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Hi all,

I'm about to rebuild my '74 450 Mark 3 engine. It has the 32mm pin and will be pushed out (by necessity) to an 87.0 mm Wiseco piston. I'm interested in your thoughts about the value of balancing the crank for a standard road use bike. If I am to do it, then now is the time. Is it worth it? And if so, what balance factor makes best sense?

Regards,

Kev

Hi Kev

is there a lot of weight differance between the std piston and the Wiseco ? if so you certenly must re balance .

static balancing would be OK for a road engine .

what balance factor to use ? the factory drawing of the 450 crankshaft states 70 % as the factor .
but i use a little lower factor . around 66.5 to 68 percent works for me .

if it was my own engine i would re balance for sure . i have seen a lot of cranks that where way of

Eldert

Hello Eldert,
Where does your 450 vibrate with the balance at those figures? (Given 450's vibrate always)
I've tried 70%, 60% and now 55% which seems best using a 250 ungusseted road frame.
70 was too much at just over 4k
60 broke pieces off the rear guard inner and made the shocks rattle till they leaked.
55 has been nice so far and nothing breaks or falls off.

Kev, the above is with 34 mm crank pin, 1mm longer Honda rod and 87mm Weisco piston.

Be aware there are several 87mm Weisco pistons for 900 bevels. If you can wait a week I can get you the numbers, as some are heavier than others

Graeme

graeme wrote:
Kev, the above is with 34 mm crank pin, 1mm longer Honda rod and 87mm Weisco piston.

Graeme, which Honda rod is that?
Thanks.

Kev,
Seems that we have the same thing on our mind, I was getting ready to post almost the exact same questions... I am getting ready to build a 72' MK3 Non-Desmo 450 engine. I was also specifically looking at the Wiseco piston kit for the 900ss/900 Darmah. The only one that seems to be available is this one
https://www.wiseco.com/ProductDetail.as ... AppID=5018
part # 4627m08700
Without buying one I have no idea what it weighs, and as to Eldert's inquiry as to the weight difference, I dont even have the original piston to weigh.
I am assembling my engine from "scraps" All good stuff, but purchased from various sources. The crankshaft was the last thing i needed (besides a piston, rings, wristpin) and I just bought one (finally) from a guy I know in Japan.

One other thing is... The 900 seems to have a .60mm shorter stroke so (using a stock oem 450 rod) im assuming i will need to space the cylinder accordingly
Has anyone used this piston in an otherwise stock engine ?

For those wanting to try an aftermarket rod, I believe it is a Honda XL500 Con rod, at least I know thats what this post from ducati ms says (from Graeme)
http://www.ducati.ms/forums/14-vintage/ ... cture.html

Joe

Thanks Joe,

Honda XL500 con rod.

Something else to consider is compression ratio. Lower compression will result in a smoother running engine (and easier starting). I built my BSA 650 engine with lower than stock compression and am very happy with the way it runs. So many people bump up the compression because they think they want a hot-rod, only to discover that they seldom ride the bike because starting it is so intimidating. They then end up with an elaborate piece of garage furniture.

If the Weiseco piston is heavier than the stocker, the piston maker can probably machine it to duplicate the stocker's weight. Or, they can tell you where you can safely remove weight from. Also, when ordering pistons from piston makers, you can usually specify what sort of dimensions you want and they'll make you a custom piston.

Not exactly relevant, but my stock 350 Sebring that has never been apart is dead smooth at highway speeds. To me that indicates that it was either carefully balanced at the factory or I just lucked out and got a good one.

the Wiseco piston Joe talks about is very heavy . between 573 and 579 grams .
i had J/E copy that Wiseco piston in 87 mm to and it weights less

the grooves you see in the top of the pistons are options . anti detonation grooves and the groove between the first and second ring is called a accumulator groove



Eldert

Hello, the rod is Honda 500XL, 1mm longer than stock Ducati 450. I use a .35mm spacer to end up with about 10/1.
Weisco have several different 87mm pistons for 900 bevels, 3 that I know of.
One is VERY heavy, one has a rounder top ridge and one has a flatter top.
I have the old piston boxes but they are in Tasmania (I'm in Brisbane until next week) so if you can wait I will tell you the Weisco numbers of the lighter ones.
You will have to bush the little end to fit the Honda rod if you want to go that way.
Graeme

Ps
Eldert, what's the vibration like with your balance factor?

Graeme

i cant say i have heavy vibrations by a certain RPM level . sure it vibrates a little but it is a big single without a balancingshaft .

if you wanne have a look at the Honda XL conrod and see some dimensions look up E bay item nr 400699646759

the Prox or Pro X part number for this rodset is 03.1553

Eldert