Putting the motor back together

Hey it looks like I'll get this motor back together this year! A set of pistons from e-bay should get the bike running nicely again. They are 3mm overbore for a CB500 = .5mm overbore for a CB550. I believe that brings the displacement to 555cc. More importantly, the cylinders will be cleaned up and aligned properly. I read in the FAQ section of SOHC4.net that the cylinders get slightly out of alignment as mileage adds up. Reboring them straightens things out and restores power. I hope that's true!

I used a set of hose clamps to compress the rings on cylinders 2 and 3. Once those were in, I moved the hose clamps to cylinders 1 and 4. I did this very slowly to make sure not to break a ring. It would be hard to find replacements.

Another Important Lesson with CB550 Motors

I was pretty excited getting at making progress on the motor. Then I got to the cam installation. On CB550's this is a tough thing to do. Gotta slide the cam in thru the chain, put it in place and then slide the sprocket in "just right". The issue is having enough slack in the cam chain to get the sprocket mounted.

I read about it, followed the procedures described online and I couldn't get it! Kept looking online and then I realized what was wrong: The cam chain was on the wrong side of the front tensioner!

Okay I have taken apart two other inline four motors. My CB400F, 30 years ago and and my Suzuki GS750 back in the mid 1980's. With both of those motors, the cam chain is pushed inwards by the cam chain tensioner at the front of the motor. On the CB500 and CB550, the cam chain goes AROUND the front cam chain tensioner guide. See the diagram below.

Now I had to pull the cylinders off after having so carefully fit the pistons in them! And that's what I did. With the cylinders off I could remove the front tensioner, turn it round and reinstall it with the cam chain in front. With that done, the cylinders went back on (easier the second time), then the head and I was back to installing the cam.

It was still tough to install the chain and sprocket on the cam, using up every little bit of slack in the cam chain and with the tensioner tightened as much as I dared. Eventually I got the chain on the sprocket and the sprocket bolted to the cam.

If you've never done this before, note that the camshaft must be TIMED to the crankshaft. Read the shop manual to learn how to do it. If that's not done correctly, the engine might not run OR the pistons might hit the valves and you're screwed. If you're off just a little, like one tooth from where the cam is supposed to be, the engine will run but it won't be nice.

The motor is pretty much back together now. Last night I worked on the wiring harness, cleaning up connections and crimping some wires. I'll put it back on the bike, then reinstall the carbs and airbox. We're getting there.

Important info when working on a CB550 motor

As you can see by the dates in these posts it's taking me a long time to work on my CB550F. Work comes first and this year I've been busy.

Here are some observations.

When I split the cases a couple of months ago I put the transmission parts in a bag. Last week when I started putting the motor back together, the bearing race seen in the photo fell off and out fell some tiny needle bearings! Usually needle bearings are "caged," that is they are held together in a race. This set of bearings has a race but they are not attached. After sitting around for months the oil keeping them in place drained out and the bearings scattered. Most of them were easy to find but I had to hunt around the carport to find the last two on the floor. There are a total of 16 needle bearings. I packed them with automotive grease to keep them together when I put the race back on the transmission main shaft.

Another item to keep an eye on is the kickstart shaft. It's easy to take motors apart and harder to remember how they go back together. I installed the two transmission shafts and saw that the countershaft was engaging the kickstart shaft. Then I was trying to remember how these two shafts should work together. When I turned the countershaft it would wind up the kickstart shaft. That's okay for starting the engine with the kickstarter but we don't want the two gears to mesh all the time.

I was having a hard time figuring this out. So I went to SOHC4.NET and looked for an answer. I did find one post with a video where a guy had a similar problem. Some other forum members made some suggestions, he said "thanks" and did not ever go back to explain if the suggestions worked. I e-mailed the guy and he didn't respond.

Next, I made a new post about the subject. One person gave the wrong answer, another said the kickstart shaft was in the wrong position, still there was not enough detail.

Then I figured it out. Wasn't that hard, just had to sit down, look at the parts and move things around.

Here are the photos:

In the first picture note that the two gears on the kickstart shaft are meshed together. They should be separated when the engine is running and only meshed together when the kickstarter is being used to start the motor.

In the second picture, the arrow is pointing at one end of the kickstart spring, wrapped around a tang on the shaft. The other end of the kickstart spring is hooked to the engine cases.

The problem I had was because one end of the kickstart spring was not properly connected to that tang shown near the arrow. Once I hooked it onto the tang everything was okay. The two gears on the kickstart shaft separated and then they would mesh together when the shaft was pushed down.

Things are moving now. And I have two more motorcycles to work on. I hope to get this Honda back together soon!

S&W Shocks for a CB550

I had been trolling E-bay for sometime, looking for a good pair of shocks to replace the stockers. There are several nice sets, available and brand new. I'm not crazy about spending several hundred bucks on a set of shocks.

Awhile ago I got lucky. Instead of looking for CB550 shocks I looked for CB650 shocks. CB650's were around for a few years, never as popular and the CB500 and CB550.

A company had an old pair of S&W's for a CB650, starting bid $15. I emailed the seller and asked for the length eye-to-eye. The seller did not reply. I checked some websites and CB650 shocks were approximately the same length as CB550's - 13 inches.

So I went ahead and bid on the shocks. I had the only bid and won, $15 plus $15 for shipping, $30 total. Okay, they were kind of ugly but they weren't leaking oil.

They cleaned up pretty nicely! I took them apart with my bare hands, no spring compressor required. Repainted the shock bodies black and found a Rustoleum paint - Marigold! - that matches that gold color that was a trademark of S&W shocks back in the 70's and 80's.

Here are the before and after photos:

You'll see them on the bike later. I still have to take the cases apart, paint them and put it all back together.

The holiday season is here. I've now owned the Honda for over two years and ridden it less than 1,000 miles. Once the oil started leaking on the engine it became less fun to ride. When the bike is back together with the oil leak fixed, a rebore and new pistons, new shocks and a rebuilt front brake I think it's going to be a fun ride!

Searching for Acorn Nuts

Acorn nuts have those round caps and are (or should I say "were") commonly used as fasteners on twin shock motorcyles. These day there aren't a lot of twin shock motorcycles!

In the photo above you can see one of the old acorn nuts on the left. It was time to replace them. I figured no problem, head to the cycle shop and pick up a pair. I started at South Seas Honda on Nimitz Highway. They checked their parts fiche and came up with nothing. I mentioned to the parts guy, they used these nuts on nearly all Japanese bikes in the 70's and into the 80's. I found it hard to believe they didn't have any acorn nuts in stock. He went and looked in the parts room and came back with an acorn nut for a Yamaha. Cost: $4.99. Okay, that will work. Please make it a set. Oh, he only had one! The Yamaha nut was a different style with a flange. Forget it.

Next I headed toward Waipahu (I was working) and decided to check the Kawasaki shop. Same situation. They only have acorn nuts for Harleys, which are not metric.

I couldn't believe it. No acorn nuts. City Mill carries acorn nuts, however the thread for Hondas is 1.25 pitch, which is not common. Home Depot doesn't carry metric acorn nuts.

Next stop - Ebay. It still took some searching, eventually I found Johnny's Vintage Motorcycle - an Ebay Store. He carried the correct size, 10mm x 1.25 pitch. I ordered three nuts - two replacements and a spare. The cost, with shipping was $7 bucks.

The acorn nuts came in today. As you can see in the photo, the new nuts are a great improvement over the old rusted ones.

Continuing with the rebuild....

KBS Coatings

I am painting the frame with primer and topcoat made by KBS Coatings. I learned about these products from craigslist ads placed by a guy named Jason who works at Mr. Sandman in Honolulu. KBS coatings stop rust and are very durable. The coatings are flexible, like a thin coat of plastic which should be durable. Jason's number is (808) 636-8995.

I am pretty happy with the KBS coatings results. Take a look at their website and the results look really nice. My first mistake was that I bought the primer and topcoat about six months ago and only this week I got around to using them. Opening the cans for the first time was very difficult. I pried the lids with a screwdriver and then used vice grips to pull the lids all the way off. The topcoat splashed onto the tool bench, the floor and on me. This stuff does not come off easy either.

Okay, with the front half of the frame sanded down I went to work with a brush applying the primer. The following day I put another coat and noticed the coats were not coming out smooth. Get out the sandpaper, smooth it down and apply the topcoat. It looked pretty nice but not super smooth. More sanding and applying topcoat and the results were... good enough! I figure most of the frame will not be visible with the bike back together. So I mainly want the downtubes, tubes on the sides and the swingarm looking good.

Then I noticed the primer and topcoat were getting hard in their cans. I called Jason and asked if I could add thinner to the paint. He said no, come down and get some new paint. He actually gave me a can of the topcoat. He said the primer should have been okay and I should not paint from the can. Yeah it says it on the can but I did it anyways.

So I went and got my free replacement can of topcoat and bought another can of primer for about $15. With the front part of the frame pretty much done, I removed the rear fender, wiring harness etc. and got to work on the back side. I noticed that the fresh can of primer still did not go on super smooth, it was better though. Then I sanded it down and applied the new topcoat. The fresh topcoat went on better than the original can. I think the first can of topcoat had aged and thickened, making it hard to paint the frame nicely and have the topcoat "level" - smooth out.

Tomorrow I'll do a little more finish sanding and put another layer of topcoat on the back of the bike. Next - put the front forks back on, then remove the rear wheel and get to work painting the swingarm.

I tried this paint on some other parts such as the top triple crown. It just doesn't come out smooth enough so I'm sanding it down and then I'll spray paint it with regular paint.

The Rebuild Has Begun

It's been close to a year since my last post and I finally found the time to start working on the CB550. The oil leak (probably from O-rings in the head) had worsened to the point where the fins were saturated with lubricant.

The wiring harness has lots of connectors which I carefully unplugged and checked to make sure they all matched up color-wise.

So far I've removed the top end of the motor and painted it with KG (formerly Kal-Kard) silver coating. The coating is darker than stock, I think it looks good though as long as the color is consistent. After the coating dried I noticed there are still thin spots that need another coating or two. I might run out of the coating and do not want to order another bottle from KG (it's expensive!). If it looks like I won't have enough of the KG coating, maybe I'll switch to VHT silver engine paint.

The valves removed and lapped, then new valve seals were installed by Al at Cycle Tech in Moiliili. While he was at it, Al decarbonized the combustion chambers and valves.

Yesterday I removed the pistons, then removed the rings and cleaned them up. Pistons 1 and 4 were pretty clean. Pistons 2 and 3 had some carbon on the rings as well as in the ring grooves. I scraped the carbon off the rings and used a scotchbrite pad to clean out the ring grooves.

Piston ring gaps were also measured and found within spec. Okay, I admit that I only measured the top rings for each piston.

Next step - removing of the crankcase from the frame!

CB550 gas mileage and switching to reserve

I found the answer to this question a few days ago. I rode from Honolulu to Aiea and the tripmeter showed about 130 miles on this tank of gas. On the return trip the Honda started to sputter and I switched to the reserve.

As I got back into Honolulu, the Honda started sputtering again. Shoot, I had only driven about 15 miles after switching to reserve and it looked like I might have to walk! As I pulled along the side of the highway I realized that this bike does not have a crossover tube at the bottom of the tank. The petcock is on the left side, fuel on the right side doesn't trickle over through a hose. I got off the bike and tilted it as far left as I could without letting it hit the ground.

After that, I got back on the bike and pushed the starter button. It came to life and I headed for the nearest gas station. I thought about how lucky I was for not having to walk. In the future, when it hits reserve I'm heading straight to the gas pump!

When I filled up the empty tank the tripmeter read 150 miles. I put about 3.9 gallons in the tank, which works out to around 38 miles per gallon. That's pretty much the MPG I've experienced with each fillup.

Advice for fellow riders: when you go over 100 miles on a tank of gas, plan ahead for a fuel stop. And when you switch to reserve, find a gas station right away.

Happy riding, Mike