Just got a 1982 GS400E

[dude99]

so your thinking I need to go bigger?

[BigD_83]

130 IS four sizes larger than stock already...

In my opinion, plug chops are the way to go right now, but that's going to be difficult if you can't get it opened up past 5000rpm/run it at WOT.

Can you get it to break through the wall if you open up the choke when it starts to crackle?

[dude99]

I'll take it for a ride and find out as soon as I get a chance.

[Mekanix]

117.5 is stock,
130 might be compensating for something else like really small pilot jets or missing air jets.



Take the pod's off and put something accross them to restrict air, like a rag and clamp them back on. This should ritchen it up a lot! IF it acts better then you have an idea of the direction you have to go.

what was the pilot jet ? 42.5 is stock.


what was the float height?

By chance was one of the diaphram's pinched and not raising the slide?

What about the air jet's on the intake side of the carb? are they still there?


Often times a bike without an airbox acts the same way until the carb is restricted a bit or jetted for so much open air.


Have you checked compression or done valve clearances yet?



Take a look at this site as well for part numbers.

http://www.cmsnl.com/suzuki-gsx400-1981-ex_model13617/partslist/

[jfman]

Maybe a little OT but what is the purpose of the air jets at the mouth of the carb?

I still dont get what they do really.





As far as you jetting issue goes I would jerry-rig something to restrict the air flow to see if it makes the bike run any better. Like a tshirt around the pods or something. If the bikes runs as bad than you know the problem is related to something other than the jetting vs air...

[dude99]

I believe the pilot jets were stock, the air jets are still there. I didn't check the float hight, adjust the valves, or checked compression. I can't see valves or compression doing this though. I'll try restricting the carbs along with pulling the choke on next time I have a chance to work on it. Neither diaphragm was pinched.

[koolaid_kid]

Koolaid Kid and TCK (TheCafeKid) are good carb guys...and KK is on here quite a bit these days. TCK seems to be on a hiatus

A good rule of thumb is +2 for pods and +2 for a freer running header. So if you have both, then up four sizes, 117.5 to 127.5 would be the upper end. That sounds really large to me though. Just two sizes on the main would put you to 122.5. I suppose you could split the difference and start at 125 and take it from there. Jets are not that expensive, and seeing as you have a twin, cheaper yet.

Just dialed in here. BigD, thanks, but TCK is an expert. I will never be as good as he is, but he is currently on hiatus while he plays with his new Kaw toy.
Some initial questions, please. You mentioned the needle being on the bottom clip. US CV carbs do not have adjustable needles, does your bike?
With pods and a pipe you have to do the following mods to the carbs:
Mains: 2-4 sizes over. You must do plug chops and tune the mains before you can tune the needles.
Needles: ~2 clips higher than stock. Using stock needles, which in the US do not have adjustable needles, you use washers instead. Again, you have to do plug chops to dial them in.
Pilot air/fuel screws: usually out ~1 turn. This is the most variable part, and the most difficult to dial in.
Does your bike have 4 valves per cylinder? It will have rectangular cam end caps.
Do you have the link on tuning Mikuni CV carbs?
Thanks.

[dude99]

My needles do indeed have adjustable needles (but I am in canada, and I'm not sure if there was an 1982 GS(X)400 sold in the US)
It does indeed have rectangular cam end caps and I believe it has 4 valves per cylinder. I don't have a link to tuning the carbs but I do have a repair manual for it.

So if I understand what your saying you think I should move the needle to a leaner position? (2 clips higher than stock, I assume stock is the center position.)

[koolaid_kid]

No, needles are second. I have finally understood where you are at this point. Using the choke won't help on a CV carb, unfortunately. You would need to restrict the airflow instead, perhaps wrapping the filters with a cloth, like a t-shirt or something.
The correct way to dial in CV carbs is to get the mains correct first. All the other circuits depend on the mains being correct.
What color are your plugs at the moment?
Did you find a manual for a 4-valve 400?

AFA the needle, let's make sure we are on the same page. The needle probably has 5 slots, the center one I assume is stock. Placing the clip in a slot higher than the center slot, let's call it slot 4, will lower the needle, making it leaner. Placing the clip in slot 2 will raise the needle, making it richer.
Which slot did the clip start in, and which slot is it in now?

[dude99]

Ok, progress has been made here. I took the filters off and took it for a run and, while still slightly boggy, it revved easily past my 5000rpm wall. So it would seem that it was rich. So I gave the pods a really good clean wil some solvent and put the needles back to the stock, middle position. (they were in the richest (bottom) position when I got it). Then took it for another run. Still not quite right, a little less smooth than without the filters but it now revs past 5000.
So, my conclusion here is 2 fold. One, the previous owner (or whoever did the work on it) mistook the rich bog as being lean and tried to fix it by richening it up some more, and 2, when finances allow, I'm going to buy some better pods for it.
To answer your question, the plugs looked a hair on the rich side when I got it, bit so much as to be concerned about. I guess it was only rich in the mid range (on the needle).... SO yeah, thats where I'm at now...

P.S. The manual I have is for a 4 valve 400

[BigD_83]

Why won't the enrichener (i.e. choke) work?

Glad to hear you are on the right track, dude99. You'll have it sorted in no time. Any chance you'd want to go back to the airbox instead of pods?

Using the choke won't help on a CV carb, unfortunately.

KK,

Can you explain why using the choke to richen things up won't work in a too-lean situation?

My experience says otherwise. Nursing the choke got me through some rough patches getting a couple of new to me bikes home from their POs.

- Derrick

[dude99]

The only reason I'm running pods is because that what it came with. I don't have the stock air-box, mounting hardware or anything for it. I do have to say though, they make getting the carbs out an absolute breeze...

[koolaid_kid]

Glad to hear you are on the right track, dude99. You'll have it sorted in no time. Any chance you'd want to go back to the airbox instead of pods?



KK,

Can you explain why using the choke to richen things up won't work in a too-lean situation?

My experience says otherwise. Nursing the choke got me through some rough patches getting a couple of new to me bikes home from their POs.

- Derrick

Were you at WOT?

[koolaid_kid]

Ok, progress has been made here. I took the filters off and took it for a run and, while still slightly boggy, it revved easily past my 5000rpm wall. So it would seem that it was rich. So I gave the pods a really good clean wil some solvent and put the needles back to the stock, middle position. (they were in the richest (bottom) position when I got it). Then took it for another run. Still not quite right, a little less smooth than without the filters but it now revs past 5000.
So, my conclusion here is 2 fold. One, the previous owner (or whoever did the work on it) mistook the rich bog as being lean and tried to fix it by richening it up some more, and 2, when finances allow, I'm going to buy some better pods for it.
To answer your question, the plugs looked a hair on the rich side when I got it, bit so much as to be concerned about. I guess it was only rich in the mid range (on the needle).... SO yeah, thats where I'm at now...

P.S. The manual I have is for a 4 valve 400

O.K., without having to read thru all 3 pages, what are stock numbers and existing numbers for your mains?
Leave your needles in the center until you get this sorted out.
What brand, if any, of pods are you running?
Were they oiled when you got them?

[koolaid_kid]

The reason why I ask if you were at WOT is because the mains provide so much fuel than any tiny amount provided by the fuel enrichment circuit (aka choke) is inconsequential.