1981 CB750K - Repair/Tune-up

[cdaiscool]

I don't really have the power tools to polish anything, and Im on a limited budget. No power tools allowed this month. Since it is already unmounted couldn't I just mask the important bits off and hit it with some black paint? Obviously use some lacquer or something first so I can get the oils etc off first.

[TOOLS1]

The thing is, as soon as the break fluid touches the paint; it will eat it right off. That's why, you should do the re-build, and mount the parts to bleed them. After, you bleed them take them loose (do not undo the break line though) and mask them, and paint. Then they will look great.
TOOLS

[cdaiscool]

Hmm. Good point. Could always put DOT 5 fluid in it lol. Another way to be unique. Though I run DOT 4 in my Integra.

Any suggestions on brand and stages for paint? Primer or self etching required? Or just a blast of decent brake caliper paint?

[bosco39]

Remember that DOT 5 can't be mixed with DOT 3 or 4; it's gotta be 100% if you go that route.

Also, with the brake piston, it'll depend on how much pitting there is. If the piston is pitted where it contacts the seal, you'll get leaking. If the rust is further back on the piston, you should be fine with just removing the rust. Rust expands to something like 10x the volume of the metal that "made" it, which will cause the piston to bind. Just as long as that mating surface is good, you'll be ready to rock.

Not sure in general how many folks are aware of the rust removal method via electrolysis... Battery charger, some TSP, some sacraficial anode (metal coat hanger, rebar, whatever...) and you're on your way to rust free parts without a lot of scrubbing, and there's no loss of finish like a wire wheel might produce. This is a great thing for any metal you might want to de-rust. Here's a link to the XS11 forum on how to do it to the inside of a gas tank: http://www.xs11.com/forum/showthread.php?t=22621&highlight=electrolysis 

[cdaiscool]

I know way too much about brake fluid; something I actually know about! I'm amazed. :D I'm getting a brand-new master cylinder and completely rebuilding the caliper. I can flush the brake line with alcohol, then blow it clean with air. That will ensure all old fluid is out of the system. Otherwise I wouldn't even have mentioned it. Honestly, I won't go with it as I don't race the bike and the fluid is way too expensive. I can get DOT 4 for $2 from Lowe's, or $4 from Wal-Mart when they're out. Much better than the $8 - 10 or more, and availability and issues if someone borrows the bike and doesn't realize the purple is DOT 5 and puts in 3/4/5.1 if the fluid's a little low. 

I'll have to look more into the electrolysis method. Never done that before, not sure I want to try it on something like this. I've seen it done, I've looked into it before, but never really did it. 

I will probably just sand the piston and the inside of the caliper with 300-grit sandpaper. Of course, I'll take pics before and after... :D

On Fri, Mar 23, 2012 at 10:01 AM, bosco39 [via Honda CB750'S] <[hidden email]> wrote:

Remember that DOT 5 can't be mixed with DOT 3 or 4; it's gotta be 100% if you go that route.

Also, with the brake piston, it'll depend on how much pitting there is. If the piston is pitted where it contacts the seal, you'll get leaking. If the rust is further back on the piston, you should be fine with just removing the rust. Rust expands to something like 10x the volume of the metal that "made" it, which will cause the piston to bind. Just as long as that mating surface is good, you'll be ready to rock.

Not sure in general how many folks are aware of the rust removal method via electrolysis... Battery charger, some TSP, some sacraficial anode (metal coat hanger, rebar, whatever...) and you're on your way to rust free parts without a lot of scrubbing, and there's no loss of finish like a wire wheel might produce. This is a great thing for any metal you might want to de-rust. Here's a link to the XS11 forum on how to do it to the inside of a gas tank: http://www.xs11.com/forum/showthread.php?t=22621&highlight=electrolysis 

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NAML

[sgtslag]

Never heard the trick with using alcohol to flush out brake lines before.  Good to know.  What type of alcohol is best?  I assume Rubbing Alcohol (only 80% alcohol?) is not pure/dry enough?  Seems like De-natured Alcohol that is around 95+% pure would be best?  Thanks for the information.  Cheers!

[cdaiscool]

Denatured does the trick best. Followed by a blast of compressed air. Make sure there's not one single evidence of other DOT rated brake fluids. ANY contamination at all will mess your brakes up. 

Honestly, DOT 5.1 is probably the best product out there right now. Highest boiling points of 3/4/5.1, and no risk of contamination of silicone-based 5 vs hydraulic-fluid 5.1. 

Rubbing alcohol may work, but I wouldn't use it. As you said, not pure enough - and why risk it when we're talking brakes? 

On Fri, Mar 23, 2012 at 11:24 AM, sgtslag [via Honda CB750'S] <[hidden email]> wrote:

Never heard the trick with using alcohol to flush out brake lines before.  Good to know.  What type of alcohol is best?  I assume Rubbing Alcohol (80% alcohol?) is not pure/dry enough?  Seems like De-natured Alcohol that is around 95+% pure would be best?  Thanks for the information.  Cheers!

1979 CB750K
1993 Kawasaki Voyager XII

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NAML

[TOOLS1]

I have used rubbing alcohol to flush break lines before. It does work, but, you must be sure to flush it all out also. As, for the "caliper" paint. It's CRAP!!!! Just use a good quality paint like Rustolum.
TOOLS

[cdaiscool]

I know what I'm doing this weekend! 

-Bleed brakes on Integra. Get into driveway if possible... (wheels aren't screwed into lower ball joint; gas line is dragging as it's currently being upgraded...)

-Tear apart brake caliper; paint with black Rustoleum

-Remove brake master cylinder from handlebar. 

-Remove valve cover, side cover from motor

-Clean, adjust chain. Lube. Using DuPont Chain Saver. 

-Gaze longingly at wanting to freaking ride already

-Check valve clearances; mark down so when I have the tool, I can just start removing shims and start looking at what I need to get. 

-Sand piston, inside of brake caliper to remove gunk. 

-Before painting, clean brake caliper with paint thinner to remove oils etc. Paint liberally. Because liberals should always be happy - they have guns. 

Drink tequila for my friend that didn't get the job he wanted. 

Yay, a productive weekend ahead of me! Maybe. I'm supposed to go to GR tonight to hit a car meet, but looks like that's going to get cancelled. So I can just put the car outside instead. Hopefully that can go outside tonight. Then I'll clean the garage tonight, and tonight or tomorrow put the bike in the garage and start work. 

I'm -slightly- excited. Feel like a 17-year old going to prom for the first time. With the school, uhh, popular girl. 

Yes. Popular girl. 

[cdaiscool]

ARRRGGGHHH.

That damn piston does NOT want to come out. I tried with a pliers, couldn't get it out, so I hooked it back up to the brake line. Couldn't get bleeder off. Removed from line. Took off bleeder. Put back on line. Bled brakes.


Fucker bounced back-n-forth but refused to come out. Couldn't get 'er to budge. At all. I don't have an air compressor.

Going to ask the neighbor if I can borrow his tomorrow. I hope I can catch him. I'm getting that damn piston out TOMORROW. Come hell or high water.

[shinyribs]

You ought to be able to just keep pumping the brake til it pops out. Thats what I did. Im guessing that is what you were trying,though.

[Piute]

                                                                   

You ought to be able to just keep pumping the brake til it pops out. Thats what I did. Im guessing that is what you were trying,though.

                                                                 


                                                    Over an inch (rain) yestarday.
                                                                 

[cdaiscool]

Yep, that's what I was trying! But it kept bouncing back-and-forth. My guess is that it's corroded so badly inside, it needs a constant pressure to break its bond/seal. Previous owners probably never did any maintenance on this bike.

So now I am the lucky fool that gets to fix his previous work. WHOEVER WORKED ON THIS BIKE BEFORE SHOULD NOT BE WORKING ON BIKES.

End of story.

[cdaiscool]

Okay. So what cover do I remove to turn the crank to do the valve adjustment? Dealer said it was the smaller of the 2 covers on the left side, and the manual says that cover is for the pulsar or whatever. Says to remove the a.c. generator cover.

Which cover is that? Can I get away with removing just the pulsar cover? Because that's the gasket I've got on order and is coming...

[cdaiscool]

Oops.

So, I decided that it didn't look right, that small cover that the dealer said to pull. So I went ahead and pulled the bigger cover. Apparently, that's not the right cover either.

Instead, I had oil come out. I'm guessing that's a big no-no for the ac cover:


So I put the cover back on to stop it pissing oil. (Picture taken AFTER the cover was put back on.) Which means the other gasket I bought is ALSO the wrong one. So now Monday I need to order 2 more gaskets. The ac gasket, and the one I just ruined.

However, there was some good news:





No varnish! So it was kept up on oil changes. Or the oil pump is bad. Let's hope it was the former.

In other news, I'm not sure if these are good or bad pictures:





As you can see, there was no gasket on there. So not entirely sure if this is okay or not. Obviously the bike ran okay, so I'm assuming it's all right? Also, found this under the valve cover:



Now I'm going outside and measuring valve clearance. I don't have the tool to remove the shims, so can't measure what I need for replacements, but I can at least get preliminary measurements. Hopefully the neighbor comes outside while I do these so I can borrow his air compressor. He was asleep when I ran up there an hour ago, so I couldn't ask then.

[cdaiscool]

Rebuilding this caliper sure was the right idea!

Piston doesn't actually look too bad!





Needs a little cleaning on the top, and the inside, but overall not too shabby. The caliper, however, I can't say the same for.







Any tips on how to clean that groove out? It definitely needs it. The entire thing needs it, in fact, but I'm going to use 300-grit sandpaper to clean that bore out. Also to clean that piston out.

Also did the valve clearance measurements. Can't take the shims out as I don't have the proper tool though. Overall:

6 valves: .004"/.102mm
9 valves: .005"/.127mm
1 valve:  .006"/.152mm

Not bad, when the tolerances are .003" +.002 -.001 (.08mm +.05 -.02). So .002"-.005" and .06mm - .13mm.

Should I adjust the .005"/.127mm valves, or are they fine as-is? I'm obviously going to adjust the 1 that's at .006 though. But SO CLOSE!

Time to get to sanding the brakes down!

[shinyribs]

I wouldnt sand that bore. It is supposed to be very smooth.300 grit issomewhat smooth for sand paper,but very rough actually. If you do sand it you will need to finish with something around 1500-2000 grit the get it remotely smooth.It doesn't have to be polished,but pretty durn close to it.

Anything with a hook will clean that groove out.Bend a piece of wire and scratch it out.Small scratches won't matter there cuz the new seal will cover/seal them just fine.

That sure is a clean motor inside! Can you measure your lash with a set of feeler gauges or does it have to be done with a dial indicator? I am DOHC ignorant

[cdaiscool]

Oops. Already done with 300. Looks so shiny and clean!

I'll follow up with 1500. I really wanted to get that gunk out of there.

As for the groove, that's what I've been doing. I've got some dentist tool-esque picks from Craftsman that I've been cleaning it out with. Good to know I've been doing it right!

The only pits whatsoever on the piston is up near the groove for the dust cover. I've hit that with 60-grit briskly so I could get the rust off it, then hit it with 300 to smoothen it out. I'll hit the piston all over with 1500 as well so it smooth-matches the bore.

I did the valve measurements with a set of feeler gauges. Move the exhaust cam where the FSM says to, check the 4 valves it tells you, then carry on! Hoping to get the tool for it this week; didn't get a notice the seller shipped it on Friday, so hopefully Monday. Or they just didn't e-mail me and it went out anyways. That'd be awesome.

Hoping my dealer guy can get me my other 2 gaskets by like Wednesday or Thursday. Thursday at the very latest; I want my motor running by then! And then I'll button up the bike Friday, and ride with my dad then.

Maybe I'll ride it to my weekly car meet Friday night or Saturday night. If my dad's down to go. Hmm.


Oh, and oil IS getting up to the valves up top. This I know, as there is a puddle of oil in the top end. So yay! It's not having pumping issues!

I think.

[TOOLS1]

I use a little wire brush on my Dremel tool to clean the bore, and grove in the caliper.
TOOLS

[cdaiscool]

Well, I sanded the inside bore and piston with 600 grit sandpaper. Feels exceptionally smooth, piston fits w/ no side-to-side play. I'd say I'm going to be fine. At least, I hope so.

Here's pictures of the piston, I'm assuming this is a safe amount of pitting? It's the best I could get it.





Threw a couple coats of paint on the parts, and they're currently drying. Not going to start pulling off tape until tomorrow, when it's had a chance to dry for 24+ hours.

In other news: cleaned and lubed my chain. Holy cow that chain was DIRTY. Probably 1/8" inch of grime on it. Cleaned it with kerosene. Threw (sprayed) Dupont Chain Saver on it, it's happy now.

Also found that my exhaust is hitting my chain. I'm betting that's what the dealer guy said was my center stand. Who knows. But now I've gotta find a way to make it not hit. Don't know if I'll do a bracket, or just heat it up and hit it with a rubber mallet to move 'em out just a tad.

So, overall, this weekend has been a decent success:


-Bleed brakes on Integra. Get into driveway if possible... (wheels aren't screwed into lower ball joint; gas line is dragging as it's currently being upgraded...) Didn't even touch the Integra. Oops.
-Tear apart brake caliper; paint with black Rustoleum DONE. Semi-Gloss looks nice.
-Remove brake master cylinder from handlebar. Yep, waiting for new one to come in.
-Remove valve cover, side cover from motor Yep, even removed the wrong side cover!
-Clean, adjust chain. Lube. Using DuPont Chain Saver. God what a mess....
-Gaze longingly at wanting to freaking ride already Unfortunately, this did happen.
-Check valve clearances; mark down so when I have the tool, I can just start removing shims and start looking at what I need to get. Only need to adjust one! Off by a whole .001"!
-Sand piston, inside of brake caliper to remove gunk. 600-grit made 'er smooth!
-Before painting, clean brake caliper with paint thinner to remove oils etc. Paint liberally. Because liberals should always be happy - they have guns. So true. And done.

Not bad, not bad. Just need to get some feedback on that piston. And order up the 2 gaskets for the left side. And also adjust the one valve. And do the brakes. Then it's off to town to go riding some more. :D