80 CB750K First Street Bike Project

[shinyribs]

Man,that forum is so irritating. It won't let you even view threads without registering.


I've heard of people swapping cylinder sleeves before. It's obviously doable. If that's all your budget allows then I don't see why not! Besides, a little elbow grease to salvage some old parts is cool in my book.

[TOOLS1]

Seems like a lot of work to avoid something you could do in just a few minutes, for free yourself.
TOOLS

[hlewis12]

TOOLS1 wrote

Seems like a lot of work to avoid something you could do in just a few minutes, for free yourself.
TOOLS

I'm not sure what you mean. Could I just swap the other piston and rings into the good block without switching cylinders and home them myself and use the old rings? I guess that might work. I'm not sure though. I don't know why but I'm nervous about honing the cylinders myself with the stone type hone.

[TOOLS1]

Why be nervous? just go to an autoparts store that has a tool loan program, and borrow one. Chuck it into a drill, stick it into a cylinder, put some lube on it (I use a little gas to lube them), start the drill spinning, and move it up, and down in the cylinder. When you have a nice cross hatch, your done.
TOOLS

[shinyribs]

Cylinder hones are pretty fool-proof , so don't let that worry ya buddy. If you have the option, and it really does scare you, opt for the bottle brush style hone.

Like this:


Those 100% fool proof. Just keep her moving and you'll be just fine. Just to put it out there I've personally always used Marvel Mystery Oil for honing. Not to knock Tools, because I've heard of using gas too, I just never liked the smell of gas being whipped around very much. MMO smells minty clean.


It's actually a lot less risky to hone cylinders than it is to swap them in the jugs. When you swap the cylinders those suckers have got to be in there just right. Chances are, if you swap them, you'll probably have to take the cylinder case to be milled afterwards to get everything laying flush.

[shinyribs]

Oh, and being nervous about approaching a new task is a good thing IMO. It means you're cautious ,not reckless. There's way too many reckless people working on these older machines already, but I'm sure you'll be fine.

[hlewis12]

OK so I finally made some progress.  I got the cylinders honed.  Got them put back on the bike.  New cylinder seals,  new gasket, new stud seals.  I've lapped the valves.  Installed new seals.  Leak tested by filling intake and exhaust port with gas.  Almost every valve leaks a little.  I'm not sure if I should just keep lapping the valves or what.  How long should they hold liquid?  Forever?  Also I assumed this needs to be tested with the valve springs and everything back in place.  

[seestheday]

I had to lap the valves a lot more than I thought I would have had to.  I'm glad I took the time to make sure none of them were leaking.  

I've read that if you use a lapping stick (like I did) it takes forever because the valves and seats are super hard.

[hlewis12]

I actually have been using the drill method.  The valve look nice and shiny but the seat side doesn't seem to be quite as shiny.  I guess I'll give it another go.  The thing I'm worried about is I've already put on the new valve seals and I definitely don't want any lapping compound to get down near them and I can only imagine what that would do to the seals

[hlewis12]

Well I successfully have the bike running.  Actually she runs quite well.  I'm surprised at how well she runs.  After two days of trying to get it started with old plugs and gas that I have no idea where it came from I finally decided to try new plugs and new fresh gas and she fired up immediately.  Now she starts easily with a little choke and then purrs like a kitten.

Upon riding I've discovered that I basically have no front brake.  I opened up the master cylinder to find almost no fluid.  This was more than likely due to the fact that there was no gasket below the mc cap.  Also the bottom of the mc bracket was broken allowing the brake lever to flop around.  So I decided to purchase a new mc on eBay.  Great.

Next I thought it would be a good idea to go through the front caliper.  I took everything apart only to discover that I need a rebuild kit.  Which I can't seem to find anywhere.

It's not clear in the diagram which bolt is which.  #13 and #12 are clearly different and one hole in the carrier #9 is different as well.  Does anyone konw which bolt goes is which hole.  One of the holes in the carrier is smooth and the other has little dimples in it.  Also one of the bolts is a bronzish color and one is a zinc color.  In addition to this I also need #16 and #17 Rubber bushing.  None of the rebuild kits I saw have this bushing.  I could probably get away with reusing everything else because all of the rubber parts are still good except one #15 Rubber Shaft Boot is a little deformed but I think it will still work because it looks only to be a dust type shield.  Anyone have any thought on this?



Oh and here she is all back together.
Lapped the valves
New Valve Seals.  
Adjusted all the valves to .005.
Rebuilt the carbs wih all new seals.
New Hex Engine case bolts
New Hex Carb bolts.  
All new engine gaskets.
I replaced the non working speedo with a DCC speedo and indicator lights and hopefully soon a tach (out of stock) soon.
New chain
New Sprockets
New Speedo cable.  
Gloss Black Supermoto handlebars.
DCC original aluminum bar end mirrors.
Retro Black "Solid" Barrel Style Grips
New headlight mounting brackets
I've got a new taillight and turn signals ordered.  
Shinko 706 Tires front and rear currently at the shop being mounted.  
Painted the exhaust with a high temp header paint.
New Rear Suspension.  I really wanted to go with new 12 series progressive shocks but I couldn't justify the cost.  I went with the parts n more $90 rear shocks.  I figured they had to be better than the 34 year old ones on the bike currently.

Here are the things I have left to do.
New seat
Rear Hoop for seat
Rewire everything and move electronics under tank.
Fix pinhole leak in tank.  Any ideas?
Clean up the wire wheels.  Lots of rust on the rear.  Powder coat or paint?
Paint the tank
Paint or powder coat the frame
Rebuild front forks Seals are on the way
I want to do something with the humongous rear fender but I'm not sure what.

[seestheday]

Nice. I just cut my rear fender and mounted a smaller rear tail light. I also stuck one of those blinking brake light adapters on because I'm paranoid about getting hit. I like how it turned out, but I have a spare stock seat I'm planning on cutting down.

How are you planning on attaching the reat hoop?
Any issues with that speedo? I have one as well but I haven't put it on yet. Can you adjust the mileage? Is it smooth or does it bounce around? I'm worried that mine will bounce because it's likely worn at the hub.

[hlewis12]

I was thinking I would cut the frame and have my buddy weld a hoop on for me.  I may or may not go that route.  The speedometer seems to be doing perfectly fine.  It doesn't bounce around at all completely smooth.  I haven't looked into adjusting the mileage yet.  In fact I hadn't even thought about doing that but it would be a good idea.  Did you cut the rear of your fender?  I would like to rotate it forward about 75 degrees in order to keep the factory edge without cutting it and possibly do away with the plastic inner fender.  But I'm not sure if that will work.  

seestheday wrote

Nice. I just cut my rear fender and mounted a smaller rear tail light. I also stuck one of those blinking brake light adapters on because I'm paranoid about getting hit. I like how it turned out, but I have a spare stock seat I'm planning on cutting down.

How are you planning on attaching the reat hoop?
Any issues with that speedo? I have one as well but I haven't put it on yet. Can you adjust the mileage? Is it smooth or does it bounce around? I'm worried that mine will bounce because it's likely worn at the hub.

[seestheday]

I actually got a hold of an old cb900 rear fender and cut that so i could keep my old one in case I ever wanted to go back to stock. 

If you try to rotate the current one you'll have to cut some bolts off of it and bend it to get it to fit right. Take it off and you'll see what i mean.

Sent from my BlackBerry device

From: hlewis12 [via Honda CB750'S]

Sent: Tuesday, April 22, 2014 3:46 PM

To: seestheday

Subject: Re: 80 CB750K First Street Bike Project

I was thinking I would cut the frame and have my buddy weld a hoop on for me.  I may or may not go that route.  The speedometer seems to be doing perfectly fine.  It doesn't bounce around at all completely smooth.  I haven't looked into adjusting the mileage yet.  In fact I hadn't even thought about doing that but it would be a good idea.  Did you cut the rear of your fender?  I would like to rotate it forward about 75 degrees in order to keep the factory edge without cutting it and possibly do away with the plastic inner fender.  But I'm not sure if that will work.  

seestheday wrote

Nice. I just cut my rear fender and mounted a smaller rear tail light. I also stuck one of those blinking brake light adapters on because I'm paranoid about getting hit. I like how it turned out, but I have a spare stock seat I'm planning on cutting down.

How are you planning on attaching the reat hoop?
Any issues with that speedo? I have one as well but I haven't put it on yet. Can you adjust the mileage? Is it smooth or does it bounce around? I'm worried that mine will bounce because it's likely worn at the hub.

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NAML

[Truck]

The fenders flare out where they meet the bike and bolt to the body.

[hlewis12]

Any tips on removing rust from the wire wheels?  I was thinking about doing an electrolysis bath but I've never done one before and wasn't sure how well it would work.

The front wheel isn't that bad but the rear it looks like water sat in the inner ridge near the spokes and it badly rusted all around.  One I get most of the rust off I'm not sure if I'm going to paint them or what I will do at that point.  I would really like to have black wheels with stainless spokes but I don't know how to easily accomplish this.

[TOOLS1]

If they are as rusty as you make it sound, I would recommend sandblasting, and then they would ready for paint.
TOOLS

[hlewis12]

Ok so I decided not to worry about the spokes until winter.  I got the new tires mounted and had the wheels trued and balanced.  Got everything back together again and took her for a spin.  Oh also I checked the forks and there was very little/no oil in them so I completely drained and added 5.2oz of atf in each.  Rebuilt bled the front brakes with a new master cylinder.  Got her on the road and I honestly can't believe how harsh of a ride it is.  I'm not sure what is going on but every little bump in the road I can feel.  When I come into my concrete driveway it jars the crap out of the front end.  I don't think this is normal but this is my first street bike and the other that I have been on were considerably newer so they were much better rides.  I checked the front wheel bearing and steering bearing and all was good with no play. I can compress the forks but it takes some effort.  Any suggestions on things I can check.  It was rough before with the old tires but I thought it was just the tires and that the new ones with the wheels trued would fix it.    

It is worse when just cruising.  During acceleration it smooths out some.

[TOOLS1]

Has someone changed the springs, or is the air pressure too high in the forks?
TOOLS

[hlewis12]

I'm not positive how I can tell if someone has changed the springs.  Will there be any identifying marks on the stock springs?  Also this is a k model so I don't think it has a way to adjust air pressure in the forks.  I could be mistaken about this though and just not know how to adjust them.  But I do have adjustable air forks on my 2000 KDX200 dirt bike and these forks are more similar to my non adjustable 86 XR200 forks.

[hlewis12]

I got the front end off and took some pictures.

 

Seems to be stock spring.




Does this need to be replaced?


Before. Parts washer


After parts washer. Nice and smooth again. Thought I had pics of top bearing as well but I guess I didn't take them.


Top race


Bottom race


I was able t loosen this with my finger. Maybe part of the cause of the front end harshness/vibration


Bike seems to be coming along nicely. Now if I could just quit taking it apart.




Finally a pic of my 86 XR200. Love this little bike.