Topic: just bought a 81 cb 650 C, help me

[stanghater]

as the subject states, i just bought the bike off an old man. it sat in his garage and hardly ever got ridden. as a result, it only has 6000 miles and is in excellent condition. it runs fine until i take it on the interstate. it runs strong until about 60 then it kinda coughs and sputters its way up to 80. i looked at the plugs, they look brand new, looked at the air filter, the isnt one . my question is: the lack of air filter, is that what is hurting me? what should i do, i want to take this bike on the interstate and have the confidence to pass some one going 75.... please help
josh

[MetalHead550]

Well first off the bike sat alot so I'm willing to bet your carbs need a good cleaning.  Fuel sitting in the bowls (if he didn't drain them/use fuel stablizer durring storage) will corrode and make the floats stick, and clog the jets which of course will hamper performance.  If the carbs are clean then yes mabey the lack of air filter is causing the bike to lean out at higher rpms.  You'll definitly want to get an air filter anyway, you dont want all that dust goin into your carbs and intake.  Start with the simplist things first though.  For instance, is the gas good.  May sound stupid but I had the same symptoms once and it disapeared with a fresh tank.  I'll bet your main jets, carbs in general,  need cleaned out though.  Hey, how much did you pick it up for if you dont mind me askin?  Good bikes!

[SCJIM]

i cant say ive had that problem at 60 mph

but i have had that problem when she was cold

once she warms up she runs great.

do you have any photos of yours yet?

[Zeke]

BTW, should have plenty of passing power to blow doors from 65 - 80.

[Robert]

Get an air filter. Otherwise bike runs in a too lean condition, can cause problems -> poor performance/overheating etc.
Carb should be cleaned propably. A carb sitting in a garage for one year often looks worse than an uncleaned but constantly in use carb with 50.000 miles. Give also attention to spark advancer.

Rob.

[stanghater]

i got the bike for 1200 bucks which i thought was a real good deal. here are some pics that i posted on another forum that i am a member of. http://forums.probetalk.com/showthread.php?t=1701153946
these pics were taken before i cleaned it, it looks wayyy better now. i tried to spray some carb cleaner up in the air box towards the carbs but i dont think i really did any good

[Zeke]

Yeah, that's a damn nice bike that's for sure -- great shape.

I bought my 80 for 600 and have invested another 1200+doing a rebuild and it doesn't look that nice.

You need an airfilter for sure.  Some have good luck with using Yamaha carb clean right in the float bowls -- you might try that.

Lose those 25 year old tires -- they will be hard and dangerous -- get some sticky new dunlops -- it's another 200 bones but you want to be able to corner and stop, right?

[MetalHead550]

Rock on man, nice bike!  I'd say you got a decent deal!  But listen...by cleaning the carbs I mean take those bad boys apart and soak the jets, neadle and seats, and float bowls in carb cleaner.  Spray all the ports and then hit the jets with compressed air after theyve soaked for a day or two.  Is this your first bike?  If youve never done carbs before, just grab a Clymer,ect. manual for it and it will detail how to tear them down.  Plus you have all of us to help you out. Its not as hard as it looks if you are reasonably mechanical.  Study up and you'll have it running like a sewing machine, youll love it.  BTW THIS is how you actively hate on Mustangs.... Later.

[stanghater]

here is some clean pics for you guys

[smithrelo]

Gorgeous bike and I love the wheels!  Is that a 4 cylinder??

Linda
(who is just now getting back to bikes after 29 years of walking!)

[oldbiker]

Linda, after 29 years of walking, I bet you've worn your legs down till you're only  four feet tall.

[SCJIM]

stanghater, great looking ride.

for some reason it looks familliar....

hummmmm

[MetalHead550]

Cool...Is that a GS850 in the background?

[rob]

Hi Josh,

i am working on fixing up an '81 CB650 Custom as well, excet this one has the candy red side covers and gas tank.  I am wondering though, yours has a 4 into 4 exhaust system, and the one I am working on has only two exhaust pipes.  I was walking down the road last night and saw another CB650, couldn't tell the year, and it had two exhaust pipes as well.  I am wondering if anyone knows if having the two pipes is stock?  Or was it modified.  Most pitures on the web I see of '81 CB 650 Customs show the 4 exhaust pipes.

Rob

[MetalHead550]

Yes the 4 into 4 exhaust is stock but they rotted out on alot of these old bikes due to the fact that they dont build up enough heat to burn up the condensation durring short rides.  Old cb500-750s with origina 4 into 4 exhaust is considered a bit of a rarity because of that.  Ive seen good stock exhuast pipes for these machines will go for as much as $500 on ebay!

[cb650]

The 4-4 is the custom and the 4-2 is the standard.  Wheels will be wire on standard to. But this is all interchangable so who knows what has beed changed over the years.



                    Terry

[rob]

The bike i am working on is definately a custom, has the comosite spoked wheel rims and custom on the side panels.  It must have had an exhaust change somewhere over the years.

I've seen some posts about the 4-into-1 exhaust, won't these create too much back pressure to get the exhaust out and slow the bike down? 

Rob

[cb650]

No they have a bigger ID in the muff and they cut the weight down.



                    terry

[Zeke]

Yep, I got a set of 4-4s on my 1980 650C that are almost dead.  The 4-2s look cooler if you ask me -- check out Ibsen's bike.  I think all the euro 650z had the 4-2.

Last week a pretty nice set of 4-2 sold on ebay for $450!!  I've pretty much given up on originals because of that, and I'm not a serious fan of the 650 4-4 pipes.

Anyway, the 4-1 pipes are actually the best for performance.  Each cylinders exhaust impulse actually helps to suck more air through the engine!  Doesn't make logical sense I know but it works.  Tough thing is getting the jetting right I'm told.  Cheap 4-1s can be had for 300 for a MAC setup -- some say they aren't very durable and have thin metal.  They are better though that a rusty set.  Not too many choices for 650s -- they were only made for 4 years.  I've looked at MAC, Jardine, and Motad.  I like the Motad the best but expensive and only for the 650z -- the pegs on the Z are in a different spot so I'm not entirely sure they'd fit without a little mounting mods.

Anyone else know of other AVAILABLE 650 pipes?

Zeke

[Robert]

Anyone else know of other AVAILABLE 650 pipes?

BSM is the only one I can add, 4 in 1, fits CB650 and CB650C

[stanghater]

Cool...Is that a GS850 in the background?

no it is a yamaha xj 750 maxim

i like the 4 to 4 pipes, i have never seen anything like that before. I am gonna order the air filter from honda tomorrow. it is 31.95. does anyone know another place to get it? i am gonna change the oil tomorrow so that may tell some stories about the bike.

My friend that has that yamaha wants me to jam a pipe down the exhaust and break out all the baffles. he did it to his and his is annoyingly loud. he claims it will free up all kinds of hp. is this true?

[Zeke]

Hey there:

Sorry if I was harsh on the 4-4 pipes -- I have the same on my bike.

4-4 is OK, but from the old hondas I like the old shapes better than my pipes.

Please don't wreck those pipes -- you can't get a replacement set in the shape yours are in for less than several hundred bucks -- at least your pics from a distance don't show any rust, etc.

But seriously, you could sell those pipes to somebody wanting stock pipes and buy a brand new set of MACs or something and they'll be loud unless you add some muffler packing.

[smithrelo]

Will the 4 to 4 pipes on his 650 fit my 550?  I need to replace mine!  If they would fit, I'm interested in closer photos to see if we can work out a deal.

Linda
(who is clueless on what pipes interchange with what)