Just been cleaning up the 350 barrel before I take it to my machinist along with the crankcase halves to have them machined for the 350 barrel and I must have removed 16 of the little rubber absorbers (Japanese nomenclature) that go between the fins on the air cooled barrel. These ones wont do much absorbing as they are pretty hard... but the big question is.. .do they do much? I assume they are more for noise absorption than anything else. They are available as spare parts but they are a little expensive when you add in freight etc.. plus they look daggy when the barrel will be painted an aluminium colour.. if it was black it wouldnt be so bad... lol What are the opinions of the learned group we have in here on using them and not using them?
Vibration dampers most likely, as vibrations will be bad for the longevity of long narrow cast alloy fins in my opinion
I think you'll find that they do double duty - big pistons lolling about in air cooled cylinders make a lot of noise - my IT465 was noisy - so the noise will be suppressed somewhat if the cooling fins cannot vibrate in tune. The linear orifices can act as strange speakers radiating the sound. I remember walking past a building site on the other side of the road 40 metres away, the building was just support columns and two storeys - there was an earthmover behind them - the building focused the earthmover exhaust noise into beams that was like getting belted with the sound in waves along the street They'd also give a little bit of strength for if the cylinder collided with something hard
They are there to stop resonance noise which can also cause metal fatigue...you can soften up the old ones by soaking in three parts rubbing alcohol to one part wintergreen oil..
Try boats.net, they sell them in a set of 6 for $3.12 US and postage is normally really cheap, you just cut each one of individually, and they have paypal. (my 2x IT200 front fender's were $7 each posted) https://www.boats.net/product/yamaha/583-11127-00-00
Thanks all for the input... pretty much what I thought / knew. It was interesting to compare Boats with Megazip... I had a few other items I needed to order so I did the comparison and Boats was cheaper, not by a massive amount but they also had cheaper freight too so overall a good saving. It will be interesting to see how they compare to Megazip on the delivery side.. I found Megazip very good but I only purchased from the Japan store..
