Topic: The Hot Mess - 1975 CB550F1 Frame/1981 CB650 Engine

[SOHC4 Cafe Racer Fan]

This is my back-burner project.  It is a distraction while I work on my Bionic Mongrel CB750.  I need another project like I need a hole in my head, but I have not been able to put this one out of my mind.

I love the pull and power of my 836cc CB750K7 Restomod, but I sure wish it wasn't as heavy.  I love the handling of my stockish CB550K1, but I wish it had some more power/torque.  I want the best of both worlds - a street bike that is light and nimble as a CB550 package, with the grunt of an 836cc engine. 

Now commeth The Hot Mess:  a CB550F frame with a 1981 CB650 engine stuffed into it.  Not any CB650, but a 650 with a Dynoman 674cc kit with 10.5:1 compression and a mildly ported head (at least until I save my nickels for something more on the order of a Mike Rieck job).

Let's start with the frame.  I picked up a rolling chassis 1975 CB550F1 on the cheap from a listing on craigslist.  It had not been registered for many years, but not long quite enough to fall out of the California DMV system.  Of course, the guy who sold it to me (and told me it was out of the system) only gave me a bill of sale, and I did not have a chain of title documents, bill of sale or release going back to the last legal owner.  AAA told me I was out of luck without a release from the legal owner, but of course would not give me the owner's information.  I could have done a DMV records request and waited a month, but I contacted a DMV expediter I know and she was able to cut through the red tape and get me a title.  Whew!  And she got me a waiver of the back fees, too!!

image_zpsbvf9nfsg by Donald Leonhardt, on Flickr

image_zpszejhyqhh by Donald Leonhardt, on Flickr

image_zpsgxuhte5c by Donald Leonhardt, on Flickr

[flatlander]

sounds like a good idea. i'll be watching this.

[Bigsam302]

Sounds like a pretty cool project.  I can't wait to see how it turns out.  I wish that I would have done the same and got a little back burner project to work on while I am waiting to finish my 750.  All this waiting is driving me crazy and I keep spending money changing things and making adjustments.

[SOHC4 Cafe Racer Fan]

So there are some parts already sourced for The Hot Mess.  This project was the successor to a prior back-burner 550 project that turned into a flip.  So most of those parts are slated for this one.

This includes a 2007 GSX-R600 front end:

7_zps669f5464 by Donald Leonhardt, on Flickr

A Cognitomoto hub:

CM1_zpsc075e992 by Donald Leonhardt, on Flickr

CM2_zps6cd05546 by Donald Leonhardt, on Flickr

CM3_zps3221acca by Donald Leonhardt, on Flickr

And a used TTR400 swingarm from a fellow forum member:

boxedswingarm_zpsc83ae0d7 by Donald Leonhardt, on Flickr

[MessnerMoto]

Nice project! Also nice hub from Cognitomoto. Can you tell me the weight of the hub so I can compare it with my hub

[SOHC4 Cafe Racer Fan]

Nice project! Also nice hub from Cognitomoto. Can you tell me the weight of the hub so I can compare it with my hub

Messner,

I'll weight the hub and let you know.

Don

[Retro Rocket]

In for the ride...

[Bootsey]

This should be interesting.

[MessnerMoto]

Nice project! Also nice hub from Cognitomoto. Can you tell me the weight of the hub so I can compare it with my hub

Messner,

I'll weight the hub and let you know.

Don

Thanks!

Just one question about your choice for swingarm. Are you sure about square look? Personally I go first for the looks.

[calj737]

The Cognito hub is heavy because it's not hollowed, and it's run on a 3-axis CNC. He knows this, but without significant changes in the machining time, the weight can't be reduced. And, there is the liability aspect of making aftermarket critical parts for mass buyers who are making modifications. So I would not get hung up on the weight aspect as it tends to equal out with modern discs (much lighter) compared to stock cast iron rotors (heavy) and the stock caliper.

[Restoration Fan]

Oh, I'm so in for this one. Maybe I'll slow down on Logan's 550 build and wait on you to solve the problems for me, Don! 

[2strokeTrush]

LIke LIke Like

[SOHC4 Cafe Racer Fan]

Nice project! Also nice hub from Cognitomoto. Can you tell me the weight of the hub so I can compare it with my hub

The Cognitomoto hub weighs 7lbs (with powdercoat). 

Still lighter than the stock hub.

[SOHC4 Cafe Racer Fan]

The saga of the donor motor.

I bought an entire 1982 CB650 standard for a couple hundred bucks.  A Craigslist special with a pipe for a steering wheel.  An abandoned project.

image_zps7af77dd8 by Donald Leonhardt, on Flickr

image_zpsfee0a619 by Donald Leonhardt, on Flickr

The motor appeared to be in okay shape cosmetically, and it was not seized.

image_zps0091cbd7 by Donald Leonhardt, on Flickr

image_zps99c9c0d1 by Donald Leonhardt, on Flickr

[SOHC4 Cafe Racer Fan]

The motor came out of the frame with not much of a fight.  The 650 frame has a built in "frame kit" in that the lower right downtube is removable -- making it extremely easy to drop the motor out.  The advantage of a 750-frame kit, by comparison, is that you can do an entire top-end rebuild with the engine in the frame; not so with the 650 since the motor has to be removed.

Here's the empty 650 rolling chassis (same for 1980-1982) compared to that of the 550.  The forward engine compartment of the frame is pretty much the same.  The rear is a whole different story on the 1980-1982 650 -- the frame rails dip down, cruiser-style providing for a lower seat position.

650_zpsojzcuhi1 by Donald Leonhardt, on Flickr

[flatlander]

interesting to see the comparison of the frames. you can really make out how they developed one from the other.
i must say, i prefer the stance of the 550 but i've never really been a cruiser guy.

[riverfever]

I was just going to ask about this project the other day when we spoke but forgot. This will be cool Don.

[rb550four]

You have spoke wheels, Excellent !! Will that work with the ttr 400 swing arm? meaning, will the 650 axle can slide through or have enough metal left in it after proper drilling to accept the 650 axle safely, of course there may be some custom spun spacers for centering , but that sounds like it'll clear up that chain size difference without using the 650 swing arm, if you didn't want to use it ,right? Yay, now I have another option next time.

[calj737]

Nice project! Also nice hub from Cognitomoto. Can you tell me the weight of the hub so I can compare it with my hub

The Cognitomoto hub weighs 7lbs (with powdercoat). 

Still lighter than the stock hub.

I just sent a front hub from my 500 to Momo, shipped and packed was 4.1#. What hub did you measure that weighed 7# ?

[SOHC4 Cafe Racer Fan]

Nice project! Also nice hub from Cognitomoto. Can you tell me the weight of the hub so I can compare it with my hub

The Cognitomoto hub weighs 7lbs (with powdercoat). 

Still lighter than the stock hub.

I just sent a front hub from my 500 to Momo, shipped and packed was 4.1#. What hub did you measure that weighed 7# ?

It's weird.  I just re-weighed it, and it came out to 6 lbs this time.  Digital bathroom scale so it's not the most accurate.  Powdercoated by Devin.

image_zpsnhmd3i0a by Donald Leonhardt, on Flickr

image_zpsoagqes8j by Donald Leonhardt, on Flickr

Thanks!

Just one question about your choice for swingarm. Are you sure about square look? Personally I go first for the looks.

Yes, Messner, I am pretty sure about the TTR400 swingarm.  Not only is it a great deal from a good member friend, I am a fan of the boxed-style swingarms.  I have a different style boxed swingarm going on my CB750K2 project right now.

[SOHC4 Cafe Racer Fan]

Sometimes a good deal is too good to be true. 

When I pulled the 650 engine from the frame, the oil looked clean -- almost brand new.  Hey the inside must be good if the oil looked so sanitary, right?

Not so.  The head was the first warning.  The head had two stripped screws and three helicoils installed.  This inside of this motor has definitely seen the light of day before.   

image_zps5vgdus2y by Donald Leonhardt, on Flickr

The cylinders were much worse.  One of the sleeves has a section sheared off like the engine threw a rod.  Yikes!   

image_zpsrsatfmqh by Donald Leonhardt, on Flickr

It's a good thing I have spare set of cylinders and a spare head -- both of which are in good shape. 

[db22]

Following!

[rb550four]

Good thing you have spare a top end.... What's the bottom end look like?
Does the crank tell a sad story too?
Hope that giant chunk of steal didn't get into the gears or the primary chain.
Looks like somebody is splitting cases.
Sorry to see that.

[SOHC4 Cafe Racer Fan]

There was a good 3-4 month gap between pulling the engine from the frame and commencing disassembly.   

During that time the remnants of the oil had time to seep down to the pan.

If you have a weak stomach, avert your eyes.  This is not pretty.

image_zpsoxtufbyh by Donald Leonhardt, on Flickr

[Bootsey]

There was a good 3-4 month gap between pulling the engine from the frame and commencing disassembly.   

During that time the remnants of the oil had time to seep down to the pan.

If you have a weak stomach, avert your eyes.  This is not pretty.

Looks like you should save that for the Sunday roast . Hope the rest of the unravelling presents a little kinder.