Jetting/tuning question

[BassCliff]

Going to try and figure out how to test fuel level as I still think my floats (even though set about a mm higher for more fuel) might be off some, as I'm Still lean down low.

Hi,



You can make your own "wet" level tester by drilling out a drain bolt and attaching a clear tube.


Thank you for your indulgence,

BassCliff

[BassCliff]

Hi Mr. singletrack,

It sounds like you're getting closer every time. Keep up the good work, a little tweak here, a little tweak there.

Only thing is she's popping like hell on decel. I've got a colortune coming so I'll see if that can help.

For the popping on deceleration, you can try turning out the idle mixture screws another 1/8th of a turn (at a time) and see if it goes away.

(On the air screws, once I get a couple of turns out it doesn't seem to make much of a difference on rpm's.)

You can also start with your screws about three turns out and twist them in until you hear the idle just start to fall. Then turn them out 1/8th turn from there. More notes HERE.


Thank you for your indulgence,

BassCliff

[singletrack]

Basscliff, you rock man. Thanks for the tips! Didn't get any more tweaking in today, was out riding the GS750 (yeah!) It was in the high 50's F for the first time in a while. I did check out the headers, Nic, seemed tight. I ran the 1100 for a little while this AM, it wasn't really popping until the engine warmed up, then it was pretty loud with the burbling. Back to idle mix, I guess. More to come!

[niclpnut]

Reference the thread I started about the pilot air jet...


Sounds like you are exactly where I am right now.

Might need to go back to the larger pilot air jets for whatever reason...

http://www.thegsresources.com/_forum/showthread.php?t=173919

[posplayr]

Basscliff, you rock man. Thanks for the tips! Didn't get any more tweaking in today, was out riding the GS750 (yeah!) It was in the high 50's F for the first time in a while. I did check out the headers, Nic, seemed tight. I ran the 1100 for a little while this AM, it wasn't really popping until the engine warmed up, then it was pretty loud with the burbling. Back to idle mix, I guess. More to come!

Popping can be too lean or too rich

http://www.allthingsmoto.com/forums/f-13/deceleration-popping-explained-10/

But mixtures get richer as the bike heats up (more heat expands the air and richens the mixture) So if it popped more when hot it is too rich. Turn in the idle mixture screws.

[rapidray]

Here is one for you: since you said you installed DYNOJET needles, did you drill the slide holes? Ray.

[Guest]

I think your too rich on the needle. Put it back up two notches.
Put the stock pilot air jet back in.
Set the idle mixture screw with the highest rpm method and ride.
Also you do have to drill the slides as Ray suggests.

[Katarat]

For the wet float level check take the carbs to a hardware store and get a threaded plastic nipple thats as close to the drain plug size as possable. You can screw the plastic nipple into the drain hole and it will seal even though the threads are wrong and it wont hurt the threads. Attach a piece of clear plastic hose to the nipple and plastic tie it vertical, turn the fuel on and check the level. I hope that makes sense , its the best I can explain it

[singletrack]

Here is one for you: since you said you installed DYNOJET needles, did you drill the slide holes? Ray.

Yes, I did drill the slides. Scariest thing I've done on a motorcycle yet!

I think your too rich on the needle. Put it back up two notches.
Put the stock pilot air jet back in.
Set the idle mixture screw with the highest rpm method and ride.
Also you do have to drill the slides as Ray suggests.

The "stock" air jets were Mikuni 160's. Someone had messed with the jets before me. I didn't realize air jets were equal sized between Mikuni and DJ, so putting in DJ 160's did nothing. Should I go back to 170's? That is stock.

I did try turning in the air screws a bit today as Basscliff suggested, they were around 2 turns out afterward. Didn't seem to affect the popping.

about lowering the needle 2 notches. That would put it on the 2nd notch, it barely ran off idle at the third notch, seemed to be a lean condition at 3rd. What am I missing?

I appreciate the assistance!

[ironsheik]

How did you end up making out? I'm currently in a slightly better but similar situation with my 83 gs1100ed. Mine will pop and gurgle a bit at 1/8-1/4 throttle and on decel (when warmer I think). I've got a Yoshi 4-1, K&N filter in the stock box, 120 mains, needles on the 4th clip and everything else stock (45 pilots, stock air jets) and about 3 turns out.

I think I need to tighten the mixture screws just a bit. Plug chops show a perfect ring of gray/black on the ring at 1/8, 1/2 and WOT but a bit too much heat as the ground strap color changes too close to the ring. It will ping once or twice if I open it up under 2.5k rpm in 3rd, sometimes in 2nd. Maybe I need to retard the timing a hair...

There are so many carb threads that end right when it seems like a solution is at hand! Don't leave us hanging anymore!

[singletrack]

Sorry, never did post the final resolution. It still isn't perfect, but here's what I ended up at:

dynojet needles (DNT406) 4th clip from top
Mikuni 117.5 mains
Mikuni 47.5 pilot jets
Dynojet 160 air jet (DH160)

mixture screws are out 3.5-4 turns. My popping on decel was from a too lean setting on the mix screws, and I also found some small exhaust leaks around where the tail pipes slip on the headers, sealed that with RTV silicone

The minor issue I had was a bit too rich on the needle jet, my next step was to shim so needle was between 3rd and 4th clip, but I never got around to doing it. I was having too much fun riding the bike to break it down

[AJ]

I'm printing this thread, as it describes well what my bike is doing (exactly what Singletrack described in his original post).

As for air-jet and richness/leanness.... The air jet controls the airflow directly over the fuel jet to aspirate the fuel. In other words, it is dragging VERY dense fuel vapor up to the three holes at the top of the carb, where it mixes with air coming down the main throat of the carb. A smaller air jet results in less fuel being drawn from the jet, hence, a leaner overall mixture. The "mixture" screw controls how much of this very dense fuel vapor comes out the small hole at the top of the throat nearest the engine. Thus it makes sense that you'd need your mixture screw out further than normal if the smaller air jet is installed.

[singletrack]

Hey Ajay, thanks for the explanation on the airjet, guess I had it backwards. Good luck with your tuning!

[ironsheik]

So I've got my similar 83 1100ed with a Yosh 4-1, stock airbox with K&N currently most successfully running 117.5 mains, needle at 4th clip, 47.5 pilots, and the stock 180 airjet. It pops a bit on decel but I haven't set the mixture screws yet. They're at 3 turns now. There is the slightest dip around 4-4.5k running WOT from 3k to redline but it pulls the strongest from 5-9k. I'm definitely not rich.

My plugs seem to always look the same with full turn of dark around the ring, white insulators and a light gray tip. It was definitely too lean with the clips on the 3rd ring. If you get it running any better, let us know! I'm going to do some 1/4-1/2 throttle plug chops this week and see what the needle is doing...

[TheCafeKid]

Not to bust your balls fellas, the lot of ya with tuning troubles, but why are you using Mikuni jets?? Those dynojet kits are nearly plug and play. You're making it harder than it needs to be.

Here's the deal. Put your stock pilot back in. Those kits, needles and jets are designed around stock pilot jets. Using a larger jet will not only make tuning harder, but your fuel mileage will suffer dramatically. You realistically spend most of your time on the pilot or pilot needle transition circuit.
Also, the pilot is fed through a port in the emulsion shaft that is in turn fed by the main. If your main jet is too small, your pilot will starve. Which is why the MAIN must be right before tuning any other circuit. You tune these carbs from the main back. First the main, then the needle then the pilot. A stock pilot should have no problems with your set up so long as the correct main jet is being used. Dynojets jets aren't junky. They're just measured differently. One company bases it on gauge, the other on fuel flow or something.
For your set up, you really need to probably be running the smaller of the stage3 kit, or the larger of the stage one kit (there should ve four mains in a stage three kit)

I used a complete kit with my 1100ES in both the stock carbs and then later in 36mm 1150 carbs and the only thing that needed changed was the needle position.
And on the air jet, a smaller jet leaning it out doesn't sound right, he must be mistaken. I didn't use it on the stock carbs but did on the larger 1150 because it was a little wetter than I liked down low.

Popping can be a symptom of both being too lean, or too rich, or simply an exhaust leak.