Not enough gas????

[gsryder]

Okay so I have been doing a little fine tuning on the 81 GS750 after finishing all my cafe mods to the frame, removing side panels and such.

It was running great last year and the plugs were a perfect light brown cinnamon color with cheap emgo pods and a Kerker 4 into one.

After removing all the body panels I replaced the old emgo's with new emgo's but now she is running real lean.

Did I change the air flow by removing the side panels?

Last year I was running:
stock pilots
132 mains
needle shimmed up about 30 thousands

Now I have:
Stock pilots
190 mains
needle shimmed up 100 thousands

The bike runs strong and pulls hard down low but when I get on the express way and really lay into it the top end falls off like I have a rev limiter by the time I hit 4th gear WOT it will start to sputter cough and die.
If a deaccelerate and wait about 30 seconds or so let the clutch out while coasting it will fire right back up and run strong again.
Check the plugs and they are way lean!

I think I am sucking the float bowls dry?????????

I pulled the petcock off double checked everything screen and diaphragm every thing is clean and operating properly.

New gas and vaccum hoses on the carbs, no vaccum leaks, and the carbs have been throughly cleaned and synced.

It ran good last year and earlier this year just after removing the side panels and changing the pods it went real lean.

Has anyone ever come across anything like this am I missing something.

Sorry for the long post just trying to all the info out there

[Mark Harrop]

I don't think just swapping pods would cause the condition you described. I replaced the side panels on my 82 750 with homemade aluminum and ran it for a while without them and had no changes...

Sounds like there is something else going on...did you mess with the float levels?

[gsryder]

No float levels and everything else are the same, the pods I had on there last year were a little to small I think they were 48 or 50 mm I dont remember I just remember they were real tight to put on.
This year I bought the right size 54mm and they fit right on like a glove. Maybe the smaller ones I had on last year were a little restrictive. The filter / pod section is the same size just the rubber boot that mounts to the carb is a little bigger, probably flows a little better.

Either way is any one running 190 mains in a stock 1981 750.
The only mods are the pods and the 4 into 1 kerker.

190 seems big to me but is drinking the fuel like its a hot summer day.

[skidMarkNZ]

132 and it wasnt running right and you only put slightly more free flowing pod filters by the sounds of it, but that doesn't justify 190...

that a hell load of fuel, you are sure its lean and you arn't flooding it, only thing i can figure is as you say the 190's are so big that its sucking the bowls dry...

go back to like a 135 jet or something... 190 is ridiculous, im suprised it runs at all to be honest... thats silly rich.

Why did you goto 190's??? did you do this after the sidecover removal and pod filter change? ie... did you have problems with new pods then changed jets to try and fix it? or have you just messed with the jets for the sake of it.... from what i have read some people going with bigger main jets go with softer springs on thier slides...

Hope something in this helps...

I'm off to bed lol

Skid.

[rapidray]

WAAAAYYYY too much main jet!! Who told you to go from a 132 to a 190? Ray.

[gsryder]

Nobody told me.
After changing the pods it was falling on its face on the top end and sputtering big time could barley ride it. Checked the plugs and they went way lean.

Put new plugs in just for good measure stock recommended NGKs (I forget the number)

So i tried 140s better response didnt fall off quit as quick still lean.

went to 150s same thing little better still falling off but later on

170s now pulling hards as hell all the way through but on the expressway it was I believe sucking the bowls dry. Still way lean absolute white plugs

190 is the largest jet they sell for the Mikuni at my local speed shop so I figured I would give them a try.

Put them in same problem runs great but still way lean.

I raised the needles up by putting the yellow plastic spacer on the stock needles from on top of the clip to under the clip with the washer 100 thousand ( I know crazy big) it should foul right out right? Nope.

On the bottom end it is running great it will pull the front wheel up 8 to 10 inches just cracking the throttle no clutch. It has never done that before.

I know it sounds crazy but I think those pods are just like running straight velocity stacks very little to no restriction.

I even tried putting gym socks over the pods to much restriction wouldnt run right.

So I went and bought some knee high panty hose put two layers on each pod with not much effect.

I dont know it is running strong with the 190s but very lean and sucks the float bowls dry I dont think I would make it down a quarter mile before it runs out of gas.

[rapidray]

Next thing then is a Pingel petcock! Ray.

[gearhead13]

Well, something is wrong, I am running a 137.5 main on a more hopped up engine and my plugs are a nice tan color.
How do you know your main is lean if it wont run at wot?
It is likely the pilot jet, float level or something else making your plugs white

[rapidray]

That's what I believe too! Ray.

[gsryder]

Thats what I was thinking especially after I raised the needle and the bottom end got better.

I think I will try going with a 45 pilot

I have another question though on the pingel style pet cock.

What do you do with the vacuum line just plug it off?

Also with the pingel style just on/off will the floats keep it from dumping to much fuel in? For example when I shut the bike off do I have to shut the pet cock off or will the floats stop the flow when they are full?

[tejasmud]

Ah.... ha!

Here is the rest of the story....

See response in Pingel Petcock thread...

Too big of main jets. I'd say...

#190s Waaaaaa.....

Go back to #132s and shim to .030"

May want to bump the pilots up one, but never know..

You do oil your filters? Right?

Yes, the vacuum just plug it off, but always turn the gas off too.

If you forget to turn the gas off.

Metal float valve needles will usually leak, elastomer/rubber valves will seal, but you must keep tabs on them. If the indentation of the rubber gets too deep. Replace.

Anyway, go back to what you were running. Seemed like it was a good set-up for where you are.

[skidMarkNZ]

I dunno you shouldn't need 190's...

I would really really really hate to have that kind of fuel consumption....you only have pods and an exhaust and you are running another 3/4's fuel over the stock mixture, and this sounds crazy to everybody except you.

[gsryder]

I never said it didnt sound crazy.

In fact I am having a hard time believing it if it wasnt for having the plugs in my hand.

I dont doubt that the 190s are to big but the 132s are definitely way to small.

With the 132s it wouldnt run for shizz, it would just fall on its face 150s got better 170s pulled strong 190s and my azz was sliding back on my seat.

It doesnt make any sense.

What kind of filters are you guys running that are in the 130ish range.

The only thing I can think of is that these filters are flowing free as can be,
and no I did not oil them they are the cheep Emgo filter paper / fiber stuff.

I could be wrong but I dont think they you can clean them like the K&Ns.

[tejasmud]

The EMGO pod style filters have a gauze material as the element, oiling doesn't hurt the air flow if done correctly. I oil mine with no issues, and just wash them out as needed. Not sure the micron rating, but I tend to like something to catch some of the dust particals.

I assume you are running the CV stock carbs.

Here is a theory or thoughts....

You switched to the 54mm EMGO filters from the 48-50mm ones. If you still have the old ones, check the "stop lip" just inside the filter. On the 54mm filter that "stop lip" reduces down to about 40-41mm from eyeballing it, this is where it slides onto the carb. It looks like it will interfere with the air jets at the inlet of the carbs. On the 32mm CVs I pulled off the 700E the air jets are right up on the face of the inlet of the carbs.

Possibly the tighter fit on the old ones help distort or pull this "stop lip" away from the air jets, thus things worked well.

Less flow thru the air jets would require the main bore of the carb to struggle in pulling fuel through the jets, thus the larger jets helped.

Anyway, just some thoughts.

Eric

[gsryder]

tejasmud - I believe you are correct I was looking at them last night and the ones I had on last year were definitely interfering with the air flow.

I have made some other adjustments last night but it has been raining in Ohio for the last couple days it is supposed to be nice out the rest of the week.
Here is what I have done now

New pods (I am going to try oiling them a little)
stock pilots (42.5) I have 45s on order but dont have them yet
190 mains (I know that should be way to big)
I am going to reset the air fuel screws again

Then I am just going to run it for a couple days and see what happens.

I dont disagree with any of the comments posted and everything that everyone has been saying makes perfect logical sense........but when I am on the bike and behaves
the way I have described and the plugs are porcelain white....
I dont know.....big sigh.........