Author Topic: 82 cb650sc - take 2 (Read 3158 times)

odioanonimo · « **on:** December 18, 2018, 09:01:58 am »

so i have an 82 cb650sc, my first build. i sold to my brother... but then we found him a different bike and i ended up with this one back.

but not before he dropped it and let it sit outside... uncovered for most of the year.....

and its charging system is fried....

and it, of course, needs the head gasket addressed...

and it was my first build.... so now im pretty sure i can do better, and some things i didnt even notice or think about a few years ago annoy the #$%* out of me now... so we are gonna do it again! i have a few questions ill get to in the next post here. mostly just advice i suppose.

anyway, here is what we "started" with.

odioanonimo · « **Reply #1 on:** December 18, 2018, 09:14:36 am »

so i was inspired by kerryb's thread to do the switch to a 79 or 80 cb650 head so i can use a pair of cb750 keyhole carbs i have. partially cause hell yeah. partially because i hate hate hate hate the cv carbs that came with it, partially because there are so many more options to tune the keyholes. jets are more plentiful, rebuild kits are cheaper, and i feel like they are more forgiving. and because hell yeah. i considered some round tops, but i think this bike would suffer without the accelerator pump.

anyway. i pulled off the 82 head. and in taking a gander at the pistons, i think it looks pretty good in there, aside from some carbon build up... but, what the hell do i know? so i figured i would ask you guys what you thought.

also im trying to think of all the things i should address or replace while im in here, so i hopefully dont have to pull the engine every single winter.

https://imgur.com/2GVmtiI

https://imgur.com/EbCPuy1

https://imgur.com/iYKvj2o

https://imgur.com/55ZYK47

https://imgur.com/5Ykl04R

SOHC4 Cafe Racer Fan · « **Reply #2 on:** December 18, 2018, 10:43:56 am »

You may still want to re-hone the cylinder walls as part of a top-end refresh. The carbon build up at the top of the pistons looks normal. There is some cross-hatching shown on 2 of the photos of the cylinders but it's not apparent what shape the rest of them are in. There's a simple drill attachment you can use to re-hone the cylinders. You can also use the opportunity to blast the outside of the cylinders to remove all of that baked in oil/grease.

odioanonimo · « **Reply #3 on:** December 18, 2018, 05:34:39 pm »

Racer Fan... youre right. i guess i knew i should, becuase you might as well..... but i was hoping for someone to be like "naw, odio, that looks legit"

anywhere heres so more picture after i removed the cylinders. two of the four still look pretty good, and honestly i probably could have gotten away without doing it... but it did need it. compression was alright but not great (which i attributed to the head gasket), and in retrospect i do recall suspecting that oil was getting past at least one of the rings... though i cant recall why i believed that to be true. either way, tomato tomahto, no half measures. if im gonna do it i might as well nut up and do it all the way.

https://i.imgur.com/M8ea81s.jpg

https://i.imgur.com/Gwbux84.jpg

https://i.imgur.com/doct7Pu.jpg

https://i.imgur.com/3XgimkF.jpg

SOHC4 Cafe Racer Fan · « **Reply #4 on:** December 19, 2018, 09:41:48 am »

One sign of oil getting past your rings is smoke (from burning the oil). Of course the top of your piston will also show more build up as well.

kerryb · « **Reply #5 on:** December 21, 2018, 06:06:20 am »

While you're in there is a good time to check on the starter clutch rollers and springs. I have to replace mine and while researching it there seems to be consensus this is a weak point of this engine.

odioanonimo · « **Reply #6 on:** December 21, 2018, 05:37:46 pm »

Ah, I didn't think of that either.

Is there a way to check service limit on those with splitting the cases?

rb550four · « **Reply #7 on:** December 22, 2018, 09:17:51 am »

In the 2nd batch of cylinder pics, 3rd one down, doc7... looks like a couple of deep rust holes where the rings were rusted to the cylinder walls before the first rebuild....looks to me there is your blow by and oil ring leak.
There was also visible scoring down the other cylinders walls that will lower the compression . Hone could help some of that usually or it could make it worse in this case, as it seems that the cylinders have been heavily honed once before.
But those rust pits make me wonder if there is enough meat left to over bore , then there is machine shop cost, new pistons and rings. The 650 has never really been in high demand and it's resale value will reflect that...so the question becomes how much do you want to spend on this machine?
I would be on the look out for some jugs to replace them. Sure it'll still run the way it is and probably make a fun bar hopper for a while , but if it's doggin' performance is already bothering you and you're already up to your elbows in it, why not see if there are better jugs out there , hone them and install new rings? A complete gasket set will have all the Orings , base and head gaskets, and valve seals and all the rest of the top end seals that you'll need to button it up . And will come with some extra case gaskets that you'll be wanting later. Just my 2 cents. It'll be fun no matter what you do.

DaveBarbier · « **Reply #8 on:** December 23, 2018, 04:59:01 am »

Might find this useful. A list I put together with close to, if not all seals, o-rings and gaskets for the 650 motor.

http://forums.sohc4.net/index.php/topic,140833.msg1877156.html#msg1877156

Also in my signature there’s a link to my build thread’s table of contents if you want to find other things.

odioanonimo · « **Reply #9 on:** December 23, 2018, 11:30:56 am »

Rb - I believe that is a dirty trick of the light, but it wouldn't be the first or last time I've missed something. I'll check it again, good eye, thank you

Dave - #$%* man, that's awesome! That's a great resource, thank you

odioanonimo · « **Reply #10 on:** December 31, 2018, 12:39:06 pm »

Progress.

So I got in the new head, it's in worse shape than my old one, but not bad. I also got a whole variety of gaskets and seals and chemicals and this and that.

I want to soda blast this engine. And I was also considering getting rid of the rigid struts in exchange for an actual hardtail, which would mean blasting the frame for a fresh powder coat. A local place quoted me a ballpark of 300 bucks to blast it all.... But I feel like for not much more I could buy some things and just do it myself... Is there any good reason I should send it off? Also if my plan is to do the whole engine should I do the various pieces that are removed? Or assemble it and blast it in one go?

Now to the more important questions.

odioanonimo · « **Reply #11 on:** December 31, 2018, 12:49:46 pm »

alright, first question:

while i was scrubbing the new head with lots of soap and such a bunch of washers came out. for a minute i was really confused, then i identified the larger and smaller valve spring seats... but i also have a couple of these thick washers... and i have absolutely no idea where they came from.

https://i.imgur.com/fHkNny4.jpg
https://i.imgur.com/Pp2wSbe.jpg

next question:

actually i cant remember what my next question was... only that i felt it was pretty important... i guess if its that important ill remember it?

thanks for all the help.

scunny · « **Reply #12 on:** December 31, 2018, 01:00:34 pm »

Those heavy washers are from the head bolts, they are often stuck tightly in place.

odioanonimo · « **Reply #13 on:** January 01, 2019, 10:09:06 am »

So my piston rings came. I removed the old ones and put the new ones on in the same order. I mounted the Pistons and honed and oiled the cylinder and it was getting late. So I went to bed. Then I got to thinking... Trust nothing. So I checked and my first and second rings were backward. No big. I'll just switch em. Broke a damned ring. After a string of choice words I finished the job. Less one ring. What do I do? Can I order one ring? How frustrating

odioanonimo · « **Reply #14 on:** January 01, 2019, 10:47:16 am »

I guess I don't really expect I'll be able to order a single ring. But a single set of Honda rings is as much as my four sets of crusinimage ones. Though I suppose that may speak to the quality of my broken ring. Anyway. Is there somewhere to order a reasonably priced single set stateside? Otherwise I figure I might as well buy another set of four from Japan at that price. Bah humbug. Should been more careful.

scunny · « **Reply #15 on:** January 01, 2019, 11:17:56 am »

just order the set of 4 from CI. I have been running them in my 650 for a few years, seem to be holding up well. He takes offence easily and might block you if you say you broke one.

odioanonimo · « **Reply #16 on:** January 01, 2019, 05:31:37 pm »

I have read that his block finger is pretty strong. Whatever the case... What's one $40 mistake really? The price I pay for not being careful enough I suppose.

Speaking of not careful, I too hastily ordered my exhaust baffles from 4into1 and order the wrong size.... So those are off in the morning for exchange.

So now that I'm stalled out on the top end I figured i might as well get into these cb750a carbs I bought on a whim long ago. And if I'm not mistaken, if I remove all the fancy "a" stuff, vacuum solenoid? And the like, then just cap off the ports where they would attach to the carbs.... These carbs are just like any other keyhole 750s, right? I figured I might as well start tearing them down and blasting them and cleaning them up, and ordering jet kit and such. Overall they look alright. Not pristine or anything but far from the worst set I've seen.

CarbonK · « **Reply #17 on:** January 05, 2019, 07:49:59 pm »

Hey odioanonimo I got a question, what model cv carbs did your 82 sc come with?

odioanonimo · « **Reply #18 on:** January 05, 2019, 10:05:39 pm »

vb44c. and in their defense.... i dont know what they ever did to me that made me so against them... they seem to work fine and any issues are probably user error.

odioanonimo · « **Reply #19 on:** January 08, 2019, 02:32:41 pm »

Broken fork lower circlip. How the hell do I get that thing out? All I can think is just to pry it out in brittle little chunks

kerryb · « **Reply #20 on:** January 08, 2019, 02:41:13 pm »

Bummers! A picture might help me come up with a solution. Had it happen to me before but I can't remember my solution at the time. Mavbe pry the edge out of the groove with the right dental picks and pull it up a little at a time.

kerryb · « **Reply #21 on:** January 08, 2019, 03:15:41 pm »

hey Odi, is this the offending circlip? I pried it out from one side with the pick/hook that came in a set of picks for orings and seals from Harbor Freight. Took me about a minute working from only one side.

hope this helps

odioanonimo · « **Reply #22 on:** January 08, 2019, 03:53:05 pm »

i wish man. those clips i can manage. and one of these clips i got out no problem. this one was in poor shape. it was rusty and corroded so i soaked it in pb blaster for... i dunno... days? a week? and every day i would go out and run a screwdriver along the edge trying to break up some of the stuff that was sealing it to its little groove, then apply some fresh blaster. today i got into it and both ends where the little hole for the snap ring pliers go gave a bit... then just snapped off.

https://imgur.com/lYsLvjc

the one i got
https://imgur.com/ewjo3If

kerryb · « **Reply #23 on:** January 08, 2019, 04:48:54 pm »

I was afraid you would say that. I had that experience with a rear master cylinder once, ended up ok, but you can't get this one the way I did.
So...my suggestion is to use the engine unseizing trick on it first before digging it out. Pour a 50/50 mix of acetone and auto transmission fluid on it for many days to break the rest of it free. Then try prying it out with various small pointy stuff.
Good luck, I think you'll need it

odioanonimo · « **Reply #24 on:** January 08, 2019, 04:54:44 pm »

Thank you, sir.

Broken ring so I moved to carbs and ordered new ones from Japan

Ultrasonic cleaner broke so I moved from carbs to forks, and ordered a set of diodes from China

Broken clip and it's gonna have to sit for some time in kerryb magic oil

I guess I'm gonna have to get into the exhaust or the frame... See what else I can break

kerryb · « **Reply #25 on:** January 09, 2019, 05:31:26 am »

Ok, I think you need a change in goals, new goal should be to break this streak of breaking things!

. Then pick something with a high possibility of success...so you can start a new success streak. Happy building!

odioanonimo · « **Reply #26 on:** January 22, 2019, 06:29:53 pm »

Alright... It's time to start a success streak.

The rings got lost by the post office... And I complained and complained and eventually I went in and found a super nice clerk who dug through some things and found them!

..... And I immediately broke another one, probably at least partially due to the butter cold they sat in... At least that's what I'm telling myself. Good thing I ordered four sets! Rings are on! Now I just need to put it back together.

Got my new stator.

Got my new ultrasonic cleaner.

Things are looking up. Now if only the kids would have school, I'd have some quiet time to assemble it all.

News:

Author Topic: 82 cb650sc - take 2 (Read 3158 times)