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Just got a 1982 GS400E

  • Thread starter Thread starter dude99
  • Start date Start date
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.
 
BigD_83 said:
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.
Click to expand...
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.
 
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.)
 
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?
 
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
 
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Why won't the enrichener (i.e. choke) work?

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?

koolaid_kid said:
Using the choke won't help on a CV carb, unfortunately.
Click to expand...

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
 
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...
 
BigD_83 said:
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
Click to expand...
Were you at WOT?
 
dude99 said:
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
Click to expand...
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?
 
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.
 
Stock main jet is a 120 (or a 117.5) it depends where you look. The fiche at the dealer says 120 and my repair manual 117.5... Either way it's a 130 right now. The pods don't have a brand on them and were not oiled when I got the bike far as I could tell. Again, they came with the bike, I did not put them on.

As for choke making a difference to nurse a sick bike home like he mentioned, some CV carbed bikes have choke plates on them. That would make a difference as it would restrict airflow, no?
 
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koolaid_kid said:
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.
Click to expand...
Aah yes, I clearly see your point, KK. Thank you for the explanation.

In all of my situations the "choke" has been an enrichener rather than a true choke.

In my situations I was able to close the choke after getting through the lower rpm range, and then could run up through WOT, but had to nurse the choke as traffic slowed down. I wouldn't recommend the practice.

My thought, prior to dude99 discovering he was running rich, not lean, was that 5000rpm wouldn't be WOT, and opening it up at the "crackling point" might help him get through it.
 
Good point. After I posted I considered the case of the throttle being just cracked open, and you are correct, it will richen the mixture considerably.
 
dude99 said:
Stock main jet is a 120 (or a 117.5) it depends where you look. The fiche at the dealer says 120 and my repair manual 117.5... Either way it's a 130 right now. The pods don't have a brand on them and were not oiled when I got the bike far as I could tell. Again, they came with the bike, I did not put them on.

As for choke making a difference to nurse a sick bike home like he mentioned, some CV carbed bikes have choke plates on them. That would make a difference as it would restrict airflow, no?
Click to expand...
Yes. In the old days a choke was a butterfly valve that closed off the air to the carbs. Not so with our CV carbs, which is why some are so sensitive about calling it a fuel enrichment circuit. Although it performs the same function as long as the throttle remains closed, its physical operation is quite different from the old way, where you can open the throttle and the butterfly valves still restrict the air.

O.K. Unfortunately, your pods are the biggest hindrance to tuning your carbs. While it can be done, it makes it significantly more difficult. If you can, get a pair of K&N or APE (a bit cheaper if they have them for your bike) pods.
The jet sizes are in the ballpark for pods and a pipe. However, to get you going right now: You can't oil those pods, it will run too rich (duh, I think we figured that one out already).
Since you are now able to do some WOT runs, it is time to do some plug chops. If you understand the concept, go ahead and do a couple with the 130s and report your results.
 
Will do some plug chops as soon as time allows. Rode it into school today though. Seems to run alright up to about 5000rpm, then burbles a bit but I can get through it now up to about 7500 where it clears up and revs smoothly...
 
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