Great technical articles from Jaguar, question about piston wrist pin location

Drilling out the pin usually does the trick. But engine compression is a big factor also. Everyone should change out the wrist pin bearing.
 
Okay I guess I'll try that, drilling out the wrist pin, and changing the bearing, wow this is like starting over. Got to find a better way to go than this, John:eek::eek::eek:
 
Since no one sells the lighter wrist pins then we need to look online for a source.
Here's the dimensions of the stock wrist pins:
48cc piston: 33mm x 10mm dia.
55cc piston: 37mm x 10mm dia.
60cc piston: 37mm x 10mm dia.
Looking just now I found these:
Honda Hobbit 33mm x 10mm wrist pin $9 [site]
Yamaha QT50 33mm x 10mm wrist pin $9 [site]
Generic 33mm x 10mm wrist pin $9 [site]
Generic 36mm x 10mm wrist pin & bearing $13 [site]
Generic 36mm x 10mm wrist pin $9 [site]
I'm going to ask the sellers for the inner diameters of these pins.
 
the QT50 wrist pin is perfect for our use since it has a bigger 7.5mm inner diameter. All 48cc engine owners need this item unless they like engine vibration.
 
You'd have to measure the wrist pin. To see if using a lighter one would help you should stuff the standard one with something metal to see if the vibration gets worse. If so, then you should try a lighter pin.
 
Ludwig II said:
There are dynamics involved, it might be that torque is improved at the expense of absolute power and slightly reduced crankshaft acceleration.
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A longer rod has been proven to increase torque by allowing greater piston dwell at top dead centre; holding the piston at top dead centre and slowing down piston decent for a greater period of crankshaft rotation, however it slightly reduces peak power compared to a shorter connecting rod, for various reasons.
 
JVROOM said:
Thank you for your reply, no I haven't tried that and I haven't changed the bearing either, will that help reduce vibration? Anxiously awaiting a Walbro carb. Sincerely, John
Click to expand...

A single cylinder engine cannot be balanced. All you can do is play around with the balance factor to alter the rpm zone where the engines gives the least vibration.
That said, a single cylinder engine will vibrate (by design), no matter how much you alter the reciprocating weight.
 
That is true, from my experience the 48cc engines have less vibration in the useable rpm range for normal riding. My grubee 48 vibrates the least of the three engines I own, after notching and ramping the piston it is fairly light.
 

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