Carb cleaning questions

[Lucky 1]

SEESTHEDAY.....
This is that "O" ring in question on the top of the float bowl.
The top of that float bowl would have a machined area for the "O" ring
to fit into.

[seestheday]

I'll take a pic tonight.  Will the quality of the pics above be sufficient?  Those were taken with my BlackBerry, but I have a DSLR that I could use to take a very high quality pic with if needed (just a little bit of a pain to transfer as the file size is huge).

I hear you about the thread name.  I really didn't think this thread would morph into what it has become.  I am surprised by the amount of quality info that I'm getting.  I shouldn't be though because this place is great.

Regarding washers, I think that some of them might have been lost and I'll need to get new ones.  I can't seem to find all of the washers for the fuel mixture screws.  I was able to get one out of the #3 carb, but fishing in the hole for the other carbs comes up empty and I can't see them with a flashlight.

Any tips on where I can get those tiny flat washers?  I'm planning on going to partsource (Canadian auto parts store) to look for some as I'm pretty sure that a hardware store won't have ones that thin.

[mikefootusa]

Sees...yes, that oring is the "dash" 901 I was telling you about...I too needed one.  I also was missing a washer for the pilot jet screws...I wound up digging through my crap and finding one with the same hole size...pt it on a dental pick and touched it to my fine wheel on my bench grinder.  Rubbed it around a bit on some wet/dry sandpaper and couldn't tell it apart from OEM.

[seestheday]

I took a bunch of high quality pics so you guys could see the float bowl and diaphragm easily.  I resized the images using the upload feature on this board, so hopefully the aspect ratio isn't all messed up.

I'm pretty sure I need an o-ring.






Other updates on today's progress.  

I pulled the body out of the pinesol soak and cleaned everything I could using a mix of instructions from the repair source write-up on this forum and the manual that mike posted earlier in this thread.

Step 34 of the write-up says: " Open the main butterflies (not the choke butterflies). Insure that the very small holes in the bottoms of the carb throats, where the butterflies rest, are clear. If clogged, try running a small wire through them and chasing that with a blast of carb cleaner and then compressed air. Note: the CB750 VB42 carb has three (3) such holes including the pilot hole about ½” closer to the front or head side of the carb. The CB900 VB43 carb has five (5) holes including the pilot hole. "

How deep should the wire be able to travel?  On my CB750K there are three holes, and on the one not covered by the butterfly the wire easily slid down fairly deep with no resistance.  For the holes either partially or fully covered by the butterflies the wire did no want to go down very deep at all.  I'm hoping that this is ok.

Another note: The guide that mark posted describes in detail how to check to see if the accelerator pump nozzles on each carb are clear.  I'm happy I did this because one of mine was obstructed and 2 of the others were partially obstructed.  I'm hoping to see a big difference from that.

I think I have all of the cleaning now done and plan to pick up some new screws (stripped one getting it out) and any missing parts tomorrow to start the rebuild.

[seestheday]

I checked the auto parts store and they definitely didn't have the washer size that I needed (nowhere close).  I'll check out an electronics supply store next, and then maybe a remote control/hobby store as some google searches come up with those types of stores for very small washers.

[seestheday]

TOOLS/Donald, any ideas on this question?

Step 34 of the write-up says: " Open the main butterflies (not the choke butterflies). Insure that the very small holes in the bottoms of the carb throats, where the butterflies rest, are clear. If clogged, try running a small wire through them and chasing that with a blast of carb cleaner and then compressed air. Note: the CB750 VB42 carb has three (3) such holes including the pilot hole about ½” closer to the front or head side of the carb. The CB900 VB43 carb has five (5) holes including the pilot hole. "

How deep should the wire be able to travel?  

On my CB750K there are three holes, and on the one not covered by the butterfly the wire easily slid down fairly deep with no resistance.  For the holes either partially or fully covered by the butterflies the wire did no want to go down very deep at all.  I don't want to force the wire if I don't have to and they are already clean (really don't want to damage my carbs).

[TOOLS1]

I have never rebuilt any of the Honda CV carbs, but if, you look the carb over, you should be able to visualize how the passages run, and that should give, you an idea of how far in the wire should go. Also, you should see the carb cleaner coming out the other end of the passage if it is clean.
TOOLS

[Lucky 1]

Those little holes do not get clogged hardly ever because they just have air going through them.
Just a little carb spray and watch where it comes out.
Protect your eyes and keep your mouth closed. Not kidding.

[seestheday]

Thanks Donald,
I took another look at them and was able to figure out that if I covered the one hole that was directly in line with the fuel mixture screw with my finger and spray carb clean I could see it come out of the other two holes.

Now to find those tiny washers.  I might need to break down and buy new fuel mix screws just so I can get those damn washers.  There is a store called "fastenal" close to my house that I'll check out on Monday that will probably be my 2nd last resort.

My other option would be to find someone with a drill press so I could try my hand at fabricating something.

[seestheday]

Thanks for the tip Donald, and yes I always wear the goggles when working with the carb cleaner, but thanks for looking out for me .

That said, your comment on them only passing air threw me for a loop and made me question how I understood the carbs worked so I looked up their theory in a book and found the following picture explaining what those holes are.


This made things really clear for me.  The one small hole that I was able to easily pass the wire through was the pilot discharge port, and the two small holes where the wire wouldn't go in very deep are the holes to the pilot bypass chamber.  They shouldn't go too deep as the bypass chamber is very shallow.

According to this diagram, fuel goes through these holes, not air.  It is essentially sucked out of the bypass chamber via a vacuum as the throttle plate opens up from idle.

The book is "Motorcycles, Fundamental Service and Repair" and that pic is on page 163 if anyone cares.  It mentions that it a HD carb diagram, but the principles should be the same.

Always appreciate your input though, I seriously would not have been able to get as far as I have with these carbs without input from you, tools and Mike.

[seestheday]

Ok, so I bought some o-rings but was only able to get assorted pack of the kind that stands up to fuel well.  Unfortunately for me the ring that fit was too "thick".  I'm assuming that this will give me problems, so I'll keep looking for that dash 901 that Mike referenced.

Do the rings have to be the kind that stand up to fuel well, or will regular o-rings work well?

[TOOLS1]

Any O-ring will stand up to fuel. That O-ring should work. It will compress down when, you tighten down the screws. Also Most auto parts will have metric O-rings. You just have to find a sales person that is not lazy. Because they are often kept in the back. I picked up all the O-rings I needed to rebuild a set of carbs awhile back at Advance Auto.
TOOLS

[seestheday]

Thanks tools, I was worried it would compress down too much and block the fuel, or at least impede it.

Sent from my BlackBerry device on the Rogers Wireless Network

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From: "TOOLS1 [via Honda CB750'S]" <[hidden email]>

Date: Sun, 13 Nov 2011 12:57:53 -0800 (PST)

To: seestheday<[hidden email]>

Subject: Re: Carb cleaning questions

Any O-ring will stand up to fuel. That O-ring should work. It will compress down when, you tighten down the screws. Also Most auto parts will have metric O-rings. You just have to find a sales person that is not lazy. Because they are often kept in the back. I picked up all the O-rings I needed to rebuild a set of carbs awhile back at Advance Auto.
TOOLS

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[bklion]

Say about those small washers, If you have a electronics repair place near by ,or if you have a old radio or TV, tear it apart, there are some very small washers under the screws that are holding the circut boards in.

[seestheday]

Thanks Bklion,

No old radios or tv's lying around.  I've moved too many times for work and have cleaned house every time.

I put the carbs together tonight with the thick o-ring and it doesn't work.  The accelerator pump wasn't able to spray any fuel at all, even into the #2 carb (the one that sprays the hardest if I just spray carb cleaner into the accelerator hole).

I'll go pick up a ring from the auto parts store tomorrow.  If anyone is interested, the "dash" 901 that mike referenced earlier in this thread has an inside diameter of .185 inches and a cross section of .056 inches.  I'll be looking for that tomorrow.

Oh ya, and I should mention that I'm a bonehead .  I found the missing fuel mixture washers.  They were either stuck to the fuel mixture springs or I was able to dig them out of the used pine-sol (I ran it through a sieve because I suspected that I might find them in there).

[TOOLS1]

Well, you gave it a try. I hope that a different O-ring will cure that problem. Removing those tiny balls, and springs is not any fun.
TOOLS