GS650E Carb woes

[EZ_650]

Well folks, she runs again! Thanks to chef1366 for supplying the needed carb body. I was able to get it cleaned up right, an installed the jets. I threw it all together, bench synced the set and adjusted the floats. I set the pilot screws at 2.5 out initially. I Installed them all and made sure everything was correct. I then installed the tank, and tried to start her up. It took quite some time of tinkering, and after adjusting the idle adjustment screw down some, she started up. She was idling around 1200, but when I revved, it hung. I figured I needed to just make some adjustments, and after scrounging around for a good replacement tank to use for gas, I went out to the store. I was just so fed up with spilling gas everywhere, lol. I ended up buying a nice container funnel and some vacuum caps for the petcock port.

So I went home, set up the funnel and gave a shot at adjusting the pilot screws. Before this though, I pulled the plugs, just to check them. Oddly enough, they were all BLACK. And this matched additional observations of a strong gas fume smell when it was running. But why the hang? I was sure there were no air leaks...

Well after tinkering a bit more, trying to get it to run less rich, I realized that I couldn't adjust the richness out with the pilot screws... In the mean time, I realized that the idle adjustment screw was a bit too far in then I realized. I adjusted it out, while holding the throttle open a bit at the grip. A few quick hang-free revs made me suspect that the hang was because the throttle wasn't closing all the way. But still, with the pilot screws were out 4.5-5 turns (can't remember exactly right now), and STILL, she was running rich. My eyes were burning, and I had the garage door open with the fan on!

I wish I had colortune and vacuum syncer... anyone?

So in a nutshell, she runs rich, stock jets, stock needle position, even with the pilot air screw full out. She'll idle but only with the idle adjustment screw in to the point that the revs hang. If you back it out, it revs good, albeit rich, but it won't idle.

 

[Suzuki_Don]

Check that your pilot air jets are correct. They should be #175s on the GS650E model.

 

[waterman]

Thanks for the experience and tips Merc!

Sadly, I am having a terrible experience putting this all back together... Let me start by going back few days.

Sometime in the middle of last week, I pulled the carbs and tore them down to re-dip them, in order to clear up an loctite and what not. So that all went well, and I even bought a second can of Barryman's to knock out two at a time. Well all went well with cleaning them and all passages looked great. So later on that night, I started assembling the carbs, and even replaced a few of the o-rings I had already replaced, but with the ones I got with my intake boot kit (i just bought them all).

Well I had everything installed on each carb, save for the floats... Yes, I'm sure most of you know what I'm going to say next, and you are right. I broke the top of one of the posts off. Actually, I cracked it though the hole, but I was not about to trust it cracked.

So, I jb-welded it that night, supposing that i'd get a head start on letting it cure, if that was even a viable option. At the same time, I began looking for a new carb body. Well that search brought me to kparkfan's FS thread. After not so carefully looking over this site I bought the carbs off his 81 650glx thinking they would work, somehow though it went over my head that he had an 81 and the specs on the carb chart were for 82-83s.
Well, upon quick inspection, they look the same, aside from a shorter brass choke tube on the bottom side. Mechanically, it didn't make sense to say this difference would produce discretions in how this carb and mine would perform.

Fast forward to today. Even though Rob dipped the one carb I needed before I bought it (thanks!) I decided to throw it in the chem-dip while I was at school. Anyway, I got home today and while spraying out the passages, I noticed something concerning... Yet another, bigger difference.

Just take note of the below pictures.

Notice how the '81 carbs' pilot jet housing has a hole that jets into the venturi. The original '82 carb does not have this... What does this mean as far as usability?

The bottom set of pictures shows what the 650 carbs I have look like. I think someone has drilled the hole that you are seeing. I would assume that this is what is causing your excessive richness and probably would not be able to be corrected without a new set of carbs.

I would think that turning your pilot screws in would make your idle mixture leaner not richer. After 3 or more turns out, I believe it is past the point of adjustment.

I happen to have set of stripped 650E carbs that I don't need anymore, I will have to check what condition they are in, but would get them to you for postage. I just shipped the air jets away and I am not sure if the diaphragms are with them yet. One of the posts may be broken off also. Likewise, I will have to check on what jets are with it yet. Let me check this afternoon to get you a list of what is there.

 

[Nessism]

A few comments, not sure if any of these are pertinent so disregard as appropriate.

- The pilot jets need to be set snug in the carb body - not adjustable.
- Pilot mixture screws should be somewhere in the 2.5 open range as a starting point
- The stock airbox/exhaust must be in place or the bike won't run properly without carb rejetting
- The intake pipe boot O-rings MUST be replaced if you haven't already done so or they WILL leak. The "spray" test to look for air leaks is unreliable.
- Using a fuel level gauge is the most reliable method to set your float height.
- All the carb O-rings should be changed if they are originals since they harden with age and don't seal properly
- A vacuum sync is necessary once you get the bike up and running
- Adjusting the valves is critical, both for the life of the engine, and to get the bike running properly.

Again, not sure how much of this applies but hope it helps.

 

[EZ_650]

A few comments, not sure if any of these are pertinent so disregard as appropriate.

- The pilot jets need to be set snug in the carb body - not adjustable.
- Pilot mixture screws should be somewhere in the 2.5 open range as a starting point
- The stock airbox/exhaust must be in place or the bike won't run properly without carb rejetting
- The intake pipe boot O-rings MUST be replaced if you haven't already done so or they WILL leak. The "spray" test to look for air leaks is unreliable.
- Using a fuel level gauge is the most reliable method to set your float height.
- All the carb O-rings should be changed if they are originals since they harden with age and don't seal properly
- A vacuum sync is necessary once you get the bike up and running
- Adjusting the valves is critical, both for the life of the engine, and to get the bike running properly.

Again, not sure how much of this applies but hope it helps.

Just to address these vital measures:
-Pilot jets are snug. I double checked.
-I started with the pilot mixture screws at 2.5. It ran way rich though (and even still.
-The stock airbox is in place. I have no intention to remove it nor an desire to.
-All o-rings in the carbs and intake boots have been replaced with ones from Rob Barr, and I installed his SS bolts too.
-I do not have a fuel level gauge...
-Again, O-rings have been replaced.
-I understand a vacuum sync is necessary, but I'm more trying to address the rich running condition first. Which is more important to get sorted out first?
-I have to adjust the valves, but with such low miles, it not an immediate priority. I will check them though.


Waterman:
The ones with the holes were ones that I bought, and came from an '81. In a previous post, I said that I was not using them. I have since found a correct carb body to replace the one I broke. That means that all 4 of the carbs on the bike currently do not have this hole. Thanks though!

Suzuki Don:
Thanks! I was clueless about what they should be, seeing how that info is missing from the table on BassCliff's site. I will check them and make sure that I didn't install the wrong ones! I am willing to bet this is my problem!

 

[Nessism]

How is the petcock? A failed petcock diaphragm will dump fuel down the vacuum line leading to a rich condition. Other than this the only thing I can think of is the float valves are leaking...that's where the fuel level gauge comes in. You can make one by taking an old carb floatbowl plug, drilling a hole though the bottom and epoxying a nipple on the bottom for a piece of clear tubing. Good stuff.

 

[EZ_650]

Ok, well, I just went and checked and sure enough, I put in the 160s that must have came in a rebuild kit I bought long ago. I was excited to have finally figured this out, until I went to my workbench to look for the stock 175s. I found 5 pilot air jets, one from each of my carbs (originals) and one the chef1366 forgot to remove from the carb I bought. Well, of the 5, I had four 160s and one 175...? I'm going to assume that the 175 came out of the carb I bought.

So what's going on here? Should I just find someone with 3 more 175s?

 

[EZ_650]

The petcock diaphragm is good, trust me lol. Besides, as I ran it last night, it was by use of a separate gas reservoir, with the petcock vacuum line capped off. The float valve points are in good condition, and the springs were still springy. I personally don't really see this as being the problem.

How then do I measure the fuel height in the tubing? Do I just bring the tubing up to the side of the carb and let gravity do it's trick with the gas?

 

[LarryA_Texas]

I think that hole came from the factory. It's just a slightly different style of carb.. But there was something that didn't make sense to me. Maybe I got it wrong or it's already been cleared up but: The pilot jets (under the rubber plug in the bowl) should be screwed in snug. Not overtight, but snug. Somewhere up there I read that you turned them out 3 turns. The "Out 3 turns" would be the mixture screws. These are the only screw adjustment you can make on a carb and they are on top of the throat where the carb is mounted to the engine. Every other setting is fixed by the size of the jet. To make changes you have to change jets.

Having said that here's my advice;
When you clean the carbs you have to follow step by step the cleanup series. It's very easy to miss one little thing and completely ruin your chances for a good running engine. It may not run at all. Some of the things I've run in to with these carbs that you may want to look for:

Make certain the boots are good. GS650 boots are part rubber and part aluminum and the bond between the two materials can break causing air leaks. A serious leak here will shut that cylinder down completely. And there are o-rings under those boots that have to be good to make the seal to the cylinder head. Bad o-rings won't usually make it not run at all, but it won't run well.

The air flow from the filter box to the carb is very important, too. Again, a problem here won't usually make it not run at all. But you'll never get it to run right.

Make sure the pilot jets are clean. There is a hole at the bottom of the jet that is easy to overlook. You should be able to spray cleaner into the top (where the screw threads are) and have it squirt out all the holes on the sides of the jet and a stream out the bottom. I think you said your's are new so that's not a problem...but be sure the new ones are the right size.

Another easy to overlook part is the choke tube and the hole it fits into at the bottom of the float bowl. Needles can be wrong and the needle jets can be a problem if they have debris in the small holes.

The mixture screws are sealing a very small hole...make sure it's clear. The tip of those screws sometimes break off into that little hole and can seal it completely. I've never heard of 5 turns out. that seems like it would never be necessary. And remember that as you screw them out the mixture is getting richer. Screw them in to lean it out. Yes, it's cutting off air, but the venturi affect of that air flow is what draws the fuel in. Try taking a look at the Mikuni website for more info on how carbs work and how to detect and correct problems. http://www.mikuni.com/fs-carburetor.html

Hope this helps and I haven't opened up a bunch of issues that have already been solved.

Larry

 

[Suzuki_Don]

Ok, well, I just went and checked and sure enough, I put in the 160s that must have came in a rebuild kit I bought long ago. I was excited to have finally figured this out, until I went to my workbench to look for the stock 175s. I found 5 pilot air jets, one from each of my carbs (originals) and one the chef1366 forgot to remove from the carb I bought. Well, of the 5, I had four 160s and one 175...? I'm going to assume that the 175 came out of the carb I bought.

So what's going on here? Should I just find someone with 3 more 175s?

OK from my searching of the Alpha-Sports microfiches I have come to the realisation that the #175 pilot air jets are no longer available. Maybe you can get them second hand or aftermarket. Personally I would not use anything in my carbs that was not made by Mikuni except "O" rings from Robert Barr. At present you are six sizes too small on the pilot air jet. The #170 air jet is still available as it is used on the '82 1100s and this jet would put you only two sizes out from stock.

Just a few ideas.

 

[waterman]

The petcock diaphragm is good, trust me lol. Besides, as I ran it last night, it was by use of a separate gas reservoir, with the petcock vacuum line capped off. The float valve points are in good condition, and the springs were still springy. I personally don't really see this as being the problem.

How then do I measure the fuel height in the tubing? Do I just bring the tubing up to the side of the carb and let gravity do it's trick with the gas?

Somehow, according to the service manual, you are to measure the fuel level when the bike is idling with the tube alongside of the bowl. I have no idea how you would check the inner carbs with the motor running unless you have leprechaun hands.

I first check to see what float height is and then check fuel level. Like Mr. Ness said, the fuel level check is best. I use a plastic vacuum tubing connector screwed into the drain hole in the bowls. I connect a piece of clear vinyl tubing and then proceed to check level with carb rack firmly secured in my trusty 6" bench vise. I use a piece of wire to secure the tubing alongside the carb body. I try to set the carbs at the same angle as they are attached to engine. Then it is simply check one carb, drain gas, adjust and check again until fuel level is correct. It is tedious but it does dial the carbs in.

I have cheated in past and used water as opposed to gasoline to check levels, that way when I had a leak it wasn't stinking flammable gasoline all over my bench. I believe it will show you how far off the floats are. It has been a few years since I have needed to do this so I am a little fuzzy.

 

[EZ_650]

So I've been looking around for replacement #175 pilot air jets and I have had little to no luck. I'm still stuck wondering how the bike ran so good when I got it if I have but one #175 pilot air jet sitting around. All the rest are #160s... Suzuki_Don, are you 100% sure that the E's have #175s? Explain to me how could that be, because the only visible differences between an E and G are the Es have smaller main jets and slightly larger starter jet (which make no difference). If the pilot jet is the same, how could I be running rich with stock G jetting minus the bigger 110 main?


Anyway, I found some jets at http://www.pjmotorsports.com/mikuni-jets.html, but they are for B42/55 Carbs, apparently. Without looking at the parts for my BS32, a 6mm long air jet just sounds too long. But if it is the right diameter and threading, then I suppose it could be usable.

What do you all think?

 

[EZ_650]

And LarryA_Texas: I will try to run the bike again and turn the air screws in, and see if that leans it out.

 

[Flyboy]

I know this may sound stupid, but have you checked that your chokes are sealing fully and not letting fuel drizzle through when closed?
I might have missed it, but I did not see it mentioned yet.
Just a thought.

 

[Suzuki_Don]

So I've been looking around for replacement #175 pilot air jets and I have had little to no luck. I'm still stuck wondering how the bike ran so good when I got it if I have but one #175 pilot air jet sitting around. All the rest are #160s... Suzuki_Don, are you 100% sure that the E's have #175s? Explain to me how could that be, because the only visible differences between an E and G are the Es have smaller main jets and slightly larger starter jet (which make no difference). If the pilot jet is the same, how could I be running rich with stock G jetting minus the bigger 110 main?


Anyway, I found some jets at http://www.pjmotorsports.com/mikuni-jets.html, but they are for B42/55 Carbs, apparently. Without looking at the parts for my BS32, a 6mm long air jet just sounds too long. But if it is the right diameter and threading, then I suppose it could be usable.

What do you all think?

OK. The only place you will find the GS650E carb specs that I know of is to look up the microfiche diagrams and the jets on the diagrams have the size against them in the left hand column. See picture below. Sorry it's a bit fuzzy but you will get the picture, excuse the pun.

The reason that the jets are so different between the "G" and "E" in my opinion is to do with the air intake system. If you look at the two different microfiches for the two models you will see what the differences are. And anything that slows air down coming into the carburettors will then require smaller fuel jets to compensate. Study the microfices and I think you will understand.

the best ones to view if you don't have a parts book is the Alpha-sports website.

 

[EZ_650]

Thanks for the information Don. Despite your supplied info, I stopped by the Suzuki store (because I was near and had time), and sure enough the parts guy showed me that same fiche and he confirmed they were discontinued and unavailable. That I figured, but thought it was worth a shot. Plus I like window shopping for accessories, and bikes, and such... Anyway the parts guy told me he used to have some GS's and told me he would remove the air cleaner lid. I didn't really say that I would or wouldn't do that, but thanked him anyway and left. Of course, I am not going to take his advice.

When I cam home, I got online and went back to http://www.pjmotorsports.com/mikuni-jets.html and bought three of the bs42/55 air jets, in #175 size. They look identical to my jets, so figured why not. Unfortunately, they won't ship until Tuesday. I am excited again, and I am anticipating their arrival.

 

[Suzuki_Don]

Thanks for the information Don. Despite your supplied info, I stopped by the Suzuki store (because I was near and had time), and sure enough the parts guy showed me that same fiche and he confirmed they were discontinued and unavailable. That I figured, but thought it was worth a shot. Plus I like window shopping for accessories, and bikes, and such... Anyway the parts guy told me he used to have some GS's and told me he would remove the air cleaner lid. I didn't really say that I would or wouldn't do that, but thanked him anyway and left. Of course, I am not going to take his advice.

When I cam home, I got online and went back to http://www.pjmotorsports.com/mikuni-jets.html and bought three of the bs42/55 air jets, in #175 size. They look identical to my jets, so figured why not. Unfortunately, they won't ship until Tuesday. I am excited again, and I am anticipating their arrival.

Well done, it takes a bit of research sometimes to find this info out and to my knowledge this fiche is the only place that has the jet sizes for the 650E as it was a lesser known and available model.

I too am waiting for a set of #175 air jets to turn up from one of the members on here.

Good luck

 

[EZ_650]

Well everyone, I put the 175 air jets in, and while it seems to be running a bit better, she is still running a bit rich... Particularly it's obvious because of the excessive smoke out the left tail pipe. I have yet to check the fuel level, plan on doing that next.

Would that really cause it to run so rich at idle though?

Ugh, right now, I just want to sell this thing. Even if I get it running right, I think it will end up being sold soon anyway. I'm at the point in my life where I'm trying to consolidate projects, not make more. Plus school and everything. For the right price I'd probably even sell it right now...

 

[Guest]

Well everyone, I put the 175 air jets in, and while it seems to be running a bit better, she is still running a bit rich... Particularly it's obvious because of the excessive smoke out the left tail pipe. I have yet to check the fuel level, plan on doing that next.

Would that really cause it to run so rich at idle though?

Ugh, right now, I just want to sell this thing. Even if I get it running right, I think it will end up being sold soon anyway. I'm at the point in my life where I'm trying to consolidate projects, not make more. Plus school and everything. For the right price I'd probably even sell it right now...

What do you have in the carbs now? I'm sure it is in this thread but maybe I can help you.
Is your intake/airbox sealed?
Valves adjusted?
Good compression?
Good spark and at least 12 volts at the coils?
Cam chain timing on?

 

[EZ_650]

What do you have in the carbs now? I'm sure it is in this thread but maybe I can help you.
Is your intake/airbox sealed?
Valves adjusted?
Good compression?
Good spark and at least 12 volts at the coils?
Cam chain timing on?

Ah see, I hate to sound lazy, but I'm getting tired of taking time to work on this darned thing.

The intake and airbox are sealed. I thought about checking valve clearances, haven't yet. I can check compression, will post back results, it will be cold compression though. Timing shouldn't be off...

How do I go about checking the 12V at the coils?

Keep in mind this thing is old, but it only has 46xx miles on it.

Thanks for offering a helping hand btw.