Even my 77 KZ has a balancer, I don't think my 77 XS does, never looked.

They are available again? Cool. Do you have a link or are you going to make a grumpy ole bastard search for them? Lol

 

[O' Darkness]

The

They are available again? Cool. Do you have a link or are you going to make a grumpy ole bastard search for them? Lol

I will NOT have you using that word in this forum again! Do you understand me???

Nobody on this forum is "ole" or "old" as you so eloquently put it.

We are... ahem... "Well aged."

 

[OleDirtyDoc]

I will NOT have you using that word in this forum again! Do you understand me???

Nobody on this forum is "ole" or "old" as you so eloquently put it.

We are... ahem... "Well aged."

View attachment 55906

I'm grandfathered in...

 

[dirtrack650]

# 92075 & 92075A

1995 Kawasaki VULCAN 750 (VN750-A11) Crankshaft | Kens Sports Kawasaki

Shop online for OEM Crankshaft parts that fit your 1995 Kawasaki VULCAN 750 (VN750-A11), search all our OEM Parts or call at 920.788.0220

www.kenssportskawasakiparts.com

 

[OleDirtyDoc]

# 92075 & 92075A

1995 Kawasaki VULCAN 750 (VN750-A11) Crankshaft | Kens Sports Kawasaki

Shop online for OEM Crankshaft parts that fit your 1995 Kawasaki VULCAN 750 (VN750-A11), search all our OEM Parts or call at 920.788.0220

www.kenssportskawasakiparts.com

Thank you