Author Topic: huh (Read 1904 times)

nevernoluck · « **on:** May 23, 2013, 02:01:05 PM »

First I should start out by saying I am an automotive/diesel mechanic not a bike expert. I've read and read over the past couple of days and it just makes my head hurt and can't keep up with it all. Here it goes: Just rode my bike home today, '80 CB650, it's been sitting a year or two. I know very little about it's past but I know my brother had it and it run ok. The problem is the lack of throttle response and the hesitation at all rpms and no more than quarter throttle. Once you get past quarter throttle and it catches up to itself it takes off just fine. It has this hesitation idle, in gear, 50 mph it don't matter at all ranges. I figure it's in carburetion but where do I start? Where is all the adjustments at? I see one adjustment on the outside at the bottom of the carbs but they have a stop on them that wont allow a full revolution. Are these the pilot screws? what are there purpose? Looked in a manual I downloaded from here but it didn't explain anything about what they do? I have to understand things before I work on them. I know I could do all the reading on this same kind of topic but I get lost in translation. Basically all the extra reading is overwhelming me. Give me any and all advice I will take it. For now I must go work on a broken bolt extraction for a friend. Thanks in advance.

flybox1 · « **Reply #1 on:** May 23, 2013, 02:12:40 PM »

can of carb spray
simple green
compressed air
wire to clear tiny holes
beer
...sit down and clean your carbs.
probably gummed up from sitting
pilot screws are there to aide in metering air, or fuel (depending where the are on your carbs) for better/cleaner/even burn.. up to 1/4 throttle.

78whiteorbs · « **Reply #2 on:** May 23, 2013, 02:13:50 PM »

3,000mile tune up,I see in your future.
A friend with carb sync gauges, I see you need.
Lube up them cables, you should for sure.

Vinhead1957 · « **Reply #3 on:** May 23, 2013, 02:16:24 PM »

Sounds like carbs and or bad gas left in the carbs. There is little difference with bikes they are very temperamental to gas flow. Clean clean clean fuel and fuel delivery system! I run a mixture of seafoam and gas to clean on the run. Other than that you are a mechanic you can figure out anything! Best of luck

curemode2002 · « **Reply #4 on:** May 23, 2013, 02:27:51 PM »

On my CB650 the issue was my pilot jets were all gummed up. If you drop the carb bowls you will see the big main jet right in the middle of the float arms the pilot is forward towards the air mixture screws. I cleaned mine out and the 1/4 throttle issue is a thing of the past. Also our 650's have an eccelerator pump in the number 2 carb if it is clogged up or not working it can hurt on the low end too.

bjbuchanan · « **Reply #5 on:** May 23, 2013, 03:15:53 PM »

Compared to what you work on these are just smaller less beefy and complicated stuff, you just gotta sit back and start identifying things to familiarize yourself with the bike before you start fiddling. If you were gonna fix a car/truck would you just start randomly playing with stuff or would you run check engine light, troubleshoot codes, test sensors, check for vacuum leaks?

Manuals are in the FAQ. I'm linking the stuff but you gotta find the specific manual for your bike that is still a functional link.

http://forums.sohc4.net/index.php?topic=426.0

In either case it seems like carbs that need to be cleaned up. Very small passages that ethanol laced gas gums up after only a couple of weeks of sitting

nevernoluck · « **Reply #6 on:** May 24, 2013, 04:27:51 AM »

It did have some bad gas left in it, enough to warm it up, run it a mile down the road and run out

Glad it's not a heavy bike as I had an uphill push most of the way. It runs better with fresh gas in it but still as I stated in the first post. Sounds like carb cleaning is due and I will slowly go from there. This is my only mode of transportation and without a job at the moment I will start with the simple cheap/free stuff and go from there. Thanks again, Clint.

Don R · « **Reply #7 on:** May 24, 2013, 08:02:04 AM »

Good luck and don't forget, this is fun. Even with the added pressure of it being your transportation at the moment. The tank / petcock can be gummed up too, have a look in there. I've used laquer thinner to melt out the goo and there are threads here about de-rusting/lining if that is needed. I still have a shop nearby that can get Honda parts. Locate one if possible.

mono · « **Reply #8 on:** May 24, 2013, 08:08:10 AM »

Quote from: 78whiteorbs on May 23, 2013, 02:13:50 PM

3,000mile tune up,I see in your future.
A friend with carb sync gauges, I see you need.
Lube up them cables, you should for sure.

*facepalm*

DJ_AX · « **Reply #9 on:** May 24, 2013, 08:17:22 AM »

Yeah ... last bike I fixed ('72 350 for a friend who couldn't get it running at all) ... I did the whole 3k before even trying to start it up.
So nice then when it fired right up and ran well from the get go. Yeah... it's a practice of patience. Makes me look good

...and all I did was follow the steps. lol

JimJamerino · « **Reply #10 on:** May 24, 2013, 08:30:00 AM »

I also run an 80 CB650C. I'm in the process of cleaning up the carbs, too. Since yours runs, you'll probably just need a minimal cleaning. In your place, I'd just pull the carb bowls and clean up the jets and emulsifier tubes. It's not a perfect solution, but it should get you back on the road. The main jets are easy- it takes a 7mm wrench to pull the emulsifier tube, and a big screwdriver to get the jet out. To make sure you get the slow jets clean, you'll need to pull them.

The slow jets are press fit, but all you need to do is get a good grip on them with pliers or vice grips, give them a slight rotational wiggle, then pull them out. There are 4 tiny holes in the emulsifier tubes on each of those jets, and just blowing aerosol carb cleaner through them doesn't guarantee they get cleaned out. It doesn't take much to clog the idle circuits because the late 70s and early 80s bikes attempt to use mechanical carbs to achieve EPA-mandated emissions controls, resulting in an extremely lean design. Because they're made to be so lean, clean jets and emulsifier tubes are a necessity.

nevernoluck · « **Reply #11 on:** May 24, 2013, 08:38:09 AM »

Guess I know what to be doing on this holdiay weekend

jerry h · « **Reply #12 on:** May 24, 2013, 09:00:36 AM »

Just a thought..... I had a 79 - it required the choke until FULLY warmed up, then it ran/idled perfect with no choke.

curemode2002 · « **Reply #13 on:** May 24, 2013, 12:28:51 PM »

Mine is cold blooded too

nevernoluck · « **Reply #14 on:** May 28, 2013, 10:12:18 AM »

Alright so I pulled the float bowls off the carbs and cleaned up everything I could from there and now it runs much better, I did notice the float level in #4 was low so I got that adjusted too. Only two things I notice now, first off is if you crack throttle wide open at idle it stalls and dies if you don't get back off of it and as a side note if you have rpms up it won't do this? I did mess with the accelerator pump some while I had the bowl off and it works, Second thing I notice, well more like hear is what I consider it misses while crusing down the road. Spark plugs are all nice and tannish gray maybe but nonetheless all look good. I checked out the timing and that is good, the advance mechanism works and moves freely. i can't find any vacuum leaks. I'm guessing the carbs need synced but haven't made it that far yet. One other question is I keep hearing in numerous posts about a 3000 mile tuneup but too dumb to find anything on this site about what all it entails, what is everything? Carbclean and sync, valves,oil and filter change, air filter, fuel filter, timing adjust, spark plugs? Anything else I'm missing?

p.s. all that has been adjusted is the pilot screws which are ALL are sitting 1 1/2 turns out

flybox1 · « **Reply #15 on:** May 28, 2013, 10:44:39 AM »

first, yes, a carb vacuum sync makes many noises such go away.
second, it is done LAST of all of the 3000 mi maintenance items.
download the shop manual for your bike from here. all the maintenance requirements are listed.
third, dont forget a cam chain adjustment

that sucker can be noisy

question, when you cleaned our carbs, did you pull out the emulsion tubes under the jets to ensure all their tiny holes are clean and clear? they aerialize fuel, and if the holes are clogged, they cant do their job. sluggish acceleration can result.

a 'crack' of the throttle is not something carburated bikes respond well too, especially if any part of the carb and accel pump arent perfect. now, in tune and with a strong roll of the throttle, they can really get up and go

phil71 · « **Reply #16 on:** May 28, 2013, 11:17:20 AM »

A nice set of d'addario .010 guitar strings makes for good cleaning.

nevernoluck · « **Reply #17 on:** May 28, 2013, 01:30:30 PM »

Yes carb sync done last, gotcha

I have downloaded a shop manual but have yet to print it due to no ink in the printer, I do way better when I can use it as a book, I jump back and forth a lot and something bout doing that on a computer frustrates me.

cam chain adjustment will happen too. Gotta work up some money before I can even afford to buy some gaskets.

emulsion tubes??? Thats the ones in stuck in the float bowls with those little bitty holes, if so yep those are clean as can be, like I said it runs great other than when stabbing the throttle or at speed the sound is off but it has the power and throttle response I deem acceptable. I will do a proper 3000 mile tuneup before I get this thing plated and on the road, right now I am just doing minor tinkering when I am in the mood cause I can't afford to plate and insure it, that and I am taking my time to keep from getting overwhelmed

flybox1 · « **Reply #18 on:** May 28, 2013, 01:39:56 PM »

i hear you about the printed version. way easier.
to add....any gas you get having debris in it, or any loose crap, like rust, in your tank, can really ufk up your carbs.
check with a flashlight that you have a good in tank filter on your petcock. if not, at least run an inline filter.

nevernoluck · « **Reply #19 on:** May 28, 2013, 03:25:12 PM »

Just occurred to me what the emulsion tubes are and yes they are clean. Also I do have an inline filter, the glass type you put the replacement elements in. I found next to nothing in the float bowls which was better than expected, one pilot needle had gunk on the top of it when I took it out and a different one had the washer under the spring but other than that all seemed fine.

lucky · « **Reply #20 on:** May 28, 2013, 03:32:31 PM »

Quote from: phil71 on May 28, 2013, 11:17:20 AM

A nice set of d'addario .010 guitar strings makes for good cleaning.

You can buy a single #10 electric guitar string at almost any music store.

nevernoluck · « **Reply #21 on:** May 30, 2013, 01:22:45 PM »

Well went out and bought some feeler gauges today, came home and adjusted the valves. Every one was loose somewhat now it's all nice and quiet, no more tick tick tick tick. I've done all of the 3000 mile tune up except for the carb sync as I do not have the gauges.

One quick question on the gauges, if I could come up with 4 automotive style vac gauges and adapted them to the port on the carbs could I use them? Is a vac gauge a vac gauge for these machines?

flybox1 · « **Reply #22 on:** May 30, 2013, 01:44:23 PM »

yes, you certainly can, just calibrate each one to say #1 carb. just to ensure they all have the same reading before you start the sync.
you can get 4-gauge sync units online for under $100. I got mine for about $60 years ago.
it came with all the adapters. you'll get your money's worth out of it.
this is the one i got, and now it comes with the adjuster tool. at the time, mine did not.
http://www.saber-cycle.com/store/product859.html

nevernoluck · « **Reply #23 on:** May 30, 2013, 05:56:17 PM »

I like the looks of that sync gauge set, now if I only had the money

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Author Topic: huh (Read 1904 times)