Author Topic: CB650 3 banger...lol...advice please  (Read 5611 times)

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slick68

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CB650 3 banger...lol...advice please
« on: August 13, 2008, 11:07:38 PM »
i own a 1982 cb650...i bought it this spring, cleaned the carbs, replaced the plugs, the bike idles rough... the other day i started it, let it run for a couple minutes, i accidently brushed up against the outer right side header pipe, it felt cold, i put my hand on it and confirmed that it was...now your gonna laugh yer ass off---i grabbed the header pipe right next to it and scorched my FU&%$NG hand...i pulled the plugs, they are all the same and according to the pics ive seen in manuals they are the way they are suposed to be(all four),,the only difference is the plug fron the cold header pipe had slightly wet threads...when i ride the bike it tops out at 130km/hr or about 82 mph..the throtttle seems to have a sweet spot...if i "floor" it at highway speeds it seems to sputter..if i back off a bit i gain power back...i have a k&N filter, i cut a hole in the cover, i have checked for spark,,,all four seem to spark fine...the air screws are screwed out 2.5 times....ive read up on this a bit..it seems that other years require it to be 1.5 turns out but 81 calls for 2.5 turns but i guess its right cause my plugs are all the same with the exception.....o yeah the right side dexhaust pops a bit when i let off the throttle


my questions are

why is that pipe cold---i got spark---plugs look good

what kinda top speed should i be able to reach

Please help


slick68

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Re: CB650 3 banger...lol...advice please
« Reply #1 on: August 13, 2008, 11:10:12 PM »
exhaust pops when i gear down aggressively

Offline scunny

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Re: CB650 3 banger...lol...advice please
« Reply #2 on: August 13, 2008, 11:17:39 PM »
check your valve clearances.
popping on decel usually means it's a less restrictive exhaust, I take it you've got a 4into1
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slick68

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Re: CB650 3 banger...lol...advice please
« Reply #3 on: August 13, 2008, 11:18:19 PM »
nope...stock 4-2

martino1972

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Re: CB650 3 banger...lol...advice please
« Reply #4 on: August 14, 2008, 12:39:24 AM »
yeah i would start by checking the valve clearance......
how well did you clean the carbs??? did you have the idle jets out???

Offline tomkimberly

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Re: CB650 3 banger...lol...advice please
« Reply #5 on: August 14, 2008, 06:18:06 AM »
The 82 carbs should be VB44C's which have screw in idle jets. They are still avalible from Honda if you need new ones.

Tom

Offline Sporkfly

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Re: CB650 3 banger...lol...advice please
« Reply #6 on: August 14, 2008, 06:27:36 AM »
Idle jets
Valve clearances
Needles
Pop on decel = a little lean on the idle circuit
Float valves

Basically check your valve clearances then pull the carbs to have a look inside. If the one plug is wet with gas then your idle jet is probably working... I was having similar problems and it kept moving around. I just cleaned the carbs a couple more times and checked needles, IMS screws, main jets, bench synced each time, worked at my float valves because they were sticking every now and then... Eventually everything was working properly.
1977 CB550K
1979 GL1000 - Current project, winter '09-'10
1979 CX500
1976 Suzuki GT500 Titan

slick68

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Re: CB650 3 banger...lol...advice please
« Reply #7 on: August 14, 2008, 08:27:06 AM »
they are keihn carbs...not sure on model.....


i do have a small exhaust leak...was a huge one underneath the shroud by the foot peg i welded it with the mig---power turned right down butstill seemed to be too much...paper thin metal..lol

i'll try to find that page where it told me to do the air screws to 2.5....maybe it should be discredited...anyway on that page it le3d me to beleive that if i had them in 1.5 turns it would be pretty lean

when i cleaned the carbs i took them completely apart, used aresol cleaner and compressed air

slick68

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Re: CB650 3 banger...lol...advice please
« Reply #8 on: August 14, 2008, 08:38:56 AM »
the websight where i foun the info on the air screws is



http://www.bikecarbman.com/


the page on that site that has the chart on it is

http://www.motorcycleproject.com/motorcycle/text/specs.html

martino1972

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Re: CB650 3 banger...lol...advice please
« Reply #9 on: August 14, 2008, 09:21:04 AM »
did i meantion that i do have a mechanic shop and work on bikes... ::) ::) ::) ::)

slick68

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Re: CB650 3 banger...lol...advice please
« Reply #10 on: August 14, 2008, 06:20:51 PM »
and yer dutch too....so far so good...im 3rd generation dutch canadian....what is yer shop called...gotta website???

Offline Sporkfly

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Re: CB650 3 banger...lol...advice please
« Reply #11 on: August 14, 2008, 06:42:36 PM »
My 550 was just 3 banging a bit ago. I had an O-ring on the bowl goofed up (I ruined it now :'() holding the float closed.

Yeah, I'm dumb.
1977 CB550K
1979 GL1000 - Current project, winter '09-'10
1979 CX500
1976 Suzuki GT500 Titan

martino1972

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Re: CB650 3 banger...lol...advice please
« Reply #12 on: August 14, 2008, 07:21:57 PM »
and yer dutch too....so far so good...im 3rd generation dutch canadian....what is yer shop called...gotta website???

no website....it's just a small shop,nothing faincy....
i work on car's,truck's,dirt bikes,race quad's,4x4 quad's and motorcycles....
shop rate..$50.00/hour....but for sohc'ers a little less of cource... ;) ;)

martino1972

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Re: CB650 3 banger...lol...advice please
« Reply #13 on: August 15, 2008, 12:04:27 AM »
Could someone post a pic of these screw in idle jets? I have been into several sets of vb44b's and c's and have yet to see anything except pressed in. I'm not arguing the fact that they may exist, I have never seen them!

I sold the carbs off my 82 650sc parts bike and they were vb44d's. Never heard mention of them before or since.

i think he confused main with idle jet's..

Offline Soos

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Re: CB650 3 banger...lol...advice please
« Reply #14 on: August 15, 2008, 03:57:01 AM »
The 44D's cannuck mentioned did indeed have screw in slow jets... And they run awesome.
Perhaps the easiest and cheapest clean/inspect/rebuild I have ever had to do.
Drop main jetsize for altitude, and 45+mpg all day long.

But they don't compare to 750 carbs on a bored out '79 650. :)
Have since sold that bike(to pay medical bills) to a good friend, and he gets me off the line(gearing differences), but when I shift to second i've already shot past him.   ;D ;D



Slick, have you doublechecked that all your electrical connections are tight?
I had a intermittent problem once, it was a connector for the timing plate.
it would short out(?) intermittently.
When it was wet, it wouldn't work and dry it was good some days, then 3 cyl action others.
In the end I sanded the terminals to remove the corrosion, and putting di-electric grease in the connector, and no problems from that again.
Possibly doing this will either fix your problem or stave off any electrical gremlins from popping up in the future from corrosion and water.



Your coil wires?
These are nearly 30 year old wires, you could have a crack in the wire causing a intermittent spark loss?
Trimming 1/4 off the ends and re-installing might be the solution.
Or new wires to be sure.
 

Have you tried swapping spark plugs around to see if the cold cylinder follows a bad spark plug?
You never know. I have once had a spark plug go bad and still look as if it is sparking correctly when resting on the motor. drove me nuts finding that one.



Good luck!

l8r
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(61mm)652cc 1979 cb650

Offline tomkimberly

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Re: CB650 3 banger...lol...advice please
« Reply #15 on: August 15, 2008, 08:14:15 AM »
You can view the parts diagram at Service Honda for a 1982 Honda CB650C and it will show the idle jet.


Tom

slick68

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Re: CB650 3 banger...lol...advice please
« Reply #16 on: August 20, 2008, 10:06:47 PM »
heres an update.


i set the valves,,,double checked the plugs....not much difference...a little tho...definately ran smoother


today i took the cover off of the air box...i didnt before because the previous owner butchered it by cutting a hole in it so i assumed that it was getting the air flow that it needed, while i had the cover off and air filter out i ran the bike,,,i cracked it wide open and gave it a good shot of aresol carb cleaner...i stopped early cause i thought i was being lazy and decided to take the carbs off at a laterr date........anyway....i am going somewhere with this...i promise...sooner or later. nice weather today eh?...lol...ok here goes.....way more get up and go...bran new bike,,,,still not perfect but way better....i took it for a ride,,,i got up to 145 in 4th 155 in 5th....even got the front tire up off the ground....never before....now i dont usually beat the #$%* out of it like that but this new found performance had me like a kid on Christmas day


thanks to everyone who helped in this thread

definately martino

thanx
             chris

martino1972

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Re: CB650 3 banger...lol...advice please
« Reply #17 on: August 20, 2008, 10:23:58 PM »
cutting a hole in the airfilter cover is a very common mod,most 650 owners do to the're bike,due to the restricted airflow in the airbox...
one point of attention is,WITH PLAYING WITH THE AIRBOX.YOU HAVE TO CHECK YOUR JETTING...!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

and spraying carb cleaner into the air opening of the carb's will not clean the carbs(sorry, :D),in order to clean the carb's,you will have to take them apart,take all the jet's out,including the idle jet's(very important) and soak the carbs and jets etc. in a carb cleaning solution...sorry dude,thats the only way.. ;D ;D



slick68

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Re: CB650 3 banger...lol...advice please
« Reply #18 on: August 20, 2008, 11:49:01 PM »
martino....dude...c'mon man


i cracked it wide open and gave it a good shot of aresol carb cleaner...i stopped early cause i thought i was being lazy and decided to take the carbs off at a laterr date........

read the whole sentance man ;)


today i took the cover off of the air box...i didnt before because the previous owner butchered it by cutting a hole in it so i assumed that it was getting the air flow that it needed,

the cover had a hole in it before,,,,im assuming leaving the cover off and using the washer trick i read about here wouldnt creat enuf of a difference to worry about jets

maybe read it twice :o



slick68

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Re: CB650 3 banger...lol...advice please
« Reply #19 on: August 21, 2008, 10:20:59 AM »
no offence to people who cut holes in air box covers...i said butchered because it looks like this guy did this one with a steak knife or maybe even a rusty spoon with 151 proof rum as a cutting agernt....lol

slick68

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Re: CB650 3 banger...lol...advice please
« Reply #20 on: August 21, 2008, 02:44:35 PM »
martino....


sorry for bein an azz

ive been havin a bad week...

you woulda gottin a kik out of my 750 800 thread

its been deleted now,,,i hope

sorry again.....

what i should have said is your right about the carb cleaning...i agree,,,,wich is why i stopped and decided to do it right at a later date.....

and

do i need to look at the jets cause i took the cover off and used the washer trik even tho the cover had a bigass hole in it already?

slick68

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Re: CB650 3 banger...lol...advice please
« Reply #21 on: August 21, 2008, 05:29:44 PM »
cool trik.....thanks


i think im gonna take em off and clean em with a little brush, carb cleaner and compressed air

Offline MJL

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Re: CB650 3 banger...lol...advice please
« Reply #22 on: August 21, 2008, 05:53:48 PM »
cutting a hole in the airfilter cover is a very common mod,most 650 owners do to the're bike,due to the restricted airflow in the airbox...


Yes, but if you still have the factory exhaust I'd leave it, they are both restrictive but they match. I don't know what it would do if you did the airbox mod with stock exhaust. Free flow exhaust and stock unmolested airbox cover won't work well together.
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