Topic: CB550 rat/cafe (complete?)

[cheftuskey121]

I love the rich brown man. Charcoal would look good too though. I would ride the balls off that thing

[seaninc]

I'm also loving the brown. I was going to do a black seat, but now I think I'm going brown for my 550/650 project.

[Pinkley]

Great build! Ill be keeping an eye on this thread! Good work!

[macisaguy]

This is sick.  Leave the seat.  That thing looks so good.  The whole homemade vibe gives a vintage feel more than anything else you could throw on there.  I mean, maybe except for actual old school cowboy leather.  But dude...that seat, and that tank?  They were meant to be together.

Now, thanks to discovering your bike, I have to head out into public with a major bike boner.  Thanks.

[icecoast]

Resolved some of the rear brake issues I was having. Mostly caused by the stock rod and pivot setup. I went ahead and threaded some stainless rod I had and bending it up to fit a little tighter.



Jetting has been more of a bear than I anticipated. I went up to 42 pilots but am still getting a relatively high idle (3-4k with the throttle plate fully closed).  No vacuum leaks anywhere and everything has been double and triple checked. I even raised the floats and extra mm to try and compensate but with little improvement. I should have a couple sizes larger pilots in by weeks end so hopefully I can set the final tune before the cold weather sets in.

[cwchan]

Did you have to offset the sprockets for the chain to clear that 150 tire?

[icecoast]

It's a 78 cb750A hub which has about 10mm offset over the 550.

[icecoast]

It Lives!!! Had to go all the way to 48 pilots. Still running with the 120 mains, stock cb650 needles with a 1/2 shim and 2 1/4 turns on out on the mixture screws. I was almost to the point of giving up on these carbs but I'm glad I didn't. Even considering the displacement increase I didn't expect a big difference in performance but throttle response and power is unreal compared to the 550 motor. I had to swap to a a 17t front sprocket as the gearing was incredibly short with the 16.

My only complaint is with the gl1000 front master cylinder. The brake pull is a little hard, which I'll either have to get used to or swap for a different unit. Low speed turns do require a little more muscle but at speed its very stable. Overall I think the extra effort on turn ins and transitions is very acceptable especially when considering the in corner stability and feel gained with the wider tires.

There is still more work to be done but with the limited riding time left this season and the winter to work out the "kinks" I think I'm just going to enjoy it as is and ride.

[Kemp]

Very cool build! Curious what CB650 head you used. Is it the one for the CV carbs or the throttle body carbs. I think just 79/80 CB650 were throttle bodies and the the 81/82 were CV carbs.

[RustyOlive]

It's a 78 cb750A hub which has about 10mm offset over the 550.

Off set the rear but not the front? Or did I miss that?

[icecoast]

Just referring to the sprocket offset. Not the actual wheel alignment.

[icecoast]

And yes it's an 81 head for cv carbs with 87 zx600 carbs (keihin cvk 32mm) and rubbers from the same bike. Possibly the only parts that arnt 10 years older than me.

[RustyOlive]

I believe I get what you are saying. The stock sprocket on the stock 750 hub is naturally 10mm off set compared to a 550... My question is... Did you not put on a front off set sprocket as well or did I miss that part?  Or did the chain line remain relatively straight? In my head, I would think you need to run a 3/8" cyclex off set up front to keep chain line true.   

[icecoast]

The 650 front sprocket has a 2mm protrusion where others use a washer. I flipped the sprocket and machined out a recess about the same depth. This, along with rear spacers and offset lacing put everything really close.

I'm not very good at explaining in detail what I do. Most of the work is just seat of the pants with a small notepad. Sometimes when looking back on notes I can hardly tell what I was working on at the time.

[icecoast]

Its about 25 degrees out and I think my riding is done for the season. My winter to-do list is being compiled and sadly I don't think theres much more to be done. I still need a tach and speedo as well as finding or fabricating a longer kickstand.





Since my last visit I did manage to swap out the ugly clubmans for a set of clip-ons and trim the bar mounts off a spare upper triple.

[KrautKoffin]

Loving it.

[SF]

Looks great man

[SOHC4 Cafe Racer Fan]

The GL front looks good on the 550.  What did you do to the lower triple/steering stem to make it work?

[icecoast]

The GL front looks good on the 550.  What did you do to the lower triple/steering stem to make it work?

Its just a matter of swapping the stems from the 550 into the GL lower tree. A little grinding, hammering and welding. The stems are the same diameter just different lengths. No modifications to the steering stops or another part.