Time to start the definitive VM Carb thread

[satchmo]

In other words I need lots of help.

Not mention that back searching through the forum yields some goodies, but no definitive way of rebuilding VM Carbs.

So here's the situation, as a few of you know. I've got a 1977 GS550 that needs to have the carbs rebuilt.

I've recently received my 4 keyster carb kits off ebay. They appear to have lots of parts that I've never seen before

Sorry for the poor picture quality.

I take it the last pic is of the seat assembly?

So now for the real questions.

1. What parts do I have?
2. Once the carbs are off the bike, what is the step by step procedure for cleaning/rebuilding them?

I know this is asking a lot, and I thank everyone for their input in advance, I know you guys can help me out, and I think this thread would be beneficial for others in the same situation.

I've got both the service manual and a clymer manual for my bike, but they already assume that you know which parts are which, etc.

thanks,

Satch

 

[bgk]

Dem is carb parts. Dey go inda cadibidaders! You gonna need a big hammer and lotsa beer!

Seriously, there are two simple answers:

One answer is that you get/read a service manual (Suzuki factory manual or a Haynes or Clymer manual which are better written and easier to understand by non-professional wanna-be mechanics like us). Then you pull your carbs apart, carefully keeping track of what came out from where. Sometimes this is easier if you open all the carbs, but finish pulling just one all the way apart, then another a little less apart, the third less so, etc. Then you put the new stuff in, in the same places where the old stuff came out. Critical things are float heights, etc. The manual will guide you through this.

The other answer is to wait for a post from Keith Krouse (sic?), who I believe is the resident expert on VM carbs, here on the GSR. He knows these things, inside and out.

 

[bgk]

Sorry Satch,

In the midst of reading your post, one of my kids had a paper jam crisis while printing his homework. I didn't note that you already had service manuals. I'm a a little perplexed though, my manuals, particularly the Clymer manual are rather good at identifying and illustrating the parts. Sometimes things are clearer when you pull stuff apart and compare with the photos in the manual.

I must confess, when my carbs came apart, I did most of the watching and a gifted mechanic friend did most of the crititcal work. But after seeing/helping it get done once, I could do it myself the second time around. (My carbs got gunked twice with small rust particles from the tank that got through the in-line fuel filter. I now run two filters in tandem, one a paper element filter designed for a commercial lawnmower, the other a standard little cone-shape motorcycle filter.)

 

[Anonymous]

Parts you have in picture (top one) left to right then down:

Bowl gasket, top gskt, "Needle" needle looking thing with grooves in the big end, O-rings --> flat gskt type for the main small one for the A/F needle next one for the "Seat" w/screen, looks like a Main jet (but not sure form blurry pic)

NEXT ROW
Spring that goes on the A/F screw/needle, then A/F screw/needle, "E" clip for the "Needle" (one up top), Main jet, Pilot Jet.

NEXT ROW
Thing in plastic Bag--> "Seat" with filter screen (is what the fuel comes into the carb through & is also what the fuel needle sits in) & looks to have the needle in it too (fits in the bottom of the carb under the float)

Read you manual, study the Daigrams, and the parts infront of you.
Then Take all of them apart, EXCEPT ONE if your not sure how they go back together (but you shoiuld be, you have the manual ) noting where the "E" clips are on YOUR needles, remove them clean each one, blow out with Cleaner then compressed air (ALL passages) making sure that all passages are clear, then you can re-assemble them..

Good Luck,
Busafied

 

[KEITH KRAUSE]

Hi Satch. Your pic's show the bowl and top gaskets, then the jet-needle, the o-rings are hard to say for sure, but the medium sized one I hope is your needle jet/bleed pipe o-ring, the small one is for either the pilot screw or side air screw, the large one is not always in all VM carbs but it may be for the float valve, next to the large o-ring is the main jet, then you have the spring which goes on the air screw next to it. Your fuzzy pic looks like the air screw already has its o-ring on it? If so, then the small o-ring would be for the pilot screw. The "E" clip goes on the jet-needle, the jet next to the clip looks similar to a main, but it's not. It looks too big for an air jet also. The last jet is a pilot jet. The last pic is the float valve/seat assembly.
When you take the carbs apart you'll find everything and be able to match it up. Just rebuild one carb at a time and you'll be fine. Keep the parts in order and keep everything on a towel so things don't roll around.
I suggest taking the carbs completely apart, both slide assemblies and bowl area.
I use a couple of cans of carb spray with a cleaning tube attached. This really does a good job with varnish build up, etc. I still recommend compressed air to blow out all the small passages. If you do the same, be careful of back spray in your face. Sometimes you spray in a hole and it comes right back at you.
I have to take off right now but I plan to be back later tonight and I'll try to explain a complete carb cleaning, at least the way I do it.
I know your carbs are running rich and I want to find out why. Cleaning them and rebuilding them may solve this, but I still am curious if your carbs have been "tampered' with in the past and may have incorrect jets or jet needle/float adjustments. It would be great if you can find out what your stock pilot/main jet sizes are and what position your needle clip is supposed to be in from the factory.

 

[KEITH KRAUSE]

Your carbs are sure to have differences from mine. Your choke assembly, cable brackets, etc. You'll have to rely on your manual or ask lots of questions if you get hung up. I'll try to keep this as short as I can but offer tips that may save you some hassle. I realize you have at least one bad air screw and possibly other things, so I'll try to keep this in mind.
Working with cleaners, work with good ventilation. Keep notes/drawings on ANY part of the carbs that you think will be hard to remember how to re-assemble. There may be a small friction washer on a choke shaft, etc, that notes will help you with. You also need to know where your pilot and air screws are set at. Here's how I clean a set of VM carbs.
Before you take the carbs off the bike, loosen the bolt for the throttle shaft stopper plate. It can be very tight and more difficult to loosen off the bike. It fits in a groove in the throttle shaft. You can see the ends of the shaft under the round rubber plugs near the top of the # 1 and # 4 carbs.
Take the carbs off and tilt them to spill out any fuel in the bowls. Find a place to work on them with enough room to lay out the parts as you remove them. Keep all parts on a towel. Remove the carb tops and
throttle pulley spring. Remove the stopper plate and note the little tit on one side if yours has it. Remove the bolts that mount to the throttle shaft.
One bolt should hold the cable pulley to the shaft and the other 4 can be found under the carb tops you took off. Take off the outside rubber plugs and push the shaft out. Remember which end is "left and right" and replace it the same way when you re-assemble.
Now take out the 4 slide assemblies and keep them in order, 1 to 4, left to right. Don't take them apart now. Your choke plungers have rubber parts and should not contact carb cleaner, they need to be removed for better cleaning too. Removing the choke assembly will vary from bike to bike. Loosen the 4 screws that hold the choke lifters to the choke shaft. You may also have another bolt that mounts the cable arm to the shaft. Carefully remove the shaft spring on the left and pull out the shaft. Watch for a small spacer near the right end of the shaft. Also, make sure each choke lifter goes back right side up. They may have a "bump" that contacts the plunger shaft and if you put them back in upside down, your plungers may be out of sinc'. Now loosen and remove the 4 plunger assemblies.
Now take out the side air screws if you can. If they are too tight and you think you'll strip the heads off, stop. We might just have to hope the screws are set OK if you can't get them out. I know you don't want to start replacing carb bodies. These screws have an o-ring to replace and their adjustment is important to the jetting. So it would be good if you can remove them. If they move OK, turn them IN first, counting the turn(s) for each carb. Write it down. Now try to clean out any junk in the screw threads and then remove the screws and spring and any washers.
Now turn the carbs on their tops and go through the same procedure for the pilot screws. CAUTION, when seating these screws, seat them LIGHTLY. They have a sharp tip that can break off in the carb body. These are very sensitive to adjustments. Count the turns as accurately as you can. They are set at the factory and cannot be exactly re-set. But we'll get them back just fine with some testing/fine tuning. They have an o-ring to replace and I think yours may be out of adjustment.
Now take off the float bowls. Remove the float pin and note which way is "up" on the floats. Remove the float valve and seat that the float rests on and note any gasket/o-ring. Remove the pilot jet. Hold the needle jet/bleed pipe and remove the main jet. Remove the needle jet and note the o-ring. This o-ring is VERY important. If it's bad, you will have a rich mixture caused by fuel passing around it and up into the carbs main bore.
Put all the removed parts in order in front of each carb.
Your carbs should be apart enough now for cleaning. Your carbs don't have to be seperated from each other to clean them well. However, they do have rubber coated fuel lines/tees that need to have the carb cleaner rinsed off them ASAP. So keep that in mind.
Spray the outsides and remove all dirt, etc. Use a small stiff nylon brush to help. Once clean, put some Armor All or other protectant on the rubber fuel lines mentioned. This may be overkill, but I don't like cleaner just sitting on rubber any longer than necessary. Now carefully (watch for back spray) spray every hole and passage you can see. Try to see spray exiting out at some point to be sure that passage is clear. You will learn a lot by watching this. You'll see how the fuel and air passages make your carb work. When you are positive you have cleaned every passage and inside part, spray off any new dirt that's on the outside. Now blow everything out again with compressed air if you can. Re-coat the rubber fuel lines with protectant if needed.
Clean the parts up that you removed earlier and will re-use.
You can do one carb at a time if you're worried about putting things back right, but it's a bit harder to do. None of the parts are so identical that you can mistakingly put one part in anothers place. We'll help you if you have trouble.
Now, with the exception of the slide assemblies, you can start re-building the carbs. The slide assemblies can be cleaned as they are, but if you want to replace the needles and find out their clip settings, you'll have to take them apart. At least the carbs are clean now.
I'll end this since it's so long already, and wait for any questions you have on putting everything back. Let me know about the slide/needle assemblies. I'll help you with adjusting the floats, manual sinc', etc.

 

[satchmo]

Thanks Keith. Wish me luck, for it begins today

Satch

 

[jimcor]

Dem is carb parts. Dey go inda cadibidaders! You gonna need a big hammer and lotsa beer!

Finelee sumwon wats nose how to rite tecknickel! Now weeuns is gittin sumwers! Ahm gunna go git dat beer! :wink: :lol: bgk ah bet yall be likin dert track crs too!

 

[satchmo]

Aight y'all.. time for another question.

I've got the carbs off the bike - not that much of a chore (although I know on the 550, putting them back on is a pain.

I've removed the covers, removed the choke and the choke lifters, the throttle plate, the nut holding the idle screw stuff onto the throttle rod, loosened the bolts holding the slides to the throttle rod.

Now I'm having trouble removing the throttle rod itself, it appears to be stuck, and I"m wondering how do I go about removing it. The manual says to use a socket extension to push the rod out, I tried that and it still won't budge. I even tried lightly with a hammer and it wouldn't budge....I don't want to hit it any harder cause I don't want to damage anything.

So how do I lubricate this puppy to get it out. KY? (kidding).......

Thanks in advance.

Satch

 

[Anonymous]

Enough with the CAJUN IMITATIONS!!! :x Where's CLAUDE???? :?

 

[satchmo]

Alright. So I decided that I could still do some stuff until I figured out how to remove the throttle shaft.

I removed the float bowls. They actually look pretty clean, took out all of the jets, the floats, the little needle thing that the floats push down on, etc. The jets all appear to be the right size. The mains are 80 and the pilots 50, with the little one under the pilots at 15. These are the same as the ones in the replacement kits.

They also all appear to be clean, with no blockages.

Now two of the o rings under the mains on carb one and four were shot. The other two appear to be ok, but I'll probably replace them anyway.

There were no o-rings anywhere under the pilots, is this normal?

Secondly. There is a long other thing which appears to be attached to the carb bodies - possible idle jet? I don't know. The thing is, on carb #4 it is broken off. Is this an enormous problem?

Satch

 

[Anonymous]

Alright. So I decided that I could still do some stuff until I figured out how to remove the throttle shaft.

I removed the float bowls. They actually look pretty clean, took out all of the jets, the floats, the little needle thing that the floats push down on, etc. The jets all appear to be the right size. The mains are 80 and the pilots 50, with the little one under the pilots at 15. These are the same as the ones in the replacement kits.

They also all appear to be clean, with no blockages.

Now two of the o rings under the mains on carb one and four were shot. The other two appear to be ok, but I'll probably replace them anyway.

There were no o-rings anywhere under the pilots, is this normal?

Secondly. There is a long other thing which appears to be attached to the carb bodies - possible idle jet? I don't know. The thing is, on carb #4 it is broken off. Is this an enormous problem?

Satch

#1) Are you trying to totally pull the carbs all the way apart for a reason?
It is not necessary to take the throttle shaft out of the Carbs, just for a "Cleaning Job"
You will need to have them "Synched", if you totally take them apart.

#2) Good to replace ALL the Gskts & O-Rings if you have them onhand, Always. Trust me on that, leaky leaky..

#3) Yes, there are no O-Rings under the Pilots.

#4) Do you have a Picture of the broken piece you are trying to describe?
Your not referring to the A/F Needle are you?

Pics would be helpful

Bout the only answers I have for you .
Peace,
Busafied

 

[KEITH KRAUSE]

Satch, the throttle shaft has a bolt and plate that needs to be removed. Between carb 1 and 2 on yours? There should be 5 more bolts that thread into it. 1 in each carb and 1 that mounts the throttle cable pulley to the shaft.
You said the mains are #80 which sounds OK, but I'm not sure what you mean by "the pilots are 50, with the little ones under the pilots 15"? The PILOT JETS are #15, not 50. And what are these "little ones" under the pilots themselves?
There should not be any o-rings under the pilots.
You MUST replace any bad o-rings, etc, to make these carbs run well and avoid taking them apart again. If you are patient and take your time, things will be fine.
The long thing that is attached to the carb body, but now broken off. Do you mean attached to the floatbowl?. Is it a small brass tube? If so, that's for your fuel overflow. If the bowl level goes over this tube, fuel will spill out of the overflow line under the bowl. If it's broken off, then it needs to be replaced or repaired. With no overflow tube, the fuel will run out constantly. Yes, you could plug the hole where the tube went but that would be mickey mouse.
If you want to replace the jet needles with the ones in your kit AND find out where your needles are set, you will have to remove that throttle shaft.
It would be helpful to find out the correct size jets for your bike either from members here or the dealer. Because your carbs could have been tampered with before you got the bike. We need to figure out any possibilities of why your carbs are running rich before you re-install them. The #80 main and #15 pilots seem correct, but I would like to know where the factory sets the jet- needle clip. Example: 2nd groove from the top?
Pictures of your carbs would sure help. It would eliminate communication problems. Sorry I cannot always answer quickly.

 

[satchmo]

Missing part

Missing part

Here's some pics of the part that's broken.

These are carb bodies 3 and 4. Notics how in number 4 the little thing in the top left corner is missing.......is that going to be a big problem?

Thanks,

Satch

 

[KEITH KRAUSE]

Satch, that broken part is the starter jet/starter pipe. It supplies fuel for the choke to that carb. With it broken off, your choke will not be able to draw fuel. If the bowl fuel level could reach it, you would actually draw an un-metered amount of fuel which would be too much. It's very close to where the normal fuel level is, so it's hard to say. In your case, I think your choke will not operate. This won't stop your bike from starting but it will make it a little more difficult. The other 3 carbs should be able to get you started. At cold start ups, you may notice that cylinder not firing because the mixture won't be right for immediate combustion. It would be great if you can find a replacement carb body and it would be the right thing to do, but if it's too much trouble you can probably live with it.

 

[satchmo]

Thanks.........I'll live with it for now. And replace later if I can.

I've got the bodies back together, and am just checking the slides and stuff.

I had a couple of bad o-rings, and all of my floats were out. The factory setting was 26mm and most of them were between 20 and 22mm .......

So that was probably why they were running rich right??

So what's the procedure for a manual sync?


Satch

 

[KEITH KRAUSE]

Yes, the floats being that much out of adjustment would cause a rich condition. 26mm seems a bit high but if that's what your manual says...
You did'nt mention anything about your air and pilot screws. How did things go with them? Also, did you replace the rubber manifold o-rings? Very important.
A carb sinc' using a vacuum tool is very important to get the carbs truly synched. I have manually synched carbs the best my eyes will allow but still not come close to what the tool does. A good manual sinc' makes the tool sinc' a lot quicker and easier.
If just one carb is pulling more vacuum than the others, that carb will run richer and vice-versa. So I recommend buying a tool such as my Motion Pro ($39). If you can do a carb rebuild, you can tool sinc' your carbs.
Ok, here's how to adjust the fully closed and fully open throttle valve positions, manual sinc'.
Fully closed position first. Turn the idle screwknob out to create a good clearance between its tip and the throttle pulley. Hold the carbs with the ENGINE side of the carbs facing you. On top of the throttle valve arm is a slotted screw held by a nut. Loosen all 4 nuts. Make sure the bolts are tight that connects the throttle pulley to the throttle shaft and the throttle valve arms to the throttle shaft(3 ft/lb). You may or may not have a "master carb", but start the sinc' with that carb if you do. The master carb would be #3 from the left. While watching the bottom of the carb slide, turn the slotted screw to fully close the valve or as much as it will drop down. DO NOT turn it any more than necessary. When the valve stops dropping, you stop turning. Do the other 3 the same way. Now carefully hold the slotted screws so they can't move and tighten the holding nuts. 3 ft/lb is good. Don't over-tighten. If you think the screws moved when you tightened the nuts, re-sinc'. When done, the bottoms of the slides should look uniform to the eye.
Now the fully open position. There is a slotted screw under spring tension mounted on the carbs bracket, the throttle stop screw. When you open the throttle the pulley will stop when it hits this screw. Turn the carbs so the FILTER side is facing you. Raise the valves fully by pushing up the pulley until it hits the screw. Hold that.
Look up inside the rear of the carbs and note the bottom of the valves. The bottom of the valves should be 0.5 to 1 mm above the top of the intake chamber. If an adjustment is needed, turn the screw in to decrease this gap and out to increase the gap. Now turn up the idle screwknob enough for the bike to start and idle. This 0.5 to 1 mm gap is for my GS1000 VM26mm carbs. I am assuming your 22mm carbs would be similar.

 

[satchmo]

Well the carbs are back together I'll attempt the manual sync tomorrow.

In total, I replaced all 4 needles - 3 indents from the top by the way.

3 air screws and accompanying o-rings. - the last one wouldn't come out.
All the main jets, and pilot jets and seat assemblies.

The o-rings on the main jets and the fuel screws.

I hope these are the manifold o-rings you're talking about Keith.

I reset all the float heights to spec. which was 26mm according to both the suzuki and clymer manuals.

I've reassembled everything. And don't have any parts left over.

Thanks for all the help everyone. Now I guess it's time to buy a carb tool to vaccuum sync them all, and hope it all works.

Satch

 

[KEITH KRAUSE]

Sounds good.
Two things, turn the side air screws out 1 3/4 turns. This should be in the ballpark. When the bike is warmed up, adjust them for the highest idle. Where were the pilot screws set?
The manifold o-rings are inside a groove in front of the rubber manifolds. The manifolds are between the carbs and the head. They are not expensive and yours are probably getting cracked/brittle unless they have been replaced recently.
This will cause intake leaks. Do yourself a favor and replace them while you have the carbs off. You can't do a sinc' with intake leaks.
When you replace them, give them a good coat of hi-temp' bearing grease and torque them about 6 ft/lbs. You probably still have the phillips screws holding the manifolds. I would replace them with allens so you can torque them. Just don't over-tighten them. This just flattens out the o-rings too much and decreases their service life.

 

[satchmo]

Will do. Thanks for all your help on this Keith, and everyone else who answered all my questions in doing this carb rebuild.

And to anyone contemplating doing this, if I can, anyone can.

Satch