Topic: 1980 cb650c cafe/brat

[Cobrajet94]

Recently picked up a 1980 cb650c project bike. Im new to this and this if my first motorcycle. The engine runs and is rejetted for the 4-1 and the pods filters, it needs to be finished and i intend to get it road worthy in the next month or so.

Mods already done
Suzuki tl1000 forks, swingarm, wheels and hand controls
Cbr929 rear shock
Unknown 4-1 exhaust
Pod filters

I still have a lot of work ahead of me like:
Make a rear brake master and pedal mount
Mount a seat
Wire in a fuse panel and hook up hand controls
Make rear marker/brake light mounts
Clean out tank and reseal
Offset front sprocket and inset rear to align the chain.
Weld upper shock mount

Im sure there is some things i forgot to add.

[SOHC4 Cafe Racer Fan]

Cool project.  I'm becoming a 650 fan.  That battery looks humongous!

[Cobrajet94]

Some more pictures

[Cobrajet94]

Cool project.  I'm becoming a 650 fan.  That battery looks humongous!

The battery works for now. Ill eventually get a smaller one and make a box to hide it omewhere. Im new to this. I have built two jeeps and i have no problem with fabrication. Do you know of any small batteries that would be good for this application

[SOHC4 Cafe Racer Fan]

Cool project.  I'm becoming a 650 fan.  That battery looks humongous!

The battery works for now. Ill eventually get a smaller one and make a box to hide it omewhere. Im new to this. I have built two jeeps and i have no problem with fabrication. Do you know of any small batteries that would be good for this application

You definitely have some fab skills tackling the swingarm monoshock fitment.

For smaller batteries, I would recommend a lithium ion unit.  On the higher end, Shorai makes great quality batteries; on the affordable end, I've had good experience with Alien Motion.

[SOHC4 Cafe Racer Fan]

Is there something going on with your shift lever?  Looks extended.

Also, can you post a picture of the frame mount for the monoshock?

[Cobrajet94]

I bought the bike as it sits in the first picture but the swingarm fit inbetween the frame with no modifications. I need to nasiclt finish and add a touch of my style to the bike. Thanks for the iinfo on the battery. Il have pictures handy when i go to my shop tonight

[SOHC4 Cafe Racer Fan]

Did you have the complete TL or just the front and swingarm?  I've ridden the TL-R widowmaker.  Killer V-Twin, but I liked my RC51 better.

[Cobrajet94]

Is there something going on with your shift lever?  Looks extended.

Also, can you post a picture of the frame mount for the monoshock?

Heres the shock and shift lever, i dont know if its extended or not

[SOHC4 Cafe Racer Fan]

Hmmm.  On second thought.  I think the shift lever IS stock.  Here's mine.



As to your shock mount, do you think the bottom of the shock being anchored on one mount to the swingarm is robust enough?  Maybe you can cut off one of the extras to the left and re-weld it to bolt onto the other side of the bottom of the shock.  Otherwise, I think enough repetitive stress may cause a failure.

[calj737]

Yeah, there's something amiss with the shock on the lower. Obviously just "attached" for the moment.

[Cobrajet94]

Yeah im going to secure it better. I may cut off the two outer tabs and put a bolt and bushing on the two inner tabs

[calj737]

It looks to me that the original configuration used an offset lever and did not have the shock directly bolted to those tabs. If you can weld, cut all four off, then properly space two with very little side-side space to hold the shock eye snug. Then secure with a Grade level shouldered bolt.

[SOHC4 Cafe Racer Fan]

The frames on the 80-82 CB650s have a raised rear end (after the triangle) leading up to the rear cross-member.  This can make for awkward seat mounts, since the rails are not straight back on this section of the frame.  I've seen some 650 builders cut the raised portion of the rear rails, weld new rails (with a new cross-member) following the lower line.  Have you figured out what you are going to do?

[Cobrajet94]

I have somthing like that in mind. Over the winter i want to cut the rear up and follow the same line as the bottom of the gas tank and make. Flat brat style seat from a skateboard deck with padding on top heres where i got my ideas from :
 The first one is a cb450 thats where i got the seat idea from. I don't know if i want it elevated as much as that one. The second bike is the bunker customs cb650 and i love this build. They did not change too much in the rear of the frame from what i have seen from the video of them building it.

[SOHC4 Cafe Racer Fan]

Cobra,

I've seen the Bunker brat on bikeexif.com -- cool except for the lousy grip of those Firestones.  If it is a 1980 as described, they definitely had to cut the rear subframe, since the 80-82 frames curve immediately up after the triangle.  Only the 79 has the same flat lines (for the rear frame rails) as the 550 frames.  The good thing about your monoshock set up is that you don't have to worry about mounting new upper bolts for the old twin shocks.  You can simply lop off the subframe at the end of the triangle and weld straight tubes backwards with a new cross-member.

I've seen a couple of bikes using a skateboard as a seat pan.  The look is very cool, but keep in mind one practical concern.  If you leave the wooden edge of the skateboard deck exposed (as with all of the ones I've seen) it becomes incredibly UNCOMFORTABLE on your inner thighs.  With a bike made to corner with the suspension upgrades you have, you will probably move on the seat as you transition from turn to turn.  The last thing you will want is a wooden edge chafing the inside of your thigh (and man parts) as you lean off or slide to the other side. This assumes you plan to take advantage of those upgrades and not just ride cruiser-style straight up.  Otherwise, why bother with the USD fork and monoshock rear?

I suppose you could have the upholstery cover the edge of the skateboard deck, but that would take away from the whole look.  From a practical standpoint, I would recommend the Bunker style seat (if you are set on a flat Brat seat) -- maybe with an upturn at the very rear.

Just my $0.02!