1980 GS1000G POD replacement with stock airbox

[Guest]

Hey Guys,

I'm the guy who replaced the POD filters that come on my 1980 GS1000G with the stock airbox and didn't change the jets. One member got really upset, I can't remember his name. The bike I bought was advertised on this forum. Have done quite a bit to it so far but have other plans now that the weather getting nice.

The reason for my post is I finally took the carbs off and removed the oversized jets and washers and replaced them with the stock ones the original owner provided. The stinky rich gas smell is gone and the bike runs pretty good. It's not so "jerky" off of idle, (had to be careful letting out the clutch when leaving my driveway because the steering wheel had to be turned to the left) and seemed a bit dangerous to me. The bike doesn't have the ridiculous low end (too low for me) torque now, rather it reminds me of my stock GS850G that I sold before buying this. It's still really fast however.

But it's got an issue that I'm not sure of what to do next. It doesn't stumble, miss or anything like that, and in normal riding, acceleration etc. it's beautiful. But if I have the opportunity to crack it open on a straight road in 2nd or 3rd gear however on WOT the bike breaks up. It's like it won't accelerate like it should and just well, breaks up.

I'm wondering if there is other stuff the guy did to the carbs in addition to the over sized jets that he forgot to tell me about. But I'm thinking maybe their are adjustments I can make to the carbs that don't require some expensive sync job.

I'm sure this question has been asked 100 times, but my searched didn't yield much. The bike isn't running too rich like before, it's just right now. And it's more driveable. But I'd like to get rid of the breakup at WOT if possible.

I hope this post makes at least some sense because my eyes or shot and I'm brain dead from two straight days of dealing with the IRS etc. to try and get my taxes done.

I'll post a pic of the way the bike looks now.


Thanks in advance, Mikeymoe

[azr]

If there were pods the PO could have easily raised the main needle. As well did you check the pilot jet size? Those could have been increased as well. What is your mixture screw at?

[Mickeymoe]

As I mentioned in my post, the PO had installed aftermarket / oversized main jets and the needles were raised with washers. He gave me the stock original jets. I took out the oversize jets and washers, and replaced them with only the factory jets. (no washers) The bike is completely driveable but has the breaking up problem at WOT. Does anyone know what the mixture screws should be set at? How many turns out, etc?

Thanks, Mark

[thebrandonbeezy]

2.5 turns to start i believe, but you need to do a plug chop.
See if its lean or what. Does it have after market pipes?

[tom203]

"But I'm thinking maybe their are adjustments I can make to the carbs that don't require some expensive sync job."

Did you at least bench sync them? One or two of these carbs might be lagging behind and not performing correctly giving you a wot stumble.

[Mickeymoe]

2.5 turns to start i believe, but you need to do a plug chop.
See if its lean or what. Does it have after market pipes?

\

What is a plug chop? Also, I haven't really gotten into the carbs yet- I don't see any screws that can be adjusted on mine other than the throttle arm position screw on each carb....

[Mickeymoe]

"But I'm thinking maybe their are adjustments I can make to the carbs that don't require some expensive sync job."

Did you at least bench sync them? One or two of these carbs might be lagging behind and not performing correctly giving you a wot stumble.

No I didn't sync them. Since the bike ran fantastic I didn't see why just putting the stock jets back in in place of the oversized ones and the washers to hold the needles open would make the carbs go out of sync?

[Steve]

... I'm thinking maybe their are adjustments I can make to the carbs that don't require some expensive sync job. ...

Not quite sure how to tell you this, so I'm just going to come right out and say it.
A "sync job" is NOT expensive. To have a shop do it should not cost over 1/2 hour of labor. OK, that might be about $50. Pay a shop to do two "sync jobs", you will have spent more money than you would to buy the best tool available and do it yourself. AND, ... since you should sync the carbs after every valve adjustment, you can keep spending that $50 every year or just get the Cabtune (currently about $91) and do it yourself.

No I didn't sync them. Since the bike ran fantastic I didn't see why just putting the stock jets back in in place of the oversized ones and the washers to hold the needles open would make the carbs go out of sync?

Even though you think it "ran fantastic", what guarantee do you have that the carbs were properly synched in the first place?

Out of sync carbs will run fantastically going down the road. Where you will notice an out of sync conditin the most is at idle.

.

[thebrandonbeezy]

Also your idle mixture screws are the ones on top at the rear of the carb

[thebrandonbeezy]

There are a lot of good tutorial videos on YouTube and such explaining how to sync carbs on many bikes including the gs1000 equipped with cv carbs such as yourself. A plug chop is a wide open throttle run and kill power when you let off so as to see how its burning as it breaks up. Adjust jets sizing/needle placement accordingly.

[thebrandonbeezy]

this is your idle mixture screw. Not to be confused with adjustment for synchronization of the carbs

[thebrandonbeezy]

Also 3 things you have yet to mention.
1 what jets did you receive as (stock)
2 assuming you put the stock airbox on, did you install the filter?
2b what filter?
2c is the box completely sealed air tight?
3 are there stock exhaust pipes on the bike,
3b if stock are they modified?
3c if not what pipes are on it.
Knowing that will help us help you. But you have to remember diag through the Internet is a shot the dark at best haha

[Mickeymoe]

Thanks for the reply Brandon.

I see where the mixture screws should be but it looks like there are plugs in the holes.

1-The PO gave me the stock jets and airbox that came with the bike. He bought the bike new and had the dealer put the larger jets, needle washers and pods on the bike. I don't know the actual size but when I took them out the holes on the stock ones were visibly smaller in diameter. The bike now has 17k miles on it.

2- I replaced the airbox and everything is tight. The boots are like new and the airbox looks like brand new because he had the upgrade done in 1980 when he bought the bike and stored the stock airbox. I installed a K&N high-flow air filter. I came with filter oil which I applied as per the directions.

3- The exhaust is stock and has no corrosion or dents. The bike is in extraordinary condition.

4- The exhaust system is stock and has no corrosion or dents. I'm having trouble uploading pictures.

[thebrandonbeezy]

There should be a number on the jets do you remember what it is?

[Buffalo Bill]

Thanks for the reply Brandon.

I see where the mixture screws should be but it looks like there are plugs in the holes.

1-The PO gave me the stock jets and airbox that came with the bike. He bought the bike new and had the dealer put the larger jets, needle washers and pods on the bike. I don't know the actual size but when I took them out the holes on the stock ones were visibly smaller in diameter. The bike now has 17k miles on it.

2- I replaced the airbox and everything is tight. The boots are like new and the airbox looks like brand new because he had the upgrade done in 1980 when he bought the bike and stored the stock airbox. I installed a K&N high-flow air filter. I came with filter oil which I applied as per the directions.

3- The exhaust is stock and has no corrosion or dents. The bike is in extraordinary condition.

4- The exhaust system is stock and has no corrosion or dents. I'm having trouble uploading pictures.

Yeah, you have to drill through those plugs and pry them out. No biggie.
Sounds like you need to do the basic carb tuning, idle screws set and carb synchronization. Clear away those possibilities.
Sometimes that WOT issue is fuel starvation. Caused by carb float level, or fuel line restriction, bent hose, faulty petcock, clogged petcock screen. Sometimes old gas tanks have some debris in them, like all of them. That will show up in the bottom of the carb bowls and petcock screen. A bit can clog the jets.
The PO may have left the old jets uncleaned. Just a ridge of encrustation inside the orifice will cause trouble. Have to check that with a strong magnifier, and clean it with a guitar string.