Author Topic: Vintage Racing  (Read 2253 times)

jefferson

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Re: Vintage Racing
« Reply #40 on: November 12, 2017, 12:10:37 PM »
Was it running hot at the time?. Both of my spun rod bearings were when it was getting hot. No other problems except for those 2 incidents and it was always the rear cylinder that spun. I would really like to know why the problem always manifests itself in the rear cyl. rod bearing.

Dean

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Re: Vintage Racing
« Reply #41 on: November 12, 2017, 07:03:32 PM »
The engibe temp was 3/4 in the green but I did over rev the engine.

I was in a corner right behind another bike and rather than keep an even throttle I accelerated to close the gap waiting to up shift at the corner exit. The bike over reved trying to close the gap. Two corners after when I down shifted I felt the tire wanting to lock up.

When I slowed down to exit the track was when it locked up tight.
You do not need a therapist if you own a motorcycle, any kind of motorcycle! Dan Aykroyd

Rikugun

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Re: Vintage Racing
« Reply #42 on: November 13, 2017, 08:16:36 AM »
Was the lean angle extreme or moderate and was it a long sweeping turn? Oil starvation at the pickup was a thought but others have raced these bikes with no ill effect so maybe that is just a contributing factor.

Was this a high miles engine?  To your knowledge was it ever run low on oil? Maybe the design is such that the rear rod is just a more vulnerable item. Coming from the filter, it looks like maybe the mains are given preference over the rods? And, of the two rods, the rear gets oil last. If pressure is low - high miles/wear at all journals, brief periods of starvation, etc. - maybe this is just the mode of failure on these engines.
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jefferson

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Re: Vintage Racing
« Reply #43 on: November 13, 2017, 07:17:46 PM »
Neither of my incidents was the engine in the red, but just in the upper regions of normal. Your overrev probably didn't help anything, but I don't think it was the cause of the problem. I also found  that I went faster if I shifted earlier rather than revving it out. These things have a strong mid range and run out of steam in the upper ranges. My tachs always quit on me and I just shifted by sound. Yours may be different with the different exhaust, but that is what I found with mine.

QBS

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Re: Vintage Racing
« Reply #44 on: November 13, 2017, 09:05:31 PM »
I have found that shifting at 9-9.5k drops the engine into the early to mid part of the torque curve.  It loves to operate there.  It loves to climb through the torque curve.  There seems to be more to be gained there than hanging on to red line and beyond.  I often short shift in normal traffic.