need a little mechanical help with my new 87

Aaaahhhhaaaa! The passageways....that's what I was missing. I removed everything that could be removed and sprayed carb cleaner and compressed air through everything I could get to. But without soaking the carbs, I see where the carb spray and compressed air could have failed to clear the passageways from hardened gunk. Which is what I found throughout the carbs. I attached a pic of one of the bowls but don't know where it went to??? Maybe a combination of leaky boots and clogged passageways??

 

haste makes waste

Don't start jumping to conclusions. I want to tell you a cautionary tale about fixing a cycle I loved and rode for a long while until some bandits came by in the middle of the night and picked it up into a truck and I hever saw it again. It was a Triumph 650 and this was 1971. It was a 63 TR6 and it was sitting in a ladies garage in Tucson. I got it started and It sounded like it was thrashing around inside the cylinders. In my ignorance I told the woman that it might have this terrible thing wrong or that terrible thing wrong and in the end I bought it for $270 and carefully drove it home. I proceeded to take this and that apart and throw money at this and that thing until finally I broke something. And that cost me. Time and money and the loss of the use of the bike. Turns out that I didn't need to do a thing to the bike except keep it the way it was. Yea, clean it up, but it did not need any changes. I just had to fix all the things I had done wrong to it to get it back to what I had bought in the first place. I rode that bike from Tucson to Lexington Ky in a snow storm and back to Tucson through a tornado in Memphis and all I ever had to do was adjust the valves so the pushrods weren't so noisy and clean out the jets and float bowl, I learned to set the ignition and change/gap the plugs and every time I did I checked the compression and it was always 150 psi on both cylinders. I broke everything else myself by making a lot of assumptions and jumping in without a plan. And I 'd say that a $270 motorcycle I bought of an old lady whose son was probably fighting and maybe dieing in vietnam, cost me another $270 just because I was fool who couldn't go easy. Don't think the guy who had the Honda before you was a numbskull. He rode it for reason and it was supposed to be reliable. Depend on it. Don't go changing jets and making up stories about why it runs one way or another. It's probably just fine except for something that makes perfect logical sense.

I don't want to be rude here. But, did you test the compression? Any tuneup starts with a compression test. Did you check the timeing, any carb work is proceeded by setting ignition. Did you torque the head or set the valve clearances? you are going to get into alot of money real quick if you go for the carb rebuild. Each carb costs $60 or more in parts to rebuild if you go with new. Why throw money into carbs when you aren't even sure it is the carbs or that they might not be OK with a little cleaning.

You are getting into what was called a 'mystery' in the middle ages and on into the renaisance. There were men's clubs created around these mysteries called Guilds. If you were lucky you and your father and his father might have been in one of these guilds at that time in history. What they did is train their family members in the mysteries of their guild, sort of keep it in th family so to speak. Automotive repair is a sort of latterday guild. Its all sort of mysterious and arcane. But really it's all science and physics. So you are the apprentice and your asking help from the guild masters. But actually its all in the book and in your head, as Socrates might have explained it to you. You just need someone to explain the confusing parts. When it's over its all gona make perfect sense. If you take your time and use a plan.

Don't chuck any of the old parts out, especially if they are hard parts and go by something to replace them because " new and expensive" just has to be better. Wrong. What the factory put in their worked great. Unless the engine has been modified by some speed fanatic, leave it the way it was. Re jetting is mostly for nothing. You use more fuel because you think you have to. It more of the "new and expensive" mindset. Moswt people just want it to run smooth and start in the morning. I can tell you from experience that rejetting is a sometime thing. Rejetting requires miles of driving and removing the plugs over and over again to see if their is an incremental change in the color of the plug electrode. It takes many miles of running a carb lean to burn a hole through a piston and you can run a carb too rich for years because you think its supposed to be that way. But none of this makes any difference if you haven't got a solid engine (compression and head torque) good valve operation (valve clearance) and proper ignition. If those things aren't right and you goof with the carbs you just never will get it right and you'll pay for it at the pump.

Carbs are a whole sub mystery in and of themselves, thats why there is this false separation between ignition and fuel people. The real master knows that they are inseperable, you can't have one without the other, they work together and otherwise they hardly work at all.

Carburators are fancy perfume applicators. They work on the principle of air flowing over a small hole very fast. If the hole is open to the air the fast moving air will suck the dead air up the hole and into the faster moving jet of air. If you put a liquid in the way of the dead air getting up the hole the dead air will push the liquid up the hole in its attempt to join the fast moving stream of air. Its differential pressure of air that makes the carburator spray. Thats what a carburator does: it distributes fuel into an oncoming stream of air which atomizes the fuel so it can be efficiently burned in the cylinder. The high speed stream of air is created by a piston decending in an enclosed cylinder. The better the cylinder is sealed and the more perfect the opening and closing of the entrance to the cylinder the higher the lower the pressure in the cylinder during sucking in and the consequent higher the velocity of the air as it flows in. The air that is allowed to flow in is constricted into a tube that is called a venturi. The venturi is actually a constriction on the tube where the air velocity is increased to it's greatest speed. It is at this point where the holes are placed for the introduction of fuel. The holes have their own constrictions. These are called jets. Jets meter the amount of fuel that can be introduced into the air stream for any condition of differential in pressure with the atmospheric pressure and the lower suction pressure at the venturi site. Jets size is a function of air fuel mixture. There is an ideal air fuel mixture, @ 15 to 1. The factory and other tuners can measure the mixture and thereby optimize the size of the jet used in any carburator. Even a smog test center can tell you if your mixture is optimal by letting you know if you are pukeing unburned HC molocules (rich)into the air. Optimal running means you used up all of the available HC molocules when the charge in the cyliinder was ignited, but did not run out of HC molocules that could combine with available oxygen (lean).

So what you got is a spray bottle with gasoline as perfume. The gasoline sits in the bottle ( the float bowl) and a tube that exits at the venturi stick down in the gasoline. You start the motor and the intake valve opens to allow air/fuel into the cylinder. If the tube that leads from the carb (the object that carries the venturi(s) and the bowl of fuel) has a hole in it then air that has no fuel mixed with it can enter and dilute the mixed air/fuel charge coming by the venturi. Having hole or leak downstream of the carb will also reduce th amount of air coming across the venturi and therefore less fuel will mix with the lower amount of air through the Carb. To compensate for the excess air from a "vacuum leak" you will have to choke the carb. this will artifically cause the carb to introduce more fuel into the air stream.

You take it from there. I'm pooped.

 

sorry if I confused you with the high/low pressure

I think you get it. The cylinder decending creates a vacuum effect which sucks air into the cylinder. The air inlet to the cylinder is restricted to cause the air velocity to speed up. Less area to flow through means that the air has to flow faster in order to get the same volume of air past a certain point. The pinch point is called a venturi. Thats were they they put the holes that the fuel comes out of. That high speed point is also the point of lowest pressure in the stream of air going into the cylinder. The air outside the carb senses that low pressure and tries to push into it and fill it in so to speak. But the other end of the tube is sticking into the fuel in the bowl. the outside ambient air pressure tries to push the fuel out of the way andends up pushing fuel out the tube that dumps into the venturi. The subtly here is in the level of fuel in the bowl. If the fuel level is too high it is less difficult to push fuel out the tube from the bowl (runs rich). If the fuel level is too low its harder to push the fuel out the tube from the bowl (runs lean). You have to keep the fuel level relatively constant and at the desired level to properly meter it into the air stream. That is what the needle and seat and float are for in the bowl. They keep the fuel level optimal and constant. Kind of like a toilet bowl. If the float is wrong the toilet runs over all the time or you don't have enough water in the bowl to flush the mess down. PS remember that a carburator is a very complicated perfume atomizer. It has lots of different holes drilled in it so that the spray can be eavenly increased or it will spray when the main jet are shut off, but its all the same physics.

Now I have favor to ask of you. I'm not a perfect computer idiot, but I cannot ffigure out how to get a picture to load or attach onto a forum. I especiallly want to load a picture onto the BUY SELL FORUM. But I have not even been able to load any pictures of my bike on the site. Please tell me how to get a picture up and on the site. You did it with that close up of the float bowl. I'd like to know how you did that, the step by step process including snaching the picture from your hard drive. Could you do that for me?

 

Wow! what a response! my eyeballs hurt after reading that. Unfortunately I have a very small attention span and probably a touch of senility and can't remember what the heck it said.....sorry! jk
anyway, I came home and fired up the bike. I inserted a towel in part of the air intake of the air box and it ran like a champ. Even with the choke completely OFF! So now i am on my way to removing the carbs, and completely soaking and cleaning every little hole and inlet and passageway I can find. I will also completely inspect the carb boots. I did spray some WD40 around them while it was running and noticed a very small difference in idle when spraying one particular carb. The others had no change. So if nothing else, I will just stuff a towel in the air box and be on my merry way!!!! jk! I will do what it needs to be correct, or at least close enough....remember this is a learning project not a money pit....I have enough of those!
To attach the pic, I just clicked on the manage attachments" button just below the box that you reply in. Browse to the folder where you have the picture and click on it. Then upload the picture. It will take a few seconds to load, but you will not see it until you submit the reply and go back to the thread. I think you have to use the submit reply box at the bottom of the page, under additional options.
Later...

 

New question........should all the jets be open through the center? The smaller of the two jets in the picture, is not open through the center. I have drill bits small enough to go through there and I tried to get it through but I didn't want to damage anything. I noticed this when I had them apart before, but I convinced myself that they were supposed to be that way because they were all like that. If they are supposed to be through, I believe I have found the problem. If so, whatever it is in there is as hard as the brass. If i do have to drill them through, what size should they be or where can I find that information?
The second pic shows where the drill bit stops when trying to get it through.
The third pic shows where that jet came from, its the one partially in the hole with the exposed threads.
Everything else seems to be clean and open.

 

Masonv45, In this pic, does this show the tube that picks up the fuel from the bowl. It looks like it has a little ball inside of it. It also looks like I may be able to gently pry it out to get it cleaned?
Thanks for your input!

 

don't pry on anything.

First of all, never pry or pull any hard part out of a carburator. If there is ball in a part of a carb its there for a reason and unless it falls out by itself or has some sort of screw or nut that loosens to allow it to fall out you are not supposed to remove it. Take that from a mechanic who worked over a decade on vehicles before electronic fuel injection became the norm. You take a pliers to the inside of a carburator and you are asking to buy a replacement.

Next, a carb is just a stone with a bunch of holes drilled in it. The holes are big enough to let gasoline pass through and therefore they will let carb cleaning fluid through just as easily. Make sure that the cleaning fluid is not dirty or gunked up from 20 previous carb cleanings.

If there is a "bb" imbedded in part of the carb its there to block off a drill hole that meets up with another drill hole somewhere in the body of the carb. Leave it alone. You are not inspecting drill holes, you are dipping them in cleaning fluid and then blowing out the gunk.

Next thing. you said that you put a towel in your air box. What do you think putting a towel in an air box is. Its the same thing as choking a carb. What does choking a carb mean? In the old days it meant you went to the inlet side of the carburator and you literally put your hand over the inlet to "choke off" the inflow of air. On cycle carbs the choke is different but the same term applies. Cycle carbs are a modification of the type of carbs that were designed for use on airplanes because of the altitude changes that piston aircraft have to deal with. I'm not going to go into that, but consider the carburated Spitfire in the Battle of Britain fighting the fuel injected Messerschmidt ME 109. Anyway, because of the design of the Spitfire carburator it was possible to make the main jet movable and thus reposition the main jet to act as a "choke". But look into the throat of any american 4 BBl or a Weber two barrel or even a Beetle single throat Solex and you'll see a flap that shuts off the air when the motor is cold and slowly opens up as the engine warms up. They don't allow such contraptions today because they tend to hang up and they pollute the air with an over rich mixture. So you are doing nothing more than restricting the flow of air to the inlet of the carbs when you put a towel in the air box. You have merely traded one kind of choke for another. Except in this case you have a potential fire hazard on top of all the gas in the float bowls and under the tank. You could shut the bike down after driving it and walk out of the garage and have it blow the bike and the garage with it three minutes later.

Now back to my problems. I tried putting up a picture and I don't get any like a "manage attachments" option after I write something like this reply. I'm looking at a book titled "Trackback" and two small option boxes beneath that that say "Submit Reply" and the other says "Preview Post". Beneath that is a red bar that is titled "Additional Options" with a button on the RHS. Below that are 4 more boxes with the following names:

Miscellaneoous options
Atttach files
thread subscription
rate thread

Below that I get the "Submit reply" and "preview post".
If i choose Submit my reply is posted. No attachment queery. What do you have on your computer that I don't have?

 

you only have one jet in the pics I have looked at

The longer tubes with holes in their flanks are called emulsion tubes and NO they do not all have through holes. They are sites where air is being introduced into the fuel before it is pulled/ pushed in to the high speed airstream passing over the venturi. So put down the drill and stop thinking you're going to improve on Mr. Honda and his engineers. Get a sieve bottom basket and put all the little brass tubes and whatnots in the basket and dunk it in the carb cleaner along with the large parts. Don't use a drill or an icepick or some other hard implement to dig or scrape the holes out. The cleaner will soften that gunk out and you will spray it out after you remove it from the cleaner. This includes the little brass tubes and jets. Don't enlarge the holes by pushing steel through them. Steel is harder than brass and wears it away. Don't wear any of the passages of any parts of the carb. Don't lose any of the small brass parts and for gods sake don't drill them or add any new holes. Leave them in the cleaner along with the larger rocks with holes drilled in them overnight. Tomorrow they will be clean and shiny if you are using new cleaner. Take them out of the cleaner. First wash them down with water, try to get all the cleaner off of the parts with water. Carb cleaner is very corrosive and carcenogenic. Try not to get it on yourself. The cleaner will commonly turn milky white when diluted with water. Keep all the little parts together in the sieve bottomed basket, don't spray them so hard that they fly all over the ground. Try to irrigate each piece so as to force water in where the cleaner was. Let the parts sit and drip dry. Try not to forget where each tube and jet and piece went. Best to get a drawing of the carb assembly to refer to. they have them on line at parts houses.

You can buy compressed air in a can if you don't have access to compressed air. If you do have access to compressed air try to get a nozzel with a rubber tipped nose so you can make a seal with the holes and find out if and where the water is being blown out of on the carb body. It will help you to understand how the various circuits make their way through the carb body.

blow everything dry including all the passages. Heres where you have to consider buying stuff. One of the reasons the bike ran rich may be because of a bad float or a bad needle and seat. you will need to consider if you need these parts when putting the carbs back together. You may also need to replace certain gaskets because the old ones tore or disintegrated when you tore the carbs apart.

Put all the jets and tubes and other parts back on the dry carb bodies. Re use the old needle and seats and if the floats have no obvious holes in them and they seem intact put them back on. The manual should explain how to adjust the floats on the old needles/seats. check for rot and tears in the diaphrams. replace as necessary. The pistons should be cleaned along with the carb bodies etc. They should freely move up and down in the venturi bridges. Put the diaphram covers on and get ready to reassemble the quad setup. Replace the inlet manifold gaskets if you can. Torque the manifold and carb bolts when replacing the quad set up.

When you start the motor up notice if you get any of the float bowls leaking from the bowl gaskets or gas coming from the inlet of any carb. If so you have a bad needle and seat or a bad float or both, you have to tear that carb down and replace them and reset them.

If you did this for a living you would charge someone up the nose if they made you reuse old parts. If anything goes wrong with an old carb part it can mean you have to take the whole quad apart again and practically start over again from scratch. Then you never know if an old part is going to crap out in a week or a month and the customer bitch and call you a bum because it failed. It's like the old Fram oil filter commercial. "Pay me now or pay me later".

Good night boys and good luck. The best part is yet to come. That's when you try to balance that set of carbs you spent hours on and possibly some 100's of bucks on to clean and run with proper float bowl fuel levels on a motor with goofed up valve timing and poor ignition. I told you to get the torque wrench out and redo those valve clearances. Might as well as long as you have the the carbs off and the cam covers are there for you remove.

 

check balls

the little balls you are wanting to "pry" out are often part of a valve system that lets fuel flow in from one direction but stops reverse flow by the seating of a small metal ball down on a curved outlet by an attempt to reverse flow. They are commonly used in acceleration pumps in carburators. If yours is gunked up you should be able to blow it loose with compressed air. Don't dig around it their and mess up the sealing surface of the valve. Other times metal balls are swedged into the open ends of drill holes to block of close them. Don't try to pry these out. You will only ruin the carb.

 

DKC,

Click on "Post Reply" and it will allow you to insert attachments It is on the right side just beneath the last post also up at the top before the first post. the "quick reply" will not allow attachments.

You are doing a hell of a job with this carb question. You should write a book. I am not kidding.
I learned all these lesson you speak of some the Hard way others from being taught by others.
Lesson 1 A man needs to know his limitations
replacing ruined carbs can be very expensive.
keep up the good work

 

I understand the fragility of the carbs and their components. I don't want to pry the balls out, I was asking if the entire tube could come out. I have seen in other carbs, that some of these tubes are a press fit into their hole and if you wiggle and twist them just right, they will come out. And of course not with pliers. And the drill bit is just for poking not drilling.
I also didn't really stuff a towel in the air box. I just covered part of the intake hole of the airbox with a towel to see if it helped, and to add further evidence that the carbs really were starving for fuel. In theory, I could restrict the flow of air to better match the amount of fuel they are getting now.
I am about to remove the remaining parts of the carb on the diaphragm side and see what I can get into on that side. I think this is where my problems could be.

 

Yes, all three parts: slow jet, main jet, and emulsion tube should have a hole all the way through. You can use a strand of copper from a multi-strand automotive wire to clean the gunk out of the pieces. Copper is softer than brass so it will not enlarge the holes.

Do not even let the fumes from the carb dunking liquid get near the diaphragms. The fumes will weaken them and they will tear. Don't let any rubber or plastic near the dunking liquid. It will make rubber swell and/or get hard and will distort/melt plastic.

Don't let the filter under the valve needle go in the dunking liquid.

I think the valve needle has a hard rubber tip, so I wouldn't dip it either.

Don't forget about the pilot screw on the side of each carb. They are covered by a metal cap from the factory. The manual will show you how to remove it. You should have a small brass shaft with threads on the end, then spring, then washer, then O-ring. Most of the time, when you remove the pilot screw, the washer and O-ring are stuck to the bottom of the bore. A dentist's pick us the proper way to get them out.

The improper, but easier way, is to find a deck screw with wide threads.
Now insert it into the bore until it stops.
GENTLY! twist the screw clockwise until it stops.
While GENTLY! pulling back on the screw, twist it counter-clockwise until it comes free. Both the washer and o-ring should be on the screw between the threads. If only one is, look into the bore. It's probably sitting in the middle on it's side.

 

I found that the smaller jet or emulsion tube really was supposed to have a hole all the way through. Upon further inspection of all of them, i happen to see a hint of light through one of them. So, I cleaned and blew through them until I could see all the way through all of them. While i was in there, I removed everything, cleaned and blew through every hole I could find. Put it all back together and..................YUP you guessed it, it runs like a champ! Choke all the way off and idling down to 1000 without skipping a beat. As soon as I twist the throttle, it revs up to wherever I tell it to stop. It does seem a hair slow revving up from idle and coming back down to idle. But that is probably normal for this engine. I am use to the newer 4 strokes that are very responsive. Maybe this one will eventually get that way if I keep fooling with it, but for now, I am one happy camper!
Thanks again for all y'alls help. I will post some pics once I get it painted and back together.

 

Glad everything worked out well.

Try upping the idle to 11-12k. This should help the off idle hesitation.

A carb sync will make the revs drop like they are supposed to.

A lighter crankshaft will cause the revs to drop faster than a heavier crankshaft.

 

I believe he meant 1.1-1.2 k RPM
book says 1200(1.2k)RPMs
glad you got finally

 

I've made my share of mistakes,

but what's important is that you learn something from them and not make the same ones over and over again. I taught auto mechanics at a Community College full time for a couple years. So I have some practice explaining the subject and I 've had to read the books that the students buy but don't read. I mean I have had to think about how to explain auto mechanics to students. I could write a book on the subject if I took the time.

Anyway, the most important thing is that Digdoug2 and his friends not think they can drive around on two wheeled Molotov Coctails by putting towels in their air boxes. Rags, gasoline, and heat are a lethal combination. Just ask Russian tank commanders in the Hungarian revolution of 1956.

I keep trying to post attachments. Maybe I'll succeed today.

 

Click on POST REPLY
Now write something in the big white box.
Now scroll down until you see a little white box that says "manage attachments"
click on it.
another little black box will pop up
hit the "browse" button
now another little box will pop up, it is your computers "file upload" box
look through there to find the pic that you want to load
I usually put my pics in a folder called bike pics or whatever the pics are of.
now once inside the folder that your pics are in, click on the one pic that you want to show.
now click on the pic you want and then click on "open" at the bottom of that window that you are in.
now you should see a bunch of words and letters in the window to the left of the browse button that is in the little black box that opened a while ago.
now click on the "upload" button to the right of the browse button.
wait about 30 seconds or so and a little pic icon will show up in a little window called "current attachments" That just shows you that everything is good to go.
Now scroll just under the original window that you opened to reply on and are typing words in until you see the second "submit reply" button. Push it and you should be good to go.
I attached a pic of me and some co-workers as we rented some Harleys last summer to ride up and down the coast of California. We were there for work for a few weeks and got bored. We went from Sunnyvale to the Golden Gate bridge one day and then from Sunnyvale to Big Sir the next day.....what a ride. I was jealous of all the sport bikes that were passing us through the twisty windy roads. It was quite a scenic ride and they didn't even charge me for the scraped up floorboards and exhaust on my rental!

 

a good looking group of guys

Sounds like you have the carb thing in hand. Mason45 knows about carb cleaner. It's bad on the lungs, keep it out of doors or in a paint cabinet, someplace where you don't have to smell it. Remember that you are doing the carb thing four times if you decide to go that way. If you intend to ride far then having everything squared away will make for a nicer trip. Its a bummer to breakdown on the road and not have a place to get parts if you're touring the country. I had the rectifier on the Triumph go in the first quarter of Oklahoma and I had to catch a bus back to Little Rock to get the part. Left the bike over night in a little town in the indian country.

 

press fit tubes and posting pictures

Press fit tubes are not meant to be removed. But the nature of the beast is that the heavier brass cantilevered out of the alunimum/potmetal of the carb body eventually gets shaken loose and you can sometimes work them out of the body by teasing them. There usually no reason to do this. Rather you should take a soft copper or brass punch and rap them back into the body of the carb with a light ballpeen. Although these VFR carb emulsion tubes have holes all the way through them, don't make a generalized assumption that all such parts will be the same.

As for the loading of pics. My complaints got the ear of "derstuka" and he passed my problem to "WhiteKnight" and mysteriously this morning the "attachments manager" box appeared under the list of allowed file types in the "Attach Files" grey line box.

Hope you get to ride that twisting road soon. The throttle response is just as good on your VFR as any VFR, including new ones. check the lubrication in the throttle cable covers and for any problems in the linkage at the carbs. WD 40 can help to free up stuck linkage. Remember , these bikes are all basically the same. And the VFR is one of the swiftest of a very swift group.

 

Just would like to say that I bought a 90 VFR750 and have been reversing the previous owners "mods", if you can even call them that. I'm doing carbs and so far so good thanks to everyone's and Masonv45's posts. In my head Mason45 is like this really hot blonde down the street who knows all this stuff about my bike...