Topic: New guy here

[Newhavenmike]

Hello all,

My username pretty much sums up the basics about me, 31 years old. Ive been reaearching the forum and other places, including reading over shop manual to gather as much as i can about my motorcycle.

I purchased a non running 1980 CB660C earlier this year and put it to the side.. I have a couple other bikes that i was occupied with so thats why the 650 has been been sitting.

My first bike was a 1976 Yamaha XS360 that i bought with a seized engine. I tore it down to nothing and had a used jug bored out and rebuilt the entire engine myself. I had no money at the time so it took me 2 years before i heard it start for the first time.

Well, then i got a much better job and started picking up pretty much any bike i came across under $500 lol. Which leads to this CB650.

Im in the process of gather parts and getting the engine up to spec. I was intending on rebuilding the carbs and keeping it all stock. After testing the carbs down and ultrasonic cleaning, the carbs are just too far gone.

I picked up a working set of carbs from a 78 750.. from what ive read afterward, these arent the best carbs... whatever.  I do notice that the flange on these 750 carbs are 4mm wider than 650s. The 650 has straight rubber boots too, whereas the 750 has angled ones because the cylinders are at a forward angle.

Is my only option to buy 650 boots and force fit them to the 750 carbs? If i use 750 boots, the carbs will slant down. Ive been trying to find compatible boots but its hard to properly identify what i need because i cant tell if the images im seeing are just general images or specific. It seems that honda changed up their carbs a lot in yhe 70s.

Im not intererested in picking up another set of carbs so id like to avoid that for now.

Thanks for any tips

Heres a pic of my Xs360 next to my MG:

[Bankerdanny]

I know that the 750 carbs are supposed to work on the 650, but it may need to be '76 or earlier round top style rather than the later PD series carbs you picked up. Someone will clarify shortly I'm sure.

Nice MG, I have one myself, a '72 GT. This is what it looked like a few years ago, right now it doesn't look nearly so nice as I started a sill replacement project about 4 years ago which has been stalled.

[TurtleSnifferII]

Nice to see some young blood on here like me, I'm 22. I have a CB650C 1980 as well but it came with an unknown background and took me a couple years to get it to run perfect. I don't have an answer but I will say this place is a great help with some smart cookies on here.

[Newhavenmike]

Nice MG. Id like to get mine in a better state as well. I dont have a proper garage as of yet though so its on hold for now..

So i reread over another thread for the 5th time... im going to pick up a set of replacement 650 boots and see if i can wiggle them over the 750 carbs.

I see theres really cheap junk repro sets available so i may give those a try before committing to a real set. I already know the rubber/plastic will be of a different composition than the real deals.. i could probably juat try reusing the ones i have too.

As far as the bike goes. Its in decent shape. One of the POs did his fair share of repairing stuff. The chain is incredibly worn and loose. The turn signals have homemade brackets drilled into the fender. Front brake needs rebuild, and the almighty starter clutch is broken. So it does need some work, but far from a full teardown.

I think i want to take this into a scrambler sorta thing. Basically i plan on getting a new seat and handlebars and updating the lights.. i dont want to get crazy with this one, im not doing any frame work so itll all be reversable.. the tank has a couple dents in it as well, which im not even gonna bother with.

I really just purchased this bike because i have a highway commute of about 90 miles. My XS360 does the job, but i didnt build it to ride 45 miles one way at 80mph.. and also i thought having a 650/4 would be a better ride with a passenger, even though i ride passengers on my 360 just fine as well.

[Bankerdanny]

Fortunately the 650's are not particularly collectible, so turning one into a brat or café or scrambler style bike won't really have an impact on value. A super clean original 650C won't be worth as much as a clean earlier SOHC4. The nice thing is the 650 engine is probably the best overall in terms of power vs physical size and weight, so you should end up with a really nice bike when you are done.

[DaveBarbier]

Is it possible I’ve see that Yamaha around? I’m about 30 minutes south of you and go to New Haven fairly often. I’ve also got a 650 that I’ve done a fair share to. Feel free to skim through my build thread. In the table of contents you’ll see a link to a bunch of part numbers you might find useful.

I’m currently using OEM 650 rubber insulators, but I did squeeze on some 550 ones to test for a friend. They’re tight, but looks like it could work. I bet others would work too. Since the insulator inside is shaped to guide the air/fuel it might not work exactly as it’s supposed to but I bet it’ll be fine.

When you get that thing going let me know. I’d like to get some riding in this fall season. I’ve still got a couple more things to do after a front end swap. I ride with a friend of mine who lives in New Haven, incidentally.

[Newhavenmike]

I dont think the 650 will be one the road anytime soon.. i really plan on getting into it by next Spring. Until then i want to at least get it running and then get some more parts over the Winter.

My XS360 is the only bike i ride at the moment. I wouldnt be surprised if youve seen me around new haven. My bike gets a ton of attention from all sorts of people. I ride through downtown often and all over the area. I mainly ride around in areas that include Milford, New Haven, West Haven, Orange, Hamden, and Bethany where i now live. I grew up in West Haven and i like the beach cruising..

Im ordering the cheapo 650 boots but not im going to try the fitment with the crusty old boots first. Thanks for the tip i will check out your thread.

The real pain is dealing with a bad starter clutch, which ive read the how-to on how to do it without having to tear the engine completey down.. ive had the tebuild kit for months now too.

[DaveBarbier]

Cool, yeah the Yamaha looks familiar.

I’ve removed the starter clutch and full primary shaft on my 650 and reinstalled it when I forgot to install my primary chain tensioner during my rebuild. That was with the engine flipped over on the bench though. Took like an hour max. Shouldn’t be that hard with the engine in the frame.

If you need a hand let me know. If I’m free I’d be happy to help. Beer is my currency. A night at Keepers is too but that gets pricy, haha.

[Newhavenmike]

Thanks for offering some IRL help lol.. I really appreciate that.

To be honest, Im mostly a loner when it comes to working on my bikes. I have a small shed and I sometimes bring the work inside to the attic. Doing this sort of work has become sort of a peaceful meditation state lol..

Actually, I am considering getting a shop space for my bikes and maybe my cars. I just cant seem to find anyone that wants to do the same. Id really like to do this if I can find the right people. Maybe 2-4 people together could get a decent space.

I love my XS360, but after getting it mostly finished, Ive realized some of what Ive done wrong with it.. I wont change it, but I know now. Most of it was due to inexperience, lack of proper tooling/workspace, and severe lack of funds.

As Ive said before, I don't plan on going crazy with this one. I was going to pick up a 550 frame and go that route, but then I got sidetracked with my ironhead rebuild and simplified my plans for the 650.

I will be picking up a 750 tank when I get the chance, I was going to pick up spoke wheels, but then decided I don't want to be bothered with custom fitments and more expenses. I have a large disliking for the reverse comstars but the normal comstars I think are decent.. I got a really good deal on a 17" comstar and I think itll look a little better.

As for the engine, I need to get it running, even if I can get it pop started that will be good enough for now. I want to give it a couple heat cycles and do a compression check. Its got 16,000 miles on it. Ive heard of Hondas going for quite a bit more than that  before needing a rebuild.. I did pour some gas in the cylinders and let some fuel into the carbs and got it to kick over once or twice, but the carbs were so bad I was only getting fuel to one cylinder. Then I ran out of energy from trying to pop start it.

Pending compression test results.. I am very willing to get into engine work if I have to and also for piece of mind, but if compression is very good, Im not touching it.

I haven't gotten into the charging systems on these bikes yet, but I plan on going all LED if I can. Ive heard they aren't the most reliable?

Ignition will get upgraded as well, honestly I cant remember if this bike has points or not.

[DaveBarbier]

You’ve got an electronic ignition. No points in the 650. Not quite a CDI ignition, but something else that’s not very reliable. One option for you is fitting a 750 PAMCO unit. All that needs to be done is make a new plate or modify the one that comes with it so if fits in the bosses. Second option is more expensive but requires no mods. C5 ignition. I have one and it’s great. But disclaimer, me and another guy with a 650 are experiencing an ignition cutout issue when it’s hot outside. But we’ll get that figured out and post results. I’m sure there are other options but I didn’t do that much research.

You’ve heard LEDs aren’t that reliable? I have all LEDs in mine including headlight and they’re all good.

Definitely let it go through heat cycles before you base whether or not your tearing it apart on compression results. If it’s been sitting, it might take a handful of miles before it gives reliable actual results. Cylinders can be rusty, rings can get stuck, etc. Just don’t let it idle for longer than a few minutes without a big fan or leaf blower blowing on it. And doing that under load (meaning riding it) is better. Even if you get it all together, ride it around and find the compression isn’t the best, you can remove the cylinders, hone them, rering the pistons and get it together all while in the frame. Could be done in a week if you send out the head and cylinders for decking and honing.

[Newhavenmike]

I mistyped my post. I meant that ive heard the charging systems arent reliable. But its mainly the rotor? I prefer LEDs just to keep voltage drain down some. I think the bike was last registered a few years ago. My guess is that it was only taken off the road because of the starter clutch.

From doing a bit more research, it seems that the ignition system on the 650 is the same style as my MG. The MG is from 1977 so it is electronic.. i even have a GM ignition component that i installed because the original Lucas one went bad.

Im going to try and squeeze the carbs on today with the old boots.. other than that, id be attempting to get it started this weekend.