Author Topic: Am I crazy? Thinking of changing frames when so close to finishing project  (Read 1282 times)

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Offline Dracon

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Sorry in advance for the long post…  I'm stressing myself out trying to decide where to go with my project and figured I would get the opinion of all of you who know these bikes so much better than I do.

What I want out of the finished project is a motorcycle that is fun to cruise around on and not too expensive to maintain.  I don't care a whole lot about performance. I know that these bikes are capable of great performance, and it's not that I don't appreciate that, but this is a bike that will be used for the fun of cruising around, listening to the motor, and enjoying the classic look of it.  Here's where you can insert the comparison of a bike looking pretty sitting outside of Starbucks versus one that stops better and is faster on the street.  I don't go to Starbucks, but yeah, I guess I care more about the looks on this one then extra performance from stock -  if my father-in-law ever reads this I'll never hear the end of it…

Anyway, I bought a '78 750K with a blown motor that I had planned on taking apart and rebuilding from the frame up. While looking for a super sport gas tank I came across a '78 750F that would start, but had some charging issues. It was in good shape and a good deal so I bought it and started fixing it up instead. I never took the motor out of the frame since it was still running but I did rewire the bike, order several new parts to make it my own, and other than a few cleanup items it is close to being finished - By finished I mean ready to sort out any remaining charging issues and then make sure the carbs are tuned right.

The things I don't like about this bike are the wheels, and the guy I bought it from detabbed the frame and cut off the tabs for the stock airbox, oil tank, and electrical and battery compartments.  I keep looking over at the 78 K with its spoke wheels and fully intact frame and thinking how easy it would be to just move everything from the bike I've been working on over to it. Of course by doing that I will lose the disc brake in the rear and the dual disc brakes up front. The price to put spoked wheels on the super sport almost makes it an impossibility for me.  I've looked at all the options of replacing the spoke ring, swapping wheels from other years, and the gl1000 swap.

Am I crazy for thinking this way? Are there any other difficulties in basically moving the drivetrain from a F bike over to a K bike and using only the K frame, wheels, and forks?  I know it will not stop as well, but other than that am I missing anything big?

Thanks!



Offline lrutt

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If it's just going to be for cruising, all those extra disk brakes really won't matter. just swap motors.
06 Harley Sporster 1200C, 06 Triumph Scrambler, 01 Ducati Chromo 900, 01 Honda XR650L, 94 Harley Heritage, 88 Honda Hawk GT, 84 Yamaha Virago 1000, 78 Honda 750K w/sidecar, 77 Moto Guzzi Lemans 850, 76 Honda CB750K, 73 Norton 850, 73 Honda Z50, 70 & 65 Honda Trail 90, 70 & 71 Triumph 650s, 65 Honda 305 Dream, 81 Honda 70 Passport, 70 Suzuki T250II, 71 Yamaha 360 RT1B, 77 BMW R75/7, 75 Honda CB550K, 70 Honda CT70

Offline Geeto67

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I'm stressing myself out...

Stop. It's a motorcycle. If it is causing you stress get rid of it and get a different hobby.

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I don't care a whole lot about performance. I know that these bikes are capable of great performance, and it's not that I don't appreciate that, but this is a bike that will be used for the fun of cruising around, listening to the motor, and enjoying the classic look of it. 

There is caring about performance and then there is common sense. in just reading this mental gymnastics to justify your decisions I can tell a few things: 1) you aren't a very experienced rider, 2) you haven't had your first close call yet. 

I want you to think about this for a second - when the cb750 was new it was in traffic with drum brake cars that were better measured in yards to stop. It's greatest danger in braking was outbraking the chrysler imperial behind it. Now a 10 year old Honda odyssey can out stop you by several feet (im going to say more than 10). I'm not saying it's unsafe to ride a bike with the old tech brakes, I rode a 75K into Manhattan for almost 20 years, but it won't be all that forgiving if you don't have experience. Last weekend I had to use all the brakes on that same 75 750K to stop because of an inattentive driver - had I not had 25+ years of riding motorcycles, reading traffic, anticipating people's actions, sharpening my reaction time, etc...I probably would have been inside someone's car. Sometimes performance is going above and beyond, but sometimes it is just catching up with the traffic around you.

Anybody who just says "I am going to cruise around on it" is lying to themselves. You can't control the chaos of the environment around you. You can't keep a dog/squirrel/skunk/racoon/deer etc...from running in front of you, you can't keep someone you don't know from drinking and driving, or cellphoning and driving, or yelling at their kids and driving. You can't control your misjudgement in the face of peer pressure. If you really are a gearhead at some point some compulsion is going to take over and you are going to get on it in front of a crowd at your local cars and coffee before you realize you don't have enough room to stop before that red light.

If you want spoke wheels - own that decision. Understand the risks and weigh the consequences. Compensate for the added risk in other ways (like real gear, not a stupid 3/4 helmet and some vans) be honest with your self. don't make up excuses about "i'm just going to baby it" or "it's not here to race around on" because they are lies. I'm not saying don't do it, but if your lying to yourself, maybe that's your conscience saying you aren't ready for this yet.

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Am I crazy for thinking this way?
Crazy? no, you just have your priorities mixed up. riding a motorcycle is all about managing your risk. Not just the risk the bike presents to you, but the risk you present to yourself and everyone else around you. Right now you are not doing a good job of that because it's more important to have a cool looking part than a sound functional motorcycle. It doesn't sound like you bought a motorcycle to ride it, so much as look at it, to which I say - if that is most important, make the K as pretty as possible, park it in your garage and just stare at it in a lawn chair. You'll miss out on a lot of stuff by not riding it but you'll get what you want. Or you can make your motorcycle run, stop, ride, etc...and use it like a motorcycle.


 
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Are there any other difficulties in basically moving the drivetrain from a F bike over to a K bike and using only the K frame, wheels, and forks?  I know it will not stop as well, but other than that am I missing anything big?

There are no issues other than you are hoisting a big honking engine out of both frames and it's a lot of detail work unhooking and hooking everything up proper. anything of significant difference is in the chassis. you are basically swapping a black painted engine to where a silver engine was. To do it right and dial it in properly it is more than a weekend's worth of work for a novice.



« Last Edit: August 04, 2017, 02:34:15 PM by Geeto67 »
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Offline Dracon

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Maybe "stressing out" is a little dramatic. I'm just so anal about projects that I constantly think about every option...

Originally had added some of my motorcycle experience in my first post, but then took it out. I'll add it back in now…

I have had a few motorcycles in the past. Started off at 12yrs old with dirt bikes when all my friends had quads and I took the MSF course at 16 to be able to ride Harleys with a friend whos Dad had several bikes - I still think the MSG course should be mandatory for a motorcycle license... Ive owned everything from brand a new sport bike off the showroom floor, an old kick start only Sportster 1200 that a friend's dad let me have for a couple years, and a Ducati Monster 900s, I've taken Keith Code's weekend super bike course at Barber Motorsport Park, and I also enjoy just cruising down country roads enjoying the sound of the bikes engine.

As for close calls, I've had too many to remember them all - 3 stand out as the closest and most scary, but those are for beer talk. I've been with friends when they've gone down on the interstate at 80 miles an hour and shattered their wrist with the bone sticking out – actually got my picture published in Superbike magazine in the road rash section several years ago next to him for that one.  Other friends have simply been coming to hot into corners and not made the turn and wrecked, my father-in-law's partner's husband (say that quick) lost his leg last year from a motorcycle wreck.  Somehow with all of my close calls and the bad things that have happened to friends of mine, I have managed to not actually put a bike down myself - KNOCK ON WOOD!

Let me also say that I don't consider myself a bike expert by any means! The only reason I said any of this is to let you know my background and that I think I'm reasonable with what I expect out of this project.

Sure at some point I'm going to goose this one a little. I know this... but if I was going for performance (I mean no disrespect) I would have never considered a sohc cb750... If the urge strikes, there's a cbr954rr I can take out any time. But unless we start telling every single owner of a K bike that if they don't upgrade their brakes they are inexperienced riders, I don't think my question makes me one...


Offline ekpent

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 Sounds like moving the engine over to an unmolested good solid K8 frame would make for a safer ride then a hacked up F bike ;)  Riding these bikes is just a simple matter of knowing their limitations as you are aware of I am sure.

Offline TwoTired

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Gonna be tough to mount the F's stock 4 to 1 on the k, I think.
If you do the 4to4, keep the k carbs,  but I still don't think the stock jetting will be right, as the F engine has bigger valves and hotter cam.  But, you'll learn a lot while tweaking it in with jet selection and carb adjustments.
Red line is different on the F.  But, you can swap tachs. 

You do realize that once you do all this swapping, you'll wind up with a bastard bike.  And all this to have spoke wheels?

Personally, I prefer a riding experience, to style maven demands.  If it works good, it looks good to me.

So yeah, I think you are probably crazy.  But, its likely that it is peer pressure driven.  I tend not to listen too seriously to peers.  Different goals, and all that.

If you won't weld on new tabs to the frame, check out rubber cushion mounting straps.

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

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Offline seanbarney41

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here is my thing...the 78f is the better bike, in large part because of those ugly ass comstars.  Comstars are rounder than only the finest spoke wheels, and are gonna stay that way unless you crash them into something really big.  Honda's steel spoked wheels are heavy, not very round or true (especially when in 40 year old dilapidated condition), if they do happen to be fairly round and true they will not stay that way, ugly when dirty, garden variety common, and anybody who cares about riding motorcycles just sits there and says to themselves "this guy must not care about riding his motorcycle" when they see someone go out of their way to have #$%*ty steel rims and spokes when they can be replaced with something better.  Bottom line is you can't see what wheels are on your bike while you are riding it, but you sure as hell can tell.

If I were you, I would swap the F2 forks, swingarm and wheels onto your unmolested k frame and save that 77k from an eternity of being the nerd bike that it is
or
build the F as an F, hang out here lots and get some deals on parts so you can put dual discs on the k, lace up some nice aluminum rims, and what up NOW, two bad ass cb750's...!
If it works good, it looks good...

Offline BomberMann650

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I think having the oil tank tabs would be motivation enough.

Offline Dracon

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or
build the F as an F, hang out here lots and get some deals on parts so you can put dual discs on the k, lace up some nice aluminum rims, and what up NOW, two bad ass cb750's...!

I though about this - just finish the F and then strip the K and start from the frame up on it while I have the F running.

Then when the k is done I could strip the F and turn it  into a light as possible cafe with a hidden oil tank and battery since the tabs are already gone.

Offline 754

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Putting it in the K is a few days work  for one not used to it.
Remember, you can go dual disc on the K and have good stopping. Or swap the F fork onto the K frame.
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