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Redline on a 78 550. Just a suggestion?

  • Thread starter Thread starter Rustybottom
  • Start date Start date
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Rustybottom

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As stated above, I've got a 78 550 I've enjoyed for close to 10 years and I've grown very fond of it, and it's subtle idiosyncrasies. I did a quick search, but didn't really find what I was looking for about the 9000 redline on my 2 valve model. Cranking it in first I've been slow on the shift and run it up to 9500 or so a few times. Is this detrimental long term, or more of a either it explodes or it doesn't situation? The thing is that it pulls hard past the redline, so I'm instinctively not looking for another gear yet so have to keep an eye on the gauge. It's interesting, as it's the absolute opposite as my cousins Ducati a rode for a while. It didn't have a tach, so you had to listen, and shift when the power lagged.

I think the 4 valvers redline at 9500? Is this a valve thing? Or crank balancing?

thanks gang.
 
Hi,

Hint: Valve float.



Thank you for your indulgence,

BassCliff
 
valve float is what happens to me when I over rev, ya. I suppose some crazy stuff could come out the exhaust when that happens, but it should just fly out at ludicrous speed and not do any real damage yes?

Another thing about the Ducati is they have desmodronic (sp?) valves that don't use springs but are forced up and down with actual metal. Supposedly cuts down on float. Pretty neat, and likely expensive to maintain.

I blew an engine in my s-10 blazer over revving, the crank broke after the second cylinder bearing, obviously wasn't balanced too great.
 
Rustybottom said:
I blew an engine in my s-10 blazer over revving, the crank broke after the second cylinder bearing, obviously wasn't balanced too great.
Click to expand...

You think the engine exploded because it "wasn't balanced too great"?
 
Well, that and revving it like 3000 rpm past redline :oops:

I was young and silly.
 
I frequently take my 2V 550 up to 10k, and have seen reports from several other members who do. I recently got a shot of someone else's gauges on their 550LZ and 10k is where the red line was on that bike. Mine is marked at 9500. I don't think the gauges are original on mine though, but probably from an 80 or 81.
 
Ha! Well, I can still do the silly, but youth is quickly sliding to 40 this summer.:eek:

Mostly with my 550, when valve float starts happening, doesn't power drop off fiercely? That's what has me wondering about why it still feels strong if I sneak past redline. Realistically, I shift with my ears, figuratively, not literally, when the exhaust reaches a certain scream I know is 9000.

So is the valve float the main issue solved for the crazy race engines that zing up to like 14000 rpm?
 
There's no way you over-revved that S10 by 3 grand.

Think about it... 8.5~9000 rpms out of a S10? Ain't happening...
 
Well the redline was 6 grand, and I floored it in first/four low, and it revved high enough to fail. I didn't have a tach in it, so I'm really guessing, and it was almost 20 years ago...
 
My '77 550 was redlined every time I ever rode it, flogged it mercilessly. Far past the redline often. At 120,000 miles or so we rebuilt it due to oil leaks, but it still had great compression and ran fine. I rode it another year, sold it to my brother who rode it a few years flogging it almost as hard as i did, then sold it to some poor sap who rode it several more years. He never had a clue how many miles it had on it, my brother never told him.

Never broke anything, never floated any valves, no problems at all from over revving or anything else.
 
Rustybottom said:
Ha! Well, I can still do the silly, but youth is quickly sliding to 40 this summer.:eek:

Mostly with my 550, when valve float starts happening, doesn't power drop off fiercely? That's what has me wondering about why it still feels strong if I sneak past redline. Realistically, I shift with my ears, figuratively, not literally, when the exhaust reaches a certain scream I know is 9000.

So is the valve float the main issue solved for the crazy race engines that zing up to like 14000 rpm?
Click to expand...
14k rpm? The stock Gixxer 600's redline at 16k or something like that. They also have titanium valves. F1 engines go to 20k or so IIRC.
At the time our engines were made, the heavier springs to allow the engines to rev higher would result in parasitic hp loss and greater wear of cams/ followers. Also, Manufacturing tolerances and material quality consistency meant that redlines had to be kept at 9k to ensure the engines would live through the regular abuse and missed shifts we put them through.
I have buried the tach on my bike a few times and nothing ever broke.
 
That's probably part of it, if you are shifting at 12,000 it might not survive a missed shift.
 
Rustybottom said:
Well the redline was 6 grand, and I floored it in first/four low, and it revved high enough to fail. I didn't have a tach in it, so I'm really guessing, and it was almost 20 years ago...
Click to expand...
Fuel injected S10? injector drive cuts off the fuel around 6500.
 
I brought my 550 to 10k-10.5k rpm every time I accelerated for it would just keep pulling up high. I've accidentally buried the tach on a miss shift. My Old 16V GS750 didn't have much past 9.5k so I never crept into the red... However my throttle got stuck once and it buried the tach deep!!..(past 12k). Shut the bike down pulled it over fixed it and was pleasantly surprised to see the bike started and ran like nothing happened. Ran it for another 20k miles then sold it.
 
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