Sunday, October 17, 2010

rebuilding the cb360 phoenix engine

 I finished some new modifications to my cb360 cam bearing setup and am reinstalling the head on the engine.  I like to have my workspace set up as neatly as possible, it keeps things clean and speeds up the process.  When I'm done using a tool, it goes back on the wall instead of the bench, it's actually quicker to work this way than to keep a few wrenches laying around on the table.
 I like to have the parts I need already sorted before beginning work, that way I know if I'm missing anything before I have to go hunting through an engine looking for a part that may not have been there in the first place.
 Clean parts make a job easier too, it's a lot easier to manipulate a clean part than one coated in grease.  I use some long tweezers to get the valve retainers in too.
 Once the valves are installed, I double checked the cam fit.  You can see the needle bearings, as well as the needle thrust bearings installed on the cam.
 Installing the head is a job best done carefully, the copper head gasket must be prepared carefully, first spraying copper sealant on both sides, and cleaning both mating surfaces with MEK before laying the gasket on.  You can see the modified oil seal on the points side of the cam as well.  Applying some lok-tite to the cam sprocket bolts is necessary when working with a slotted cam.
 Degreeing the cam is simple with the tool I made from an old cb360 head.  The tool holds the #1 intake rocker arm in place while setting the cam and crank offset.  It's an important step on a built engine to set the cam properly in relation to the crank, 1 degree of offset can really change the performance characteristics of an engine.
This shows how easy using my tool is to change the cam offset without removing the valve cover.  I'm using some vise grips to move the cam in relation to the sprocket after lightly loosening the sprocket bolts. The cam was set back to stock specs, but had to be slotted to compensate for the removal of the base gasket to increase compression.  I will be using the stock cam timing as a base for reference, and will be able to change cam timing to both adjust for cam chain stretch and to experiment with changing torque vs rpm characteristics.

Wednesday, October 13, 2010

new idea for my alloy seats

I thought it might be interesting to show some progress I've been making on a seat and tank for a customer's 550.  I usually mount seats with screws to go to the frame directly, but sometimes it's nice to have a seat you can lift up to access the battery or electrical box etc.
 I found some parts at the hardware store and came up with an idea to make this easy for my customer.  I used a stainless hinge at the front of the seat, and some push in rubber bumpers to rest the seat on the frame.
 The rubber bumpers keep the alloy seat from vibrating and rubbing the powdercoat off the frame.  The seat pad is made separately and secured to the alloy base with velcro.  I make all my seats this way so if recovering the seat is ever needed, it's an easy job.  The look is cleaner too.  I just hate snaps.
 The seat hinges at the front, and for the back I imagined some kind of latch would be good.  I didn't want my customer to have to reach up under the seat to unscrew anything to lift the seat up, so I found a cabinet latch that latches under a given pressure.
Now the seat can be lifted up to access underneath, and setting it down and pressing it into the latch secures it for riding.  Lifting the seat up with enough pressure releases the latch and lets you hinge it up again.  I'm definitely going to be doing my seats like this as much as I can now!

Wednesday, October 6, 2010

handcrafting an alloy fender

 I built a fender for a customer today, so I decided to post some progress pictures to help out those who are trying to get into metalworking.  First I start with an annealed aluminum blank, with a centerline and two sidelines 1" away from each side.
Start hammering along the centerline to stretch that section of the metal and start developing both radii of the fender.  A fender is a good part to learn because it has two separate curves to it, a major curve along the tire, and the minor curve around the profile of the tire.
 Using a dolly and soft slapper, bring the sides in, which will flatten the folds developed in the hammering and begin to shrink the sides.
 Go back to hammering the center to keep developing the crown of the fender, at this point, you can move gradually out to the side lines with the hammering, blending the force as you go out.  The sides will continue to fold, and this is a good thing, as you want the sides to shrink as you stretch the center.
Back on the dolly, bring the sides flat again, and this will gradually shrink the sides and start smoothing the piece.
 Now's a good point to check your work against your "template" here I am just using the type tire the customer has.  You want to leave the fender a little flat at this point because the english wheel will stretch the middle more, developing the major radius a bit further.
 Using a steel slapper, work out most of the hammer marks, and check for straightness of the part by sighting down the centerline.  Use the sidelines to check the minor radius for symmetry.
 Using the english wheel and a 12" radius die, roll the fender lengthwise, which will even out the part.  You're not moving much metal here, just smoothing out the hammer marks and giving the surface a smoother finish.
Continue checking your work to make sure you don't put too much crown on the fender, it's hard to shrink metal and much easier to stretch, don't go to far.
Using the steel slapper and dolly, the sides can be planished and straightened, as the sides are brought straighter, the fender will lose some crown, so check against your template as you're working.
After sanding, you can begin polishing with a heavy wheel like sissal or my favorite, a finger buff.  A hard cutting compound is a good choice.  Work in one direction only at this point.  When moving to a softer wheel, work in a perpendicular direction, this will help you see your progress and eliminate the bigger marks from the tougher compound.

1971 CB350 Cafe

The next project in the shop is rebuilding a 1971 CB350 into a true biz cafe racer for a customer.  We agreed on a look for the bike, and the work began.  The first thing I did was to build a stainless 2-1 exhaust while I had the bike together.  The bike was in fairly rough shape when purchased, though the body work looked alright, the tires were flat, shocks were mush and tank was full of kreem covered rust!

I got the bike up on a stand and waited until I had some time to work on it, then I stripped everything off that wasn't going to be part of the completed bike or wasn't in good enough shape to keep.

Before doing any body work, I decided it might be a good idea to go through the engine and do a thorough reconditioning, along with replacing any parts that were worn past service limits.  Pulling the engine was very easy, once I removed the mounting bolts, the motor lifted right out of the frame.  

The engine turned out to be pretty rough too.  When we changed the oil after getting the bike, we cleaned a mess of metal shavings and chips from the oil filter (not a good sign).  Assuming it was probably a chewed up tensioner, we hoped for the best.  Turns out the engine was chewing itself to bits and the previous owner probably thrashed the hell out of this bike.  Going through the top end, I discovered the cam was badly pitted on the lobes, the rocker arms were also ground down due to the pitted cam, the cam chain was stretched probably because of the added friction, the tensioner was indeed chewed to bits.  When I got the head off, the condition was less bad, the valve seats looked serviceable, though one of the exhaust valves was too pitted to get a cup on for lapping.  
One of the combustion chambers also showed some damage from what might have been a foreign object, but the valve seats weren't impacted, so the piston and head could still be used.  Looking at the cylinders, I thought they were serviceable, until I did a hone and discovered some deep scoring that will require at least a .25mm overbore and piston kit to match.  

Cleaning up the parts was pretty simple, and facing the mating surfaces will ensure a good seal and proper reassembly.  Once replacement parts are approved by the customer, rebuilding can proceed.  The good news is basic inspection of the bottom end showed splitting the cases will probably not be necessary.  And my advice is to replace the cam chain with a heavy duty type with a rivet master link so the chain can be upgraded without splitting the crankcase and involving that much more work.  

Sunday, September 26, 2010

1974 CB 360

After bending two intake valves due to a loose tappet lock nut, I am finishing up reassembly of the 360 engine, I made some improvements to the bearing setup as well, notably the stainless sleeves on the cam and a change to the shim system used to keep the cam lined up with the rocker arms.  I cleaned up the pistons and inspected for any cracking due to the valve collision, and none was found, nor were the wrist pins or conrods bent or damaged, so I got off fairly lucky.  I reringed the pistons and renewed the base gasket sealer (not running a base gasket) and installed the block.  These bikes are nice because you can to a complete top end rebuild with the motor still in the bike, which saved me at least a few hours of work.

I bought a new copper head gasket for the motor as well, from Lani at copper gaskets unlimited, he fixed me up with a .050" gasket and already had the pattern for the 360 on file, so I was happy.  I sprayed both sides of the gasket liberally with copper gasket spray, waited about an hour and then installed the gasket, everything lined up nicely so I was ready to install the head.
A friend donated some old cb350 intake valves, and since the guides and seats were fine (seats were a little damaged, but not enough to affect the seal), I lapped in the valves using Goodson 280 compound, and reinstalled the valves.  I checked for seal by putting the head on its side and filling the ports with paint thinner, it has a low vapor pressure so it can find the tiniest of leaks to get through, and after a half hour, no drops made it through, so the seals were good.  I did some additional machining to prep the head, and installation went fine.

I had a spare 360 rockerbox laying around (I bought a used one for the rocker arms, as one of my old ones had what looked like a crack forming), so I cut it up to make a holder for the #1 intake valve rocker. This tool can be used to properly degree the cam without removing the rockerbox to adjust the sprocket.  The cam sprocket needs to be slotted so it can be adjusted in relation to the cam, this is necessary if you change the distance of the cam to the crank, as removing the base gasket does.  This modification bumps up engine compression slightly, and being able to properly degree the cam ensures the engine will still run well.  It's not a bad idea even for a stock motor, as the cam chain will stretch and retard the cam timing as it does.  Degreeing the cam is a fairly simple maintenance step to keep the engine running strong.  It's amazing what a noticeable change in performance even 1 degree makes.

Wednesday, September 22, 2010

1974 CB 360

CB360 cam adapted for needle rollers
Part of the rebuild for the CB360 engine at the shop included converting the cam to a needle roller setup, this involved having a friend machine the head to accept 28mm bearings, modifying the oil holes for the old bearings, and creating a new oil passage to the center bearing.  After riding a few miles, oil started coming out of the left oil seal and I found that the cam didn't have enough of a shim on the left side and was pushing out the oil seal, so I split the difference with the 1mm shim on the right side, and used two .5mm shims, one on each side.  After 300 miles, the engine was again pulled due to another issue, turns out one of the tappet locknuts came loose and backed out with the tappet, got stuck in a valve spring and siezed the cam, the camchain slipped over the sprocket and the pistons nailed the intake valves.  Because I had the engine apart, I inspected the cam and also found spalling on the bearings where they rode on the needle rollers.  Turns out the chill hardened cast iron of the cam isn't hard enough to run on needles, so the solution became machining some stainless sleeves to the original OD of the cam bearing, machining down the cam bearing to the ID of the sleeve, and heat fitting the sleeves over the original bearing areas.  After a few tests, it was found the stainless has much better wear properties and should last indefinitely.
machining the cb360 head allows for a larger
shim on the left and right sides of the cam,
this is better for the longevity of the shim

the installed cam without bearing shows
the machined stainless steel sleeve that
will allow the cam to ride on needle
bearings without causing damage
to the soft cast iron of the cam
I found that the head can be machined about .090" on each bearing side, to make it even with the valve cover sides, making it easier to install a thicker shim which should last longer.

After machining the head, the replacement intake valves were lapped into the seats and tested for sealing.  I used a method of installing the valve with spring and retainer, then resting the head on it's side and filling the intake ports with paint thinner, after letting this setup sit for 15 minutes, any tiny leaks will be apparent, as the thinner has a way of seeping through the smallest of pores.  A little condensation around the seat is normal, and can be seen if you dab at the seat with the edge of a paper towel, but any actual runs of thinner indicate a less than adequate seal.

Saturday, September 18, 2010

1969 CB 350

The Honda CB350 Vintage Fighter “Spitfire”  is complete, we took it around town with a photographer to get some nice shots of the work. 
This bike is an example of the kind of custom work Roc-City really strives for, a very minimal look with a highly developed form.  I spent most of the design time considering how to combine the necessary parts of the motorcycle to simplify the overall appearance, and still achieve a unique and eye catching result.  Not much on this bike is left over from the original donor bike, it’s actually easier to name the parts that are stock, such as the engine, frame and wheels.  The all aluminum bodywork is handmade for this individual bike, no templates or forms were ever made in producing the parts, and there were actually no drawings made before beginning the work.  When I began stripping the bike down, I really had no plan for the outcome, but let a mental picture begin to form in my mind as I created each part.  As the bike grew nearer to a finished piece, the design decisions became more critical, as new parts not only had to function themselves, but also had to work well with the look of the rest of the bike. Equally challenging was keeping the bike comfortable and safe to ride, features like the rear brake cable conversion and increased swingarm angle do a lot to improve the old bike’s handling and stability.  I’ve seen many custom bikes which pay little if any heed to the actual purpose of the motorcycle, there are probably hundreds of these barely rideable motorcycles filling gallery space and living rooms in the trendiest of circles.  I however, feel that a bike is only a complete piece when it is ridden.  The proof is in the pudding, I was riding behind the new owner of this bike as we approached 100mph, the bike handled and sounded great, I couldn’t have been more pleased. 
I see this bike as a step in a direction of design that I have begun pursuing, a departure from the aesthetic of the cafe racer, which, as a form necessitates functionality and speed, all else being secondary.  The development of the chopper also appears to have dead ended, having been careened into a heap of gaudy detail pieces and utter lack of composition and flow.  From somewhere in this mix, I hope to see a form of custom bike come forward that combines rideability with excellence in design, form and function being complimentary rather than in contest.  I imagine this form will draw heavily on vintage style, as I am myself attracted to designs from the past.  I have already begun work on the next project, and look forward to finding out where this path will lead.