Kawi2strokes.com Forum

I have 3 Wiseco +.080's here, which weigh 249.5 g each, they are the same weight. I don't think you can "balance" a Triple crank without it being assembled, and having the rods spinning somehow, I mean you can't balance a triple crank like you can a car engine crank....... Maybe the crank guys can advise?

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"One day, your life will flash before your eyes. Make sure it's worth watching." : anon.

Exactly!
It seems ( to me) you should get the pistons to weigh the same.
Match the crank end of the rods, then total weight of the rods.
Spin the crank assembly and balance (without the rods ) then assemble the crank.
Can't see spinning with the rods attached. Simular to inline 6 (no bob-weights)

From what I can envision, a triple crank really doesn't have any natural balance at all. It's pretty much three single cylinders engines next to each other. A four can have two going up while two go down, for example. So all we can do is try to make each single cylinder section correctly counterweighted. So then the question becomes what is the right rod configuration and piston weight for a stock triple crank? I sure don't know enough to answer that one. I'm pretty sure that to get a really balanced triple engine, we'd need at least one balance shaft.

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If it surges, that's normal, upshift.

That's right, and a balance shaft would be err, problematic........

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"One day, your life will flash before your eyes. Make sure it's worth watching." : anon.

A smooth h2 is a rubber mounted motor. The 3 cylinder design screams "vibration".

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Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........

WOW, .0027, that is worn out for what I do for clearances. I've never seized any H2 piston at my spec of .0013 to .0015, not even the rirst really bad forged factory ones. I see no reason to bore and hone an "already worn out" clearance into a cylinder and piston. I feel a lot of piston issues are from people going bonzo with clearances, and not keeping them as tight as reasonably possible. And, it all depends on the metallurgy, and expansion rate and consistency of the piston being used.

retro, these balance the same way any engine does, rods end for end, both ends, bob weights on the pins, etc. One thing I do when I do mine is to short press the main wheels together, so they won't have two full press operations for balance and assembly, and I made pins that were held in place with nuts on the ends, so the real pins don't have to be pressed into place for the balance operations. I simply add or subtract from the bob weight to mimic the overall pin weight.

I do my own cranks, have done so since 1972, when I worked in the road race department. I also build my own aluminum center seals.

I build a lot of the fixtures and tools I use for engines, cranks, whatever, etc., H2 is no different.

Tuner, someone mentioned "balancing a triple crank" in another thread, and I began to wonder how they did it without assembling the crank (without the rods), balance, then disassemble, install rods, reassemble. Thanks for confirming my thoughts on this.
I'm a believer in balancing rotating parts. Most production engines have range of acceptable imbalance.
But, when you change to aftermarket rods, pistons, it could bump you out of that range.
I balance high performance rotating assemblies regularly, also Clutch/ Flywheel assemblies.
Heck, I even balance my lawnmower blade

Sorry, Thread hijacked unintenionally

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Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........

retro, yes, there are ways.
the main things are, don't press the entire crank all the way together, just enough on the main axles to keep it togehter, and it must be aligned straight, with the phasing correct. then, if you make crank pins like I did, that are removavble, that you can set the bob weights onto, that's the way to do it. Of course, it goes to say that all the crank pins that will go into the crank need to be balanced to the same weight, big ends of rods, bearing cages, thrust washers, big, then small ends, and overall of the rods, and the top ends just like we do in a 4 cycle engine, bike, car, whatever.

The only things that get balanced differently are rotating assemblies that use a balancer shaft, and airplane engines, as they have a floating counterweight. That is the clank in them as they reach almost full loss of rotation when they are shutting down.

And, keep the piston clearances reasonable, don't bore them to already fully worn out clearances, makes for a better engine, less vibration, noise, more power. I have found that piston clearances can be set a lot closer with most pistons, and, haven't ever had problems doing so, in any engine I have built. I can't remember all the people with noisy engines I have asked what bore clearances they had, but all of them were significantly looser than I would have set them.

The first factory H2R forged pistons were so bad, we'd break a set in in two laps, they'd fully collapse the skirts in the next 3 laps, we'd go about gearing and jetting, then, for the next day, we'd put a new set of soldiers in. On race day, we'd new piston between the last testing session and the race. The Yamaha stuff I worked on, and Salaverria's Aprilia, we'd set a new set of pistons up for one race weekend, then, run 'em all weekend, then pull apart between races, new rings only most of the tme, and go around again the next race weekend. They'd go a good two full races on one set of pistons. The Yamaha and Aprilia pistons were pressure spin cast, they worked very well.

Dave you consistently act like you know more than the piston manufacturers about their product. SO, if you want to keep up recommending tighter clearances than the manufacturers, then you need to post your address and phone number so guys can bill you for the damage as there will be total carnage by your words, if they follow your advise.........

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Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........