Topic: CB550 Track Bike

[Rocketman]

After a couple of years collecting parts it is time to make a push and complete my CB550 track bike.  It started with a $300 eBay purchase.  Then seller threw in a second 550 while picking up the first bike.  The price reflected the condition (crashed) of the bikes.  They have been disassembled and the straight frame deluged.  The gas tank is another eBay find, an Airtech CR750.  I am relocating the filler, shortening the sump,  and heavily modifying the tunnel to fit a 550.  The motors have been disassembled and the cases vapor blasted.  I'll post pictures as I progress.  Thanks to everyone on the forum for their advice and inspiration.

[Stev-o]

Subscribed.....I will be restoring a 750 track bike this winter. Can you explain vapor blasting?

[Bankerdanny]

Where did you have your vapor blasting done? I have seen several owners from outside the US that have had it done on their bikes, but I have never successfully located a source here in the US that does it.

[Rocketman]

Vapor blasting is a water driven process with glass beads.  The finish is just superb, but you need to thoroughly clean any oil gallies and threaded holes of the glass bead residue.  Learn from my mistake and do not use a tap to clean the threaded holes.  Just cut a couple of slots in a bolt to catch the swarf.  Google or search the forum for "cleaning threaded holes" to see what I am referring to.  I have had great results at Bikesalot Vaporblasting in Willamina, OR.  The owner is Jeff Gibson and his contact info is is: before noon (Pacific Time) at 503-876-8740 or email me at jeffbikesalot@hotmail.com.  The website is http://www.vaporblasting.biz/index.html  Don't bead blast the parts before sending them to him, but do clean them and strip any paint. 

[Bankerdanny]

Cool. Thanks

[Rocketman]

Here are a couple of photos of vapor blasted parts.  The oil pans are not a direct comparison as the before has not been in the parts cleaner yet, but you get the idea.

[mono]

Pretty....

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[Rocketman]

Making progress with the gas tank.  First step was to cut the bottom open and the sump off.  Cutting the sump off was necessary as it was too deep for my taste.  This turned out to be a good move as there was several inches of solidified tank sealer in it.  Never could have gotten it out any other way.  Cut a 2 inch section out and glassed it back together.  I am using epoxy vinyl ester resin which is gasoline and ethanol proof.  Plan to seal the tank with Caswell epoxy when finished just to be sure it will not leak.   I also cut the vent off the left front corner and plan to put a monza cap there.  Will close off the old gas cap opening.

[Tews19]

Subscribed! What internal changes will you be doing to the engine?

[Ecosse]

subbed. what class are you thinking of running or will this be a "track day" bike?

          (the admins might move this to the racing page fwiw )                                             

[Rocketman]

  My intent is to build this as a track bike, but never say never.  I roadraced from 1974 to 1986 and still dream about getting backout on the track.  I have done a few track days since 1986 on my street bikes and one of the old Keith Code Superbike Schools on Honda RS125 roadracers.  No where near as fast as I once was, but can still turn a decent lap time.  Both WERA and AHRMA seem to have the rules set to keep Honda fours out of the 500 GP classes, but have a couple of other classes they are eligible for.  So, if this goes well, I may break out the leathers and give it a go.
  Here are a few more pictures of progress on the gas tank.  I'm using wax paper over paper towels on the frame back bone to get the tank tunnel formed.

[Rocketman]

Thanks to everyone for their interest.  Here is a list of mods/changes planned:
Frame:
Unneeded brackets cut off
Frame cut off behind the shock mounts and a loop to support the seat added
CB750 triple tree
Redwing forks (copy of ceriani)
Grimeca 4 leading shoe from brake
Convert rear brake to cable operation
Rear sets, hope to reverse the shifter for race shift pattern
Engine:
New bearings, crank, rod, and transmission (based on condition)
New primary and cam chain
JE Pistons 10.5:1 with pockets for higher lift cam
Webcam 358b
APE studs
Head has been cleaned up, Serdi valve job, oversize valves, KPMI springs, Ti retainers by M3 Racing
Leaving the kick starter on for now, but may remove later.  Not sure if it will clear the rear sets
Block off for the starter.  May use it while testing and dyno runs. for convenience.
CB750 carbs if I can make them work, otherwise will go with Keihin CR 29
Body work:
Modified Air Tech CR750 tank
Modified Air Tech CR750 seat
National Fiberglass fairing.  Terry Hanson of Team Hanson allowed me to have a couple of fairings made from his Honda RC mold.  The mold was taken from a Honda factory roadracer, RC181 I think.

[Ewan 500K1]

hi , just wondering why you are putting 750 triple T on ... shorter offset ?

[Rocketman]

The Redwing forks are 34mm if my memory is correct which is much larger than the CB550 triple tree will accommodate.  Also the Grimeca brake is too wide to fit between stock 550 forks.  I did have to shim the forks as CB750 forks are 35mm.  I did not do a detailed analysis of the rake, trail, etc so I'm keeping my fingers crossed that it will all work well together.  I'm cutting the stock handle bar mounts off and filling in the holes that resulted to give the upper triple tree a finished look.  The steering stem was sectioned, a plug installed, and welded back together.  Using tapered roller bearing on the lower, but OEM ball bearing at the top.  The upper tapered bearing would only seat 1/2 way into the steering stem which did not sit well with me.  It appears that the lower bearing takes most of the load anyway.

[bwaller]

Rocketman, here's a bunch of useless info...Both 550 & 750 forks are 35mm, plus both bikes forks are identically spaced at 182mm. The 500/550 triple clamp offset is 45mm, the 750 used two different offsets through the years but both were more than 45mm. The stock 550 frame rake is (said to be  ) 26 degrees and trail is 105mm.

There are a few of us racing these, reducing rake helps them to turn in. Raisng the rear is an easy solution, but re-increasing trail afterwards is advised. Don't ask me how I know!

[Rocketman]

Bwaller, appreciate the information.  I knew I was not going to use the stock forks and triple trees, so they went in the scrap metal pile early (10 cents a pound).     I picked up the Redwing forks and Grimeca brake years ago and stock piled them for a future project.  Once I have the bike up on wheels I'll check my numbers, see where I am, and check back with you.  The forum has been both inspirational and educational.  I am always amazed at the accumulated knowledge and experience of the members.  Hope to see you at the races.

[Ewan 500K1]

. Ask me how I know!

oh go on then

[bwaller]

. Ask me how I know!

oh go on then

Sorry.. corrected. 

[Ewan 500K1]

. Ask me how I know!

oh go on then

Sorry.. corrected. 

tease 

[Rocketman]

Made some progress with the tank and seat.  Screwed up on the mount for the gas cap!  Sealed the bottom of the tank before installing it!  Rather than cut the bottom open I think I can cut a slot at the opening, install it from the outside, and glass it in.  Keeping my fingers crossed.  Planning to have the seat cover made of suede.  It may not be the most practical material, but it appears to be what the factory Hondas from the sixties used.  Not trying to duplicate those machines, but it should be a nice touch and is in the budget.  Since the 550 is a wet sump there was no need for the opening on the seat base.  Trimmed off the edge and glassed it in.  Off to the upholster for the cover.

[Rocketman]

Good news!  Was able to install the gas cap flange without cutting the bottom of the tank open.  Cut a slot and slid the flange in, then glassed it in.  The first coats of primer are on and the next step is to coat the tank with Caswell Epoxy Sealer.  Also made some progress with the front forks and triple tree.  Cut the handle bar mounts and other extra brackets off.  Next step is to weld plates in to fill the holes.

[SOHC4 Cafe Racer Fan]

The slot worked well!  Is this an Airtech tank?  The shape looks clean. 

Stupid question:  if this is a track bike, why are you changing to a twin-leading shoe Grimeca?  I'll admit it looks cool, but dual discs would give you better stopping power while still maintaining period correctness.

[Rocketman]

Cafe Racer Fan,  It is in deed an Airtech CR750 Honda tank.  I'm going for the 1967 RC181 look which is why the Grimeca drum as opposed to disc brakes which would be superior.  This is more for fun than serious racing at this point.  Thanks for your interest. 

[SOHC4 Cafe Racer Fan]

Cafe Racer Fan,  It is in deed an Airtech CR750 Honda tank.  I'm going for the 1967 RC181 look which is why the Grimeca drum as opposed to disc brakes which would be superior.  This is more for fun than serious racing at this point.  Thanks for your interest.

Gotcha.  RC181 rep-look-a is a cool idea.  I like your solution with the Monza filler cap and the way things are going. 

[FrankenFrankenstuff]

Nice!