Author Topic: 1978 CB750K — Post 836 OIL PRESSURE - not good (Read 248040 times)

SKTP · « **Reply #225 on:** July 30, 2012, 11:03:22 AM »

CB450 Black Bomber - took me over a year to find all the pieces...having a new bezel machined right now

mrrch · « **Reply #226 on:** August 03, 2012, 12:49:12 PM »

I swapped back to the under tank mount and switch (used an Emgo switch but used relays as per Hondaman) Had to cut the harness open and crimp on new connectors (Vintageconnections.com)Not hard at all.
+1 on wiring diagrams (get both to compare)

SKTP · « **Reply #227 on:** August 05, 2012, 04:46:55 PM »

It's coming along....can't tighten the brakes down....any tips on pushing the pistons back? I'm guessing, just push them like crazy...

Syscrush · « **Reply #228 on:** August 07, 2012, 06:54:02 AM »

I fasten the caliper to something rigid (like putting it in a vise), and put the claws of a hammer into the mouth of the caliper, and crank it gently but firmly so that it pushes the piston back. Keep an eye on it and make sure you distribute the force by working your way from side-to-side or around the piston, because if it gets crooked and you keep just cranking full-force, you'll damage stuff.

MCRider · « **Reply #229 on:** August 07, 2012, 07:02:14 AM »

You know those wooden (now plastic) constructionwedges for installing door jambs? Push one in from 2 sides and drive them together.

A broad tire iron works well often.

SKTP · « **Reply #230 on:** August 07, 2012, 03:41:37 PM »

Should I spray wd40 or something on them as well? They have been sitting for awhile

MCRider · « **Reply #231 on:** August 07, 2012, 04:11:53 PM »

Quote from: SKTP on August 07, 2012, 03:41:37 PM

Should I spray wd40 or something on them as well? They have been sitting for awhile

If they are coming apart, OK. I wouldn't spray or drip anything on an assembled unit that's going to be used except brake fluid. Are the pads removed?

Syscrush · « **Reply #232 on:** August 07, 2012, 04:54:47 PM »

Quote from: SKTP on August 07, 2012, 03:41:37 PM

Should I spray wd40 or something on them as well? They have been sitting for awhile

How long have they been sitting? Were they rebuilt as part of your project?

SKTP · « **Reply #233 on:** August 07, 2012, 05:52:32 PM »

One for 3 years...the other, no idea...the pistons have never been out of either as far as I can tell

they look clean? I'll try pushing them in and see what happens

I don't have my master or my lines ordered yet....

Syscrush · « **Reply #234 on:** August 08, 2012, 05:54:24 AM »

Quote from: SKTP on August 07, 2012, 05:52:32 PM

One for 3 years...the other, no idea...the pistons have never been out of either as far as I can tell

they look clean? I'll try pushing them in and see what happens

I don't have my master of my lines ordered yet....

It takes very little time and no money to pop the pistons out and give them a thorough clean before putting them back on the bike. Lots of tutorials about how to do this. I use compressed air to push the piston out, wrapping the caliper in a rag first to keep the piston from flying across the shop and hurting someone or something. Clean the piston and the caliper with brake fluid, inspect the seals, and polish the outside of the piston with emery cloth. Clean with brake fluid immediately before final assembly. Only use no-lint shop towels and blow everything off with compressed air.

RAFster122s · « **Reply #235 on:** August 08, 2012, 06:27:24 PM »

Quote from: SKTP on April 08, 2010, 01:57:09 PM

Thanks for the replies so far....here's a shot I took of the bike right before the tranny started slipping...I have to get rid of that rear fender and taillight. Why did they design them so HUGE?

I am betting that the Taillamps became larger due to DOT rules for the minimum area of the brake lamp lense. If it is huge and bright...all the better to be seen in a busy nighttime city setting.

SKTP · « **Reply #236 on:** August 12, 2012, 06:58:54 PM »

Used an old brake pad, a spacer ring from my "allballs" tapered bearing kit and the table vise to push the caliper pistons back. One of them pressed long strings of grease out of the bleeder opening....I'm going to rebuild and clean them for sure. But for now the test fitting is a success. It's the first time I've had the right hand side caliper on the bike with pads. I read I may have to shim or file the mount to get it to work, but initially test appear that it's the same as the stock side one. Is this possible? Dud I get very lucky of is it common that added another caliper is an easy bolt-on?

Tintop · « **Reply #237 on:** August 12, 2012, 07:19:18 PM »

My experience was that everything will bolt up, but the caliper / pads are not actually sitting true to the disk. Once you get the caliper working you will find the pads aren't contacting the disk properly. You'll need to remove about 2mm from either the leg, or the pivot bolt, to get everything square. Taking it off the pivot bolt is much easier.

RAFster122s · « **Reply #238 on:** August 12, 2012, 10:11:21 PM »

+1 on Tintop's experience...
it can be a little fiddly but is worth the effort.

Grease...uh yeah, most likely water and brake fluid congealed mess. Probably want to use grease gun to pump the piston out of the caliper and clean and polish it up. You are likely to have a pitted piston. If so, either replace w/stock, stainless, or phenolic replacement.

SKTP · « **Reply #239 on:** August 13, 2012, 12:14:14 PM »

"most likely water and brake fluid congealed mess."

Rebuild on the way! thanks guys

SKTP · « **Reply #240 on:** September 16, 2012, 10:13:19 PM »

Popped my caliper pistons out today. Did one at Big-O tires down the street. 150psi and it launched into the passenger side window of a car on a lift. The other one would not budge...so I hooked up my old master cylinder and popped it out fairly easily with brake fluid. The brake fluid way was very easy and not as messy as I thought I'd be...both pistons appear to be good.

SKTP · « **Reply #241 on:** September 25, 2012, 12:59:22 PM »

Finally, getting the garage drainage issue resolved

srbakker · « **Reply #242 on:** September 25, 2012, 01:11:36 PM »

Yikes. Nothing like having multiple projects on the go.

SKTP · « **Reply #243 on:** September 30, 2012, 11:25:58 PM »

Look what arrived from APE

SKTP · « **Reply #244 on:** October 08, 2012, 11:24:39 AM »

Rivet drilling a success. Now to sand and paint

can't wait for this to arrive

SKTP · « **Reply #245 on:** October 14, 2012, 05:25:59 PM »

Taking my block to get honed this week and have a pro put the new rings on (I'm sure I'll just snap them). I have been scrubbing these pistons for awhile now, they don't seem to want to get cleaner. Can/should I try polishing then with a polishing wheel or is this good enough?

fastbroshi · « **Reply #246 on:** October 15, 2012, 11:59:36 PM »

That should be fine, if you really wanted to be anal I guess you could take a small pick and try to scratch off those last little remnants of carbon.

Syscrush · « **Reply #247 on:** October 16, 2012, 05:37:18 AM »

Quote from: fastbroshi on October 15, 2012, 11:59:36 PM

That should be fine, if you really wanted to be anal I guess you could take a small pick and try to scratch off those last little remnants of carbon.

I think that if you invest the time to get those last bits of carbon off with a pick, you'll be glad you did.

SKTP · « **Reply #248 on:** October 16, 2012, 10:27:26 AM »

Should I polish them with rouge and a cloth wheel?

MCRider · « **Reply #249 on:** October 16, 2012, 10:51:24 AM »

Quote from: SKTP on October 16, 2012, 10:27:26 AM

Should I polish them with rouge and a cloth wheel?

You'll want to clean the ring grooves, assuming there may be carbon in the grooves which will interefere with the new rings.

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Author Topic: 1978 CB750K — Post 836 OIL PRESSURE - not good (Read 248040 times)