4 valve balance shaft engines

So you're saying me at 68 have less years ahead of me than before, never noticed that before you mentioned it. Ok.
 
Vince said:
Reducing vibrations is the whole point of these gadgets, Chris. One of the Honda XR 250s a mate owned had a chain driver balancer; the chain was stuffed, that chain was loose as a goose and had allowed its weight to move from its correctly timed position. The vibrations became insane plus distructive. I guess there are restrictive loads generated by driving these shafts, so I expect that when not driven, engine power would increase. But in the case of these engines, people would have direct experience of what happens with them connected and not connected to both power and vibrations. There is zero chance of me doing this to my Atlas, but I would like to understand the effects.
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...yes remember those, and bought an XT250 back in the day because it had a gear driven balancer😁 Not sure why the XT500 I now have apparently has none....and a manual decompress or rather than the auto on the 250.
 
XT 500s are older models. From my hazy memory that Honda XR 250 had some rabbit hole engineering for its time, like Honda tended to do back then, like a 23-inch front wheel that no one can now get a tyre for now. My favourite was a twin chambered carb on that single-cylinder engine; that carb was bloody complicated to work on. At least my Atlas as a twin needed, maybe not, but handy anyway, a 2-throated carb. What's your XT like to start hot? The flogged out 2 I had were absolute barstards to start hot. The number of times I would crash them on tough off-road hillclimbs and end up with a heart rate of close to 200 beats per minute, kicking it millions of times trying to start them, horror memories. Great when they went, huge traction, instant wheel stand while spinning the rear just off idle. So much low-down torque from those 2 valve motors.
 
Vince said:
I have read a few times about removing these shafts on road race bikes to increase power and reliability. Will that produce the vibes contained by their action? What's the story regarding this mod?
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I did a full engine upgrade on my Gpz900r, which involved fitting the internals and top end of a Gpz1000rx into the original 900r crankcases. Wiseco big bore kit, weight matched pistons and rods to less than 0.05gms each, +1mm oversized valves . Yoshimura Street profile cams and ported head. There were two additional potential modifications that I had to take into consideration, and decide whether to do. The first was the crankshaft: Should it be dynamically balanced, lightened and knife-edged? The second was: Should I remove the balancer shaft? The second question is connected to the first. The answer to the first question is no, because the bike is being used for the road, and not track and a) won't be expected to work in the high RPM range for extended periods that a race prepared crankshaft is designed for and B) retaining the standard crankshaft is more desirable for lower RPM performance. The answer to the second question is: No, because unless the crank has been dynamically balanced, the presence of the balancer shaft is more benificial than it is being absent, for vibration damping.
Based on that long-winded description, my answer is no for road riding and unless you dynamically balance the crank, removing the balancer shaft isn't worthwhile for the gains obtained from losing rotational mass and frictional losses, which will be fairly minimal, and likely add to your riding discomfort.
 
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I did some digging in the Atlas parts book, and the washer that shims the neutral switch spec is Aluminium and measures 14.25mm x 23 mm x 1 mm. Ordered a packet of 10 off the net. Might fit the 3c and Atlas case drain plugs as well. Maybe.
 
Vince said:
I did some digging in the Atlas parts book, and the washer that shims the neutral switch spec is Aluminium and measures 14.25mm x 23 mm x 1 mm. Ordered a packet of 10 off the net. Might fit the 3c and Atlas case drain plugs as well. Maybe.
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For adjustment reasons, they were offered in 0.5mm as well by the factory.

Too soft and thin for oil drain plugs Vince, stick to copper.

piet
 
Vince said:
I did some digging in the Atlas parts book, and the washer that shims the neutral switch spec is Aluminium and measures 14.25mm x 23 mm x 1 mm. Ordered a packet of 10 off the net. Might fit the 3c and Atlas case drain plugs as well. Maybe.
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Hi Vince, did it work?
 
Vince said:
Haven't tried yet, my tin shed isn't fun at 40 °C. Will post if it works. Hop
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We have the opposite, 5c but dry today. At home it was sunny but became foggy. Unfortunately a trailer had to bring me home.
I think some trouble in the tank and now in the carburetors.
 

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