The best engine power at RPM zone

Long story short - as I am a little bit crazy, I decided to try a luck on moto drag. The category is A2 - lighter than 270kg and under 750cc. As now my '85 XJ700N is working perfectly, I couldn't resist to prove that this old classic precious can drive not as bad as newer streets. As I talked a lot about the strategy with the other guys, one said that every bike has the best RPM zone, where engine gives the most power. As I read all the manuals, I couldn't find any information about that.
So the question is, is there any official information about this zone, or I just need to test it out by myself?
Thanks!

 

These bikes come "alive" at around 5k

 

^^^ Once you get past 5k make sure your feet are firmly planted on the pegs, your grip is tight on the handle bars and then just TRY to stop smiling. Because that is when you will hit the 'powerband' and the bike blossoms.

 

... and when you get past 7000 rpm, the vtwin folks start to panic!

 

built to run at red line.

 

Have to love these bikes.......love 2nd and 3rd gear......the power and the pulling strength of these 2 gears when pushed to their limit...........

Awesome speed when taken to redline

 

Don't look at the Tach it's distracting. Your best bet is to go by how the bike feels. When you wring the bike out through the gears you will notice when the bikes power starts to drop off, in my experience going all the way to red line will not always produce the most power. Then again that's just me. Ride it, feel it, you will notice.

 

I was just making a point of 2nd & 3rd gear being the best 2 gears on this bike......the shear power & pulling strength of these 2 gears......I didn't mean above to take to redline for these 2 gears.......if fact.....I have never taken my gears to the redline.....about 5K - 6K RPM range is about when I shift out of these 2 gears.....if I am getting on it...

 

The XJ motahs are usually pretty bullet proof, and can run higher up in the rev range....all day long

 

Wow, thanks everyone for a reply!
I just strated to study the torque and its benefits. So by all specs, the most power is given by 7500 RPM. Then the power to the wheels is decreasing. So I think that's where I need to keep my highest RPM, and around 8000RPM I need to change the gear. Going to do some tests about it. I will keep you noticed!

 

That sounds right to me. I have an old Cycleworld article with drag times and engine test data. I'll pull that out once I get back nome from vacation.

 

On my 650 Maxim it's fairly mild up to 5K, then at 5K it starts to wake up, by 7K in 3rd gear the needles are just flying up the scale and it will quickly peg my speedo that stops at 85mph before you hit 4th . I love how much power is packed into these things, even a lot of decent modern sport bikes suspect nothing until they're eating my dust

 

These bikes have awesome power when dialed in......I love rapping 2nd & 3rd gears.....& 4th as well......by then I am flying down the road with my Hardley passing Harleys

 

A fried of mine has a modern water cooled, fuel injected, 750cc sport bike, and of course he can beat me easily but we were both shocked by how well my Maxim can keep up. Not as a big of a difference as I would have thought!

 

I've taken the UK spec 750 ones past 130, on the speedo, 'course, probably only 122-125, at best, the 650 is not THAT far behind, the Maxim I owned, well, not quite as fast, mainly because of the peg/bar ergonomics.....they will ALL happily sit at 90-100...all day, every day!!!

They can weave a bit, north of 110........

 

XJ650 torque peak is at 7200 RPM, and horsepower peaks just barely under redline at 9400. Xj700 should be similar, right?

Generally, you would shift somewhere ABOVE the horsepower peak, how quickly depending on how fast horsepower declines as RPM increases. You balance the better torque multiplication of being in a lower gear vs falling horsepower from running the engine over the horsepower peak.

Most Street small block Chevy's will reach peak HP at 4500-5500 RPM, and will shift around 6500.

Obviously with a 9400 RPM HP peak, and a 9500 RPM redline, running the bike as fast as possible would mean exceeding redline. Xj700's have a rev limiter, right? On my 1981 XJ650, there is no rev limiter. The bike wants to pull strong approaching 12,000 RPM, which is where I think the fastest drag shift would be. I don't know what design spec led to imposing a 9500 redline on a bike that easily pulls straight past that. I'm not advocating ignoring the redline as your valvetrain coming apart at above redline operation would be awful, but the power curve of the bike seems that fastest means faster than redline.

With a rev limiter, running the bike as fast as possible involves shifting right before the rev limiter engages.

 

I let my neighbor, a bike fan going way back, take my XJ550 for spin this summer. He came back grinning and could only say, "That is the hardest running 500cc I've ever seen. It really moves..."

 

Broken parts, and the risk of warranty claims.
Remember that they were trying to beat Honda in the world market, so while Yamaha was pushing envelopes in some areas, they could not afford to have a string of mechanical failures across their new model line.


The data I thought I had is a time to distance, and time to speed, graph for the Seca 750. The article does list peak HP occuring at 9,000 RPM, and peak torque at 7,400 RPM (per Yamaha).

 

Mine all pull hard up to at least redline.......even occasionally crossing redline and STILL pulling hard

 

Yup. You can't really shift "by feel" on the bikes without rev limiters, because you will get to 11,000+ before you feel power fall off.