Topic: Lightweight engine

[xedge4lifex]

After going on a short cruise last weekend on my 76 550, with my friend who has an 06 599 hornet (carbureted), it got me thinking how in the world can 50cc's + 30 years of technology = 50 extra hp. after looking online for titanium big bore kits, shaved crank weight, lightweight top end parts. and misc lapping of gears and or some race trans i could see being lighter. any vintage engine probably couldnt drop more than 15-20lbs. i understand the reduced drag / ease of turn could easily turn a stock engine making 50hp stock into a 60hp engine without doing anything to directly improve engine consumption.

has anyone built a full on raced out 750 or 550 engine, aside from rene? i was looking over her post
( http://forums.sohc4.net/index.php?topic=63228.msg688538#msg688538 ) and couldnt seem to find anything about total engine weight after the build. paulages crazy build via the intensive machine work is way outside my budget, but obviously probably the best 550 build out there. have there been any dyno'd 750 engines producing above 85 and weighing less than 160? or 550s that produce more than 65hp and weigh less than 145?

i understand that my 76 550 will almost never be competitive with a new sport bike, but someone out there knows the secret of how; two engines of the same basic construction and displacement can make a difference of 50hp.

im all ears!

[scottly]

It is more cost effective to reduce weight in the chassis than the motor, and reducing the weight of the motor does not mean the motor will make more power. It is the horsepower to weight ratio that matters as far as vehicle performance.

[MaaseyRacer]

The 500/550 Rear wheel is just over 50lbs. with tire.  Swapping wheels to a dirt bike wheel set up reduces weight so much.  Both my front and rear wheel together are sub 20lbs. without tires. With tires and tubes both wheels will probably weigh in at 40lbs. Which is still less weight than just the rear wheel alone.

It would probably cost a fortune (although be wicked fun) to lighten and build up an old SOHC engine. Ti Rods, and valve train, Lightened crank and gear box. Machine out the crank cases. The engines are super heavy on these bikes and I am sure there is a ton of room to shave weight. Though this will probably not net much more power if any.

I am very curious about new style carbs on these older engines and how they perform. Someone in the hi-po section of this site is running kawasaki zx400 carbs on his 400F, no mention of results yet though.

[754]

 Your head design is putting the brakes on huge power gains, as far as comparing to newer engines..
 Every single piece on your bike, except maybe the cam, is heavier..

[Retro Rocket]

I am using a billet aluminium block with no sleeves, just nikasil bores, also a lightened crank and rods, back cut gears and modern alloy 1000cc pistons. I will weigh the engine when it is complete just for curiosity's sake....

Mick

[xedge4lifex]

It is more cost effective to reduce weight in the chassis than the motor, and reducing the weight of the motor does not mean the motor will make more power. It is the horsepower to weight ratio that matters as far as vehicle performance.

im down to 395 from the stock 420.

MaaseyRacer - what kind of dirtbike wheels are you talking about? pic?

retro rocket -  yeah that would be an awesome figure to see, where did you get your block from?

squirly did a 02 gsxr front end i believe, i would assume that would shave around 15 lbs too.

and unless your going to a carbon, alum, or mag frame i cant see dropping the weight down too much more. aside from obviously the seat, tank, and pipe.

[scottly]

That should be as light as it gets, Mick. How about the rotor? Have you lightened it as well?

[Retro Rocket]

retro rocket -  yeah that would be an awesome figure to see, where did you get your block from?

Forum member "Mike Rieck" did a run of 6 blocks if my memory serves me well. I am using GSXR 43mm right side up forks and GSXR wheels and alloy swing arm as well so it all should be a bit lighter, no centre stand or unnecessary brackets either....


Scottly, i am considering the VFR800 rotor another member has used on this site,it is physically smaller and allows for about 18mm to be cut from the rotor cover, it also has a higher out put...

Mick

[scottly]

im down to 395 from the stock 420.

I'm trying to get my 836 below 400, "street legal".

[MaaseyRacer]

I should start a build thread. I am shaving a ton of weight off the chassis, and the wheels are probably the largest weight savings I have found.  I am running Talon hubs and excel rims.  DRZ400SM front Talon hub and a XR650 Rear hub. I am almost done with the front end of the bike. The rear end is still at the machine shop. I still need to get a custom brake line made.

I wish I had researched wheel choices a bit more, it seems that the CRF250 and 450 hubs are the same weight if not lighter than the Talon hubs, they can also be sourced for a lot less. Those would have reduce my wheel costs probably by close to half. I am running an 18x1.85 in the front and a 18x2.15 in the rear.  My front fork is from a CB500T, my triple clamp is a custom build by TTR400, and this is going on my CB350F Frame, with a CB400F engine.  I have the engine, CR26 Carbs, and Webb #3 cam.  I need to buy the 54.5mm pistons soon, and get this show on the road.

I also just got some sheet carbon fiber for my electronics tray. My goal is sub 300 lbs. wet 

I can take photos in the morning, as of right now it is fairly unexciting as everything is in pieces.  

[turboguzzi]

65hp from 550c.c. is race tune territory, you will not like that on the street, believe me. Check some of my threads too and getting 60hp from a 500 was not easy.

secret for power? four valve heads, good ports, big carbs, water cooling (allows +11:1 CR on the street), 20% more displacement, short bore/stroke=13,000 rpm redline, here are your 50hp's in 30 years.

and BTW in real life a stock 550 would give 40rwhp in a VERY good day, more likely 35rwhp, a fresh 599 80rwhp, same motor in CBR state of tune 100rwhp.

weight wise, you can get a 500/550 down to 145kg, 320lbs, but no lights, no starter, small battery

not much in it really

TG

BTW rene is a boy

[lordmoonpie]

KOS regularly gets I believe over 100bhp from his 'factory' 750 M3 Racing engines. He's the inspiration for my build and although I'm still playing with the ignition and haven't dyno'ed it yet, I hope to be well over 90bhp with mine and secretly I'm hoping for near 100. It's also 750cc, not a 1000cc big bore job.

The problem is if you try and take 30 (nearly 40?) year old technology and pump out modern power in it, you'll end up with something that is either very very fragile or will cost you more than you care to look back on. 100bhp 750s are possible but they will never be cheap...the same will apply to the 550 which let's face it is essentially the same engine design.

[bwaller]

You probably have two reasonable choices if you want to feel good,

1) Buy a new sport bike to keep up with your friend or
2) Find a new friend with an original Norton Atlas or the like. 

Honestly, you can read about a handful of guys right here who have thrown money at improving where Honda left off, and they will all tell you the same thing, the improvement is way fun, but buy a new one if you want to keep up with friend #1.
 
You're on the right track by reducing weight with the 550, now improve the brakes, handling & tires, as well as a little more ooomph in the engine department. It still won't compete with thirty years of advancement, but you won't recognize the bike anymore either.

The smile on your face will be bigger than friend #1 and that's pricless.

[mlinder]

As others have said:

It's mostly head design, and the water cooling, which give the new bikes more power.

You can shave off bits of weight here and there on the valvetrain and drivetrain, which will offer higher safe RPMs and moderate increases in performance, but you are limited by your combustion chamber and valvetrain.more than anything else. Unless you want to create a head from scratch, you're stuck with cam, porting, and displacement and their diminishing-return characteristics on a 40 year old engine design.

[iomtt9]

Hi TG .... 63.69 bhp at rear wheel, from 498cc.  Its a heavy bike with a fat bloke on it , but its all about having fun at our age !!!
Last weigh in for the bike in Assen, when Howells went tits up, was 159 kgs. It went ok last weekend at Cadwell Park.

[xedge4lifex]

thanks for all the awesome advice. a newer sportbike (probably f3 cbr600) is in the future. but that was the whole reason i got into vintage bikes, IM BROKE! haha that and they look rad. i could see a streetable 550 down to 350lbs, with about 55-60whp after about 5-700 in mods, pending the labor is all in house. or a 750 around 450lbs making 75-80whp, in the same.

i work at a kz 900-1000 specific restoration shop, and from time to time we get dudes coming in, spending SERIOUS cash on a hopped up engine. were talking the big bore, built head, lightweight rods and pistons, the whole engine done up with all the fixins. and have had a couple (from what ive heard) make 120hp. not sure if its crank or wheel. either way, my engine being of the same time period, half the size, shouldnt have a problem making 1/2 the hp.

only in dreams

thanks again guys for all the imput!

[Syscrush]

You probably have two reasonable choices if you want to feel good,

1) Buy a new sport bike to keep up with your friend or
2) Find a new friend with an original Norton Atlas or the like. 

Sorry for resurrecting an old thread, but this post was so awesome I have to reply with a big smile!

[DannyBhoy]

Same as SyScrush. I was hoping that some of the questions that has been asked would start to generate answers and data for the rest of us to ponder.
Love to hear more about total weight of some of these large $ big bore mills.
Cheers
Dan

[kayaker43]

I remember staring at a cylinder head for a 500/4 MV Agusta that Hailwood rode. The sign said 100 HP, and that was sometime in the 60's I think? It was in a glass case at Mid Ohio vintage days a few years ago, I wish I had more details.

I considered smashing the case and running for my life,.. then I remembered I have vintage knees

[turboguzzi]

I remember staring at a cylinder head for a 500/4 MV Agusta that Hailwood rode. The sign said 100 HP, and that was sometime in the 60's I think? It was in a glass case at Mid Ohio vintage days a few years ago, I wish I had more details.

I considered smashing the case and running for my life,.. then I remembered I have vintage knees

just like with manufacturer's claimed power, don't believe everything you read.... power at motor is good only if you can stick a wheel to the crankshaft , so 85 at the rear wheel is more like it.

makes sense considering these MV motors where four valvers, had sky high red lines and were built to last one-two races between rebuilds (and that comes form Arturo Magni's tales). Not sure how it all translates into building similar power small sohc motors...

TG

[bwaller]

Hell Doug, I'd have paid to watch you hoof it away with that prize in your hands. Man what a great visual. 

[kayaker43]

Hell Doug, I'd have paid to watch you hoof it away with that prize in your hands. Man what a great visual. 

Ha,.. I've been tempted before too. I was walking by the tire tent at Road America when I spotted one of the carbon fiber comstar type wheels that Freddie spencer was using on his 750F. I asked the tire tech if I could pick it up thinking it must be amazingly light?

He handed me both wheels then said sorry it took so long to change tires. I had a Honda shirt on and apparently he thought I worked on the race team. I could have been long gone before he figured it out but I couldn't keep a straight face

Freddie should thank me for being so honest...

[Sam Green Racing]

TG

BTW rene is a boy

That should put you on his Christmas card list Yossef. but it would make Yjro a baby.

Sam.