Iam Unbalanced

[Snowy 76]

Playing with early 73 CR400 Husky engine, spoke to a few people in the know RE performance tips/mods, got me thinking about balanceing. Crank, clutch basket , clutch hub etc, Can this be done ?, is it worth doing?, How do thay balance crank, conrod installed? Any info appreciated.  Birko

[Lozza]

Balancing won't gain any HP at all. I couldn't type that long to explain single cylinder balancing. Give me a ring one day when you have 2 hous to spare

[Tim754]

Into VMX that's OK,  I am into VMX Sidecars now that's unbalanced......

[firko]

Balancing won't gain any HP at all. I couldn't type that long to explain single cylinder balancing. Give me a ring one day when you have 2 hous to spare

I'm not going to argue the point here because I'm a Philistine on such issues but old Frank Stanborough has been balancing not only his own engines but those for Team Kawasaki and Honda back in the 70's when he was chief engine developer at both teams at different times. Today he does many of the top speedway, classic road racing singles and until the new batch of 4 strokes came along that are balanced pretty well from the factory, did engine balancing for many of the top line MX teams when 2 strokes ruled. He is soon going to do my TM400 and 400 square barrel engines because I believe him when he tells me it makes a difference.
I've never had a 2 stroke single balanced before so it'll be an enlightening experience for me.

[Lozza]

I take my lessons from Jerry Hall in the US and another kiwi tuner both have gone as high and as far as you can go.Both tell me that you only gain in one real area, that is over rev.That's what Aprilia do with their 58HP 125's, gains no power at all just lets them rev on further. Higher inertia or heavy cranks have been around for a while. Only recently have the real effects been isolated, and enhanced. Easy to write about but very hard to put into conscise words.

[Snowy 76]

 I`am about to drill a thousand holes in a very heavy clutch basket and hub,to lighten and maybe sparkle up the performance a bit, which got me thinking about the balance issue.

[Tim754]

Seriously  Snowy I did just that with great care, to a RT360 Yammy clutch set. It shattered causing grievous damage.

[maicoman18]

Mr Snowy 76
Did you subscribe to the Husqvarna Newsletter when Craig Comontofski was about? There was an article in one of those about lightening an engine and where to drill the holes.

Ed

[Snowy 76]

Thanks Maicoman, was sent the info this week will check it out before I start with the drill.

[firko]

I'm not looking for extra power with having my engine balanced. I'm seeing if it makes any difference to two engines that are notorious shakers. Frank likes to fiddle with balance factors so if it smooths my 400 Maico, then the reliability and ridability must improve. Methinks there's more to an engines efficiency than just horsepower and torque.

[holeshot buddy]

my alloy framed kx500 has a drilled and balanced crank
main thing i notice compared to my other kx500s
is that it is much smoother through the whole rev range
a bit like an electric train(on steroids)

birko those husky clutches are made out of good metal
drill away i did my 125  ask pete
i wouldnt drill a jap clutch though

[ba-02-xr]

How do you contact Frank. I have a KTM crank I want to be right before I assamble.

[Marc.com]

It is possible to improve on an early balance job or any given better balancing machines are available and you are doing a one off so can make the tolerances more exact than production ones/ hard bearing modern machine will out perform the old soft bearing designs.

The Harley guys mess with the balance factor (proportion you balance out to compensate for piston and rod mass and its location on the flywheel roughly speaking).

So power no, smooth running, quite possibly. Definitely I have seen stock cranks from Japanese bikes that can be improved.