how to raise max RPM's

hardr0ck68 wrote:

Lorcan; running without boost, will the ignition hold till 11,000? Are the valve springs of today any better than those of the mid 80's? Do you think 100 streetable hp can be accomplished on a 650/750 without a turbo;)

The turbo ignition is quite different to that of the NA 750 in that it idles at just 10 degrees and only goes to 30 degrees max advance. Nowadays there are all manner of digital ignition boxes you can fit, some with pre-programmed curves and some fully programmable. I'm sure you could get 100hp from a streetable 750/810 without going to an 880. I'd start with a 83-85 GPz750 motor. Valve springs aren't really an issue as there would be no need to chase 11,000rpm+, a set of Kibblewhite or APE springs would be fine. I would go bigger on the carbs and keep the stock airbox, get Larry Cavan or someone equally talented (if that's possible!) to work the head, bump the compression up, and use a few other tricks like ceramic coating. I'm an EFI guy but I'd probably stick with carbs for a project like this to keep it authentic. Some turbo rods and gearbox parts would probably find their way in there though. Older readers might remember the Muzzy tuned GPz750 streetbike featured in "Cycle" magazine in the 80s, based on the '83 factory superbike. That's one bike I'd love to re-create, it's one of the sexiest bikes ever to my mind. I really must try to find that old mag in my collection.

Someone mentioned earlier the $$$ invested in my 200mph+ turbo. I can tell you it's probably a lot less than you think. It had stock rods and gearbox, a home-made lockup clutch, used pistons & rings, a home-ported head, all the suspension, brakes and wheels were sourced from ebay, secondhand GPz1100 throttle bodies, a used Powercommander off a ZX12, and the bike itself cost £695 from a breaker's yard. Yes I had some parts already and yes some were bought/made new, but I estimate the whole bike cost me less than £4000 (about $6000). Not cheap, but reliable 200mph+ is never cheap. I do have quite a bit of time invested, but no more than some others on this site, and I share nearly everything I know through my site (and sometimes this one) - you only have to ask. In fact I expect one of the guys on my site to outrun me soon, he's a professional R&D engineer whereas I am just a hacksaw and hammer guy!

Lorcan wrote:

I rev my 810 to 10k, which is the redline on a 750 turbo. It won't rev much beyond that anyway because the (stock) ignition breaks down. Well at 30psi it does anyway. It was completely reliable at 10k though.

My old 760cc race bike used to rev to 11k+ because it ran less boost and an aftermarket ECU, but that was for race use only.

The Harris F1 GPz750s (non-turbo) and the Muzzy GPz750 superbikes used to rev to 11,500-11,750 but they had reliability problems and regularly broke valve springs. They also had all manner of tweaky bits inside and made around 130hp.

I stood there at Pocono in 83 and watched Wayne kick the pants off a full grid of Honda Interceptors with the Muzzy tuned 750 What a satisfying afternoon that was....Everyone knew Kawasaki didn't stand a chance at another Superbike championship with all the Honda $$$$ and sponsored Interceptors filling the grid :laugh:

Back to the topic at hand....This should boost some encouragement for seeing a dream through to completion. I don't care what your financial status is at the moment. That's subject to change. No matter what the goal. If it's something you have great passion for, it can be accomplished...keep your head down, ears open and take everything that comes your way for advice as a possible element in the formula to success...

I received this email today. I'm not going to play name dropper to try to impress anyone but the source of this email is one of the most highly respected induction system specialists in the world. Yes, I said WORLD.

He's been involved with ProStock cars, ProStock Motorcycles, NASCAR, Land Speed Records, you name it, he's been there, done that and had success. When this guy tells me something, you can bet your last dollar that I'm hanging on every word

Here's the email:

"You must go to this web site and listen to the video on the top of the page to the left. Its a 533cid DCRE that Brad and I built. Its two carbs on gas and twists 8500-9000rpm wide fricken open for 5 miles. He set two records using just carburetors and the BIG record was set using race gas and a single 150hp shot of Nitrous. Guys have been trying to break this record for over a decade and we did it with an engine combination that everyone told us could not do it. The other guys are running supercharged BBC engines and they cant do it! Go to this web site and play the video. Make sure to turn the volume way up! Get ready to hear a not many normally aspirated engine screaming by at 390-400+mph turning 9000rpm.


www.rett.org/speed/speed.html

END OF EMAIL:

larrycavan wrote:

I stood there at Pocono in 83 and watched Wayne kick the pants off a full grid of Honda Interceptors with the Muzzy tuned 750 What a satisfying afternoon that was....

Immortalised in my Wayne Rainey shirt

That sounds crisp Larry! I didn't know if I could run an 8 on my 750 but I did that in 2000 and I didn't know if I could run 200+mph but I did that in 2006. My next goals are a 7 for the 750 (at 904cc and no bars) and a 5 for our Storm turbo bike and thankfully we are getting some great help from across the Atlantic towards that.

If you need inspiration look no further than Joe Amo and his 1987 Kawasaki ZX10 that was timed at an unbelievable 272mph last month, beating every open-wheeled Busa on the planet. Make the impossible possible!

WOW.....look at those numbers! What is that old saying? Your attitude determines your altitude. You bet it does

Good Stuff Lorcan.....Very good stuff

Hardrock

You can check out this article, it's on pro stock car motors. I think you may find it interesting.


This one is on raising RPM's:
www.rehermorrison.com/blog/?p=201

Here's one for air flow:
www.rehermorrison.com/blog/?p=275

I read all their blogs on the left side of the page. It's about cars, but it does work on bikes.

Hardrock

I wanted to add alittle more, I hope it helps you with your project. The following is a quick quote, from Rob Muzzy in an issue of dragbike.com

The subject was about "billet engine cases", bore spacing and some of the new rules. In this part of the article he talks about piston speed. Please take it, for what it is worth.

“No matter how you look at it, when it comes down to the bottom line, engine size and RPM dictates the horsepower” he explained.

“Ultimately what really limits the RPM is piston speed. Piston speed is directly related to the stroke. The longer the stroke the greater the piston speed at the same RPM.

They should have limited the bore spacing to 93 mm which means you can only do 89 mm bore.

This way 2 valve and 4 valve motors would have the same stroke. They would therefore have the same RPM limit.

So there shouldn’t be a huge difference in performance between the 2 valve and the 4 valve.”

“If you can take a 1655 motor and turn it at 15,000 RPM instead of 14,000 RPM it will make more horsepower. Period.

Just spinning even modern liter bikes faster doesn't yield a higher max HP.

Modifying the engine certain ways is what moves/increases the max HP/power band into higher rpms. Then, if you've made the right strengthening and cooling changes, you can operate the bike at those higher rpms.

Rocket science? Nah.

GL.



Cheers!

PS. I've only ridden one of the above bikes, but can attest that the power starts to flatten out at around 10000rpm. Just after the torque starts to dip. Ramping them right to redline really isn't useful for anything but top speed.

I was tired of this thread, but it kept eating at me. Two reasons! Was it possible to make 100+ hp at very high rpm's and still be streetable? My second reason was, it's alot easier to put a guy down, then to lift him up. I thought I could do better, to help someone else with their dreams and goals.

After thinking long and hard for a few days, I think that it could be done, and still be streetable.(and on pump gas)

I have done my own math on this and will post it tomorrow night. I would like others to check it for me?

Thanks for any info you can provide. I am still constantly reading this thread, some very good ideas have been mentioned.

I just don't dare to post new questions, as it seems some folks have become tired of my constantly asking "why?, why?,why?,why,?" :laugh:

but I will take any help i can get!

hardr0ck68 wrote:

Thanks for any info you can provide. I am still constantly reading this thread, some very good ideas have been mentioned.

I just don't dare to post new questions, as it seems some folks have become tired of my constantly asking "why?, why?,why?,why,?" :laugh:

but I will take any help i can get!

All I can say is, no one is forced to read any thread here. I have been told, WHY, is an improper question, but I ask it a lot.

People have given a lot of good ideas and shared what they know. Sometimes it helps us, as much as it helps you.

I will post my answer later, I want to look it over once more. I worked on this until 2am this morning.

ask away the more questions get asked the more answers that we as a group can come up with. as i always tell my students i can't read minds so if you don't ask how can i help you find the answers.also maybe it triggers some one elses memory and a whole new train of thought start firing away.