Jets, jets, more jets.

[loudest143]

1982 850g. 4 into 1 header, Muzzy cannister. Emgo pods.

Current setup:

stock pilot 40.

stock needle, one shim.

main jet 120.

float height 22mm.

2 1/2 turns out on air/fuel screw.

I've been backwards and forwards on this beast. So I'm politely asking for assistance. I've had 122 mains in, got a nice caramel colored plug, but it wasn't worth a crap in the mid range. Had to go to 1/2 turn on the air/fuel screw to get it close. I felt that was wayy to much main jet if I had to twist in the air/fuel that far. I believe I was stock needle setup at that point.

I went down to a 117 main, and it was straight up awful all the way through. Had the air/fuel screw out to 5 turns at one point! Yeah, too lean, by alot. Carbs were sneezing and coughing alot.

I went to the 120 main, and my plugs look closer to that brown color we like so much. Here's where it's kicking my butt.... I'm at one shim on the needle right now, and it's still not pulling well in the 3-4k rpm range. Acts and sounds like it's starving. I'm at a loss here. If I go with no shims, that seems WRONG to me.

So here's my question, fine panel.... Go back to the 122s and start over with stock needle setup and see if I can get it closer, or do I just need a good aftermarket needle? The stock needle does not have the movable circlip like the aftermarket one would. I'm feeling like I just don't have enough room to work with. But what do I know?

I feel like I've overlooked something. For reference, it was running fine with a stock setup, and yes, I recently did a valve job PRIOR to adding the pods and exhaust. I also went back and checked them AFTER I added the exhaust, when I first started tuning the carbs, to make sure I didn't miss something in there. Good compression, too.

Please don't slag me too hard for my choice in setups. I don't mind the challenge, I would just like to move on to other more important repairs.

Thank you in advance,

loudest143
Columbus, Ohio

 

[Guest]

Get the Dynojet kit with the pods.

 

[Nessism]

What did you do to shim the needle "one washer"?

 

[loudest143]

I realized I didn't include that bit of information...... I removed the stock plastic washer. I then replaced it with metal washers, (above the circlip) and have it now at just one metal 'shim' above the circlip. Yes the stock metal washer is below the metal circlip to hold the spring in place.

 

[Nessism]

I realized I didn't include that bit of information...... I removed the stock plastic washer. I then replaced it with metal washers, (above the circlip) and have it now at just one metal 'shim' above the circlip. Yes the stock metal washer is below the metal circlip to hold the spring in place.

Okay, good. Sounds like you understand what you're doing (not that there was ever any doubt mind you).

I've heard that the more tapered Dynojet needle is the one part you can't replicate when rejetting on your own. I have no real experience so please talk to chef.

 

[Guest]

If you want to try to jet w/out the DJ kit I'd start with the main. Jet the main to have the best accel up to redline. If it struggles when cold and get's better when hot it's too lean. If it's good when cold and struggles when hot it's too rich. Do plug chops.
When you get the main dialed in the needle will be easier to manage.
I'd also go up one on the pilot jet and do the highest rpm for each idle mixture screw at idle.
With the stock needle you will have a hard time losing a "stumble" at midrange.
Remember you want a good tan color on the spark plug and you don't want more than 2.5 threads of color on the plug threads.

 

[loudest143]

Yeah, plugs are still too white at this point with the 120. Now, I could go up one on the pilot, and even though that doesn't affect the plug color, (that much)it might help smooth out the "transistion' between the needle and the pilot, which is right about where she gets ****ed off. I'm guessing, by the looks of the pictures of the DJ needles, they are MUCH more tapered the the 'tree trunk' needle jet that comes stock. Very straight, solid, with very little taper to a hard conical point. I see what it's NOT doing, by being that shape.

It does, IMHO, pull fine up to the redline. It's really hard to get a good judge of that, as currently I don't have lots of space to ride in.... My test track is only as long as a football stadium. (literally. I've got her at work!) I have tried a much larger pilot jet and that was a disaster. I'll look into getting the next size up pilot jet. Should be easily sourced locally. Some place to start, I guess.

 

[loudest143]

Well here's where I stand now. Besides missing out on a beautiful sunny day, the first of the season, The bike is still not where it should be.

122 main jet (115 stock)
needle shimmed at two washers, that's half of the stock plastic washer.
42 pilot jet (40 stock)
float height 23mm (22mm stock)

Emgo pods, V&H header and Muzzy cannister.

Carbs were bench synced again, I used the high rpm method for fuel/air mixture screw.

When cold, it starts with the choke, which it didn't before I adjusted float height. Plugs are whitish brown in color. (which is good)

Bike revs great throughout the rpm range on the stand.

As soon as I get out and ride, the bike begins to 'growl' through the carbs, and not in a good way. Power loss, and it slowly increases speed. I've been through every possible combination of jets and needle height, trying to cure this issue. So there's something I'm missing. Here are my questions for the learned panel.

Could valve shims have something to do with this power loss? They could be off. I did replace some of them prior to my carb tuning marathon. I believe they are correct, but I don't want to leave this out of the conversation. I did gap them, and replaced ones that were not up to spec. Maybe I didn't get that right. I felt good with my measurements, but it's possible, I guess.

My exhaust is pretty much straight through with a silencer. The Muzzy cannister and the V&H header combination are pretty good, IMHO. New header gaskets were installed, and all bolts were torqued to spec. Even if there was a SMALL exhaust leak, I shouldn't have this kind of power loss, IMHO.

Coils? I'm not thinking this could be an issue, but I am running Accel coils. Don't kill me because I'm cheap.

Ignition? I do have stock ignition, and maybe it's going bad? I wouldn't think this would be an issue either, or it would be failing when the bike is on the stand, too, wouldn't it?

Do I need to go up on my float height another mm? Maybe it's too much fuel....

I'd love to hear what everyone has to say about this issue. I'm really exhausted all my options at this point.

Thanks in advance.

loudest143

 

[Guest]

I chased my tail with the jetting war once with a bad ignition.

 

[loudest143]

I've got to start somewhere, so it might as well be with the ignition... Chef, what were the symptoms you experienced when yours went bad?

 

[Guest]

When I started doing minor mods and going up on the jetting I couldn't seem to get the jetting straight. Power was an issue and the plug readings were not consistent.
When I went with a Dyna-S and Dyna green coils that equation was solved and I could depend on plug readings and power. I should of read the plugs closer because I blew two top ends with lean conditions. Trying to jet for speed instead of doing it right reading the heat range and color on the plugs.

 

[blowerbike]

loose the emgo pods!!!
you will thank me later.
also,
st.3 jet kit is a must to get it spot on.

 

[Steve]

Your original settings were what I am using on #2 son's bike (except for shimming the needle). It has stock airbox and a 4-into-1 of unknown origin, with a good, quiet baffle. I would suspect that with your setup, that would be far too lean.

As you are changing things, please remember to change just one thing at a time. If you change more than that, you won't really know which one helped. In fact, it's possible that you won't see any change if the two things offset each other.

Also remember, when changing float levels, the float is upside down, so setting it to a larger reading is actually lowering the floats for leaner settings. Since the specs call for 22.4 mm, you are still in range, but a single mm can make a big difference.

I don't think valve adjustment would have any affect on what you are experiencing, but it does not take long to check and verify. Feel free to take advantage of the offer at the end of my sig.

.

 

[loudest143]

Chef, I too, had a top end problem late last year, snapped a bolt on a cam cap. That was an adventure. Replaced the head, and it ran great, like before the mishap. This is one of my concerns for future sucsse in tuning this thing right. I'd like to avoid more fun things like that.

Steve, are you referring to my settings of 122main, 42 pilot jet? Maybe you can give me a Y or N on that one. My reasoning for adjusting the needle was twofold. EVERYONE says the stock setup is lean to begin with, (in the needle circuit) and my problems have been above 2500rpm.

After further thought, here's the rub.... My problem has been consistantly in the mid range area. It's been suggested that only an aftermarket needle setup will give me the right responses in the midrange.... But what if it IS the ignition? The bike pulls fine on the stand, but under load, while riding, it's bogging down in the middle part of the rev range... Could that be spark advance not 'advancing' properly? It could be, couldn't it?

I'm going to start with going back to the stock pilot jet first. I know that could possibly be causing issue if the main jet gives me enough fuel already. I'm very interested to see if that will solve anything.

Blowerbike... I would love to have K&Ns, but I can't afford them just yet. Knowing that I may have to rejet with those free flow filters is not something I'm interested in at this time, either. I'm having way too much fun as it is.

 

[Steve]

Steve, are you referring to my settings of 122main, 42 pilot jet? Maybe you can give me a Y or N on that one. My reasoning for adjusting the needle was twofold. EVERYONE says the stock setup is lean to begin with, (in the needle circuit) and my problems have been above 2500rpm.

No, in your first post, you said you had 120 / 40 / shim / 2.5 turns.

Except for the shim, that's what I have.

Have you done proper plug chops? They will help immensely. Make sure you can remove your spark plugs easily enough (no gorilla-torque), mark your throttle grip, intall some new plugs, go for a ride.

Here is how to mark your throttle:

BassCliff has the procedure on his website, but basically, you will ride as long as practical with the throttle at a set position. At the lowest setting, it will take a couple of minutes to get some color, so find a back road where you can putt along at 20-30 mph in third or fourth gear, holding that 1/8 throttle setting. Find someplace to pull over, pull the plugs and read the color. Record your findings, because there's more to do. Move to the next setting, 1/4 throttle. Fifth gear, probably about the same route you just did will work. Engine speed is not important, it's throttle opening. Just remember to hit the kill switch and pull the clutch, roll to a stop, then pull the plugs. Idling for just a few seconds after a run can contaminate the reading. The 1/2 and full throttle opening tests will work quicker, fortunately. For the 1/2 throttle test, if you have a mild hill, it works great. Full throttle is easy. Just blast it, wide open. Shift as necessary. It only takes a few seconds to get the proper color on the plugs, which is good, because it only takes a few seconds to get going REALLY FAST.

Hearing that all of your problems are above 2500 rpm doesn't mean much. Was that full-throttle in fifth gear or 1/4 throttle in second gear? Different circuits in the carbs in use, different solutions. Doing plug chops will tell the story.

.

 

[loudest143]

Steve, look at you with the super sweet picture! Thanks for that, I will be using that very soon.

I've looked through all the information here, and had the opportunity to speak to a machinist/mechanic of local noteriety as well. He used to be a factory mechanic for KTM, and has built everything possible, and knew my bike, and its' factory spec of the top of his head. Yeah, this guy is worth listening to.

He explained a bit more about using pods, and what happens when you do.... I thought I would share, as it was important information....

The stock airbox reduces air turbulence around the carb intake area. With the pods, there is a large reduction in 'calm' air entering the carbs. He commented that the stock airbox was well engineered, and explained that it settles the air before it enters the carbs. He said you could reposition your legs to block off airflow to the two outside carbs and actually notice a difference. (I may try that out for fun.)

Anyways, he pointed to the needles, and said that I would never really quite get the tuning right without replacing them with a more tapered needle, just like the Dynojet ones. (thanks to all who pointed me in that direction!)

Now, all I have to do is find a source for these needles, without having to drop down 125 bucks on a kit from Dynojet that I don't need. I just need the needles....

Another story he shared.... He built a mini sprint car with a GSXR motor. They were running top 3 in their class, when they tried an experiment that a Suzuki Racing engineer shared... He said, 'try putting Gatorade bottles on the carbs'. Cut the ends off, slide the mouth of the bottle onto the carbs, (which match perfectly) and they gained nearly 50hp! Hilarious. They tested it on a dyno beforehand..... Nobody could catch that guy after that mod.

thanks again for all the help, now it's off to find needles.

 

[Guest]

I have an 82G with open can and K&N Pods.
Went with the DJ kit, 165 main, 3rd clip with no washers, stock pilots(whatever that is) Mix screw 4-5 turns out.
The slides must be drilled to allow more air flow and that little air inlet port or whatever is has to have a little airflow restrictor glued into it(someone correct my termonology please)

Get the kit! Everything to get your bike running the best it can run is there. No kidding, you'll be amazed how worth while this kit is.

 

[loudest143]

A 165 main? That seems HUGE to me, considering the stock being a 115.... Well, what do I know. I'm clearly way off base, and I can't seem to find the jet needles by themselves anyways. *sigh*. Nothin' like waitin' on payday again.

 

[Guest]

A 165 main? That seems HUGE to me, considering the stock being a 115.... Well, what do I know. I'm clearly way off base, and I can't seem to find the jet needles by themselves anyways. *sigh*. Nothin' like waitin' on payday again.

Don't let that large number fool you. DJ jets and Mikuni jets are not the same AND there is a restrictor put in the main air jet to slow the pull of the fuel from the bowl and changes the air/fuel mix.

 

[Steve]

A 165 Dyno jet is about the same as a 155 Mikuni jet. That's still richer than I would expect, but if it works, ... :-\\\

.