engine torn down... What a mess!

[dave Esch]

I got the motor torn down to the pistons today (76 750k). I had huge carbon buildup (rock hard) on a couple of the valves. I wasn't planning on replacing the piston rings but, what the hell, I got it this far. I also found that the channels for the air coming through the head to cool were completely plugged up. Since the valve cover gasket leaked so bad the dirt and sand were getting stuck inside, and plugged solid. It actually wasn't a very difficult tear down. Start to finish maybe 3 hours, including cleaning the heads in a part washer. I found that #2 cylinder piston had some light scoring and the plug was pretty fouled out. I suspect the valve seals were leaking. Every gasket and o-ring is coming out in pieces, so I imagine the PO didn't care much for oil changes. This motor got hot a few times. So that's the update. Wish me luck and if anyone has done one and has any input, such as "before you do this, make sure of this", I would appreciate it.

[TOOLS1]

Just keep checking the manual, and go slow. Double check everything. Measure twice cut once.....
TOOLS

[dave Esch]

i purchased the manual just for this tear down. I am a honda technician but I work on cars. So I understand the value of a manual believe me. I am surprised at how much piston ring kits cost. I managed to find them for $18 each, so far thats $8 less per piston than anywhere else. I want to order those shocks we spoke about, but the misses would put a whoopin on me for sure. I'll wait. Besides, I may not have it running for this season anyway. The heads going out to get sandblasted this week. I thought about dremeling all the old cracked paint from the fins, but it'll take me months. Or at least weeks. One thing I haven't found is a cylinder hone for these bikes. There is some scoring, not enough to catch my fingernail but enough to see. Besides I dont want to re ring it and not put cross hatches on the cylinder walls.

[TOOLS1]

If you want all that nasty paint, and gunk off your engine. Use Easy Off oven cleaner on it. It will eat every thing off of it.
For a hone. You can put some longer replacement stones on a break caliper hone. Where did you find the rings?
TOOLS

[dave Esch]

I dont own a brake caliper hone. I work at a dealership so we dont repair stuff we just replace it. As far as the rings here is a link. This company is out of new york. I am a little concerned though. When you buy something online you get a confirmation email. I still haven't gotten one from them yet. If all goes well, I will let you know. I should have the rings in about 4 days.

http://www.z1enterprises.com/detail.aspx?ID=1947

They also sell the side covers, chrome, very nice. I am starting another post about my side cover, please check it out too, you may know what to do.

[lcochran]

I know nothing of this subject, but just came to throw some support for Z1.  They are great and i have never had any issues with them.  You'll get your parts no doubt.

[dave Esch]

Well that's a relief. I liked their selection of things such as side covers that I have never seen on other sites. Thanks for giving me the warm fuzzy.

[TOOLS1]

I have never delt with Z1 myself, but have always heard good things about them.
TOOLS

[dave Esch]

I received the piston rings the other day. Now I am waiting on my top end parts to come back from sand blasting. It's quite funny. I have a nice, big shiny cruiser I bought last year and I love to ride it. But I just can't wait to get the old bike back together and ride it instead. Even though the bike was ugly and dirty, I could never get over how many compliments I got on it. Old guys pulling up while going 35 mph and screaming out the window with a thumb in the air. Had one guy wait outside for me to come out of the bank once. It's awesome when you can spend so little (compared to other cool bikes) and get so much enjoyment out of it. Even though this bike has been a money pit, I don't have a single regret about the purchase.

[TOOLS1]

I hear you. I always have to allow extra time when going somewhere. If I stop, for gas, or at at store. Someone always wants to check out the Toolmatic. had an old man at Borders yesterday stop me to admire it. he said he used to have a CB 750 years ago. You know I never had this happen with any of my Harley's. Also it does upset the Harley guy's if there around when this happens, and their bikes do not get any attention
TOOLS

[LukeM]

Well, it all depends on what kind of attention you want to get with your ride.  I rode my wife's scooter (orange Honda Metropolitan) over to Five Guys burgers to pick up some dinner.  Rode it because it's got good storage, and my Avenger doesn't.  3 biker guys were on their way out, and saw me riding up on the scoot.  One greeted me with "F***ot" and got on his much overly dressed Harley.  The other Harley rider and the Suzuki rider said nothing.  I just consider the source: Harley riders are a dime a dozen, and they are not known for being the sharpest pencil in the box.  There are Harley riders, and there is everyone else.

Now, granted, I probably had it coming.  It's not the most masculine 2 wheel transport out there, but I ride it for convenience, grocery carrying, and 100mpg.  It does start every time, runs well, and it's paid for.  :-)

Just goes to show you that 1) people are people, 2) opinions are like a$$holes (every one has one, and no one likes anyone else's, and 3) stand up for what you believe in, and be prepared if someone doesn't like you.

Luke M

[LukeM]

Well, it all depends on what kind of attention you want to get with your ride.  I rode my wife's scooter (orange Honda Metropolitan) over to Five Guys burgers to pick up some dinner.  Rode it because it's got good storage, and my Avenger doesn't.  3 biker guys were on their way out, and saw me riding up on the scoot.  One greeted me with "F***ot" and got on his much overly dressed Harley.  The other Harley rider and the Suzuki rider said nothing.  I just consider the source: Harley riders are a dime a dozen, and they are not known for being the sharpest pencil in the box.  There are Harley riders, and there is everyone else.

Now, granted, I probably had it coming.  It's not the most masculine 2 wheel transport out there, but I ride it for convenience, grocery carrying, and 100mpg.  It does start every time, runs well, and it's paid for.  :-)

Just goes to show you that 1) people are people, 2) opinions are like a$$holes (every one has one, and no one likes anyone else's, and 3) stand up for what you believe in, and be prepared if someone doesn't like you.

Luke M

[TOOLS1]

You know I just tried Five Guys last night, for the first time. However if I were to eat there on a regular basis I would have to get a scooter. they are a little pricy.
Anyway. i have noticed a lot of scooters around KC. I really have to admire those scooter people. they ride no matter what the weather is like. their dedicated
TOOLS

[dave Esch]

My top end is back from sandblasting. A big improvement over the chipped, peeling paint and pitted look. I have honed the cylinder walls with some top notch cross hatches. Monday I will install the new piston rings and begin the reassembly process. Wish me luck. My question at this point is how does one go about sliding the cylinders back onto the pistons? On a car we have what is called a piston ring compressor. Basically a steel sleeve tightens around the piston compressing the rings. Tap the piston in and the sleeve stops at the head allowing the rings to expand once inside the cylinder. This is a one at a time job. This motor has two pistons at TDC. Also, I am used to lowering the pistons into the block, not lowering the cylinders onto the pistons! So do I need 2 compressors? Do I have to disassemble the bottom end and take the pistons out? THen once they are in the cylinder head, bolt it back on? I sure hope not.

[TOOLS1]

I have not yet had to do a ring job on a CB 750, so I do not know if there is a taper on the bottom of the cylinders. I have seen two ring compressors being used in the manual. I have used hose clamps as ring compressors in the past very successfully on other motorcycles, and would sure give it a try before buying ring compressors.
TOOLS

[dave Esch]

hmm, not a bad idea at all. I was hoping the cylinders were tapered. I know some bikes are. We will see, and I'll let ya know.

[LukeM]

You may find more accurate information on http://www.sohc4.net

They were a great resouce for the SOHC models, according to my son, who rides a 1977 CB550 Supersport.

Luke M

[dave Esch]

I didn't look at the forums on that site. However, I just purchased a chilton manual for my bike. The photos are extremely dark from years of reprinting I imagine. The manual on that website is way better. Guess my laptop is about to get very greasy! Thanks.

[Re-run]

The manual here is the same as over there. You should be able to lower the pistons into the block though. Most people just use hose clamps on their fingers to just get the rings in. I have the clymer and it stinks too.
I used to be on that site and it does have a lot of good info, happens after being around in one form or another for 10 years. I left when the assorted egos became too much to take. It happens though.

[dave Esch]

Well, re-run, to be honest I haven't even looked at our manuals here. I fugred it would just be easier to buy one. I like the idea of using hose clamps. I ground the valves and installed the new seals today. So far everything is looking great. I can't wait to see the motor put back together with the new stainless bolts on everything. Changing the valve cover gasket has turned into quite the project.