Topic: Trouble in paradise! (carb experts please help)

[jerrit1]

here's the long story short version.
I got a new bike (deal of the century, in fact)
http://www.sohc4.us/forums/index.php?topic=24752.0

Was running a little rough but not too bad...seemed to clear up after about 30 min of riding the bike.
Yesterday I rode the bike for about 50 miles, ran rough the whole time...would want to stall easily so I have to keep the rpm's up high...at a stop sign I upped the idle screw to keep it running...on acceleration there is a sweet spot about 1/2 throttle where it feels like it's running on all 4 cylinders, otherwise...even after warm it's like it's on 3 cylinders.
I let the bike cool...started it for 60 seconds and shut it off...header pipe 1 is cold/luke warm, pipes 2,3,4 are hot.
From this I assume carb #1 is not supplying fuel to cylinder #1 like it should be....I removed the carbs from the bike.
I turned the throttle by hand and noticed a tiny stream of fuel squirting from carb 2 and 3 but not from carb 1 and 4.
Clogged carb?
what can I do with the carb, im not sure I can rebuild it myself as I've never worked on a carb before.
Should I just dunk it in the yamaha carb cleaner method?     please advise.

Thanks,

Jerrit

[dusterdude]

find a good carb cleaner you can run thru the tank,if your clog isnt too bad,that should clear it up.

[jdigga]

Hmm, in your other thread you mentioned she already had the carbs cleaned?

You definitely should have a little squirty-squirt from all 4 carbs, so perhaps they weren't cleaned that thoroughly.

Those carbs are pretty straightforward to work on, but dunking won't be enough as the slow jets need to be pulled out to be cleaned properly.

[mmtsquid]

Pull the carbs and clean out the jets!
Try compressed air first, but if that doesn't work get an "e" guitar string (the little one, not the big one) and run it through the hole.  Some people don't like that option, but it worked great for me.
While the carbs are off the bike, you may as well go ahead and clean EVERYTHING - simple green rocks, as does the yamaha stuff.

Good luck, brother.

[Tvag]

I pulled the carbs apart and cleaned everything thoroughly. Used yamaha carb cleaner but they really weren't bad enough to warrent that. For the needles I used a spray carb cleaner. The cleaner + the preassure works well to clean out all those little holes in the jets. be sure you hold the jets up to a light to be sure all the passages are clean. It's worth doing... but do you research first. Good luck.

[jerrit1]

Hmm, in your other thread you mentioned she already had the carbs cleaned?

You definitely should have a little squirty-squirt from all 4 carbs, so perhaps they weren't cleaned that thoroughly.

Those carbs are pretty straightforward to work on, but dunking won't be enough as the slow jets need to be pulled out to be cleaned properly.

Yes, the previous owner had the bike in for a carb cleaning, thats where i picked the bike up from and even that first day it was a bear to warm up and had a bit of hesitation...I was hoping it would go away as the bike got ridden...but basically the Honda dealership here has a garbage service service dept....most of that $250 bill was to clean the carbs and the carbs looked like they were worked on by a hack/moron!  #1 the hose from the top of the cylinder head to the battery box was unconnected, the throttle cable was not on the rotating cam, it was half off, the choke cable was attached to nothing and even once reattached it appears the lever was assembled wrong and the choke does not move the butterflies at all (I will have to figure that one out too).

A year ago my son had a 1985 Honda spree, low miles, ran great...but I (in my infinite wisdom) decided after all these years it should get a new piston/pin and ring so I brought it to the same Honda dealership as the CB650C was picked up from....a few days later the cylinder head pretended it was a grenade...spree engine mostly ruined....some friends speculate the piston was put on backwards and some "oil" hole was not lined up to something or other.

[jdigga]

That's messed up.  As the saying goes, "if you want it done right..."

All the more reason to go over the carbs yourself to make sure everything is in order.

[kuyarico]

Are you running a fuel filter? How is the condition of your gas tank? It doesn't take very long for the slow jets to get clogged if there's crud in your tank.

[jerrit1]

Are you running a fuel filter? How is the condition of your gas tank? It doesn't take very long for the slow jets to get clogged if there's crud in your tank.

No fuel filter, tank was recently drained and tank looks like new on inside and no crud in bottom of tank.

[Buffo]

I use Berrymans Chem Dip to clean my carbs... I think this stuff is the best...just dont drink it. get a fuel filter. install it. eveyone says that their carbs are clean... there are many posts on this site that deal with carb cleaning...I have contributed to many of them.
Do it right the first time...

Dissasemble the entire rack.
Buy the proper rebuild kit...
carb cleaner in a can sucks
sync your carbs

[TwoTired]

If your bike still has the stock petcock filter intact, it already has a fine fuel filter.  Don't waste your time or energy fitting another.  Just verify the one you have is not damaged.
For those advocating adding another filter, why is two enough?  Why not 5 or 6?

I expect you'll find that your carb rebuild wasn't very well done.  Drain or drop the float bowls and have a look at the sediment in the fuel, and if things are really clean inside them.  The slow jets are very small and clog up easily.

Cheers,

[edbikerii]

This might sound silly, but I like having the clear inline fuel filter if for no other reason than I can see the fuel flowing.  I've never seen dirty fuel get in there, as I also have the sock in the tank.  I suppose clear fuel line would be just as good or better for visibility, but I've found that the clear fuel line hardens, making it difficult to remove and replace the tank.

[flat_black_forever]

My boss' yammy was having the same problem, which was the result of a mysterious black suspended particle in the fuel. (cheap gas??)

[jerrit1]

I have the carbs on a bench now and wonce I loosened the bolts holding the butterflys on the shaft now the butterflys can move with the choke cable...is there a correct order to put those butterflys back on...they seemed to be binding.
also, when you remove the top cover on carb #2 there is a spring in there just laying on the bottom of the slide, with carb #1 I can see where this spring is supposed to go...I cant believe the stupidity of the moron who last worked on these carbs...my teenage daughter could have done a better job blind folded.

[paulages]

If your bike still has the stock petcock filter intact, it already has a fine fuel filter.  Don't waste your time or energy fitting another.  Just verify the one you have is not damaged.
For those advocating adding another filter, why is two enough?  Why not 5 or 6?

Cheers,

though i thoroughly agree with TT's disdain for aftermarket inline filters, they often filter finer particles than the stick petcock filter. whether that counteracts the potential flow problems is another story.. 

if the tank's dirty, i'd recommend first and foremost cleaning it so that there's no reason the stock filter won't do its job. if i had a dirty tank, i'd stick to the on position as much as possible to avoid picking up the sludge that will mostly have settled to the lower parts of the tank and will get pulled through the reserve passage in the 550/650 standpipe-style petcock.

[jerrit1]

The tank looks like brand spankin new on the inside

[jerrit1]

Here is what my carbs look like (these arent a pic of my actual carbs...I just found the pic and it is nearly identical).
It is a Keihin PD 50D (1980 CB650C)
I am looking for a manual or a howto article...did a search and although I did find much info about Keihin carbs in general I could not find anything that says this is the pilot jet...this is how it comes out, this is the main jet, etc.
Anyone know of a resource?
So I took one of the carbs apart as much as I could...but I have no idea what each part is called.

Thanks,

Jerrit

[TwoTired]

So I took one of the carbs apart as much as I could...but I have no idea what each part is called.

So post pictures.  In focus ones are best.  We can put circles and arrows on them with a bit of verbiage.

Cheers,

P.S.  It's not that I "disdain" inline filters it's more like... eschew.

 

[jerrit1]

ok, TT, I'll do that tonight...thanks.
My other issue is im sure this carb can come apart more than I have taken it apart but cant seem to figure out how....im trying not to separate them from each other since I was told that opens up a whole new can of worms, which Im guessing is bad...especially if you dont like worms...or cans!

[mmtsquid]

You really shouldn't have to take them COMPLETELY apart - just the bottom half (to deal with jets, floats, and any gunk) and the top end (to check the needle and to bench sync).

[jafierst]

I too am having a similar experience (got an 81 CB650C for $200).  When I got it in July I checked everything but the carbs (friend had cleaned them last year and I added seafoam to the fuel), new battery, new front tire, brakes, fork oil, oil, air filter, plugs.  It ran really good for the first 7 miles... Then it started running rougher and rougher.  At the end only the number 3 cylinder was running.  The plugs were oil fouled, and the carbs seemed to be running way to rich.  After reading up on this forum, it looks like this is a common problem on the 81.  There was so much raw fuel lying in the #2 exhaust that it was burning orange down by the bridge pipe between #1 & #2.  I currently have a set of 82 CB650SC carbs (purchased on ebay... I have never seen such nasty debris and crud in a carb before) on my bench at home and am in the middle of a complete rebuild, kits are on the way from sirius. 

The other problem that I found was that my new battery was dead, even though I had only put 8 miles on it, and had kept it on the trickle charger.  The autoparts store tested it and replaced it free of charge.  With new plugs and battery it ran half decent, for a mile... before fouling the plugs again.  I hope that after the carbs are rebuilt it will run like it did for the first 4 miles...