79 honda 750F, Race inspired Muscle for the street.

fagancl85

New Member
Im brand new to DTT as well as the bike building scene. It took me a little while to find a group that does have helpful information that appears to be based on facts rather than opinions. So I would like to apologize in advance if any of my questions come across sounding like a complete noob or are "dumb" with obvious answers to some of you out there, so also thank you for your patience and any direction or help that you can offer. I also apologize for this next section, it is a little long winded but I believe it is important so you know where I am coming from.

First, a little background about myself. I grew up in my dads garage, a run down barn with a dirt floor. It seemed like whenever I was with him, we were out there. From when i was very young, just screwing around and being more trouble than help while he worked on his jeep, to when he helped me fix my first car to help me get it on the road. Ive been around wrenches all my life but never thought it could take me anywhere. So with that mindset, I went to college for 4 years for architectural design and engineering. That field both the education and the jobs i held really developed my eye for design and enjoyment of creating something from nothing out of my own head, but also taught me that it wasn't my true passion and wasn't the field for me. While yes, I was reasonably successful and I don't regret any part of it because of what it made me, and without it, i would have never met my wonderful wife, nor be expecting our first baby girl sometime this week. But it taught me that i was miserable behind a desk and that my creativity was going from my head to paper and morphing through client changes and product changes and paperwork and more paperwork, turning into something so far away from my original idea that it was becoming almost unrecognizable. This needed to change. So with support and protest from my wife (at that time fiance), I went back to school for automotive, one of those highly advertised, and extremely overpriced tech schools we all see plastered all over the internet and tv. This particular campus though, located near Charlotte, NC, the hub of racing in the united states offered courses in fabrication and high performance race engines and really appealed to be as i was looking to get into the custom car scene. The coursework helped me to build on the skills I had learned alongside my dad, develop many new ones, and my previous career and education helped with building these new skills and even landed me a 6 month internship at one of the most prominent engine building shops for everything from dirt late models, to road course cars, drag cars and even into the highest ranks of Nascar. But as school came to a close, I had offers to work in many other big name shops and many different areas, whether it was chassis fab, engine building, sheet metal fab, pit crew, you name it, the opportunities were there. But it was not home, was not with my family, and I returned home, in much of the same situation i left architecture in. From there, I landed at a local dealership, scraping by on flat rate pay, when it just wasn't making ends meet anymore, i took a job as a maintenance mechanic at a milk processing plant. not the most glamorous gig but it pays really well and is supporting my growing family and affording me other opportunities like the one that I am reveling here. Ive always had a passion for motorcycles and had always wanted one, while i was working at one architecture firm the money was great and allowed me to buy my first, a 2008 Triumph Daytona 675. Incredible machine, absolutely amazing bike. But then i met my wife... and no, she did not make me sell it because she hates motorcycles, she actually had her own and was slightly pissed when I sold it. That quickly passed when she saw the ring I proposed to her with, buying it with the money I got for the bike. She still tells people that I'm an idiot for doing that, but then looks down and smiles at her ring. And with that she gave me her bike to ride, A 2001 Buell blast. For most, a starter bike but for me with my limited funds, it was my only bike, and was surprisingly a fun little bike to get around town on, decent low end for twisties although heavy for its size, but for my log ride to my new job, it was a little cramped and and the RPMs screamed at speeds higher that 45-50mph due in part to the Vance and Hines Pipe she had previously added. So with a little conversation and her understanding of my need for a creative outlet the Buell has been sold and i am at my current place, with my new project that I found.


I searched for a long time for a bike as a cafe project and was really leaning toward the SOHC Honda 750, primarily because of their parts availability lately due to popularity, but was having trouble finding one in good enough shape at a low enough price point to start a project. Then i came across the ad on craigslist for the bike that i ultimately purchased, a 79 cb750F that i had to have a buddy go pick up for me due to me working an evening shift, so i never got to see the bike until it was in my garage.

(tried to insert photo here - couldn't figure it out--> me=noob)

I had spoke to the guy and knew it was pretty rough, didn't run, and needed quite a few pieces to even try to get it going. None of that really scared me because i know i have the majority of the skills to get it going as a stock bike if i really wanted to. But I don't...
After running some numbers it was indeed a 79 cb750F... Frame... the motor checked out as a 1981 cb750k. Slightly duped but still not scared, it was still one hell of a deal.

This bike came with a bunch of extras:

+Some Stock Parts
-Extra 1981 750 motor (Cylinders and head Removed)
-Extra 1981 750 Case (Upper and Lower Halves)
-Extra Stock Clutch basket with new frictions and steels
-Headlight Bucket
-Misc.

+Some "Not So Stock" Parts
-900 Cylinders
-900 ported Cylinder Head
-Wiseco K985 kit, 5.5 Overbore 10.25:1 pistons,rings, wrist pins, gaskets (New-In-Box)
-L.A.Sleeve H-113, 67.5mm Cylinder Sleeves(New-In-Box)
-Megacycle Cams, 138-x4 Cams, I-open:24BTC, I-close:60ABC, E-Open:60BBC, E-Close:24ATC. intake and exhaust both .355"lift, 264 duration, 108 lobe separation (New-In-Box)
-Kibblewhite Valve Springs, 30-1017 (New-In Box)
-Lifter Buckets, shims, retainers and keepers (all New-In Box)
-Undercut Transmission Gearset (New-In-Box)
-Aluminum drag racing rear sets and struts (new but never installed)

So for the $800 for the complete package of everything, I don't feel like I did too bad. You can tell me I'm wrong, but i could probably part the bike and sell everything off and at least break even if not come out ahead, and that was my reasoning.

And Now this Finally brings me to the build!
My overall vision can best be described by a phrase I read in another forum on this site by a guy who calls himself "bananas"in his monoshock build post (http://www.dotheton.com/forum/index.php?topic=55821.0) and was one of the deciding factors in me joining DTT. Bananas described his 79 cb750 Limited build a "cafe-inspired muscle bike." this is very close to the direction i want to go. Being stripped down to the bare minimum for both form and function, throwing as much power as possible to a the rear tire but going to a more modern to make it handle with the big inverted forks, low bars and broad tank and give it a stance like that of a pitbull, muscled up like its not to be messed with ans the power to back that up.

There is a laundry list of things i want to do and accomplish with this bike, and I will continue to update as things progress, but my first order of business is in the motor. After speaking with the previous owner, his initial plan was to build a drag bike with the components he had selected but then found an 1100 and decided to build that instead. I for one like to do my homework and make sure I have the proper parts that i can put together and it looks as though he has a pretty good set up. and was planning on using the 900 cylinders and head in combination with everything else to do his build. There are just a few Specs that i have not been able to find so i can decide on a combination. those are the connecting rod lengths for both the 750 and the 900, as well as the deck heights for the 750 and the 900. These I'm assuming, along with the things i already know like stroke, valve lift, and gasket compressed thickness, etc., should help me determine the actual displacements and compression ratios as for a few combinations i have in mind, as well as determine what i am most concerned with and that is piston to valve clearance. I really don't want to smash a valve with those brand new shiny pistons because of an oversight.

Here are the combinations i am considering,

-750 case, 750 crank, 750 rods, 750 cylinders new sleeves bored to accommodate wiseco pistons, 750 Head with Megacycle cams
(worry about piston to valve clearance with new pistons and new cam lift)
-750 case, 750 crank, 750 rods, 750 cylinders new sleeves bored to accommodate wiseco pistons, 900 ported Head with Megacycle cams
(worry about piston to valve clearance with new pistons and new cam lift and losing some compression if combustion chamber larger)
-750 case, 750 crank, 750 rods, 900 cylinders new sleeves bored to accommodate wiseco pistons, 900 ported Head with Megacycle cams
(not as worried about piston to valve clearance because i know deck height is larger but losing some compression if combustion chamber larger)
-750 case, 900 crank, 750 rods, 900 cylinders new sleeves bored to accommodate wiseco pistons, 900 ported Head with Megacycle cams
(worry about piston to valve clearance with new pistons and longer stroke with new cam lift and some compression)
-750 case, 900 crank, 900 rods, 900 cylinders new sleeves bored to accommodate wiseco pistons, 900 ported Head with Megacycle cams
(worry about piston to valve clearance with new pistons and new cam lift)

I do understand that changing rod length alone really only effects where the piston travels in the bore but know that can also have effects elsewhere as well. Please Take a look and and give me some insight or if you know some of the specs I have been looking for, please, let me know. Thank you for all your input.
 
Build a Freddie Spencer replica
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Looks great. I just finished my race inspired 1980 CB750F. It's huge, heavy and still wild to ride.
 
As far as deals go, I'd say you got a good one (actually a great one)!

As far as the bits go, I'd think long and hard about what you want to do with the bike once it's done.

I ran a CB750FA for years and, even with the motor in relatively stock trim, I found the most cost effective improvements were to be had with the rolling chassis. Those CBs are heavy old lumps and, unless you're planning on long distance touring (as if!), sharpening up the brakes and suspension will help you keep it between the hedges when you turn things up to 10. Let's not forget, a stock bike in good shape should be able to hit 130mph although the stock rolling chassis makes that a scary place to be. I'd be the first to admit that there's nothing as cool as a tough looking motor that's dripping excess horsepower but if you can't get it round corners without a change of underwear then maybe it's time for a rethink.

A word about drag focussed engines, I once had the misfortune of owning a Z1100R that was fully road legal and capable of 11.5 sec 1/4 miles (timing slips to prove it - although not with me at the helm). I was suckered into buying it because it looked great and sounded evil but I soon discovered the power delivery was like an on/ off switch. I ended up selling the engine and dropping in a mildly tuned Z1000 - it still looked and sounded great and, as a bonus, I could hold an even speed through traffic!

Long story short, get the chassis sorted with the mods you mention, run the stock motor to find the bike's handling (and your) limits and then ask yourself: "How much more power can this thing cope with?". That way, you don't waste time/ money/ effort on an engine that doesn't deliver what you want, or how you want it.

And, yes, Freddie Spencer replicas are cool, that's official.
 
I apologize for the long delay, was a little busy over the last few months with a new baby. she has taken a lot of my time which i would not trade for the world. But I have also made a little progress since my last post. I understand the concern with streetability with drag focused bikes and i think it was misunderstood as being a street legal drag bike and that's not it, I just want it to have that kind of look and since the bike came with the 900 parts, I figured I would try to use them to gain a little more displacement out of the 750 case. Ive vaguely seen on other posts on a few different forums about being able to convert the top end with the 900 parts but nothing based around how it was done, problems that could arise or additional parts that are needed. So if anyone out there has done this or can point me to someone who has and can provide me with some good info or tips, i would really appreciate it.
 
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