DJ Stage 3 Jet Kit on GS850G - Removal of "float bowl vent tubes"???

[Darin Jordan]

I'm working through the process of idealizing (re: Making Mo-Betta!!) the Stage 3 jetting installation on my GS850G, and in the section 7 of the DJ instructions (7. Engine accelerates until the midrange then pauses, stumbles, or shuts down....), one of the steps says to "Verify the float bowl vent tubes are removed".

I'm assuming that these are the hoses connecting to the T-Fittings between carbs 1&2, and carbs 3&4??

Has anyone else had to do this?

WHY would I need to do this??

Thanks,

 

[salty_monk]

Yes, that's the ones. I've done it on a couple of bikes. I don't know the scientific reason for it... just that it works.

 

[Darin Jordan]

Yes, that's the ones. I've done it on a couple of bikes. I don't know the scientific reason for it... just that it works.

Interesting... So we just take them off completely? Hmmm... OK, I can do that. Did that alone seem to help, or did you have to alter the needle/jetting beyond that?? I wonder if just upping the tubing size would work, so that it would still protect the fittings from getting dirt/dust in them??

 

[mike_of_bbg]

I had a theory about this phenomenon (not that I really have any experience to know). The vent tubes are your atmospheric reference - the venturis in the carbs "suck" fuel up out of the bowls because their relative pressure is lower. Relative to what? Whatever the pressure is at the ends of those tubes. So the ends of those tubes need to be kept free from turbulence; in my case tucked behind the side covers under the seat. When I've had them elsewhere cross-breezes say when passing trucks could severely hamper performance.

If you're running pods there isn't that big airbox to help keep the air in that area calm and turbulence-free. The next best area is right there behind the head - protected on the sides by the carbs. Which is where the vents happen to be anyway if you just take the tubes off. There really isn't any flow through them per se - just a pressure tap.

Then again I could be full of it.

 

[Darin Jordan]

Wow... 2 thumbs up for DynoJet tech service... Left a messege about an hour ago, and they just called me right back.

He said to remove the tubes and turn the T-fittings straight down "to keep dirt from getting into them".

The idea being excactly what Mike was describing, to keep any presurization or turbulence from entering the float bowls.

He also suggested that, if this doesn't work, to remove the air pods and see if it runs better... They could be "over-oiled". I only lightly sprayed them with K&N Filter oil, so I don't think that's an issue.

Will have to give it a try when it stops RAINING here...

 

[Guest]

I have the same setup as you except my 850 is an 82 model.
I run the hoses pointing towards the battery area.

 

[Darin Jordan]

Tried it tonight with the hoses removed and it actually seemed to make it worse. Starts in at around 6000 or so now, sometimes even 5500.

Was told by DJ to try removing the airpods and run it that way next. Seems to happen, above the noted RPMs, and it seems to happen with throttle from 1/2 to full... almost regardless of where in this range it happens. In other words, if I rev it to 5500 by smoothly opening the throttle it happens... if I crack the throttle wide open, it pulls to 5500, then it happens...

Might go run out and try it without the air pods on and see what changes. Next step, according to DJ, is to lower the needle and decrease the main-jet.

 

[Ranger]

Tried it tonight with the hoses removed and it actually seemed to make it worse. Starts in at around 6000 or so now, sometimes even 5500.

Was told by DJ to try removing the airpods and run it that way next. Seems to happen, above the noted RPMs, and it seems to happen with throttle from 1/2 to full... almost regardless of where in this range it happens. In other words, if I rev it to 5500 by smoothly opening the throttle it happens... if I crack the throttle wide open, it pulls to 5500, then it happens...

Might go run out and try it without the air pods on and see what changes. Next step, according to DJ, is to lower the needle and decrease the main-jet.

Warm it up, then go from idle to WOT and see if you have any unburnt fuel blowing by out of your exhaust.

Have a fire extinguisher on hand.

 

[Darin Jordan]

OK, here's the skinny....

Took off the air pods and warmed it up. Trying to rev it on the stand without the airpods and it stumbles and bogs right off the bat. Slid the air pods back on and it revs up pretty well... slight hesitation on initial opening but zips right up to redline. Unloaded, of course.

No raw fuel to be seen... It appears to be burning what it's getting.

Is it possible that it still too lean??

 

[Ranger]

Weird.


I don't feel well enough to think hard right now. If it comes to me then I'll chime in but I'm sure someone will beat me.

 

[Darin Jordan]

On a positive note, the rebuild of the rebuilt fuel-petcock seems to be working perfectly! Woke up this morning and no garage filled with gas fumes! A good sign...

 

[Darin Jordan]

Talked to DJ again today. They are a little baffled as well.

I'm suppose to tape off half of the air pod on each carb, and try it again. If the problem gets better, then something is making it too lean.

I'm suppose to check the fuel level in the float bowls and fuel delivery as well, though I have already done this and they appear to be fine. Will work on checking the actual fuel level with some fuel tubing in the drain holes, if I can figure out where to get fittings for this.

Also suppose to measure the main air corrector... should be .042". The tech said it is unlikely, but possible, they packaged the wrong size, and even a .044" would be too big...

If everything checks out, then I guess the next step is to go even larger main.

I purchased this kit from Dennis Kirk, so it should be the real-deal, according to DJ.

I'll keep tinkering. As usual, any advice would be welcomed.

Thanks,

 

[Dave8338]

Try and cut a few circles out of some Scotch Brite pads, large enough to fit through the pods when folded but too large to be pulled back through and into the carbs in a WOT situation. Mist them with a light spritz of your K&N oil and I'll bet the problem goes away... :-\\\

 

[Darin Jordan]

Try and cut a few circles out of some Scotch Brite pads, large enough to fit through the pods when folded but too large to be pulled back through and into the carbs in a WOT situation. Mist them with a light spritz of your K&N oil and I'll bet the problem goes away... :-\\\

Dave, would this not indicate that the system is still too lean, however?? I do plan on testing it with the airflow restricted to see how it goes, but it seems to me that if you have to restrict airflow to make up for it, it's too lean and richer mains would correct it.

UNLESS, it's a turbulance issue. I wonder if putting the factory air cleaner rubber "stacks" on inside the K&Ns would help direct the airflow better?? Hmmmm.... :-k I have a brand new, unopened set of them...

 

[Guest]

Don't sound like a main jet issue. I'd leave it be for now.
Did you use the correct bit to drill the slides?
New pilot jet plugs?

Ya also have to glue something(don't know what its called).
Did ya glue anything anywhere? Its a little air restrictor located on the same side of the carbs as the air jet.
Someone is bound to know the correct terminology for this little task.

Edit. Looked at my instructions.
DJ is calling it a "main air jet passage" and the part your supposed to clue in there is called a "air corrector".
Shoulda came with the kit.

 

[Darin Jordan]

Don't sound like a main jet issue. I'd leave it be for now.
Did you use the correct bit to drill the slides?
New pilot jet plugs?

Ya also have to glue something(don't know what its called).
Did ya glue anything anywhere? Its a little air restrictor located on the same side of the carbs as the air jet.
Someone is bound to know the correct terminology for this little task.

Edit. Looked at my instructions.
DJ is calling it a "main air jet passage" and the part your supposed to clue in there is called a "air corrector".
Shoulda came with the kit.

Tech called them the air jets, but either way, YES, they are there, and are in the right place, and are glued in. I'm suppose to use some pin guages and measure them to make sure they are the correct .042" size, however... they are whatever came in the kit.

And yes, the slides were drilled with the correct bit... 7/64"...

Yes to new pilot jet plugs, gaskets, o-rings, intakes, etc.

No to new floats, needle, or seats, which are all original OEM parts and looked and functioned fine.

 

[blowerbike]

my experience with DJ is...
you have to have 100% stock/perfect working order carbs and then install the kit 100% as they tell you.
no variance unless your at a high altitude or such.
i used to install these kits before these bikes became 25 years old and the carbs started deteriorating/people changing parts/levels ect.. and i had zero problems with there kits.
all the bikes i did had the airbox still installed and had not been touched as far as changes being made.
triple check everything and i mean everything.
run the bike off of a fuel cell if your tank/vent/valve is in question.
DO NOT USE EMGO FILTERS.
your bike should run the same with filters on as with filters off.

 

[Guest]

Tech called them the air jets, but either way, YES, they are there, and are in the right place, and are glued in. I'm suppose to use some pin guages and measure them to make sure they are the correct .042" size, however... they are whatever came in the kit.

And yes, the slides were drilled with the correct bit... 7/64"...

Yes to new pilot jet plugs, gaskets, o-rings, intakes, etc.

No to new floats, needle, or seats, which are all original OEM parts and looked and functioned fine.

I dont get it. MIne was dang near plug and play. I did move the clips around a time or two but it was never so far off that it wouldnt run good.
How do the plugs look? Might not hurt to put in a new(NEW) set.

Forgive me if I missed it but you did go through the carbs 10000% right?
Anything you couldnt get apart? Did ya soak the bodys for a day in Berrymans carb dip?

 

[Darin Jordan]

How do the plugs look? Might not hurt to put in a new(NEW) set.

I'll do that just for drill. After the last ride, the plugs were a little black around the outside, and just a light hint of brown on the electrodes... Not as brown as I'd like to see.

Forgive me if I missed it but you did go through the carbs 10000% right?
Anything you couldnt get apart? Did ya soak the bodys for a day in Berrymans carb dip?

I had everything apart, soaked, blown out, dried, and all put together new, with the exception fo the needle and seat, floats, and slides. All gaskets and o-rings are new. Chokes are original parts. Mixture screws turn freely and are not broken at the tips.

 

[Darin Jordan]

Seems my trouble-shooting has migrated to this new thread, so I'll update here...

OK, last night I tinkered and started going back over things....

Main Air Correctors measured out to the appropriate .042" and are all in place.

Air Jet (Jet on left side of carb inlet) were re-verified to be 180s, which I believe is stock.

Did the WD-40 test around the new intake boots... no leaks found.

Removed fuel-line and did a petcock fuel flow test. Fuel seems to be flowing well, with what appears to be normal volume.

Per the DJ tech, removed the air-pods... on the stand, if you go from warmed up idle to WOT, it will stumble at around 2,000, carb slides will flutter up a bit, and then it seems to get past it and revs up.

If I put some wide masking tape across 1/3 or so of the carb inlets, there is no stumble or flutter and it just revs up.

Put airpods back on with approximately 1/2 of the filter taped up and rode it down the road. Was wet outside, so I could really get on it, but it still appeared to have the stumble around 5500 or so.

Removed the plugs and they look like this:

Cleaned up the plugs. They cleaned right up with minimal work. Underneath the little bit of idle residue on them, they look lean to me. If it was too rich, I'd expect to see way more color.

NEXT steps are to verify the actual fuel level in the floats. Hopefully I'll have some clear fuel line today to make that happen.

If all that checks out, I'm not sure which direction to go.

Other things to check are going to be the valve lash, and the Ignition timing. Found the valve lash tutorial. Done lots of those on Japanese and British cars, so it doesn't look like a problem to do. From looking at the screw heads, it appears the Cam covers have been off this bike before, so we'll have to see what we find when I get in there.

Is there an ignition timing tutorial around here somewhere? I couldn't find it on BassCliff's site. (however, it's 4:00am right now, so it's possible I just missed it... )

Not giving up yet, though I did drag out the stock airbox, just in case... It's kind of a mess and I REALLY don't want to have to use it.

I'll get this figured out eventually.