Really? how is that going to fix the over rich condition showing up in cylinder #2 ?
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FlyingSteve
Guest
I'm not screwing with cyl 2 right now, just the lean cylinders. I shimmed the needle of one of the lean cylinders with 3 .5mm shims and took the bike out for a run and the plug color didn't change at all. Looks like I'll need larger jets.
I know I'm a noob and I honestly don't know what I'm fully talking about with this stuff yet. However, I don't undertand why you would have to shim the needle to adjust the leanness. Isn't that just a matter of turning the air needle one way or the other? What does shimming it give you that adjusting it doesn't?
There are four major circuits in a carburetor. first is the enrichment circuit, commonly known as a "choke".
second is the low speed circuit, commonly known as the idle circuit. the idle circuit generally covers the throttle positions from from idle to 1/4 throttle. the air adjustment you talk about on later BS series carburetors is really a fuel flow adjustment, used in combination with a fixed air jet which is preselected by the carburetor manufacturer. although, on the early VM series carburetors, the idle air "jet" is a passage in the carburetor which uses a screw to effectively vary the diameter of the passage and it also, like the BS series, uses a fuel adjustment screw.
next is the mid range circuit, or part throttle circuit which covers throttle openings from 1/4 to 3/4 open. the fuel supplied in this circuit is governed by the needle diameter and the taper of the needle inside of the "jet, needle" at a given needle height. if you raise the needle either with the throttle, or by moving the needle higher i.e. shimming the needle, your are effectively creating a larger passage which will provide more fuel to the circuit.
lastly there is the main jet which supplies the fuel needed for proper operation from 3/4 to full open throttle...
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FlyingSteve
Guest
Ok, so I went to dealership today and I got a 102.5 main jet and a 107.5. I put the 102.5 in to the outer most right carb, which I think is cyl 4, right? Anyway, I went for a ride (about 10mi) and came back and pulled the plug... It looked the same. Still white. I even have the needle shimmed up by 1.5mm.
So, do I need to go higher in the jet size? Or is this being caused by something else instead? Tomorrow I'm going to put the 107.5 in and go for another ride.
Interestingly enough, I looked up an 82 GS550M (AKA, Katana) and in the parts fiche it says the main jet is a 92.5... Same as what was in my 80 550E. It even shows the same part number for the needle jet. The reason I bring this up is because the exhaust system I am using is for the 82 GS550M. So if the exhaust flows that much better, than they would have used a larger jet...
*The air jet and the pilot jet are also the same between the two bikes.
So, do I need to go higher in the jet size? Or is this being caused by something else instead? Tomorrow I'm going to put the 107.5 in and go for another ride.
Interestingly enough, I looked up an 82 GS550M (AKA, Katana) and in the parts fiche it says the main jet is a 92.5... Same as what was in my 80 550E. It even shows the same part number for the needle jet. The reason I bring this up is because the exhaust system I am using is for the 82 GS550M. So if the exhaust flows that much better, than they would have used a larger jet...
*The air jet and the pilot jet are also the same between the two bikes.
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FlyingSteve
Guest
The pods aren't on yet, just the stock intake.
You may be right about the intake leaks. However, the bike idles perfectly steady and rides smooth. What I'm not sure about is why three of the cylinders are showing the same lean condition (Never mind cyl 2 looking very rich for right now).
Tomorrow I am going to rip the carbs off, give them a good looking over, put 102.5 mains in across all 4 carbs with 1 .5mm shim on each jet needle and then put new o-rings on all the intake boots. I'm also going to check the petcock and try to resolve the "rich" mixture issue on cyl 2.
Now those air mixture screws, I should turn those all the way in and then back them out 2.5 turns?
This should give me a good starting point. Since things are fubar right now, I might as well just rip it down and start fresh with my final setup, which is installing the pod filters and new o-rings.
**Also, concerning intake leaks with the stock air box setup... If it was an issue with the stock air box not being sealed up tightly, then the one 102.5 main jet I installed along with the 1.5mm needle shim should have made that cylinder show up rich.
You may be right about the intake leaks. However, the bike idles perfectly steady and rides smooth. What I'm not sure about is why three of the cylinders are showing the same lean condition (Never mind cyl 2 looking very rich for right now).
Tomorrow I am going to rip the carbs off, give them a good looking over, put 102.5 mains in across all 4 carbs with 1 .5mm shim on each jet needle and then put new o-rings on all the intake boots. I'm also going to check the petcock and try to resolve the "rich" mixture issue on cyl 2.
Now those air mixture screws, I should turn those all the way in and then back them out 2.5 turns?
This should give me a good starting point. Since things are fubar right now, I might as well just rip it down and start fresh with my final setup, which is installing the pod filters and new o-rings.
**Also, concerning intake leaks with the stock air box setup... If it was an issue with the stock air box not being sealed up tightly, then the one 102.5 main jet I installed along with the 1.5mm needle shim should have made that cylinder show up rich.
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YES, lightly seated with the air screws and then backed out 2.5 turns.
Are you doing WOT plug chops to determine plug color? I've only seen you mention the main jet sizing, so I'm a little confuzzzzzed.
Needle shim will help the midrange and do nothing for the WOT, though I'm sure you already know that.
Are you doing WOT plug chops to determine plug color? I've only seen you mention the main jet sizing, so I'm a little confuzzzzzed.
Needle shim will help the midrange and do nothing for the WOT, though I'm sure you already know that.
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FlyingSteve
Guest
Yes, I all ready know the purpose/job of the needle. I haven't been doing WOT plug chops because I've just been cruising around at 1/4 to 3/4 throttle (Where most of my riding is done at)... And even with the needle shimmed up 1.5mm, I've seen no difference in the plug color. Perhaps it needs to be shimmed higher?
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FlyingSteve
Guest
I didn't mean to come off like a prick, Dave 
I just pulled all the carbs completely apart and I'm about to give them a good scrubbing in the parts washer. Turns out that 3 of the 4 float needles were sticking... As in, if you give the float a little flick, usually it has a lively bounce on the float needle... Well, 3 of them I had to push the float needle in with a little force to get it to start moving in and out properly.
I'm really surprised at how well the bike ran despite all the little issues I'm finding.
Hopefully after I'm done putting the new seals in and cleaning them up the bike will run better. They'll look hella nicer too, which will be a compliment to the pod filters.
** I think I lost (or it was missing to begin with) one of those little spring clip thingies that holds the float needle in. How important is that thing? I put the float back on with the needle in and the float held the needle from falling out... And when there is gas in the bowls, the needle will spend most of it's time up in the bore anyway. So is this something I need to really worry about or not? I can't seem to find that little spring clip thing in the parts diagram, so I don't even know if I can order a new one. Any advice on this? Anyone have an extra one laying around or know the P/N??
I just pulled all the carbs completely apart and I'm about to give them a good scrubbing in the parts washer. Turns out that 3 of the 4 float needles were sticking... As in, if you give the float a little flick, usually it has a lively bounce on the float needle... Well, 3 of them I had to push the float needle in with a little force to get it to start moving in and out properly.
I'm really surprised at how well the bike ran despite all the little issues I'm finding.
Hopefully after I'm done putting the new seals in and cleaning them up the bike will run better. They'll look hella nicer too, which will be a compliment to the pod filters.
** I think I lost (or it was missing to begin with) one of those little spring clip thingies that holds the float needle in. How important is that thing? I put the float back on with the needle in and the float held the needle from falling out... And when there is gas in the bowls, the needle will spend most of it's time up in the bore anyway. So is this something I need to really worry about or not? I can't seem to find that little spring clip thing in the parts diagram, so I don't even know if I can order a new one. Any advice on this? Anyone have an extra one laying around or know the P/N??
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Not a problem, Steve. We would have to move to the Off Topic section, before you could even begin to offend me. Not likely. 
As for the spring clip that holds the float needle in place, I would suggest either finding one OR making one out of a piece of pallet band strapping.
You may end up in a situation at WOT for longer than usual and there is a chance that the fuel level could drop low enough that with the wrong bump...the needle (may) get bound up. Just a thought...
The thin ribon steel stuff. I've used it in places just as you mention and it always holds up.
Clips fly and get lost at the track... :-\\\
Think of it as metal Duck Tape.
As for the spring clip that holds the float needle in place, I would suggest either finding one OR making one out of a piece of pallet band strapping.
You may end up in a situation at WOT for longer than usual and there is a chance that the fuel level could drop low enough that with the wrong bump...the needle (may) get bound up. Just a thought...
The thin ribon steel stuff. I've used it in places just as you mention and it always holds up.
Clips fly and get lost at the track... :-\\\
Think of it as metal Duck Tape.
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FlyingSteve
Guest
Mmm.. I think something like a paperclip would make for a better substitute. I held the carb upright and with the float in place fully distended, the needle was no where close to falling out and it moved up and down in the bore freely. The thing is, I saw the needle fall out... But no clip in site. I think it may not of been there to begin with. I can't even locate that stupid little retaining clip in the parts diagrams either to try and order a new one.
It is on an outer carb, so it won't be a big deal to remove the bowl and put it on at a later date when I can find one.
The little flat retainer that gets a screw in it to hold the float needle jet is still there... That would be easy to fabricate a new one.
Actually in the diagram there is this, .VALVE ASSY, NEEDLE
13370-44500 (replaces 13370-44080)
It's 27 dollars and you probably have to buy the whole thing to get that dumb little retaining clip!
It is on an outer carb, so it won't be a big deal to remove the bowl and put it on at a later date when I can find one.
The little flat retainer that gets a screw in it to hold the float needle jet is still there... That would be easy to fabricate a new one.
Actually in the diagram there is this, .VALVE ASSY, NEEDLE
13370-44500 (replaces 13370-44080)
It's 27 dollars and you probably have to buy the whole thing to get that dumb little retaining clip!
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Steve,
With the CV (BS) carbs, it's important to have good O rings and boots on the intake and everything sealed up on the airbox side. Many people use weatherstrip on the end panels for a good seal, since that original stuff is 30 years old
Keep chipping away, it'll get there.
Does your fuel petcock have a prime position? If so, cap the vacuum line at the carb and try running bit on prime.
With the CV (BS) carbs, it's important to have good O rings and boots on the intake and everything sealed up on the airbox side. Many people use weatherstrip on the end panels for a good seal, since that original stuff is 30 years old
Keep chipping away, it'll get there.
Does your fuel petcock have a prime position? If so, cap the vacuum line at the carb and try running bit on prime.
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FlyingSteve
Guest
Got no prime position on my pet cock.... God that is such a funny name.
Also, I'm done with the stock intake setup. I'm all ready working on the pods. Today I thoroughly cleaned the carbs inside and out and I'm putting them back together. I have new O-rings all around including new O-rings for the intake manifold boots.
Also, I'm done with the stock intake setup. I'm all ready working on the pods. Today I thoroughly cleaned the carbs inside and out and I'm putting them back together. I have new O-rings all around including new O-rings for the intake manifold boots.
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Guest
Guest
I've got a PRIME position on MY pet cock .
Cheers , Simon.
Cheers , Simon.
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FlyingSteve
Guest
I bet you do, Panama Red!
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FlyingSteve
Guest
I'm going to put a larger pilot jet in the carbs. The stock is a 40 and my options are either a 42.5 or a 45... I'm thinking that maybe the 45 would be right the one... What ya guys think?
This is with the pod filters on now. I am going to run the bike with the 40's just to see how it is but I'm pretty sure I'll need to go bigger.
This is with the pod filters on now. I am going to run the bike with the 40's just to see how it is but I'm pretty sure I'll need to go bigger.
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FlyingSteve
Guest
Ok, so here is the update:
I fired the bike up with the pod filters on and she started up quick and rev'd great. Very responsive, even when snapping the throttle real fast. I didn't actually get to ride it, I still have work to do (need to relocate all the electronics), but I could tell it sounded real strong and ready to go.
On another note, today I sold some of my spare parts to a local guy who has an early 80's 550 and he when he saw my pod filters he told me he used the exact same ones and all he did was put main jets in from a gs750 and it ran great. I asked him if he shimmed the needles or changed the pilot jet and he said no, just larger main jets and it ran good. I was really surprised and I'm hoping I'll have the same dumb luck lol
I shimmed all 4 the needles by exactly 2mm each, put in 105 main jets and bench sync'd the carbs. They were way out out on the sync. That "may" explain why 3 cylinders were lean and the cylinder 2 was really rich.
Tomorrow I'm going to make up a plate to mount all the electronics to the bottom of my seat pan and then I'll take her out for a spin and let you guys know how it goes.
I fired the bike up with the pod filters on and she started up quick and rev'd great. Very responsive, even when snapping the throttle real fast. I didn't actually get to ride it, I still have work to do (need to relocate all the electronics), but I could tell it sounded real strong and ready to go.
On another note, today I sold some of my spare parts to a local guy who has an early 80's 550 and he when he saw my pod filters he told me he used the exact same ones and all he did was put main jets in from a gs750 and it ran great. I asked him if he shimmed the needles or changed the pilot jet and he said no, just larger main jets and it ran good. I was really surprised and I'm hoping I'll have the same dumb luck lol
I shimmed all 4 the needles by exactly 2mm each, put in 105 main jets and bench sync'd the carbs. They were way out out on the sync. That "may" explain why 3 cylinders were lean and the cylinder 2 was really rich.
Tomorrow I'm going to make up a plate to mount all the electronics to the bottom of my seat pan and then I'll take her out for a spin and let you guys know how it goes.
F
FlyingSteve
Guest
Ok, so I got the bike out for a ride today with the pod filters on. It seemed to ride ok... But once and a while, sort of unpredictable, there would be a flat spot between 4-5K RPM... Seemed that if I opened the throttle more then it would pick up and take off. Higher RPMs it seemed to run real strong though and definitely faster than before.
The idle was a little odd though. I set it right around 1100, but sometimes after coming to a stop, the idle would settle around 1400... It was just being kinda goofy. Not sure if that is a sign of a lean mixture or something else being off?
Taking off from idle the bike accelerated smoothly and without hesitation. It still seems as if I am running lean though.
Cylinder 2's extremely rich plug is now becoming lighter in color.
I cleaned and bench sync'd the carbs. I am thinking that I may need a larger pilot jet. I'm running 105 main jets, 40 pilot and 2mm shims on the needles.
If I whip the throttle open she takes off damn fast. Just seems like the flat spot happened more when I was slowly rolling on the throttle.
I am going to call local dealerships tomorrow about a dynojet kit, just in case I can't get the engine tuned in right... Which would be due to the stock needle more than jet sizes. Before I buy a dynojet kit tho I'm going to get larger pilot jets and fatten my mains up and shim the needle some more. I want to see if I can just make this thing stupid rich and then try to tune it down from there.
So any suggestions?
The idle was a little odd though. I set it right around 1100, but sometimes after coming to a stop, the idle would settle around 1400... It was just being kinda goofy. Not sure if that is a sign of a lean mixture or something else being off?
Taking off from idle the bike accelerated smoothly and without hesitation. It still seems as if I am running lean though.
Cylinder 2's extremely rich plug is now becoming lighter in color.
I cleaned and bench sync'd the carbs. I am thinking that I may need a larger pilot jet. I'm running 105 main jets, 40 pilot and 2mm shims on the needles.
If I whip the throttle open she takes off damn fast. Just seems like the flat spot happened more when I was slowly rolling on the throttle.
I am going to call local dealerships tomorrow about a dynojet kit, just in case I can't get the engine tuned in right... Which would be due to the stock needle more than jet sizes. Before I buy a dynojet kit tho I'm going to get larger pilot jets and fatten my mains up and shim the needle some more. I want to see if I can just make this thing stupid rich and then try to tune it down from there.
So any suggestions?
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