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 Cylinder saga

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66T

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PostSubject: Cylinder saga   Mon Mar 13, 2017 2:28 am

Hi there everyone. Only read on if you are expecting a book...

30,580km, 1685 engine hours: It was discovered that all the dirt my poor bike had swallowed wore the cylinder, piston and rings beyond an acceptable level. I think the dumping of all the coolant in a split second due to a torn-off radiator hose might've finished it off. Very light bore scuffing, but that's it. A std bore Athena cylinder kit was fitted, and damn fine quality it is. Much quieter than stock rattle-wise, too. BUT, on my bike with this particular cylinder, when used for slow sheep work in the outback, the temp light came on in ambient temps of more than 35deg C. Slow running only. And this was useless to me. Checked all possible reasons for overheating; radiator cap, thermostat, coolant, fault codes. All ok.

32750km, 1811 engine hours: Bit the bullet and replaced fork seals and bushes (again), and the cylinder with a genuine Yamaha assembly. The Yamaha cooling jacket design is quite different. The piston rattled much more than the Ahena assembly right from the start, but apart from a brief appearance of the red light first off, it suffered no overtemping even in mid-40s heat. Just like it always used to be. Ran like a champ. Has now done upwards of 36,000km and about 2000 hours. Except that another fuel pump died. This one had done about 20,000km and >1000 engine hours. You've got to be happy with that. Anyway, I am.

So that's basically it. My bike still rides like a new one in spite of the bashing it's had through thick scrub and rocks in hot, coldish and indifferent weather. Fiddling with the suspension settings has restored its original 'safe' feeling, though that's not a word you can bank on, I admit.

In no way am I criticising Athena here. Imo, they make a very good product. I just happen to have used my bike well outside its design envelope. I also believe that my bike would never have overheated using Athena at any time in normal use, from city work to high-speed flogging. It would always cool off within a kilometre enough for the light to go out once the engine was used up and down through the gears. I'm not sure about this, but the Athena seemed to have higher compression than stock. The fuel we use is 95RON, but sits around, often in above-ground tanks for quite a while, so that might go some way to explaining things if that's so.

End of book. Sorry...





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rsteiger

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PostSubject: Re: Cylinder saga   Mon Mar 13, 2017 7:24 am

Nice write up.

Good info on the overheat issues with the Athena. I am wondering if the fit of the piston (ie rings) was too tight leading to more heat generation. Also makes me wonder about the overbore kits since they are likely to generate more heat but yet the cooling system is not sized for that.

Granted myself and most of my friends who ride WRR's do not push their bikes as hard as you do which makes your reports a gem!
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66T

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PostSubject: Re: Cylinder saga   Tue Mar 14, 2017 7:28 pm

Thanks Bob. I have no doubt most people ride harder than I do - as in faster. The only good thing about the way we have to treat our bikes is that they are usually started and run for long periods without fully cooling off. What I hate most is hard clutch-slipping in rocky hills! Try to avoid it, but which is worse? Clutch slip, or slogging crap out of the engine? Either way = abuse. Same in sandhills. Poor bikes.
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