I'm new! 1982 CB900C barn find.

MB-5 Joined: Oct 31, 2020 Posts: 20 Location: Olympia WA

Howdy all! Picked up a well taken care of DOHC that's been slumbering in a trailer for the last 10 years. Was minimally ridden before that. First thing I've done is pulled the brakes off for a rebuild as well as the carbs. I'm also swapping out the gas tank. The one that came with it is a rust bomb and it ain't my style. If anyone happens to have a spare F model, hit me up.
That's it for a start.

Anyone have opinions on Dynojet? Seems pretty simple to do and since I have my carbs off the bike already I'm thinking of doing it.

To my calipers, all three were stuck to the disks. I managed to drop the pads and was able to remove them. The front two stripped down easily and are all cleaned up. The rear has one of the two pistons fused in. Does anyone have any recommendations as to getting it freed up? Ive tried tapping it physically and brake cleaner soak but no luck. I'm removing the pistons via compressed air btw.

Last, if you all have any suppliers or small shops you like working with, let me know. It seems theirs plenty of places to get parts and other custom goodies but not all suppliers are legit.

Cheers
Pat

Posted: Sun Nov 01, 2020 5:59 pm

Welcome to the obsession, man. Do you have a Custom (C), or a Supersport (F)?

If a Custom, there's a "sister website" (www.cb750c.com). Not that you're not welcome here, but "C" specific parts will be more easily acquired there.

If it's an F, post up some pics, we'd like to see the starting point. This site has an encyclopedic amount of material, experience, and advice to give you.

Enjoy!

Posted: Sun Nov 01, 2020 6:00 pm

Hi Pat and welcome to the Forum. My advice is if the bike is a stock setup to stick with OEM Honda parts whenever possible. The one exception off the top of my head are the carburetor float needles. Keyster brand has Viton rubber tip ones that hold up much better to ethanol fuel. Have fun!

Posted: Sun Nov 01, 2020 6:26 pm

Hi Pat, welcome.

I'd avoid the Dynojet stuff like the plague.

To loosen things up on stuck brakes, I usually wham the devil out of the calipers a few times with a rubber mallet while they're still on the bike. Then the bike can roll and things come apart easier. Of course time for that gas passed.

Some have had success boiling calipers to get them unstuck. Or you can pump them out with a grease gun which is messy. If you try using air, be careful and contain the puck from flying out using rags.

TomK has really good info on doing brakes.

Also see:
https://www.youtube.com/results?search_query=piston+rusted+stuck+brake+caliper+honda+motorcycle

Posted: Sun Nov 01, 2020 11:37 pm

I use a grease gun with used oil, same hydraulic pressure as grease but without the cleanup headache.

Posted: Mon Nov 02, 2020 12:15 am

I do what TomK does... use a master cylinder to pump the pistons out. I scrounged
a master c from an old three wheeler, cut an old handle bar into, mount the master on
half the bar and clamp the bar in my vice. Hook the caliper up and pump the pistons out...easy-peasy.

MB-5 Joined: Oct 31, 2020 Posts: 20 Location: Olympia WA

Hey ya all!

Cliff, yeah, it is a C so I'll be sure to check out the other site. That said, thanks for the welcome! I'm not planning on keeping it to C in the end. Aside from the odd ball 10 speed it'll be undergoing a more sporty transformation!

Hondo, agreed! Will go OEM when doing any rehabbing or maintenance. And, I'll look into the needle suggestion. I've opened up two carbs so far and aside from a little sticky varnish, real clean!

Genesound, Howdy! I'll take your advice on the jetting. I'm thinking the only real way to get a little more out the bike, carb wise, is to go with a CR set...I'll pass on that for now. To the brakes, I just got done boiling the caliper and tried the air-compressor again. No luck. The already loose caliper came out but stuck one is real stuck. Like fused!

Sillygoose, that's my next attempt. Thanks for the used oil idea! Will give it a go.

Grumpy, yeah, I'd try that but it seems I have one piston of the two on the rear totally stuck...we'll see if the oil in the greese gun does the trick.

Posted: Mon Nov 02, 2020 1:49 am

sillygoose wrote:

grease gun with used oil

Great idea!

Posted: Mon Nov 02, 2020 12:00 pm

genesound wrote:

sillygoose wrote:

grease gun with used oil

Great idea!

+1.....although i have no doubt there will be a "what kind of oil are you guys using in your grease gun" thread. Laughing

MB-5 Joined: Oct 31, 2020 Posts: 20 Location: Olympia WA

Haha! True! I'm going with the used motor oil...

Posted: Mon Nov 02, 2020 6:28 pm

The other option is to use the master cylinder that's on the bike, with a line going straight to the caliper. The upside to this is that you can use the opportunity to flush out the old fluid while you're at it. In any case, there are several options that work, as described above. Stuck pistons will come out every time when you do it hydraulically.

Tom

MB-5 Joined: Oct 31, 2020 Posts: 20 Location: Olympia WA

Hey Tom, that sounds like the way to go. It's the rear so I'll just hook it right back up.

Thanks for the thinks!