Faster than a speeding bullet...

Tips and Recommendations from Guru Mike Nixon

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mikenixon
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Faster than a speeding bullet...

#1

Post by mikenixon »

Image
Image

I dug this up from my files the other day. I used to enjoy getting my mechanics students to think about, to consider, a piston reciprocating multiple times a second at high engine rpm. The above pictures were taken in 1984, by myself (Pentax K1000). They are of a Honda VF750S Sabre. The customer had had the bike serviced somewhere and not long after this happened. One of the rocker arm adjusting screw locknuts went through the valve cover (that's almost a quarter inch of cover thickness, and look at the size of the hole!) and must have glanced off the head as well--note the two cracks. Two things: First, consider the velocity that itty bitty nut had to attain to do this. It's mind-boggling to me. Second, not everyone is aware of this even today, but there was a Honda service bulletin on this problem that detailed the issue. It's more than you'll want to know about but all 1982 VF750s were subject.

Stare at that hole for a while. It's mesmerizing. :)
JSBail
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Re: Faster than a speeding bullet...

#2

Post by JSBail »

My youngest son had a first gen VF500 interceptor. It dropped a valve but believe it or not that's not what trashed the engine in fact when we tore it down I could've gotten away with just replacing the valve (no damage to head or piston). What killed it though was the small valve keepers had dropped into the crankcase and got between the oil pump drive and something had to give. The oil pump mounting bosses were shattered and the only way to fix that was new cases, my son ended up parting the bike out instead.
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5speed
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Re: Faster than a speeding bullet...

#3

Post by 5speed »

you haven't seen something grenade until you see an alcohol burning funny car turn the engine inside out at speed. :shock:
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mikenixon
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Re: Faster than a speeding bullet...

#4

Post by mikenixon »

I've heard about that VF500F valve deal...
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robin1731
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Re: Faster than a speeding bullet...

#5

Post by robin1731 »

5speed wrote: Tue Mar 02, 2021 6:28 pm you haven't seen something grenade until you see an alcohol burning funny car turn the engine inside out at speed. :shock:

What about a dragbike engine pulling a wrist pin out of the piston, then the rod sawing the cases in half? All while you are sitting on the bike going through the lights at about 160mph. dancr

Oh, all in about .1-.2 seconds. You hear a slight metallic sound then dead silence.

.
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Lucien Harpress
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Re: Faster than a speeding bullet...

#6

Post by Lucien Harpress »

I said it before, and I'll say it again.

Y'all motorcycle drag race guys are NUTS.
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5speed
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Re: Faster than a speeding bullet...

#7

Post by 5speed »

robin1731 wrote: Tue Mar 02, 2021 8:02 pm
5speed wrote: Tue Mar 02, 2021 6:28 pm you haven't seen something grenade until you see an alcohol burning funny car turn the engine inside out at speed. :shock:

What about a dragbike engine pulling a wrist pin out of the piston, then the rod sawing the cases in half? All while you are sitting on the bike going through the lights at about 160mph. dancr

Oh, all in about .1-.2 seconds. You hear a slight metallic sound then dead silence.

.
you win. :shock:
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