Carb cleanup questions

[Anonymous]

Hello everyone,

I'd like to preface this with a little disclaimer. This is my first bike, so please forgive me if I say/ask anything stupid, but please don't hesitate to correct me... I've gotta learn sometime!

Anyway, I'm working on an 82 GS450. It has been sitting for 2 or 3 years with fuel in it, so I know the carbs need cleaning. I replaced the gas in the tank and tried to start it at first, but it didn't produce enough vacuum to open the petcock. However, when I manually applied vacuum, it started right away. Could this lack of vaccum be attributed to the carbs needing to be cleaned, or is there something else I should be looking at?

I have the carbs apart, ready to be dipped, but the needle jet seems to be stuck in the float bowl. Is it okay to grab onto it with pliers to try to pull it out, or is there some kind of mating surface that can be damaged if I do so?

Finally... The pilot air screw... two questions: I realize that I probably should have checked to see where it was set from the factory, but you know what they say about hindsight. I've read several posts on here that say start with 1.5 turns out, but where do I go after that, ie. how do I know when it's adjusted properly (FWIW intake/exhaust will be stock).
Second Pilot air screw question: I have the Clymer book and the Suzuki FSM. The FSM shows the pilot air screw having an o-ring between the screw and the spring, but the Clymer, as well as my carb, doesn't have any o-ring. I find it odd that the FSM would be wrong, so should there be an o-ring there?

Well, I guess that should be it for now.

Thanks,

Steve

 

[earlfor]

Re: Carb cleanup questions

Funny thing about being a newbie, almost everyone I know with a bike has been one.

( Could this lack of vaccum be attributed to the carbs needing to be cleaned, or is there something else I should be looking at?)
*********Vacuum is produced by the engine's pistons moving up and down and the valves opening and closing. The carbs have nothing to do with it being available.

(I have the carbs apart, ready to be dipped, but the needle jet seems to be stuck in the float bowl. Is it okay to grab onto it with pliers to try to pull it out, or is there some kind of mating surface that can be damaged if I do so?)
*********On the visable end of the float needle under the float tab/tang, you will see the end of the needle jet has a small brass, rod like end. You can grip that end gently with a pait of needle nose pliers and the float needle assembly should pull out fairly easily. Its probably only being stuck by a little varnish build up.

(Finally... The pilot air screw... two questions: I realize that I probably should have checked to see where it was set from the factory, but you know what they say about hindsight. I've read several posts on here that say start with 1.5 turns out, but where do I go after that, ie. how do I know when it's adjusted properly)
***********So little fuel is being burned when the engine is at idle, it is difficult to tell much by the plug color. My method is once the engine will idle, I feel the exhaust pulses and also the heat on the header pipes at the exhaust port. Too lean and the exhaust pulse will have a flat sound to it and the exhaust gases will feel like a weak pulse and sound flat and the header will take a long time to warm up. The idle will also want to die off.
Too rich and the exhaust will smell particularly gassy, and have a slobbering or blubbering sound. Extremely rich and the spark plugs will start to get a bit sooty. The exhaust will also be rather sooty.



(The FSM shows the pilot air screw having an o-ring between the screw and the spring, but the Clymer, as well as my carb, doesn't have any o-ring. I find it odd that the FSM would be wrong, so should there be an o-ring there?)
******Look at the pilot air screw, if there is a groove around it where an "O" ring would fit, then you are supposed to have one. If there is no groove, then there is no place to put one.

Earl

 

[Anonymous]

earlfor,

Thanks for the reply! I have some updates and further questions.

Before I asked the vacuum question, I hadn't really looked at the carb, or I would have noticed that the vacuum port for the petcock comes before the carb. Anyway, are there any other things that would cause the petcock not to open? I hear that the intake o-rings often go bad... could there be a big enough vacuum leak through there? What else can I look at?

I still have not made any progress with the needle jet being stuck in the bowl. I sprayed it with carb cleaner, tried to pull it out with pliers, dipped it for about an hour, sprayed it again, tried to pull it out again... still stuck. Any suggestions here? Earlfor, it sounds like you might be talking about the needle valve, right?

Thanks again,

Steve

 

[earlfor]

Vacuum and the petcock opening: To Check that it is working, turn the petcock to run. Remove the fuel hose from the petcock. Put a hose on the vacuum fitting on the petcock (that is the small fitting) Stick the hose in your mouth and pretend youre drinkin a macdonald's shake. If the petcock diaphram is working, fuel will flow from the fuel fitting on the petcock.

One end of the vacuum hose connects to the petcock vacuum fitting, the other goes to a vacuum fitting on the side of your carb. (I am not sure on the 450's which carb though. Probably #2)

An 82 450 has CV carbs. Unless you have flanged intake boots between the carbs and cylinder head, you do not have intake "O" rings. Or, to put it another way, if your intake boots mount to a casting on the cylinder head that is integral to the head, then there are no "O" rings.

NEEDLE jet????? I thought we were talking about the float needle assembly. That is a drop in part and should come out easily.
All the jets unscrew for removal.

Earl

earlfor,

Thanks for the reply! I have some updates and further questions.

Before I asked the vacuum question, I hadn't really looked at the carb, or I would have noticed that the vacuum port for the petcock comes before the carb. Anyway, are there any other things that would cause the petcock not to open? I hear that the intake o-rings often go bad... could there be a big enough vacuum leak through there? What else can I look at?

I still have not made any progress with the needle jet being stuck in the bowl. I sprayed it with carb cleaner, tried to pull it out with pliers, dipped it for about an hour, sprayed it again, tried to pull it out again... still stuck. Any suggestions here? Earlfor, it sounds like you might be talking about the needle valve, right?

Thanks again,

Steve

 

[Anonymous]

First of all, the needle jet doesn't come out from the bottom. It's removed through the body of the carb. Read through the Carb Cleanup series here! You'll save yourself grief. Look at pictures numbered 58 through 61.

I don't know if these links will make it through intact, but here goes:

http://www.thegsresources.com/images/carbs/058_Tapping out needle net with wood dowel.jpg

http://www.thegsresources.com/images/carbs/059_View of needle jet being removed.jpg

http://www.thegsresources.com/images/carbs/060_Needle jet removed out top of carb.jpg

Next: I have a pair of carbs from what I believe is an '82 450. The air screws (or whatever you wish to call them) were 1 1/3 turns out, each. That should be a reasonable starting point.

These screws most definitely take O-rings! Just because they weren't there doesn't mean they aren't needed. People have had 25 years to tinker with these carbs... they're hardly virginal 1-owner items. Expect the hamhand syndrome. I can't guarantee that the carbs I have are the same as yours, so when I have time, I'll photograph this air screw and stick it up on my web site.

I currently don't have O-rings of this size. (I will in a few weeks or so, since they happen to be the same as those used in the VM carbs, which I'm developing a kit for.) I'm sure these O-rings would be included in a carb repair kit; they're kind of pricey, but at least you'll have them sooner. You most certainly will not find these at an auto parts place; these are oddballs.

 

[chuckycheese]

O ring

O ring

Robert's "O" ring kits are AWESOME!! :!: :!: :!: :!:

 

[Anonymous]

Thanks for the info robert and earlfor.

I do know that the diaphragm in the petcock does work. When I "manually applied vacuum" (ie. sucked on the hose), gas flowed into the carbs and it started. Could the fact that it didn't have any mufflers or air filter installed affect anything?

I've been looking at the Carb Cleanup series here since I started, but my carbs do not match those. Here's a pic of my float bowl with the needle jet stuck in it.
http://www.lustreking.com/needlejet.jpg

Also, although I don't have the bike here, I'm pretty sure that the intake boots are the flanged type... I'll have to double check that when I get the chance.



Thanks again everyone!

-Steve

 

[Anonymous]

Boy, I missed this one by a mile. Sorry about that.

I have apparently the identical carbs; here's a shot of the bowl:

http://www.cycleorings.com/bowl.JPG

And here's the underside of the carb body:

http://www.cycleorings.com/body.JPG

(Sorry about the size, if you're dial-up...). Yeah, it's a mess, but it's not one of mine. Anyway, I don't see any way that the needle jet could get lodged like that. It did, of course, but I don't see how.

The only idea I come up with is this: Remove the 17mm plug on the underside of the bowl. That'll get you to the main jet. Remove that, and you have a shot at that needle jet. Run a hardwood dowel up through the bore (where the main jet used to be) and tap, and I'd bet you'll get it out.

 

[matt_gs450]

Waking up this long dead thread... I'm having exactly this issue with a set of carbs from my newest gs450. The needle jets will not come out. I don't want to force them too much and score the surface though. I'm considering heat. Will heating the bowl assembly possibly give me a way to get the needle jets out?

-Matt

 

[robertbarr]

You don't mention which year. The 80-82 use an interference fit, with the interference being the compression of the O-ring. (That's why its size has to be perfect). There shouldn't be much effort involved at all -- just pliers, and try to rotate & pull at the same time.

Mine came apart with very little fight.

I don't see any consequence to scoring up the O.D. of the needle jet a bit, if necessary -- it's just a cylinder with metering holes.

Why would you heat the bowl assy? Perhaps some heat to the carb body where the needle jet fits.

 

[matt_gs450]

Hi Bob,

It's an 82. The needle jet is stuck in the float bowl... So only the shorter side of the jet is showing, where the o-ring is seated. I am tempted to just clean as well as I can with the needle jets stuck in place but I do want to be sure that the metering holes are clear. I'll try the heat trick this weekend and see if I can free it up.

I have rebuilt the same set of carbs on my other 450T (an '81) and definitely did not have this problem. I wonder if someone purposely added some chemical to seal them in there, or maybe pounded them in for some reason...

Will update on Monday.

-Matt

 

[matt_gs450]

I finally got the needle jets out of the float bowls. I had to destroy them to do so... But I have spares so that wasn't a problem. It turns out that the float bowls on this bike aren't the same as on my other GS450s. They are machined differently, and must be built for a different size of needle jet. Yet the stock needle jets were pounded into the bowl assy by someone. I guess some mechanic substituted the stock bowls at some point but used OEM needle jets... Or something. Weird.

Anyway, it's good that I have a couple spare sets of carbs otherwise I wouldn't have realized what was going on. I'm going to use the float bowls from one of my spares when I reassemble.

-Matt