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how to raise max RPM's
- hardr0ck68
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- Who put the what in the where?
Is it valve float?
Crank bearings?
Piston speed?
I have read that some folks say higher RPM's are not what it takes to make power... I have always been under the impression though that with these inline 4's higher rev's is the way to go.
**I just want to hear this discussed, I have no current build for which this information is needed but I do wonder what is needed to make it to 11,000-12,000 R's **
1977 kz650 c1
bought it because I was told it would never run again...I like to prove people wrong.
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- timebomb33
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1973 z1 2-1974z1-a,2-1975z1-b dragbikes1015cc+1393cc, 1977kz1000,1978kz1000,1981kz1000j, 1997 zx-11, 2000 z12r,1428turbo nitrous pro-mod and a shit load of parts thats all for now leader sask.,CANADA
I THINK MY POWERBAND BROKE
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- hardr0ck68
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- Who put the what in the where?
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I understand that the work to get a motor to turn like that won't be cheap...
Why is higher compression on the list? Wouldn't more squish slow the motor sown?
Do you think a motor with this work could be a street bike and reliable while still shifting at 11g?
1977 kz650 c1
bought it because I was told it would never run again...I like to prove people wrong.
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- timebomb33
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1973 z1 2-1974z1-a,2-1975z1-b dragbikes1015cc+1393cc, 1977kz1000,1978kz1000,1981kz1000j, 1997 zx-11, 2000 z12r,1428turbo nitrous pro-mod and a shit load of parts thats all for now leader sask.,CANADA
I THINK MY POWERBAND BROKE
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- PLUMMEN
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Still recovering,some days are better than others.
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- judgie
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stopping the valves from floating and getting enough fuel/air in out a 2 probs. stopping the thing from throwing its component parts all over the floor is another
have the same probs with the aircooled vw race engines i build, you can make them rev and make power but the faster you make it rev the more likly it will all end up on the floor in a big pile of broken alloy, have hit 9000rpm with my own vw motor.
it is fun doing it though.
cheers rob
forever tweeking aircooled engines, well it is my job
77 z650c1
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- hardr0ck68
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- Who put the what in the where?
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electronics, rev limiter any thing else?
Will the cam bearing surfaces (or crank bearings) need any coating to keep them from puking?
Someone I know told me to empty all the rotating mass out of the bottom end you can to make it spin up faster and he claimed that rotating weight in the engine robs you of HP.
1977 kz650 c1
bought it because I was told it would never run again...I like to prove people wrong.
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- Splandman
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Someone I know told me to empty all the rotating mass out of the bottom end you can to make it spin up faster and he claimed that rotating weight in the engine robs you of HP.
I was thinking this also. I don't have ANY experience building bikes, so anything I say is a guess.
I was just wondering, do they make lightweight pistons and rods to help you rev more quickly? If they do, are they suitable for street use? Is the cost so much that it isn't feasible for most people when compared to the gain you get?
Current Bikes
1980 KZ1000E
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- Mark Wing
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Jesus loves you Everyone else thinks your an ***
77 KZ650 C1 with ZX7 forks, GPZ mono rear, wider 18 police wheels and Yoshimura motor.
Yorba Linda Cal.
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- steell
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Maximum rpm is limited by piston speed and speed of airflow through the ports.
Maximum piston speed on the KZ motors is around 28 m/s (and that's really pushing it).
Max air speed through the ports is limited to the speed of sound.
Those are the "hard" limits, although maximum piston speed can be increased if you throw enough money at it (a la Formula One).
650/750 stroke is 54mm, 54mm x 2 = 108mm
108mm = .108m
.108m x 10000 rpm / 60 = 18 m/s
So, assuming you utilize the best alloy for the pistons, top of the line machining on the bore, and that nothing breaks (rods/valves/crank/etc), lets see what 28m/s will do.
28m/s = 28000 mm/s
28000mm/108mm = 259.259 x 60 sec = 15555 rpm.
So, the piston speed hard limit on the 650/750 motors is 15,500 rpm.
Above that limit engine life will decrease dramatically.
Although, if your pockets are deep enough, most things are possible.
KD9JUR
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- Splandman
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Current Bikes
1980 KZ1000E
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- hardr0ck68
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- Who put the what in the where?
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Soo with a hard limit of 15,500R's what do you think it would take to make a 6/750 handle 13,000 on the streets? Would 2,500 off of the hard limit be enough to keep the motor from meltdown?
Could it be done with the stock liners and wisco pistons or would the build need something more exotic?
Does anyone on these boards ahve a 6/750 that commonly take above 11,000?
1977 kz650 c1
bought it because I was told it would never run again...I like to prove people wrong.
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