Author Topic: Honda 750 Nighthawk  (Read 19461 times)

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Offline wobblywalrus

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Re: Honda 750 Nighthawk
« Reply #15 on: March 28, 2011, 10:01:52 PM »
This is the second of two posts.  Honda 100's are on the bottom of Bradley's graph.  The Nighthawk will be closer to the top.  Bradley's upper and lower curves are shown.  Disregard the dots.  They are for Triumph and I add a couple each year.

Offline Gimpy Joe

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Re: Honda 750 Nighthawk
« Reply #16 on: March 28, 2011, 10:20:06 PM »
Wow! Thanks for the information Wobbly. I didn't know it was possible to calculate top speed precisely. I figured someone would just say "maybe around a zillion miles an hour, give or take."
I'm assuming the full formula is in the section of this site that lists various LSR-related math. My math is a bit rusty but I will give it a try.

Offline wobblywalrus

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Re: Honda 750 Nighthawk
« Reply #17 on: March 30, 2011, 12:33:33 AM »
It is not possible to be precise with any method except running the bike and looking at the time slip.  The graph gives a rough estimate.  Probably plus or minus 10 mph.  It is a start.   

Offline Gimpy Joe

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Re: Honda 750 Nighthawk
« Reply #18 on: March 31, 2011, 01:09:56 PM »
That makes sense. Precise is a relative term haha.

What other books besides Bradley's should I buy? I want to learn as much as I can before I start building. I'm still waiting to get my hands on a bike. I've got the money. I just haven't found the right motorcycle yet.

Offline Old Scrambler

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Re: Honda 750 Nighthawk
« Reply #19 on: April 02, 2011, 03:48:34 PM »
Joe...........if you still looking for the bike, take a look at www.sohc4.net for a lot of good info on the older Honda 4-cylinder models.  When or if you move up to more modern bikes, you will find the competition gets very interesting. If you notice..........the number of competitors is somewhat split between modern power and very custom older models.  There also appears to be a growing interest in having the fastest bike of a particular model without regard to an AMA or FIM record. Hope to see you on the short track........
2011 AMA Record - 250cc M-PG TRIUMPH Tiger Cub - 82.5 mph
2013 AMA Record - 250cc MPS-PG TRIUMPH Tiger Cub - 88.7 mph
2018 AMA Record - 750cc M-CG HONDA CB750 sohc - 136.6 mph
2018 AMA Record - 750cc MPS-CG HONDA CB750 sohc - 143.005 mph
2018 AMA Record - 750cc M-CF HONDA CB750 sohc - 139.85 mph
2018 AMA Record - 750cc MPS-CF HONDA CB750 sohc - 144.2025 mph

Chassis Builder / Tuner: Dave Murre

Offline Gimpy Joe

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Re: Honda 750 Nighthawk
« Reply #20 on: April 02, 2011, 10:51:25 PM »
Yes sohc4 is a great site. I currently ride a CB750A Hondamatic and love it. I would use it as the basis for my lsr bike but unfortunately it isn't that reliable. If I can't find another motorcycle I may tear down the Hondamatic and race it after all. We shall see... :evil:

Offline Nortonist 592

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Re: Honda 750 Nighthawk
« Reply #21 on: April 03, 2011, 12:55:32 AM »
Allowing for what you plan to do and what Lady Bonneville will take away 130 should be a realistic target.  If you keep your expectations realistic you won't be disappointed.  Its also highly addictive.  And thankfully there is no known antidote.
Get off the stove Grandad.  You're too old to be riding the range.

Offline wobblywalrus

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Re: Honda 750 Nighthawk
« Reply #22 on: April 03, 2011, 01:38:16 AM »
Joe, on the subject of books.  Most of my library are old books that are hard to get and and articles clipped out of 40 years of magazines.  Some useful newer books are Rick Voegelin "The Step-by-Step Guide to Engine Blueprinting" ISBN 978-1-884089-26-8, David Vizard "How to Build Horsepower" ISBN 978-1-93470-17-7, and Harold Bettes and Bill Hancock "Dyno Testing and Tuning" ISBN 978-1-932494-49-5

A thought on the bike choice.  Eventually a person is going to need some strong racing rods and pistons, bigger or better valves, stronger and better quality springs, hotter cams, etc.  Honda was, and is, constantly changing their designs.  It is hard for an aftermarket company to justify the tooling, research, and development for racing parts when the design is limited to a few model years of life.  Some of the other makers such as Harley, Triumph, and Kawasaki keep their designs for longer periods.  There are many more racing parts available for these.  Take the modern Triumph Bonneville I ride as an example.  The heavy ill handling beast is the slowest bike Triumph makes.  It has been in production for a long time and a large volume were sold.  There are far more aftermarket parts available for it than any other modern Triumph.  


Offline oz

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Re: Honda 750 Nighthawk
« Reply #23 on: April 04, 2011, 01:39:08 PM »
you are spot on there Wobbly,Every single bit of the engine work on the CBR has been a complete nightmare, everything has had to be made one off and usually on your side of the water (USA)
If I had thought about it before I had started I would have researched availability of parts but unfortunatley I am too far into the project to change now.
So Joe before you go too far you may want to think about it very carefully old hondas are not the easiest of bikes to source go faster bits for but on the plus side, Strong and over engineered and forged cranks as standard.
Oz
Newcastle born and bred a City built on Coal and Steel and a people built of stronger stuff

Offline Gimpy Joe

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Re: Honda 750 Nighthawk
« Reply #24 on: April 04, 2011, 02:11:25 PM »
Maybe I should turn my '76 CB750 into the racer instead of buying the Nighthawk. There are millions of parts for CB750's. Any thoughts?

Offline oz

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Re: Honda 750 Nighthawk
« Reply #25 on: April 04, 2011, 02:41:05 PM »
Millions of parts definatley but performance parts I dont really know, I would imagine that there were plenty in there day but are they still available? it would pay you to make some inquirys I guess.
As long as you are enjoying what you are doing and aint too bothered about colossal horse power figures either would be ok I would probably opt for the CB rather than the nighthawk but that would just be a personal preference.
I would certainly make some enquirys before you commit though it will save money and headaches later.
Newcastle born and bred a City built on Coal and Steel and a people built of stronger stuff

Offline Grandpa Jones

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Re: Honda 750 Nighthawk
« Reply #26 on: April 04, 2011, 03:01:35 PM »
Gimpy Joe,

If you decide to run the CB, check out this forum;

http://forums.sohc4.net/index.php

There is still aftermarket support for the CB, and the members of that forum
can steer you in the right direction.

Cheers,

Dave

Offline oz

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Re: Honda 750 Nighthawk
« Reply #27 on: April 04, 2011, 04:15:21 PM »
I just had a quick look at that site I would go for the CB750!!! lots of good gear available by the looks of it.
Newcastle born and bred a City built on Coal and Steel and a people built of stronger stuff

Offline Old Scrambler

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Re: Honda 750 Nighthawk
« Reply #28 on: April 04, 2011, 04:46:10 PM »
Now you guys are finding the good stuff.................take a look on the high-performance page for all of the different motor builds.....and look how reliable the CB750A drag bike is at 10,000 rpms............Also search the site for the most recent builders looking for improved torque.  Then take a look at www.cyclex.com or something like that..............and we have not yet discussed the proven turbo power options..........There are roughly a half-million CB750 sohc/4 motors in the US...........Oh, and if you want a stroker, just drop a crank from a CB900 into the stock cases........along with the hyvo-chain and a Goldwing clutch basket......about as bullit proof as you can get.........just ask the builders that still perfer these motors in the midget dirt-track racing.

I think you can tell what my next build project will be for Bonneville.........just have to prove myself with my Triumph Tiger Cub so I will know my way around on the big white place on the earth with no speed limit signs.
2011 AMA Record - 250cc M-PG TRIUMPH Tiger Cub - 82.5 mph
2013 AMA Record - 250cc MPS-PG TRIUMPH Tiger Cub - 88.7 mph
2018 AMA Record - 750cc M-CG HONDA CB750 sohc - 136.6 mph
2018 AMA Record - 750cc MPS-CG HONDA CB750 sohc - 143.005 mph
2018 AMA Record - 750cc M-CF HONDA CB750 sohc - 139.85 mph
2018 AMA Record - 750cc MPS-CF HONDA CB750 sohc - 144.2025 mph

Chassis Builder / Tuner: Dave Murre

Offline Nortonist 592

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Re: Honda 750 Nighthawk
« Reply #29 on: April 04, 2011, 09:53:20 PM »
I'd definitely go for a CB750.  A ton of speed parts are still available. 
Get off the stove Grandad.  You're too old to be riding the range.