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

[flatlander]

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

i see some eyes in there and an evil grinning mouth. is it moving? are you sure it's not alive??

[calj737]

Don - we concur the Cogintio hub is over 6#. My question was regarding the stock hub weight. I don't believe it weighs nearly that much.

[cb650]

What did you do with the 650 tank?

[MessnerMoto]

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.

It all depends of what do you want to achieve in your build. Cognitomoto hub is fast and cheap solution. But I am trying to improve performance also. Lowering unsprung weight at front by ~1.5kg will noticably improve handling.

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.

TTR400 swingarm probably weights less then stock swingarm and is more stiff...

[calj737]

It all depends of what do you want to achieve in your build. Cognitomoto hub is fast and cheap solution. But I am trying to improve performance also. Lowering unsprung weight at front by ~1.5kg will noticably improve handling.

I don't know that I'd agree with that opinion about the hub. Could it be lighter, yes. It's not a particularly "fast" or "cheap" solution. A CNC 3-axis or 5-axis milling program is not much different in time to produce, given the right piece of machinery.

Then, there's the legal liability factor. How light does a part need to be for it to be usable, safe, and performance oriented on a 50-60hp motorcycle? Reducing a part's weight by 3# overall won't equate to tremendous handling improvement, especially when you factor the front end suspension changes. And, the total suspension and braking systems combined, probably are still lighter overall than stock dual brakes/forks, and much stiffer.

Your hub is elegant and it's similar to the RAD/Kineo approach. But standing alone in the abstract, it alone doesn't create a substantiated performance change. And you're running 36 spokes instead of 40, which also changes the weight and reduces stiffness. Trade-offs are everywhere in performance parts.

Sorry for the jack, Don.

[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.

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

That type of engine "gravy" would taste very good.

[SOHC4 Cafe Racer Fan]

What did you do with the 650 tank?

Unfortunately, it was rusted through on the bottom.  I am planning to use some thing different anyway.

[SOHC4 Cafe Racer Fan]

No problem, Cal.  Those were all interesting points.

I think that with an aluminum rim, elimination of the stock seat, swapping the swingarm and other changes will all result in a net loss of unsprung weight.

NOTE: To all 650 engine rebuilders, the 650 uses 10 shorter cylinder studs and 2 longer studs -- as opposed to the 550 using 6/6.  The APE Heavy Duty studs will fit, but you need to buy another package of them to get the right number of short/long studs.  Stock studs/bolts -- especially the two long ones -- are more difficult to come by.  There is an ebay seller with one (not enough) left.  http://www.ebay.com/itm/201397804617?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT  Since I am increasing the compression on this engine, I am not inclined to re-use the old ones, and I'd rather use the APE heavy duty studs.

[calj737]

I agree that changing those items will result in a net lower weight. I fabbed up some of the bits of the boy's 500 aluminum seat hoop this weekend. Cut the stock subframe off completely. Weighed the two, the new subframe is 4.2# lighter overall, 1/8" thick wall, billet 6061 tubing. Comparatively, it's probably 4x stronger and over 4# lighter. It will be interesting to compare the swing arms when that's done too.

Did you ever re-weigh the stock hub? I'm curious what you find...

[FunJimmy]

Awesome concept Don. It's pretty tough to beat the smile off the face of a 550 rider and one with a strong torquey motor will be tougher yet. Sorry to hear about the initial findings. Hope the surprises stop there.

Cheers
FJ

[SOHC4 Cafe Racer Fan]

I agree that changing those items will result in a net lower weight. I fabbed up some of the bits of the boy's 500 aluminum seat hoop this weekend. Cut the stock subframe off completely. Weighed the two, the new subframe is 4.2# lighter overall, 1/8" thick wall, billet 6061 tubing. Comparatively, it's probably 4x stronger and over 4# lighter. It will be interesting to compare the swing arms when that's done too.

Did you ever re-weigh the stock hub? I'm curious what you find...

I did not weigh the stock hub, since it's still laced up and on the rolling chassis.  I think my post was a little muddy.  I just weighed the Cognitomoto one.  I assumed it was lighter than the stock hub, in making the statement above, but it looks like I'm wrong.

[FunJimmy]

I think that with an aluminum rim, elimination of the stock seat, swapping the swingarm and other changes will all result in a net loss of unsprung weight.

You're on the right track Don. Reduction of unsprung weight has a significant effect on handling and performance but weight removed furthest from the centre of rotation makes the biggest difference.

[SOHC4 Cafe Racer Fan]

Calling all 650 parts hoarders:

I am looking for a cam chain guide for a 79-82 CB650.  I cannot find any NOS ones with the on-line dealers (including David Silver and CMSNL) and nothing on Ebay.  Mine is looking pretty worn (with cracks in the rubber)

The part number is Honda 14611-426-010

Here's a NOS one that sold on Ebay for about $8!!  I wish I knew about that listing!

_57_zpsbbs7f6yx by Donald Leonhardt, on Flickr

The part is #7 in the fiche below:

cam_zpshotrykaq by Donald Leonhardt, on Flickr

If you have a good condition spare and it's for sale, PLEASE let me know.

This part is almost as rare as . . .

sasquatch by Donald Leonhardt, on Flickr

Don

PS - I already PM'd Bill Benton and rb550four.

[calj737]

Ping Brent too. He may know of a secret, race derived option (Shhh!)

[SOHC4 Cafe Racer Fan]

Ping Brent too. He may know of a secret, race derived option (Shhh!)

That Brent is a crafty guy! I PM'd him at your suggestion.

Here's how my weekend closed out:

Got the crankcase split apart on the donor 1982 CB650 engine. 

Good news:  Surprisingly, the crankshaft and transmission are just fine!!

image_zpsm1m6jcn5 by Donald Leonhardt, on Flickr

More sludge in the case:

image_zps3ly26pn5 by Donald Leonhardt, on Flickr

[rb550four]

Where did you find the missing chunks? Did they manage to make it to the pan without hitting anything?
How bad did that piston  look?

[kslrr]

I'm following this one.

[SOHC4 Cafe Racer Fan]

Where did you find the missing chunks? Did they manage to make it to the pan without hitting anything?
How bad did that piston  look?

RB,

Here's the weird thing about it.  No metal in the oil pan or lower cases, just gravy/sludge.  The pistons had no damage -- just normal carbon build-up -- and the rings were intact.  There were signs that the pistons had at one time been seized in the cylinders but they moved free when I bought the bike. 

As crazy as it sounds, it appears that a PO took the motor apart after a catastrophic failure and/or the pistons seizing, cleaned it up quickly (removing broken metal from the cylinder sleeve), slapped it back together and re-filled the engine with new oil.  I know that sounds pretty messed up, but I cannot otherwise explain it.

[bwaller]

Sorry Don, I have no spare 650 bits. I PM'd with a lead though.

I just weighed a 550 rear hub, unfortunately it won't mean much because it's complete except  there's no sprocket, and no brakes or brake plate.....11.5lbs.

[SOHC4 Cafe Racer Fan]

Sorry Don, I have no spare 650 bits. I PM'd with a lead though.

Thanks, Brent!

[riverfever]

Don have we arrived at the point where we are posting random comments and/or pics in this thread yet?

[P.abrera]

Ooyeh! I like where this is goin. Onboard for this one giddyap!


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[SOHC4 Cafe Racer Fan]

I spoke with Mike Rieck today.  He echoed the advice I received from Brent Waller and Cal regarding an aftermarket cam.  I'll be packaging up my 650 cam for a Megacycle hardweld 126-20 and hardweld rockers!  Mike said that the CR26s would probably work best since this is being built for street rather than top end race performance. 

It's a good thing because the camshaft out of the donor motor had some VERY minor wear.  Probably not enough to cause issues, but the hardweld will rectify that.  Jeez, almost everything in this donor engine is crap-ola except the crankshaft and transmission!

[calj737]

Well surely you'll be sending the crank off for knife-edging and the trains for undercutting the up shift side, right?

[knottedknickers]

Did you ever re-weigh the stock hub? I'm curious what you find...

I just weighed my 750 hub (bearings and spacers on; rotor and speedo unit off) and it came in at 3 lb 4 oz = 52 oz = just less than 1.5 kg (on a Braun analogue kitchen scale). For what it's worth...