Ok this MUST be a repost but i still need help like no other,

So i put a Dynojet stage III kit+pods+full VH exhaust on the GS.

But now... it runs like a raped-age, but not right off of the start line. Boggs a little/lot. In fact, more throttle i give her, the more it boggs from about idle>2500rpm. We're talking about a second of bog, not more than that.

here's what I SUSPECT is the problem: The instructions said to drill out the vacuum holes in the vacuum operated slider (whatever it's officiallys called) and put correctors in it. One corrector has a smaller hole than the original, the other corrector is solid and has no hole. Then it says one line below that "for better acceleration, take out one corrector out of each side." O.K. I was sold.... so i took out the one that was solid with no hole. thus, i have the max amount of vacuum hole possible out of the setup. This is the condition the bike is in right now... i put the mixture screws at 2.25turns vs. what they said should be at 2 turns... rich is better than lean. I THINK that the sliders are opening up too fast. The air doesn't move until the engine naturally picks up the need for the air volume. This is what my ol' man and i think anyways.

However, Dynojet thinks its the fuel mixture. I'd imagine they think it's too lean... told me to tape up 1/3 of the pod filters and go do the same thing. If it gets better, then it's lean, worse than it's rich. Well, i'm pretty sure that's not the case cause my bike isn't running bad anywhere else in the power range.

ANY HELP/OPINIONS/WHATEVER YOU'D LIKE TO INPUT!!!!!!??

no help??? i'm stupified.

Bogging off idle indicates a problem with the pilot/idle circuit, not the slides.  In my experiance it is probably still to lean off idle.

I suggest following the DynoJet directions. They do know what they are doing...

First....Does the bogging change as the bike warms up?

What is the clip position on the needle?

Have you checked your float height? Lowering the floats about 1mm which will increase the fuel level in the bowls.

OK I have one set of carbs lying in my house with the same damn issue...
OK his issue is the opposite... he's got both holes with the correctors...
This is the reason yours is falling on its face...
The drill you used was too big... yes I know DJ supplies it and yes they give you a tap as well... and plastic plugs... but a stock slide can be fixed to have 1 hole shut, by tapping it with a 4-40 machine thread and using a nylon 4-40 screw. that 10-24 they supplied it huuuuuuuge, once you take the plug off you have a monstrous hole .. 2-3 times the diamater of stock... now... flow through a orifice/pipe... is not exactly dependent on Cross section area... which will be square of the radius.. its like square or third power or some funky math of the CSA... ergo... double the hole diamater and your flow rate is now like 16 times or more... Hence... My solution ... I am going to start drilling the constrictor... start with a 1/16 drill, and maybe go 3/32's or something... Taking it out and leaving that huge hole = very bad...
Hell I a almost tempted to start offering a regular jetting service... I cant believe 2 people in the same week did the same mistake... and BTW totally idiotic on DJ's part... stoopid people. they started out having those needles so you can jet a bike wihtout taking off the carbs... and they added more and more shaZam! to it to acheive that goal... its screwed up beyond repair now.
Cool.
Srinath.

ok, so i put the extra restrictor in the other side because i thought the airflow would be too great as well. Now there's only about a 3/16" hole in one side of the slide because the adapter. It accelerates much better now in higher rpm and the stumbling is less, but still same problem with the bogging right off of idle.

I'm starting to suspect the pilot jet.

Siranth, isn't this what you told me i'd have to do... get a pilot jet as well? Tell me what size i should use and i'll do it!!!

I attempted to adjust the mixture screw to about 3.5 turns out, and now the bike won't even start without throttle assist and then it'll idle REEEAAALL low at 500rpm, but sounds really rough... obviously too rich. I think i'm going to try leaning it out to maybe 1.5 turns, then seeing what happens. If that doesn't work, i'm going to put it back where it was originally, at 2 turns like the instructions say.

BTW, general question... how much does 1/2 turn affect the fuel mixture? Should i be doing really small turns on the screws???

-lost newbie with modded bikem, AKA: jon

OK pilots... yes... however I'd rather you get this taken care off.. The bike should run quite well down at the low end even with stock pilots. Stock is 37.5, the mod I use is 40. BUt The real effect of that is quicker starts and warm up's especially in winter... like San diego really has a winter, and consistent idle rpm when hot and when cold. Just as you are trying to take off there will be a slight loss in power with the stock ones... the falling on its face deal... isn't really pilots. Upper rev range... the slides are up well above 1/2 way... so it makes little difference. You get it right down low, and it wont actually affect up high. Pilots can be added any time...
Cool.
Srinath.

Oh, to asnwer questions:

-doesn't matter what temp the bike is, same problem.

-I followed the dynojet instructions to a "T" and this is what i got. they do not include pilot jets in their kit  :dunno: maybe that's the problem?

-the clip is on the 2nd needle groove with the little washer they included that goes on top of it+the original spring washer.

I'm about 98% sure i'm doing this all right, i just think there's a problem with the power curve with the increased power.

As far as i know the fuel supply goes as followed across RPM:
               |---------------------------------|  Main jet  
   |-------------|                                       pilot jet
idle---|                                                    fuel mixture


since my bike is bogging off line, then i was suspecting the fuel mixture, but maybe it's the pilot, since that's the only thing that hasn't been changed yet according to the new airflow. Damn, this bike better run really good after this. Which reminds me... i'm going to start another thread about a story last night.

OK it is lean at idle... try a plug pull after 5 mins of idling...
Try 40 pilots... cant hurt and you are going to do it anyway... My guess is lisde too fast... BTW one hole is smaller and the other is really big right... I might do that on shay's carbs too.
Cool.
Srinath.

No, i put in the extra plug they gave me. I think it runs better like that... but not 100% sure.

I tried adjusting mixture screw to 3.5turns out and it won't hardly idle without help... couldn't even get the bike on the road to find out if that's the problem. I shouldn't have to adjust the idle speed after the rejet, right?

:x I hate screwing around with jetting. :x

Quote from: mercdude63No, i put in the extra plug they gave me. I think it runs better like that... but not 100% sure.

I tried adjusting mixture screw to 3.5turns out and it won't hardly idle without help... couldn't even get the bike on the road to find out if that's the problem. I shouldn't have to adjust the idle speed after the rejet, right?

OK if you have both the restrictors in... I think it might be raising too slow... making the rpm not want to climb at all when you give gas. What is it doing...
Cool.
Srinath.

it's doing the same thing... it wants to take off, hits about 2k rpm and then stumbles/boggs and then once it hits about 4K rpm, takes off like raped ape. My father suggested raising the needle up so the main jet will kick in earlier. Essentially, from what experience i have... it IS running lean, but only from about 1500/2000->4000 rpm. So i think either that the main jet needs to be adjusted and/or that i need pilot jets.

I have no idea what else it could be! It's either that the pilots have been changed, possible because previous owner did change jets to bigger EU standard so it'd warm up faster, so that when the slides open up i'm getting 1. too much fuel 2. not enough. I'd have to guess on the lean side.

Any ideas?

OK rich and lean are not the only options... the third is... not getting air quick enough...
Cool.
Srinath.

Ok right. even when i had 1 small hole and 1 big hole=fast slide up, i was having the same problem. Putting the solid plug in to slow down the slides didn't have any effect... so i think that rules out the air problem.

The only thing i can guess now is that the needles need to be adjusted up so that the main jet comes in quicker. What do you think???

Obviously when the main jet kicks in at roughly 4k rpms i get tremendous acceleration... so the main jetting is good. HOwever, i'm having a horrid lull between right off idle to when the main jet kicks in. If i move the needle up, it SHOULD move the main so it kicks in earlier. This might solve the problem. It's either this or  :dunno: and then i go   all night long. But until then, i'm going to  :guns: at the damn thing.

OK good that settles it... I hate the freaking jet kit... Pilots you say... try it and let me know... if it works I'll try the same thing on Caddmonkey's carbs. His is the same as yours right now and I was certain it was slow slides....
Cool.
Srinath.

what style/type kind of Mikuni pilots do i need?

I looked on bike bandit and i saw a host of different types... none of which i could see that had the 40 sizing that you indicated.

Oh, my solution is just based on my dad's knowledge... but the man is practically a mechanical genius... his first thought was the slides too. But no, that's not it. So we're going to this. he said he just installed a dynojet kit on his/my old cbr600 and had to adjust the needles way down on the clips. shaZam!, i don't know anymore! if this doesn't work... i think i'm going to be taking her down to a mechanic... ssshhhh don't tell anyone though.  

This is good advice for anyone who is looking to put dual pod k&n filters, full V&H exhaust plus a stage III Dynojet kit on their GS.

Ok, so this is what i diagnosed "the problem" (AKA what other DJ kit owners should do) as:

1. The needles are set too rich

2. The pilots are set too lean

Solution:  One plug in with restitor hole, other solid plug out on each slide. Put the clips on the highest position on the needles and put about 2.5 turns out on the mixture screw. Adjusted idle up to 1200rpm.

SHOULD run like a champ... unless somethings really messed up with my stuff. I MIGHT have a bigger pilot jet installed, but i don't think so. I THINK that the guy before me put a bigger main jet, but i'm not a 100% on that. I will email the guy and find out. If he had put a bigger pilot jet, then that would possibly explain why the bike was bogging when the main jet kicked in. however, even after i got the needles adjusted, there was still a slight hesitation... so i SUSPECTED THE PILOT SYSTEM... like i've been thinking. So i leaned the mixture screw out, got worse. Obviously i richened it, fixed the hesitation about 100%. I MIGHT be able to go a little richer on the mixture, but then again, i might need to get bigger pilots.

Regardless, the bike runs GREAT now. No hesitation, or very very minor (i mean we ARE talking about a 500cc here), on high gear low rpm take off (aka idle-1/4 throttle position). I am about 98% sure this is about as good as it gets.... but i don't do this for a living. I might go to a bigger pilot jet, but seems to be working fine with what i got in it already... so why fix something that isn't broke???

Oh, how important is it that i get a crankcase vent breather? I don't have one on the bike yet and i'm imagining it's not that big of a deal.

Jon

Congratulations. Now there's the important questions, Jon.  Is the power difference significant? And, was it worth it(would you do it again)? :dunno:

Hell yes i'd do it again!

the power, i'd say is about a 25-30% gain. It's very noticable, but it's not like you're riding a 600 I-4. It's still a 500 twin.... so that in mind, it does run A LOT better. The acceleration is significantly improved from all ranges of RPM. But especially from about 4-redline... which is where the bigger main jet comes in... (whisper: pssst, go with the stage III instead of I, you'll be happy).

Sounds great, and now it sounds like a REAL bike... power is right about where you expect a bike on the street should be at. It'll get you out/in trouble just that much faster. But, it's not like you're on a 100hp street bike, just maybe 2/3rd of that... which makes sense because these are about 50hp rear wheel after pipe+kit+pods and a 100hp bike really makes about 85hp rear wheel.. and if you get an older sport bike, they weigh about 50-70lbs more than our bikes... so=maybe 1/3 more power.

 

hey, at least i'm happy!