Friday, August 7, 2015

CB550 Torn Down.

It runs, has good compression, ignition, the whole nine yards. An hour after it ran, it was down to the frame and engine.

Everything will get a good polish or a new coat of paint. The wheels will be rebuilt with Borrani style aluminum rims. The frame will be repainted with Interlux Brightside single stage poly. Brightside is a very durable, easy to use, self leveling paint used for boat hulls. The engine will be cleaned and repainted with either VHT or Duplicolor aluminum. I haven't decided yet. The fuel tank will be shot with single stage and the emblems will get a polish and new paint using modeling paints. Any rubber bits that are salvageable will get treated with conditioner. And I'm thinking Dunlop K70 tires. Not sure on that though.

Sunday, July 26, 2015

Cleaning out a fuel tank with vinegar

This is a followup to a previous post. Thanks for reminding me Shep.

The CB550 tank was a mess of rust and varnish inside so I used a mild acid called vinegar to clean it out. The vinegar sat in the tank for about 5 days and was shaken now and then to agitate it.

When I poured it out, it was yellow, gritty, and filled with fine chunks of rust and varnish. The inside of the tank looked like bare metal with brazing spots. It was quite clean and was enjoying a bit of flash rusting before I could take a good picture. Unfortunately, I wasn't able to get any before pictures, and the after pictures don't do it justice. There is an after picture below. 

So does vinegar work to derust a tank? 

Yes. I would say so.

Is it easier to deal with than say, MEK?

Umm. I shouldn't have to answer that, but yes. Yes it is. Vinegar doesn't cause skeletal birth defects. Also, it's easier to dispose.

Do you really have to wait 5 days for it to clean the tank?

I don't know. I didn't have time to check it for a few days but based on the results, I'd bet it would do a fantastic job in 48 hours.

Was it easy?

Filling something up and forgetting about it for a while is pretty darn easy. I can forget things without even trying.

Progress on the CB550

Carbs are cleaned and ready to be assembled, Ignition system is tuned up, and now I'm just waiting on parts so I can get the engine fully running.
In the mean time, I had to at least hear it fire up. So I sprayed some carb cleaner down the ports and gave the starter a spin. It ran for a few seconds.
Very happy.

Sunday, July 19, 2015

Mike's 1978 CB550. New Restoration Project

This is my uncles bike. He bought it new in 1978 down in North Carolina. He rode it around until the mid 80's and it was parked in his garage for the next 30 years. 

I would love to do a complete restoration on it but the amount of corrosion warrants replacing some potentially pricey items. So for now, we'll be getting it operational, repainting and managing the rust as best we can. New chrome might come later if I can find a nice set of pipes and fenders.

The cheap and lazy way to remove rust from a fuel tank

White vinegar and time. We'll see how this goes. The inside of the tank was spotted with rust and will need to be coated.

48 hours of vinegar with a few shakes now and then.

Updates in a few.

Saturday, July 18, 2015

New Jet Blocks for the VM29 Carbies

I've been spending a lot of time on these carbs recently. This is mainly because they were beat to death before they ended up in my hands. I got the rack for 75 bucks, which turned out to be about all they were worth. Damage inside and out.

Luckily over the years, these carbs have become more and more desirable and the once obsolete parts are now coming back. Gaskets, jets, screws, etc. Have been available but hard to find on occassion. But nothing was worse than the jet block.

The jet block is a cast piece that rests in the throat of the carb and makes the transition in the slide region smooth. It is obviously critical to the function and performance of this carb, but is also the weakest link. The area of failure is where the needle jet threads into the bottom of the jet block. The cast aluminum is soft and porous, making for fragile threads. Many people who have worked with these carbs have dealt with stripped jet block threads by boring the boss open, pressing a brass slug in, and retapping. This makes a better block than the original but it must be perfectly straight.  Others have just used epoxy to glue in the needle jet. This can also be tedious and it's not permanent. I ran a set with an epoxy-ed needle jet for two years and it was ok. Eventually it began to disintegrate even though I used PC-9, which is approved for fuel.  All these bandaids aside, there is a much easier way.

Z1 Enterprises has been making new billet jet blocks for a few years and they are quite nice. For about $40, you get a block that is nearly drop-in with stronger threads. Don't  forget to replace the small paper gasket underneath and clean the area well. The jet block must be centered well in the slide bore to avoid rubbing.

That being said, when I installed a new Z1 block, I used the small screw and the jet needle to get the new block seated as well as I could. With a few iterations it only has a minor bit of contact on the inside of the slide. It slides smoothly but witb a bit more friction than the others old blocks. I would expect that the interface will clearance itself a bit after some short use. I may mark the contact areas and polish the block where needed to prevent scoring on the slide.

Thursday, July 2, 2015

Bore Scoping a Couple of CB750s

I borrowed my friends bore scope just to poke around a bit.  Did I find anything interesting?  Ehh, I'll leave that up to you.  It's not the best scope but it was good for some more than basic diagnostics.  It was fun to poke around.

Here are a few shots from my 836 engine.  Ported head, oversized intake valves, and about 10k on it. The #4 cylinder burns a tiny bit of oil noticeable on startup.
#4 cylinder

 #4 cylinder.  Hone-y isnt it.


#4 cylinder
#1 cylinder.  More carbon.

#1 cylinder.

#1 cylinder
#2 Intake Valve

#3 intake Valve

The next engine is a 1978 F3 but the top end was rebuilt with K model parts.  No clue if it's any good. I found some debris, rust, and what looks like bad honing patterns. The #4 intake spigot is also broken but that's another story:
#1 cylinder

#2 cylinder.  Maybe has a little rust from sitting on the right side of the picture

#3 cylinder.

#4 cylinder.  It has some debris in it.
Ohh and I found a little kernel in the #4 intake.


Friday, June 12, 2015

Tuning Results: Testing a few adjustments on Rock Flute

I've spent some time verifying the settings on nearly everything for the engine. I also adjusted the compression on the rocker bolts for the front end.

First off, VM29 carbs don't have vacuum ports for synchronization so I added some. After the vacuum sync, the off-idle stumble is gone, idle is much smoother, and the throttle response is more crisp. A well synced set of carbs is paramount.

The plug gap was increased from .026 to .036. This made a huge difference in the heat of the plugs. They're running much cleaner and the exhaust note sounds a lot sharper. I'm going to bump up to .040-.045 soon.  There is plenty of spark energy to cross a bigger gap. The plugs should take the heat too. The resistor plugs have helped with noise in the Tachometer signal and should also help develop more spark duration. I am planning on testing out some 10 kohm Resistor caps to increase the spark duration. The duration on a dyna spark is about 0.9 ms. The stock points system had a duration of 1.5 ms and the cb operates best with a minimum duration of 1.0 ms according to the wisdom of Hondaman.  With the addition of a 10 kohm cap, I can run non resistor plugs and increase the spark duration by 15-20%.

I also verified the ignition timing and found that 1/4 was set to 39* and 2/3 was at 40*. Not a huge difference but certainly not good. I also noticed that the screws for the 1/4 pickup weren't very tight. After some thought, I decided to reduce full advance back to around stock so it's now set at 35*. I changed the timing curve to setting 5 on the Dyna 2000 which moved full advance up to 6500 rpm from 3500 rpm. When riding the bike after these changes, I noticed that the bike would load up easier at lower rpms. I think this might be due to the lack of timing advance below 6500 rpm so I switched the the timing curve back to curve 4. This curve has full advance coming in at 3500 rpm. More like stock, which works well for many differently built engines.

All in all, cleaning up the timing, opening up the spark gap, and synchronizing the carbs has made a significant difference in the behavior of the engine. It has a much smoother idle, easier start, smoother transition off-idle, and a crisp throttle throughout. The suspension adjustments have allowed the front girder to move easier and I'm running a lighter pressure in the air shocks. I will post an update after I do some testing to optimize the spark gap.

I also lubed up the cables and affixed the speedo pickup to the rear stay to reference the rotation of the rear sprocket. Road tests were done with a temporary fuel tank and no rear fender since the originals are out for paint. A bit awkward...and a bit illegal.

Tuesday, May 19, 2015

Carls Konged '78 CB750

Spent some time over at Carl's today to help get his bike back on the road. Needed lots of love after being his sole mode of transportation for a long time and then shoved in the corner for a few years like an old broom.

Just a few things off the checklist (stock k8 engine):

Set points:
Gap 0.012" to 0.016"
Static set 1-4 timing on F-mark with ohmeter
Static set 2-3 timing
Lock plate and roll.

Valve Lash:
E.O.I.C method
Intake 0.002"
Exhaust 0.003"

Set cam chain tensioner:
Push kicker to get tension on the front of the cam chain and slack on the rear. Loosen lock nut on tensioner and back out the set screw. Listen for movement in the tensioner and lock down the set screw and lock nut.

After setting the valve lash, I successfully snapped a Tappet cover off. Good word of advice: Just snug the Tappet covers down lightly. This one was fatigued or already broken because I didn't even get the gasket seated to the valve cover before it popped.

Meanwhile Carl replaced the fuel pump in his car. Lovely day.

Monday, May 18, 2015

Rock Flute Specifications:

For my own notes and for those interested, here are the specs on Rock Flute.  I'll update this as things change... because they always do. For instance, the green paint in the picture is actually a brighter green than the color code listed below.  I will update the picture as soon as the bike is repainted.

 
Engine:
10.9 to 1 CR
1978 CB750 F bottom end
1976 K model cylinders, Decked
1976 K model Head, Stage II porting, decked by Mike Reick
                33.5 mm OS intake valves, stock exhaust valves
                Megacycle 125-75 cam, 0.005” Int/Exh tappet clearance, 105 int 104.5 exh lobe centers, no adv.
                                (More cam specs in chart below)
                Adjustable cam sprocket
                HD Valve springs and titanium keepers
                Late model cam towers with unbolted early model rocker shafts
Wiseco 836 forged piston kit
CycleX Super Rods
New primary chains installed
Reinforced valve cover with cam tower stabilizers

Transmission/Final Drive:
F model transmission, backcut with close ratio 4th and 5th gear
             Primary: 1.708:1
            1st:           2.500:1
            2nd:          1.708:1
3rd:           1.333:1
            4th:           1.133:1
5th:           0.969:1
Barnett Clutch plates and springs
Drilled clutch basket with oil grooves for added oiling
Final Drive: 17/48 2.82:1

Ignition:
Dyna 2000 ignition with 3 ohm Dyna minicoils
Total Timing Advance: 35*
Timing curve: 4 (changed 6/12/15 from 5 which may be causing low/mid stumble)
Rev limiter: 10,500 RPM
NGK DR8EA 5 kohm Resistor type spark plugs @ 0.036” gap *test gap up to 0.050" for better burn, idle, and mpg (resistor plugs used to eliminate noise in digital tach and increase spark duration)

Fuel/Intake:
Ramflo Filters
Sudco VM29/CB750 Adapter boots with vacuum ports
Mikuni VM29 Smoothbore Carburetors
               Mains: 115
               Pilots: 15
               Air Jets: 1.1
Air Screws: 1.5 Turns
Needles: #5DL31 with clip @ #1
Needle Jets: 0-6 (verify)
Throttle Valves: 1.5
Float Height: 23 mm

Exhaust:
4-2, 2” long baffle with 1.25” inner diameter

Frame:
Cycle One Manufacturing rigid
2" forward
4" up
36* rake, Harley 1" neck
5" ride height
Paint: Sikkens Rally Black
 
Body:
Fuel Tank: 1969 Triumph Tiger Daytona 500
Rear Fender: 5" Ducktail ribbed fender, 7 Metal West
Paint: Gloss Black/MD State Police Green - BMB1B (ICI Autocolor paint code)
Seat: Satin black powder-coated Accufast seat pan with single leaf spring suspension
 
Suspension/Front End:
Vincent Style girder with Cannondale MTB air shocks @ 60 psi each
 
Wheels/Tires/Brakes:
Front Wheel:  Satin black powder-coated SOHC CB750 rim laced to a CL450 dual leading shoe brake hub
Front Tire:  Shinko 705 110/80-19
Rear Wheel:  Satin black powder-coated DOHC CB750 rim laced to a late model CB750 drum hub
Rear Tire:  Shinko 705 130/90-19
 
Gauges/Info Center:
Vapor Computer System
     Speedometer, Tachometer, Trip/Odometer, Top Speed, Time, Head Temperature, Shift Lights/Redline Warning
Analog Oil Pressure Gauge
 
Lighting:
Headlight:  Cycle Standard 4.5 inch early style headlight with high beam indicator
Taillight:  Bullet style dual filament

Oil:
Capacity: 5 Quarts
Mobil 1 20w-50 Full Synthetic

Fuel:
Capacity: 3.7 Gallons
Premium 91+ Octane

Curb Weight:
450 Lbs

 

Cam Specs
Valve Lift
Duration
Int. Open
Int. Close
Exh. Open
Exh. Close
Lobe Center
Overlap
tappet Clearance
Sealed Duration
Int.
Exh.
Int.
Exh.
BTC
ABC
BBC
ATC
Int.
Exh.
Calculated
Int.
Exh.
Calculated
Megacycle 125-75
0.400
0.375
262 @.04
257 @.04
26
56
53
24
105
104.5
50
0.005
0.005
251

 

Saturday, May 9, 2015

Rewelding and cleaning up some of the parts on Rock Flute

So I found out my kickstand can't take the entire weight of the bike dropping down on it. 450 lbs bent the tab enough for me to have to reweld it. While I had the welder out, I also added a bit of metal to the headlight mount because it had a tendency to vibrate at high speed. Both problems fixed and covered with a half assed attempt to blend satin black paint.

Wrap up with some ginger beer

Wednesday, May 6, 2015

Carburetor Return Springs

Brought to you by you local hardware store.

Monday, April 27, 2015

Installing Vacuum Ports for Synchronizing

Here's a quick and reliable way to install vacuum ports on your bike if your carbs don't have them. My vm29s don't and I want to ensure good balance. Ensuring good balance between carbs has made a big difference in ride quality and performance on many of my other bikes and it's bothered me that I've never had a way to check these.

I bought 5 mm threaded vacuum ports to install in the rubber boot. Other places to add vacuum ports are on the carb body, behind the slide of course, or on the cylinder head by tapping into the intake port. There is no room on the vm29 carb and the head of a cb750 requires removal of cooling fins on the out cylinders to make a good spot. I don't want to do anymore work on the cylinder head so to the boots it goes.

This is easy enough. Just drill a hole in the boot the same size, or close, to the minor diameter of the threads on the vacuum port. Clean off the debris nd test fit the port. Add some gasket maker to the threads and screw them into the boot. Let them dry and cap them with the supplied acuum plug.  Done and done.

Now you can go back to the precious article and vacuum sync your carbs. Woohoo!!!!!

Vacuum port with gasket and sealant.

Installed.  Maybe a little tacky looking, but with the rubber caps and the carbs back on I dont think they'll be very noticeable.

Carburetor Bench Synchronizing: Mikuni VM29 Smoothbore

This goes for most mechanical carbs. The hardware is just different.  First take the top caps off, pry back the locking tab on the lock screw, loosen the lock screw and slide adjustment set screw.

Carbs off the bike.

The lock screw is toward the back and the set screw is the one toward the air filter (both are brass).  Ensure that your cap gaskets are in good shape.

Slide adjustment set screw and lock nut fully loosened.  Lock tabs are bent back and the lock screw is also loosened.


Next, unscrew the idle knob down to a low setting. A couple millimeters from the threaded steel mount is good.  Screw the slide height adjustment down on each carb until the slide is all the way down. I do this by watching the idle adjustment cam and the tops of the other slides to see when they begin to rise. Once they begin to rise, you know the slide you're adjusting is seated. Just turn the set screw back a bit to just before the others rise. Do this for the remaining three carbs.

This is the idle screw (knob) on VM29's unscrewed to a low setting.  Note the small gap between the throttle cam and the threaded steel mount.  You can close this gap completely for setting the bottom travel of the idle adjustment, I just prefer this way. 

Now your slides are pretty close to even but you want to ensure that you have the same slack in each linkage system. To do this, crank the idle knob in to lift the slides up. Snag a drill bit of any size. 1/8" is good. Tighten  the slide adjustment nut on the set screw and the lock screw on one carb, say the #4 carb. This will be your reference carb.

Drill bit under the carb slide.  

Place the back of the drill bit under the reference carb slide and turn the idle knob until the slide makes contact with it. You want to make sure that the slide isn't resting on it and become familiar with how it feels to slide the bit in and out. You will now set the height of the other slides to match the feel of the reference carb.

Move to one of the other three carbs, say carb #3. Place the drill bit underneath of the slide and lower the slide by adjusting the set screw down. Match the feel from the reference carb and then lock the set screw and lock screw. tightening the lock screw can make a slight change in the slide height so double check the feel on that carb after locking it all down. Repeat this for the final two carbs and you've successfully bench synchronized your rack-o-carbs.  If you dont want to, or cant vacuum synchronize the carbs, bend the locking tabs back over the lock screw and replace the top caps. You're done.

Locked and ready to roll.... to vacuum sync, if you're man enough.

The best method for synchronizing carbs is with vacuum gauges with the engine running. A meticulous bench sync can get you close, but a vacuum sync can get you dead on and compensate for any cylinder variation.

To vacuum sync, place the carbs back on your engine and warm the engine to its operating temperature. Next remove the top caps and pry back the lock tab.

Install your vacuum gauges or gauge and restart the engine. Set the idle a bit higher than normal and check the vacuum on each cylinder.

If they are different, you'll need to adjust them. I like to choose a reference carb that is in the middle of the readings. Set all of the other carbs to the same vacuum reading as the reference carb by adjusting the set screws. Once complete, lock it all down, replace the top caps, and drop the idle back down to normal. You're done... Again.

Check your vacuum every couple of months and adjust as needed. A well balanced set of carbs will provide optimum performance. Do yourself a favor and make it part of your regular maintenance program.







Complete: Rebuild and reinforcement of the Chianti box

Here's the last few steps for the chianti box.

Made some brass cap nut bolts, repaired some of the wood, glued the corner braces on, drilled and tapped the aluminum insert for the wood mounts, and finally taped and sprayed the interior with bedliner (best not to spray in the dark lest yee like runs in yer paint). It turned out incredibly sturdy and looks quite nice if I do say so myself.