Topic: CB650 carb and other questions

[WiredForStereo]

I am buying a 1980 CB 650 that is in fairly decent shape, there are just a few things. 

The #1 cylinder does not fire at idle.  There is plenty of spark and fires at speed.  Is this a carb problem?  What would I need to do to fix it?

I think the turn signal blinker mechanism is iffy.  Where is that thing located so I can replace it?

What kind of bulbs do the rear turn signals take?  Tail light?

What are the signals of cam chain problems and how do I tighten it? 

How often should I adjust the valves?

What is the oil drain interval?  I have no owners manual.

Any other tips or information would be excellent as well.

Thanks
Sol

[eurban]

Your prob with #1 cylinder could very well be a carb issue.  Likely a clogged idle jet but could also be that the idle mixture setting for that carb is off or the float level is off, although if your 80 650 has CV carbs (large round covers on top) then your floats are probably plastic and not adjustable.  As to you're other questions . . . .Perhaps someone else can provide or point you towards this info but do yourself a favor and get the repair manual (Clymer would probably be best) for the 650.  It will have all the info you need to get you most of the way though the process of bringing your bike up to a road worthy state.   People on this site can then fill in any  blanks much more easily.

[rob]

Hi Sol,

I have a Clymer Honda CB650 Fours 1972-1982 manual, let me just say that it is invaluable.  You can get one on ebay for like $10 http://cgi.ebay.ca/CLYMER-HONDA-CB650-FOURS-1979-1982-REPAIR-MANUAL_W0QQitemZ8037752639QQcategoryZ34237QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

I've never hard to replace the bulbs on the bike, but here are what the replacement bulbs section of the manual says:

Tail/brakelight: 12V 8/27W - SAE no. 1157

Directionals:
   Front: 12V 23W - SAE No. 1034
   Rear: 12V 23W - SAE No. 1073
   
I think there is a difference between between the 1980/1981 CB650C in some of the electrical details.  I've never had to deal with the turn signal relay, but it is described as being under the seat and has a rubber mount.  I took a quick look on oldbikebarn.com, partsnmore.com and ebay, but couldn't turn up a part.  Perhaps someone on the forum can recommend where to get a relay, or suitable part?

I have had problems with the turn signal switch located on the handlbars: I broke the little lever that held it together.  You may want to take that apart and make sure that the mechanical switch is operating properly.  Another simple thing that may help is going over the wiring, looking for shorts, and sparying all electrical contacts with contact cleaner.  When I did that, a few nagging intermitant electrical problems I was having disappeared.

Signs of cam chain problems? Not sure what the problem would be.. maybe an engine with symptoms of poor timing.  I listen for a noise that sounds like something slithering in the engine. The instructions for tightening it are in the clymer manual, they are

1. Bike centerstand
2. Turn the ignition switch to off and put in neutral
3. Remove all 4 spark plugs
4. Remove ignition cover (the round part on the side of the engine that says Honda)
5. Loosen the camshaft chain tensioner locknut.  This is a nut located just above the starter motorcover, in between the 4 cylinders.
6. Using a wrench (15/16 size I think), slowly rotate the crankshaft clockwise while slowly tightening the camshaft chain tensioner locknut.  Rotate the crankshaft at least 4-5 times while tightening the locknut.
7. Reinstall the ignition cover and spark plugs

Also, there are a few tips on how to get a better adjusted cam chain on this forum as well, be worthwhile doing a search and seeing what comes up as it has been discussed here a lot in the past.

The manual says every 4000 miles for oil changes and valve adjustment, but I think I do it a bit more than that, usually depending on the sounds coming from the engine and the appearance of the oil. 

Once again though, the Clymer manual is a worthwhile investment.

Let us know how it goes, eh

Rob

[WiredForStereo]

Thanks for the tips,
I am planning on using LED lights (much brighter, not the cheap ones) so I will prolly need to use one of the after market turn signal doohickies.  The engine sounds ok, but I noticed a particular lack of sound from the top end which leads me to believe that the valves have not been adjusted in a long time, so i will do the work as soon as I get the bike in my garage as it is not warm enough to ride yet anyway.  I did hear some bottom end noise, it seemed to be coming from the center so I estimated it to be the primary drive making some noise because of the 3 cylinder operation.

I had a 72 SL350 that I modified for street previously, and that thing gave me no end of minor problems but remained functional until after winter before last so I sold it.  I think it had been running on one cylinder for years before I got it, and I ran it for a while that way and never noticed it.  After I did notice it, and fixed it, it smoked bad, and I think all that time running half cold did some damage.  I want to make sure that this bike runs well and lasts a long time. 

I always use Amsoil full synthetic in everything, I dont care if it leaks or burns oil (this bike doesnt now with dino) I find it is worth it.  I am not a showy rider, I plan on switching sprockets for better highway riding.  This will be my first full street bike.  I am 22 and my wife would like to ride with me in the summer, so I cant show off anyway.

I bid on the manual, kinda used, but should still be able to read the pages.
Thanks
Sol

[rob]

Hi Sol,

I'm still running the stock bulbs that the PO had put on.  One thing I've found with my 650 so far is that when the engine gets warm it can shift pretty hard.  I'd be interested to hear how you find yours.  I am getting Terry to build me one of his famous oil coolers, and am hoping it might help the problem.  I run Penzoil 10W-40 motorcycle oil, and am hoping that If by cooling it will run a little better.

I am waiting for some parts to arrive for a complete front brake overhaul: master cylinder rebuild, reservoir rebuild, new pistons, new pads, switch to Dot-5 fluid, and am planning on painting the calipers and brake lever mount.  Would like to have gotten braided brake lines, but they're a little too expensive.  Still nursing plans to get the frame powder coated, tank and side covers painted, but still haven't found a garage to borrow some time in yet.

Riding with your wife eh?  My girlfriend isn't too keen on the cycle, and won't get on.  Do you have the sissy bars and back rest? 


Rob

[cb650]

80 shouldnt be cv carbs.  If the "plug" isnt firing it idle I dont think it is a carb issue.  Is it missing cause the plug isnt firing or you know you just have a dead hole?  A manual is in order.
Rob if your bike shifts hard when hot try 20/50. 



              Terry

[n9viw]

The '80 650 is definitely not CV carbs- the carbs from my father's '80 650 are on my workbench right now, and are sliders.
The 'sound' you speak of coming from the trans is likely nothing to do with the primary so much as it is the clutch basket. Every CB I've worked with gives a characteristic 'rattle' from the clutch basket when the carbs are out of sync. My 550 was particularly noisy, so much so that I almost tore into the engine myself before Rob (or was it Glenn) here told me what it was. Even with a bench sync (aka drill bit sync) it was better, but nothing's as good as a true vacuum sync job.
I agree that the cold #1 at idle is likely a clogged primary jet- it doesn't take much to plug them. Make sure you blow all the lines clear, and rinse the tank and petcock before running it. There could be rust flakes or other nasty bits floating about in there that will block up your nicely cleaned carbs in a wink. One tip- the 650s have a plastic choke linkage on the carbs which is VERY prone to easy breakage if you're not careful. Pay CLOSE CLOSE attention to this little piece when taking the carbs off the bike, if it breaks you're up a creek as nobody I know is making replacements for it.
As for bulbs, you'll likely have to switch to an electronic flasher assembly to make up for the lack of circuit resistance that the stock flasher relay relied on to work. I thought the rear signals used 1156 bulbs though, and 1157's in the front? Something about a law against rear-facing amber running lights here in the states. I put red lenses and 1157 sockets on the rear of my 550; the more lights at night, the better.

[WiredForStereo]

Finally brought 'er home today, I am pretty sure #1 is a carb problem, it pops when revved and still only fires when revved.  There is plenty of spark at idle, so that can't be the reason.

Has slider carbs.

Looks like signals are 1156's, now they wont come on at all, headlight is burned out too, I am gonna replace all fuses and anything else that needs it.

There is a law against amber running lights in the rear, but some do it anyway, especially some aftermarket tail light flickerer jobbies.

I dont have a sissy bar, but  my bride has stopped short of insisting on one, so if anyone knows of one that will fit, let me know.  A luggage rack came with the bike, but I have not seen nor taken possession of it yet.

Sol

[WiredForStereo]

Well, got nearly the whole bike tore down now.

Most wiring issues fixed with a fuse,  will get a new flasher though.

Headlight:  broken wire in controlls, bought a new set off ebay.

Now, can someone tell me how to get the air box out?  Carbs seem stuck in by that monstrosity.  Additionally, where is the best place to buy an air filter?

Thanks
Sol

[cb650]

I only state "should be" cause over 20+ years who knows what youll end up with.  I have two 81 motors in 80 frames. If I die whoever inherits my #$%* is going to have a time figuring out what I did. 1157's fit and I use them on tail lites but the original was diff that drew less power.  Especially in the front turn signals.



                          Terry

[WiredForStereo]

Rob,
I've been out cruising around, and the shifting is flawless, silent at speed, and only the first gear clunk. 
I have heard Amsoil does wonders for trannys but this is amazing.
Sol

[rob]

Hi Sol,

Sounds awesome, glad you got everything going.  I get the air filter at a Honda dealer, pretty cheap, they always have them in stock.  I don't know if yours has the same airbox as the 81 because of the different carbs, but I found that there was a black rubber cover on the air filter which restricted the air flow considerably.   

Over the weekend I painted both front brake calipers, new pistons + seals, rebuilt master cylinder and reservoir, chome reservoir cap.  Ran out of daylight before I could add the brake fluid, that will have to wait.

Did you win the ebay bid on that Clymer manual by the way? 

Rob

[WiredForStereo]

Yeah, the Clymer manual is great, more than I need to know for sure.

There is a black plastic cover over the filter, and it restricts the hole down to about enough room to stick 4 fingers in a little.  Fortunately I got an extra cover with the new airbox and I think I'll take the more messed up one and cut a hole in it and put it on there and see how that works out.  The filter that came with the box is ok, doesnt seem used much, I'll stick with it for a few months for cheap sake.

I have a small problem with my brake fluid reservior, it's a bit weathered and a little damaged and leaks out from the cover.  I think I just need a new reservior but dont know how to get it off and havent found one for sale.  I may have to just get a whole new master cylinder or something.

I also got a hold of some Valvoline synthetic brake fluid at Wal*Mart which works really sweet.  More smooth.  From now on, I am going with synthetic everything on everything I own, I already got oil in both cars, the bike, and the lawn mower, and synthetic tranny fluid in the car.  I just got some Amsoil grease, and am gonna get some Amsoil fork oil.  I really do like synthetics, they are just better.

[rob]

I had the same issue the reservoir.  I found the thing an absolute b**ch to get off.  Drain the fluid, unscrew the cap (hopefully the cap screws aren't stripped as mine were), and then pull/twist to get the reservoir off.  I found that twisting it so that it rode up the bracket mounting the level assembly to the handle bar would get it out.


My reservoir was leaking as well.  I found that the around the rubber O-ring where the reservoir attaches to the lever had a lot of gunk in the groove where the O-ring sits.  This probably pushed the gasket out, making it both very difficult to seat or remove the reservoir, allowed fluid to leak out and let contaminants in.   I found that a combination of WD-40 and brake cleaner got rid of it pretty easy.  With that recess clean, I put a little brake fluid on the O-ring, and the new reservoir sat with not very much effort, but a very reaffirming "click".

At the website https://www.partsnmore.com/cat_index.php?model=cb650_sohc&category=chassis I got the reservoir rebuild kit, master cylinder rebuild kit, and chrome master cylinder cover (for $10 who can resist that??)

The master cylinder rebuild is straight forward, but you may need circlip pliers.  I 'd recommend is taking apart your master cylinder before ordering the rebuild kit.  On my bike I am using a different brake lever assembly, from a CM400T or something.  It happens to use the same master cyilinder as the 81 CB650C, but as Terry mentioned, on a 25 year old motorcycle you don't really know what parts could be on it, and you may find that all it needs is a little cleaning.

Is your synthetic brake fluid dot 3 compatible?  Is it silicone based?  There are a few threads about using different brake fluids on this site.  After reading them, I ended up staying with the dot-3.

I just hold the air filter on with 4 flat washers instead of that black plastic cover now.  As soon as I did that, I noticed a noticable increase in the top speed of the bike.

I've just realized, you've never posted any pics of your 650.  If you have some, throw em up eh!  Here is my bike.  I wish I had a digital camera to take pictures of the recently painted front brake calipers.

Rob

[WiredForStereo]

Hey, thanks for that website, that is sweet.

Brake fluid says "Exceeds DOT 3 and DOT 4"  Nothing about Silicone based.

It looks like from the pics on the site that my master cylinder is later than an 80 which my bike is.  But there are so many parts that are not original that who knows what is on there, I am pretty sure the bike has been down on probably both sides and definately had a good slide on the left side.

Pics, I will grab the camera and try to get some pics tomorrow, supposed to be 74 degrees so I am gonna cruise around some more.  It definately doesnt look as good or as stock as yours.  Has a cheap orange gold paintjob on the tank and side covers, and I only wish I had the original headlight, signals and headlight ears.  Also my front fender is screwed and is therefore left off the bike for the time being.  Really good looking brand new Dunlop rear tire though .

[WiredForStereo]

Yep, here's the pics.

[rob]

Looks good, thanks for the pics.  I didn't realize the 80 C was single caliper on the front.  Two horns too, eh? 

Rob

[WiredForStereo]

Yup to both.  But like I said, this bike is such a mish mash by now, who knows whats on there.  The pipes definately aint stock.  The bars are from a '79, I like them a few inches narrower and the grips are at a wider angle, more like the SL350 I used to ride.

[cb650]

FYI the dual disks had a wider triple clamp to make room for the duals.  forks are diff too.




             Terry