Topic: CB500 4 Cafe Racer ( with a 650 Engine/Rear End/Rims Swap )

[wkentkovac]

Hey Everyone!

So this is my first attempt at building a cafe racer style motorcycle, second bike I have ever worked on. 

To start I picked up a CB500 1971 ( 2nd owner, 4100 miles ) that was in okay shape but had had some modifications done to it to start.  It was fitted with 'mini apes' on the front along with a longer set of forks ( which ended up damaging the top plate of the triple tree, more on that later ) and a seat back ( sissy bar ) on the back.  Overall the bike looked fairly clean and test rode well.

Since pulling it apart I found a few issues that I would like some comments on. 

1. Damaged triple tree top plate.  Does anyone know what tree tops from other bikes I can use on this bike?  I looked at EBay and all they have listed state side is the bottom plate.  Also, any idea on how the top plate for mounts would break?  Is this common on this bike?  When I looked over the bike, I did not see any cracks indicating a problem on the top plate, but now that I look closer I can see it was painted over... scumbag seller or foolish me, I don't know.

2.  650 Engine swap in.  I was able to get a donor bike for 200USD with a swiss watch running motor and trans in it.  I pulled the motor, trans, entire electrical system, front wheel (entire assembly), rear end (swing arm with wheel, brake drum, tire).  I was reading that the motor can be 'bolted right in' in place of the 500.  Has anyone does this before? 

3. I don't think they are compatible and most people say they are not, but to make sure, the rotor (electrical) out of my 500 motor is not going to work in the 650 motor is that correct?  When I tested the motor on the 650 it ran like a swiss watch (beautiful), however I did not think to check for charging, the measurement shows an open circuit so it is toast.  So, can it be swapped in?

4. There is 1 missing tooth on the trans sprocket on the 650 motor and I was able to pull it easily, however the trans sprocket on the 500 seems to be seized on, any ideas on how to coax it off so I can clean it and put in into the 650?

5. Will the rear swing arm be exchangeable between the two bikes?  Looked like it would and the bushings in both have no slop, so I am hoping I can just shove the 650 swing arm onto the back of the 500 frame so I don't have to mess with shims to get the other wheel to fit.

I will include pictures in my next post of everything up to this point, they are on my phone and for whatever reason it won't sync to my home computer to get the pictures off of it.

thank you all and I am really excited to get this thing built!! 

Also, if anyone wants parts off the 650 or the 500 that I am not going to use please leave me a PM.

[wkentkovac]

Pics of the bike from when I first got it.

[wkentkovac]

Starting the tear down (one of many)

[wkentkovac]

More tearing down (engine pic)

[wkentkovac]

almost done tearing it down

[wkentkovac]

down to the motor and frame ( with a couple of odds and ends )

[wkentkovac]

picture of the CB650 donor motor

[wkentkovac]

Pictures from Question 1 in the original post.

Here is where the TT is broken.  Has anyone seen this before?  The weird bit is it happened to both side but opposite sides of the bracket.

[wkentkovac]

Pictures for question 3.

Here are the two electrical 'alternators' for the engines, one from the 500 one from the 650, the bolts line up on the motor, but the 500 cover is slightly larger all the way around.  Does this mean it is incompatible or incapable of being bolted onto the 650 motor?  Also, has anyone seen this white powder inside of the rotor well?  Looks like corrosion maybe?  Do I need to be worried because the 500 was perfectly clean inside of the rotor well.

500 Casing on the right, 650 casing on the left when looking at the stators

[wkentkovac]

Parts that were pulled of the CB500.

Except for the exhaust and maybe? the rear the fender, the rest of the parts I am looking to get rid of, let me know if anything is of interest.  From the other images the front forks ( no bottom caps ), mini apes, sissy bar, CB500 Motor, CB500 electrical system, front and rear spoked rims, and seat are also fair game. 

[BillGodRules]

wkentkovac,
I have a 71 500 as well.  What kind of shape are the side covers in?  What would you want for them with shipping to the Chicago area?

One side of my top triple tree was cracked as well.  I was lucky and found one at a swap meet for $2 because the owner had no idea what it was from. There is supposed to be a washer inserted in the gap.  If this is left out the tree will crack.  The washer needs to be a specific thickness.  I have seen it listed somewhere on this site. If I find it again I will let you know.

[wkentkovac]

They are in okay to pretty good shape I believe?  I will get a picture of each of them and post them tomorrow.  My 'garage' is a storage shed that I rent and it is not open after 6pm most days.  There were no washers in either the upper nor the lower mounting brackets on the triple tree.  My guess is the guy did a number to this bike before he let it sit for 30+ years in a shed.

[onepieceatatime]

3. I don't think they are compatible and most people say they are not, but to make sure, the rotor (electrical) out of my 500 motor is not going to work in the 650 motor is that correct?  When I tested the motor on the 650 it ran like a swiss watch (beautiful), however I did not think to check for charging, the measurement shows an open circuit so it is toast.  So, can it be swapped in?

Where did you measure it, on the connector, or on the copper slip rings? Did you try to deglaze the copper sliprings before measuring with some 600 grit sand paper?
You may want to check out this site.
http://www.tpe-usa.com/

4. There is 1 missing tooth on the trans sprocket on the 650 motor and I was able to pull it easily, however the trans sprocket on the 500 seems to be seized on, any ideas on how to coax it off so I can clean it and put in into the 650?

Are the sprockets the same between the 2 models?
You can get a new front sprocket for the 650 on ebay for around $20.

Also, if anyone wants parts off the 650 or the 500 that I am not going to use please leave me a PM.

What year 650?
Standard or Custom or Nighthawk model?
Do you have the nuts from inside the headlight bucket with the ground wire attached? Or the reflectors from the fork ears? Or the bolts that go between the reflectors and grounded nuts? If so, what do you want for them shipped to 21740? What about the left sidecover from the 650?

[onepieceatatime]

Also, has anyone seen this white powder inside of the rotor well?  Looks like corrosion maybe?  Do I need to be worried because the 500 was perfectly clean inside of the rotor well.

It is just corrosion. Looks like it got moisture in there at some point.

[wkentkovac]

The side covers were not on the bike when I got them  

In regards to the other questions, when I get out to the shop I will let you know ( with pictures ) of what is out there!

[onepieceatatime]

Looking at the motor and seeing the comstar wheels, I am going to guess 1980 custom model. Did you get a title with the 650? If so and it is an 80 custom, what do you want for the frame?

[onepieceatatime]

2.  650 Engine swap in.  I was able to get a donor bike for 200USD with a swiss watch running motor and trans in it.  I pulled the motor, trans, entire electrical system, front wheel (entire assembly), rear end (swing arm with wheel, brake drum, tire).  I was reading that the motor can be 'bolted right in' in place of the 500.  Has anyone does this before? 

http://forums.sohc4.net/index.php?topic=103738.0

[wkentkovac]

openpieceatatime -

To answer a bunch of your questions...

1. I am going to do my own rebuild on the rotor, I have a Croatian EE here and he said he will give me a hand so I can learn how to rewrap this stuff.  WOOT!

2. I did not get the title to the bike.  It was a 1981 CB650 (non-custom) and had some pretty heavy rust damage to the frame.  I have been using it as a practice piece for welding because of the rust damage ( literally holes in 2 places on the frame ) so I could not in good conscience sell it.

3. I have been digging through my parts bins in regards to the headlamp and reflectors question, might need more than a day to look ( mostly because I dont get off work till 5 and the storage shed closes at 6 ). 

Thank you for putting up the info with the guy that did the 650 into a 550.  That will be helpful me thinks.  I have decided I am going to put the whole bike together ( loosely that is ) to make sure everything fit and that there are no surprises later on ( especially after doing all sorts of stripping and painting ). 

Do you have pics of your bike?

[wkentkovac]

BillGodRules -

Here are some pictures of the side covers, one of them does have a small crack near the mounting hole though it does not cross into the hole, some super glue might fix it?  I am not sure.  Also, for some reason I feel like these side covers are aftermarket or something?  I am not sure, just a feeling.

[onepieceatatime]

openpieceatatime -

To answer a bunch of your questions...

1. I am going to do my own rebuild on the rotor, I have a Croatian EE here and he said he will give me a hand so I can learn how to rewrap this stuff.  WOOT!

Very nice that you have someone with the knowledge and time to teach you that.

2. I did not get the title to the bike.  It was a 1981 CB650 (non-custom) and had some pretty heavy rust damage to the frame.  I have been using it as a practice piece for welding because of the rust damage ( literally holes in 2 places on the frame ) so I could not in good conscience sell it.

Ok, Thanks. I have a 1980 CB650C, a 1980 CB650, whats left of a 1980 CB650 parts bike, and just got a $30 1981 CB650 parts bike with no title. I have enough spare parts that with an exhaust, some small parts,  and titled frame, I could probably put together a third bike.

3. I have been digging through my parts bins in regards to the headlamp and reflectors question, might need more than a day to look ( mostly because I dont get off work till 5 and the storage shed closes at 6 ). 

No hurry, I have a lot of work to do on the bike before it is ready for them.

Thank you for putting up the info with the guy that did the 650 into a 550.  That will be helpful me thinks.  I have decided I am going to put the whole bike together ( loosely that is ) to make sure everything fit and that there are no surprises later on ( especially after doing all sorts of stripping and painting ). 

Do you have pics of your bike?

Here is the CB650C Just finishing this one and almost ready to ride:



And the CB650 I just got it , and am beginging the work of getting it presentable again. I got the correct headlight with it, but not the mounting hardware or reflectors.

[bjbuchanan]

The top triple cracked because the upper clamps are missing the "d" shaped washers. You can either locate those washers or take a head washer and grind the sides so that they clear the bolt that passes through. The specific head washer, which is noticeably thicker is basically perfect. Without the washer it gets overtightened and cracks unfortunately. The lower is good to go. A lot of times triples can be tough or expensive, cheap and plentiful they are not