So this summer the bike developed a chirp coming from the 1 # cylinder area. I blamed the carb boots and O-rings because I had been babying them with silicone for a year or so. So I decided to buy new and replace them . Did this and relized the the 32 mm carbs didn't fit the same , so I switched to the 34mm carbs that came with the bike that I could never make the bike run smoothly with. I have stripped and dipped the carbs new o-rings , floats needle and seats, gaskets . Did a complete on carbs no stone unturned going over, put in stock jetting , ran bike flat spots and super lean , jetted it up from the stock 110 to 117.5 still lean with aflat spot at 3k, so I jumped to 125 mains took it for a ride no noticeable flat spots but plug chops showing still lean . I think I am working with blinders, am I over looking something? just does not seam that I should have to jump 7 or more jet sizes to make a basically stock bike run properly? Any ideas out there?
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unexplainable lean condition GS1000G
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unexplainable lean condition GS1000G
OK I have my GS 1000G 1980, I have had this bike for 6-7 yrs and have always run 32 mm carbs with 122.5 mains, the bike always ran good but never really pulled like it should have. Bike has stock exhaust, except the PO had drilled 4 holes in the end of each muffler, and a stock air box with a K&N filter, new airbox to carb boots, and new side cover rubber seals , also still running the snorkel on the back of the air box.
So this summer the bike developed a chirp coming from the 1 # cylinder area. I blamed the carb boots and O-rings because I had been babying them with silicone for a year or so. So I decided to buy new and replace them . Did this and relized the the 32 mm carbs didn't fit the same , so I switched to the 34mm carbs that came with the bike that I could never make the bike run smoothly with. I have stripped and dipped the carbs new o-rings , floats needle and seats, gaskets . Did a complete on carbs no stone unturned going over, put in stock jetting , ran bike flat spots and super lean , jetted it up from the stock 110 to 117.5 still lean with aflat spot at 3k, so I jumped to 125 mains took it for a ride no noticeable flat spots but plug chops showing still lean . I think I am working with blinders, am I over looking something? just does not seam that I should have to jump 7 or more jet sizes to make a basically stock bike run properly? Any ideas out there?1984 GS1100GK newest addition to the heard
80 GS 1000gt- most favorite ride love this bike
1978 GS1000E- Known as "RoadKill" , Finished :D
83 gs750ed- first new purchase
85 EX500- vintage track weapon
1958Ducati 98 Tourismo
“Remember When in doubt use full throttle, It may not improve the situation ,but it will end the suspense ,
If it isn't going to make it faster or safer it isn't worth doingTags: None
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resjudicata
A flat spot at 3k while opening the throttle? I would expect the carb to be running on the pilot jet and needle rather than the main jet at that point. My understanding is that you aren't running on the main jet until the needle is all the way out of it's bore. That isn't the case at 3k rpm. Therefore, I don't think your main jet changes are solving the problem which is evident from your experience.
I would drop the main jet back down to the stock 110(?) and shim the needles up (see needle shimming on this site. Then maybe look at a couple steps larger on the pilot jet as well. I don't know what sizes you should try as I don't have the same carbs or have done this myself. I can only comment on how the carbs work in general.
Chris
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Originally posted by resjudicata View PostA flat spot at 3k while opening the throttle? I would expect the carb to be running on the pilot jet and needle rather than the main jet at that point. My understanding is that you aren't running on the main jet until the needle is all the way out of it's bore. That isn't the case at 3k rpm. Therefore, I don't think your main jet changes are solving the problem which is evident from your experience.
I would drop the main jet back down to the stock 110(?) and shim the needles up (see needle shimming on this site. Then maybe look at a couple steps larger on the pilot jet as well. I don't know what sizes you should try as I don't have the same carbs or have done this myself. I can only comment on how the carbs work in general.
Chris
I found this procedure on Bascliffs site, I have used this method before many times with excellent results, just not on this bike.
Also if you go to this sitehttp://www.iwt.com.au/mikunicarb.htm, you will see that the main jet starts to come into play at about 1/3 throttle, so yes a larger main jet will help with a 1/3 throttle stumble/ hesitation, you just don't get the full effect of the main jet until the needle is fully out , or all the way up, but it is still in use at lower throttle positions.Pilot jet by itself would never deliver enough fuel to bring a 1000 cc bike t 3-4k rpm you need the main.
Ok back to your other ? 's yes I checked the needle, and needle jet and they are suppose to be the ones for this bike, also throttle valve[jet] is a 140 like it is suppose to be and a 40 pilot, needle is a 5057.3 with a x-8 needle jet1984 GS1100GK newest addition to the heard
80 GS 1000gt- most favorite ride love this bike
1978 GS1000E- Known as "RoadKill" , Finished :D
83 gs750ed- first new purchase
85 EX500- vintage track weapon
1958Ducati 98 Tourismo
“Remember When in doubt use full throttle, It may not improve the situation ,but it will end the suspense ,
If it isn't going to make it faster or safer it isn't worth doing
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resjudicata
Maybe I read your earlier comments wrong. I thought you had tried bigger main jets and that didn't get you richer at 3k rpm? Otherwise I guess you are on the right track.
Chris
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TheCafeKid
I don't know how a larger main will make the pilot jet work any better or worse. Yes the pilot is fed through the same bore the main is attached to, but the metering agent is the pilot jet itself. I assume if the main were radically too small it could choke off the supply to the pilot, but that's not the case here.
I assume that you've assure that none of the screw tips from your adjustment screws were broken off, not necessarily by you, but by any PO and left in the body?
What about your pilot air jet? Stock size?
Tried shimming the needle??
The not stock stock exhaust will have some effect on this, but I wouldn't think as drastically as you're saying. The air box holes and added KN filter would have more effect than less back pressure.
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I think I may have found the problem, I had purchased new carb to air box tubes and just pulled the old ones , cleaned up the air box and put the new ones in. Well tonight I went around spraying starting fluid checking for air leaks, and discovered that it is sucking air around the new boots where they go into the air box, so I removed the air box to investigate and low and behold the boots move all over in side the airbox, actually move enough to one side that they are not filling the hole completely. So I measured the hole and get 2 1/8 inches, measure the boot where it is suppose to seal and get 1 15/16 inches check part no,s and they are the same? So I measured the distances between the carbs and set and sealed the boots accordingly and will try it on the bike again tomorrow night. The leakage that I discovered is enough to give the symptoms that I am experiencing. Hope fully this will cure it.1984 GS1100GK newest addition to the heard
80 GS 1000gt- most favorite ride love this bike
1978 GS1000E- Known as "RoadKill" , Finished :D
83 gs750ed- first new purchase
85 EX500- vintage track weapon
1958Ducati 98 Tourismo
“Remember When in doubt use full throttle, It may not improve the situation ,but it will end the suspense ,
If it isn't going to make it faster or safer it isn't worth doing
Comment
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resjudicata
That makes sense. You can't really tune the jets, etc. until the intake and air box are sealed. Or, as sealed as they are intended to be.
BTW, are the 32mm carbs stock or the 34mm?
Chris
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Bike came stock with 34mm carbs. When I first got it I could not get it to run correctly, so I put a set of 32mm on and have ridden the bike about 8000 miles or so with no problems until the intake boots started to split this summer, I had been patching them for a couple yrs , just decided it was time to replace them . But found that the 32's didn't fit into the new boots very well . Never noticed a problem with the old boots. but the spacing between the 32's and 34's are a bit different. I would not have thought that the carb to air box tubes would have been such a loose fit kind of surprised me.1984 GS1100GK newest addition to the heard
80 GS 1000gt- most favorite ride love this bike
1978 GS1000E- Known as "RoadKill" , Finished :D
83 gs750ed- first new purchase
85 EX500- vintage track weapon
1958Ducati 98 Tourismo
“Remember When in doubt use full throttle, It may not improve the situation ,but it will end the suspense ,
If it isn't going to make it faster or safer it isn't worth doing
Comment
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Well back to the drawing board , tried the bike tonight and it is still lean, real lean. I have the carbs back off and am going to start over for the third time. Something is amiss here and I can't seam to find it. I know if I ride the bike as lean as it is I'll cook it. I have done some cross checking between Basscliffs site with the spec sheet and my Factory Suzuki spec guide and there is some conflict on what is stock and what is not1984 GS1100GK newest addition to the heard
80 GS 1000gt- most favorite ride love this bike
1978 GS1000E- Known as "RoadKill" , Finished :D
83 gs750ed- first new purchase
85 EX500- vintage track weapon
1958Ducati 98 Tourismo
“Remember When in doubt use full throttle, It may not improve the situation ,but it will end the suspense ,
If it isn't going to make it faster or safer it isn't worth doing
Comment
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resjudicata
Originally posted by hjfisk View PostWell back to the drawing board , tried the bike tonight and it is still lean, real lean. I have the carbs back off and am going to start over for the third time. Something is amiss here and I can't seam to find it. I know if I ride the bike as lean as it is I'll cook it. I have done some cross checking between Basscliffs site with the spec sheet and my Factory Suzuki spec guide and there is some conflict on what is stock and what is not
I know it isn't a perfect comparison, but my 850G is running a V&H pipe (less restrictive than yours) and K&N factory style air filter in the stock airbox (same as yours) and it didn't have that lean a condition. I bumped my mains from 102.5 to 110 for top end help. But, the bottom didn't need anything other than maybe mixture screw adjustment.
So, it does sound like maybe there are still the wrong jets in the carbs or maybe the low speed ports aren't clear.
When you did the tear down and clean up of the 34mm carbs did you blast through from where the mixture screw goes to make sure you got a good flow of the carb cleaner from the low speed ports in the throat of the carb?
Chris
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Originally posted by resjudicata View PostAre the different references listing different jet sizes? Maybe post asking what other 1000G owners have for stock jetting.
I know it isn't a perfect comparison, but my 850G is running a V&H pipe (less restrictive than yours) and K&N factory style air filter in the stock airbox (same as yours) and it didn't have that lean a condition. I bumped my mains from 102.5 to 110 for top end help. But, the bottom didn't need anything other than maybe mixture screw adjustment.
So, it does sound like maybe there are still the wrong jets in the carbs or maybe the low speed ports aren't clear.
When you did the tear down and clean up of the 34mm carbs did you blast through from where the mixture screw goes to make sure you got a good flow of the carb cleaner from the low speed ports in the throat of the carb?
Chris
factory Basscliffs
Mains 115 110
jet needle 5D58 5d57-3
Needle jet X-6 X-8
pilot jet 40 40
pilot air 160 160,
Now the specs that I am getting are from the Suzuki Tech's quick reference manual. It is a hand book that Suzuki dealers use to get for shop quick reference info. So unless this is a miss print there are some discrepancy's between the two. Although I don't believe even these will cause this condition. Also this lean condition is on all cylinders equally so it kind of directs to the air supply .1984 GS1100GK newest addition to the heard
80 GS 1000gt- most favorite ride love this bike
1978 GS1000E- Known as "RoadKill" , Finished :D
83 gs750ed- first new purchase
85 EX500- vintage track weapon
1958Ducati 98 Tourismo
“Remember When in doubt use full throttle, It may not improve the situation ,but it will end the suspense ,
If it isn't going to make it faster or safer it isn't worth doing
Comment
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resjudicata
My analogy between our bikes was just meant to say that your bike configured the way it is shouldn't need much change, if any, to run well with stock'ish jets.
I agree with you, after dipping twice and blasting the ports properly if it still isn't running right on those carbs then maybe something is damaged inside and that is why the PO had them loose.
The reason I brought up blasting the low speed ports with carb cleaner is that most people I run across don't do that. They just dip the carbs and think that's good enough. Sounds like you already know that it isn't and is why you go the extra steps.
Good luck. Sorry these carbs have been such a problem.
Chris
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Originally posted by resjudicata View PostMy analogy between our bikes was just meant to say that your bike configured the way it is shouldn't need much change, if any, to run well with stock'ish jets.
I agree with you, after dipping twice and blasting the ports properly if it still isn't running right on those carbs then maybe something is damaged inside and that is why the PO had them loose.
The reason I brought up blasting the low speed ports with carb cleaner is that most people I run across don't do that. They just dip the carbs and think that's good enough. Sounds like you already know that it isn't and is why you go the extra steps.
Good luck. Sorry these carbs have been such a problem.
Chris
And no I do not have a inline filter and yes I am running a 7mm fuel line, with good flow from the NEW fuel petcockLast edited by hjfisk; 08-25-2011, 06:21 PM.1984 GS1100GK newest addition to the heard
80 GS 1000gt- most favorite ride love this bike
1978 GS1000E- Known as "RoadKill" , Finished :D
83 gs750ed- first new purchase
85 EX500- vintage track weapon
1958Ducati 98 Tourismo
“Remember When in doubt use full throttle, It may not improve the situation ,but it will end the suspense ,
If it isn't going to make it faster or safer it isn't worth doing
Comment
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My money is on carb mount "O" rings. If they are not sealing well no matter what you do to the carbs it won't help that much. just my 2 cents
VGustov
80 GS 1100 LT, 83 1100 G "Scruffy"
81 GS 1000 G
79 GS 850 G
81 GS 850 L
83 GS 550 ES, 85 GS 550 ES
80 GS 550 L
86 450 Rebel, 70CL 70, Yamaha TTR125
2002 Honda 919
2004 Ural Gear up
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