TOPIC:

Hello Everyone;
I once read somewhere that the balancers in a KZ400 engine could simply be removed [OK, obviously the oil ports would have to be sealed up].
Has anyone tried this?
Why;
My engine has 55,000 miles on it and the balancer chain is worn out. There are no spare parts here in rural India, and anything like that sent through the mail gets stolen before it gets here [when the perp finds out it has no value he just throws it away].
I have just replaced the primary and timing chains , and their guides. But I think there is a bit too much vibration, there’s a little rattle I’m not very happy with, and I know that the balancer chain is out of spec.

The old KZ twin is still one of the hottest motorcycles in the district, and there’s nothing available here to replace it with [Enfield? No thanks!]. I bought it in the US in 1978, and shipped it here in 1983.
So; has anyone tried running one of these with the balancers out?
Regards, Mark Holden

If you take the crank out and have it balanced I think it would be livable. It would have a little more vibration, but I suspect you could live with it.

You could jsut remove the balance shaft chain and see how bad it shakes, maybe you would not even have to get the crank balanced, be really interesting to find out.

You might try shopping for the chain rather than the kawasaki part. I haven't seen any chain in a motorcycle engine that was not available as a product itself.

If sprockets are worn perhaps you could have some made at a local machine shop.

Where in India are you living?

-Duck

I’m in Goa, a tourist trap on India’s southwest coast.
In this area, industrial supplies are limited to say the least. Nothing like that chain for sure; bicycle chain, moped chain, two pitches of motorcycle chain is all. I’ve checked.
As to just trying it, well of course I could just try it, but there are a lot of hours of labor involved; that’s why I asked whether anyone else had done it already.
I just split the cases, and the chain has slipped a few notches. I’m going to try to get someone to bring the part out for me I guess; as a last resort I’ll try running it with the chain removed. I haven’t pulled the center cap off the crank yet, so I haven’t seen whether the balancer sprocket is damaged.
Balancing the crank isn’t an option; firstly, I’ve tried to find a dynamic balancing machine here before [for another job] without success. There are some in Bombay [400 miles from here] , but I’m not going that far.
In any case, the crank is intentionally eccentric, to counter the weight of the pistons, since they travel in parallel in the KZ400 engine. I don’t know if the counterweighting can be allowed for to balance the crankshaft.
Of course the crank only has a portion of the counterweight, the rest is done by the balancers; they turn in the opposite direction so as to counter the fore-aft imbalance from the weighted crank, while helping with the reciprocating couple from the pistons and connecting rods.
As far as making a sprocket locally; my machinist has done it before; I helped with the trigonometry. That was for a rear wheel.
But the counterweight sprocket on the KZ is in the center of the crank, and I believe that the crank is 1 piece [not pressed together]. I suppose the sprocket could be cut in half and then welded on, but my feeling is that success is less likely that failure. The tiniest error will cause such rapid wear that the whole project won’t be worthwhile.
Anyway, thanks for your ideas.
by the way; this '77 engine has een running with a '79 crank and connecting rods for 20 years.
the '79 crank has smaller con bearings and [had] a bigger alternator attachment end.
I converted it to monoshock 7 years ago; the roads here are very bad and kept killing the duals.
Mark

You might check www.kz400.com as I'm pretty sure that Ibsen22000 (I think that's right) mentioned that someone had already removed the balance shafts from a KZ400.

Mark-

Goa eh. Is much of the Portugese influence still apparent? One of the places I'd like to visit before getting too old to travel. Spouse has a one year paid sabbatical coming up in two more years and we plan to spend the year traveling, so maybe then. We also want to visit Kashmir if things have calmed down. I've been looking at possible motorcycle routes and hope to have her riding in the next 6 months.

I've removed the balance shaft from a car before and it wasn't too bad. 4cyl and shaft rotated at twice crank speed. Difference was noticeable though. If you're not in a hurry, I'm going to be messing with the balance shaft in the FT500 sometime before spring and can see how she runs without it. 500CC thumper so your twin should be no worse. Do the Enfields run a balance shaft? Always thought it would be fun to mess with a diesel Enfield but have not seen any floating around Atlanta or Honolulu.

Maybe you could hook up with someone in a more industrialized city to find the chai, if the sprocket's not too badly worn. Bangalore's what, a day's train ride? Guess there's always the option of rbber mounts for the bars. Yamaha XS650 has them. English twin style motor, Pistons up and down in unison.

-Duck

Mark, I replaced the balancer chain in one of my 400 engines (a 1976 D3) last winter, and the chain was considerably stretched and caused a great amount of free play in the balancer system, and the balancer chain sprocket on the crankshaft had signs of wear. The sprockets on the counterweights looked good though.
Dave Marsden at Z-Power UK said that he had seen several stripped balancer chain sprockets during the years.
And as I see it, you have got three options. You can remove the balancer chain, but you should also get the crank, pistons and rod balanced. The only article I have read about the issue, said that without balancing these parts, the vibrations will be very heavy.
There is one that I know who has removed the balancer chain I his 440 engine, but it was done together with an increase of the cylinder bore. He balanced the crank, pistons and rods though, and he also fixed the balancer weights in their lower position to maintain a good oil feed to the crank bearings.
The second option, and I have been told that this has been done by a guy in Norway, is to get a sprocket of the right side, cut it in two and weld it on the crankshaft. This has to be done very precisely, and the old sprocket has to be removed first.
The third option will be to find a crankshaft that is in good shape.

And if anyone wonders, the crank is a one piece crank. And what complicates things a bit is that the camshaft sprocket and the balancer chain sprocket are welded to the crank, very close to each other.
This is the crank and the balancer weights:



Post edited by: ibsen22000, at: 2005/11/20 04:29

Hi Isben;
I’ve just been at your site and read the article by Ian Powell about the 440 project. I tried to email him directly; found his site selling kz parts but the email address from there doesn’t work.
Anyway, what you say makes sense about the crank balancing. I think weight will have to be added to the crank counterweights to compensate for the balancer weights not doing their share anymore. That should cover the up down vibration and leave the engine with the forward back rocking, like older bikes.
I have been a pro mechanic [briefly] and I’m pretty good at this stuff, but I have no idea how a crank with a counterweight is functionally balanced against the pistons and rods. I suppose weights equal to the reciprocating components could be clamped around the big end journals and the whole assembly could be then dynamically balanced? Does anyone here know how it’s done? I wonder if I could balance it statically or by calculation [factoring in the work that was done by the balancers].
I’ll go back to the workshop tomorrow [ran out of time Saturday] and pull off the crank center bearing to see how the sprocket is doing.
I’ll have to read the factory manual again about the balancer theory, too.

Duck; not much Portuguese left except some architecture. Goa is pretty much just a tourist trap now, although there are still some nice places. It’s a good place to rest if you’re touring around India, since there is good accommodation and food here. Also some fun expats.
A friend of mine does guided motorcycle tours on Enfeilds through the countryside. Bikes are provided; a good option if you only have a few weeks for it. Otherwise you can buy a bike here and sell it when you leave [if there’s anything left of it]. The paperwork is so bothersome, many people don’t bother, but you should do it right or you have no insurance. That could be bad if you have an accident.
I drive a 7 ton truck around with either my KZ or my RD350 enduro conversion hanging on the back.
Enfield has no balance shaft, just a big mother flywheel. No power or brakes; little frame. They do sound great though. I love blowing them off the road with my 28 year old 400. Life is so easy here...
Newer models have better forks [the old ones would bend on landing after jumping a speed breaker] and even disk brakes are an option. They have a 500cc model, but it has the same hp as the 350. More low end torque though.
Regards all, and thanks for the input.
Mark

According to an article printed in Motorcycling Guide in 1975, 50% of the piston/rod weight are balanced by the flywheels, while the remaining 50% are shared between the counterweights. But the Kawasaki workshop manual does not list any figureas at all about how the weight is distributed.

If you go to this page: www.kz400.com/TechnicaltipsFrameset.html and scroll down to: Balancer mechanism 1, 2 and 3 under Service and technical tips, you can click on, and enlarge the diagram that shows how the balancer system works.

Post edited by: ibsen22000, at: 2005/11/20 12:14

After you have completed this weight matching, you are now ready to mount the Crankshaft in a special Balancing Machine that spins the Crank with the Damper and Flywheel installed, as well as "Bobweights" that duplicate the compiled weight of the Pistons, Pins, Rods, Rings, Bearings, and a calculated "weight of oil". The crank is usually mounted in Teflon or Nylon "V-Blocks" on the Balancing Machine. The Balancing Machine measures "out-of-balance" through Computer-Controlled sensors. Just like the way your wheels are balanced when you have tires installed (or hopefully during normal maintenance as well), yet the engine balancing machine is much more accurate.

www.centuryperformance.com/balancing.asp

A quick guide to the basics

Hi guys;
Well I got to the crank sprocket today, and it’s shot.
Therefore the preferred course of action will be to can the balancers and balance the crankshaft. I might have found a company that can dynamically balance it; they make turbine components though, it is not an engine shop. The manager owes me a favor from long ago... otherwise I may have to stoop to static balancing, a very crude approach.
So I need to know a bit more about how a crank is balanced; according to Steell’s post [thanks for that], my guess was right about adding weights to compensate for the pistons + rods. That will be a hassle, but my machinist and I can do it.
Now; how do I add weight? Quite a bit of weight I should guess.
I had guessed it would be by welding, and the site Steell has kindly provided a link to confirms this.
The clearance between the flywheel and piston skirts is pretty tight; there is some room to make the crank counter weights slightly wider. It will be tricky I think.
So does anyone have a working email address for Ian Powell? He actually did it, and could surely help on these details. This email address is being protected from spambots. You need JavaScript enabled to view it. does not work.
I would be great to know how much weight he needed to add, how it was done, etc.
There is no machinist here who has ever done this, so we’re going to have to figure it out as we go along.
By the way, as I said I have a ’79 crank in my ’77 engine. The connecting rod journals are considerably smaller, and therefore surely lighter; yet the ’79 and ’77 engines have the same balancer weights. in other words, the stock motor is not so precisely balanced from the factory.
Onwards and upwards...
Mark

Mallory metal is usually used to add weight to the crank counterweights, they drill a hole in the counterweight and then fill it with Mallory metal. It's a little expensive to buy the stuff though.