Topic: FAQ's, steveD and Harry etc..Another carb question...Sorry boys

[toycollector10]

My 750 K0 starts, idles and runs fine, pulls effortlessly and I have no problem with it except

The main carb jets are worn and it blows a little/quite a bit of black smoke under hard acceleration and hogs gas.

I have a new air filter element on the way so hopefully it won't run so rich when I get it fitted, but, the question is:

If I get my mechanic to take the carbs off the bike and recondition them, will I be opening up a can of worms?

His advice is that because the bike is so old, when he gets the carbs off, it could get expensive and ugly. 

Should I "leave well enough alone" or head out a bit like Shackleton for the pole? But we all know how that ended.   

I see a lot of guys having problems with carbs. I'm not able to do any carb work myself due to lack of mechanical ability and make no excuses for that. I'm not getting on the learning curve with those bloody things!!   TC

[Bob Wessner]

The main carb jets are worn and it blows a little/quite a bit of black smoke under hard acceleration and hogs gas.

TC,

How did you determine the jets are worn? At what speed are you going when this happens? When you say "hard acceleration" are you grabbing a handful? There are no accelerator pumps on the early 750's so they respond much better if you ease the throttle on. Are the carb adjustments to spec in terms of air screws? Have you ever balanced the carbs? How about other tune-up specs, timing, valve adjustment, etc?

[toycollector10]

Hi Bob, no, none of that has been done because the bike runs so well so I see no need for it. Maybe I should. I just go back to my old reference point which is, if it's not broken, don't fix it. 

My mechanic is a guy called Duane and he is a master. The local Honda dealer's chief mechanic rides a Ducati. He hands his Ducati over to Duane to service as he has done a certification course on the type and has a great reputation locally. I don't think a wrencher needs a better recommendation than that!  

Duane balanced the carbs by ear for me. He said that he used to put the tubes and spagmometer  (sp) on to get carbs all synched but after 30 years he found that by doing it by ear and feel he was always within 5 percent of perfect so he just uses his experience and nothing else now, and I am happy with that.  TC

[mcpuffett]

hi tc, the carbs are not that difficult to dismantle and clean etc honest ,  , you could do with getting a spare set to use to familarize yourself with them    mick.

[Bob Wessner]

TC, I hesitated to say something similar because you seemed reluctant enough to do them yourself since you were ready to have a pro do them (which will be expensive). In my opinion, though initially intimated myself, our carbs are probably the simplest of all to work on. When getting ready to do mine the first time, I looked at the parts diagram and estimated there were a 100 or more parts. After getting back up off the floor  I thought, OK, that's 25 or so little bits per carb. They are very simple in operation and design and if I can do it, I would think, literally, anyone can. You just have to be organized about it. I found four Tupperware containers of the correct size and started, making sure all the parts from any particular carb body stayed together. Not sure that was necessary, but figured it was best.

[mcpuffett]

you will also get the satisfaction of doing it yourself and saving some money to      mick.

[toycollector10]

Thanks guys...Now what I need is kits for parts. I saw a post about Keyster kits that said that they weren't very good. Should I try and source genuine Honda parts?  Any opinions?

[heffay]

hey tc... here's my suggestion(s)...

being a trained wrench also, i'd NEVER trade an ear for the proper tool.  he may be good, he may be great... but, he gets paid to do his job and part of his job should be using the proper tools.  if you're gonna spend the cash on a carb synch, politely ask him to use the tool.  if he says no, he wouldn't be my mechanic.

i've been working on my zx7r carbs and they were butchered by the previous owner.  all the synch adjuster lock nuts are completely stripped.  had he been using the PROPER TOOL... i wouldn't be replacing parts.

also, one thing you have to realize with carbs is that it takes a lot to mess up... most if not all of the moving parts will stay intact and you'll only spot clean them... it is really only the jets, needles, etc. that are removed.  clean them, blow out all the passagways and that is a carbclean.  in fact, most carbs that i've been in have made it hard to confuse all the tiny jets... they usually all have their own particular holes/fittings.

best of luck,
heffay

[Bob Wessner]

...Now what I need is kits for parts.

I wouldn't run off and get kits (like I did  ). Get into yours and see what's what first. Unless there are lots of miles on your bike or it has been neglected, the needles and jets may be fine and just need cleaning as Heffay says. You probably should go ahead and get a set of bowl gaskets though.

[TwoTired]

The main carb jets are worn and it blows a little/quite a bit of black smoke under hard acceleration and hogs gas.

I find this very unlikely.  Fuel is not that abrasive.  However, if you meant your main needles and needle jet, that is a distinct possibility, as they can vibrate against one another.

I have a new air filter element on the way so hopefully it won't run so rich when I get it fitted, but, the question is:

If I get my mechanic to take the carbs off the bike and recondition them, will I be opening up a can of worms?

His advice is that because the bike is so old, when he gets the carbs off, it could get expensive and ugly. 

Some mechanics set you up for a bigger bill after the job has been started.  This sounds like he is positioning the crowbar over your wallet before he even starts.

Duane balanced the carbs by ear for me. He said that he used to put the tubes and spagmometer (sp) on to get carbs all synched but after 30 years he found that by doing it by ear and feel he was always within 5 percent of perfect so he just uses his experience and nothing else now, and I am happy with that.  TC

Its called a manometer or four of them for our bikes. (A Sphygmomanometer measures blood pressure).  If Duane called it a spagmometer, I would question is knowledge.  Further, I would only believe tuning four carbs by ear if I witnessed someone do it to TEN DIFFERENT bikes and each checked properly with guages afterward.  Then I would recognize the skill.  But, Honda techs were NEVER trained in this way, I believe.

After 30 years of repeated work, I too might look for ways to eliminate set up proceedures.  And, if a bit of bravado would convince a customer to accept this practice and still pay me, well...

I hesitate to tell you that carb overhaul is not hard.  I've found several people had a hard time doing things that I do routinely and easily.
Riding a bicycle is not hard. Learning to ride a bicycle is harder for some than others.  Some people learn to do things well independently.  Others, require an instructor to get it right.  Some are much better at some other skill.

No, not everyone can rebuild carbs.  But, how will you know until you try?  If you are worried about messing up your only set.  Practice on a similar set first.  If you cannot gain confidence doing that.  Then take your chances on paying someone else to do it for you.

Having said all that, have you simply tried to lower your needles one notch to lean the midrange?
Or, before that, have you read your spark plug deposits to verify you ARE running rich?

Post a detail pic of a spark plug.  We can help.

Cheers,

[Bob Wessner]

Practice on a similar set first.

That would work. However, these don't come up often and tend to be pretty pricey.

[TwoTired]

Practice on a similar set first.

That would work. However, these don't come up often and tend to be pretty pricey.

Are they that different *inside* from pre 77, 750 carbs?

Still seems like it would be cheaper than paying someone else to rebuild them.

Cheers,

[Clyde]

My K0 leaked gas like mad and it also blew black smoke, when I got it home (from Farmington NM to Sydney Australai!!!!).
I bought it from a bike shop, but they told me there was a problem with the carbs and gave me the option of doing the carbs for me or taking $100 of the price and leaving it up to me. I took the money!!
The problem was mainly split o-rings in the fuel t-pieces and also setting up the float heights. Once I had reassembled the carbs and put them back on the bike it still blew black smoke but less so and only from 3 and 4 pipes. I did not go to too much trouble doing a visual alignment of the slides as I have a set of mercury tubes and always use them. A good visual alignment may have neant no smoke at all.
I then synched the carbs and no more problems.
Does your bike blow smoke from all four pipes or just one or two?
I actually find the earlier carbs easier to work on as you do not have all the rocker arms and connections between the four carbs. So it is easier to pull apart and work on. The K0 carbs apart from the rods lifting slides being replaced with cables, are no different to work on once off the bike. The later ones have the composite floats, which are definitely better, but use the same method of adjusting float height.
If you are a PATIENT  person I would have a go at doing the carbs.
It is unlikely that they are worn that much. As mentioned before,  jets do not wear much except  for the needles. Apart from bowl gaskets as Bob mentioned I would not be spending any money until you have a good look inside
You will need to synch them afterwards and I would not  pay money to someone who did not believe in gauges/mercury tubes to do the job.
Good luck
Clyde

[Bob Wessner]

Are they that different *inside* from pre 77, 750 carbs?

In that context, probably not. However, for someone inexperienced, getting to that point (the inside), is going to appear difficult and they may have difficulty transferring this to the earlier carbs. Or, having done it on a later set, it might make them realize how simple the earlier ones are. Hard to tell.

[toycollector10]

Thanks for the ideas, first off I will source some old Honda carbs if I can and take them to bits, see what cooks..