flat spot in power on 83gs550es

[KEITH KRAUSE]

I'm not familiar with that stage 1 kit. Yes, the main would have to be larger but I don't know how much.

[Nerobro]

The part that bugs me on that is that the stock jets are 97.5 and 102.5 mikuni's. With the inboard cylinders being richer. So it sounds like the stage 1 kit actually LEANS the bike out? That makes complete nonsence to me. I know my 550ES is running quite lean. And that's the factory setup.

Dynojet's stage 3 kit actually gives you 4 jets that are the same across the board.

The problem I have with guessing is that this is a place where you could severely hurt your bike, and or, set yourself up on a wild goose chase. "I" was on a wild goose chase for a long time. That's why I have 10 sets of jets.

http://roadstarclinic.com/content/view/61/96/ There's a chart. And you'll see that the numbers part ways. If you graphed it, you'd see the mikuni's are a straight line. The dynojets are going to be on a curve. Hmm... maybe I could graph that and extrapolate the data. *grumbles something about doing real work for the forum*

[Nerobro]

*made the chart*

I guess this is to small of a cut to show just how big of a difference different bores make.. according to the graph. a DJ 98 would be a 93 mikuni. so 92.5 is as close as you can get. Good job keith.

Is a stage 1 kit REALLY 98 dynojets? That sounds so wrong now.

92.5 is the stock jet size for a 80-82 gs550. Not the dual carb setup of the 83+ models. Those come with the "odd" jets.

[reem98]

I thank you guys for really goin into depth on this one
Now one thing I must say is that this Jet kit I have is an old K&N kit but it does say DynoJet in the instruction manual. It was never opened and the part number matches for a stage 1 83-86GS550ES
I am wondering the same thing about the jet size being smaller.
The one thing I can say is that the stock neddles have a very small taper to them so I'm guessin to bring more gas in you need to go to like a 110 muniki which I did and had very little gain on the top end. after I put in the new needles (which have a very sharpe taper) and used the DJ98 mains. I got alot more out on the top end. SO I'm guessin the sharpe taper of the new needles allows for the smaller main jet to be used.
The one thing someone mentioned was the inside cyls using larger mains, do you think this is a prob since they are all the same size??
Thanks alot again guys for all your help.

[reem98]

Ok heres what I have found I took out the DJ 98's (dynojets) on the mains, cause around 7k it would sputter bad
I put in 102.5 outers and 107.5 inner mains. not it had power up to redline but sputtered alittle around 6-7k so I dropped the needle from 5 to position 3. Well it got really bad had no pickup (way to rich) I went to positon 6 it lost the sputter but didn't have good power up around 10k. So I went between 5 and 6 on the needles it has alittle sputter around 6-7 and decent power up to redline.
Can someone please explain how I can get rid of the mid sputter and still have good top end.
Thanks

[Carter Turk]

On the 1150 the inner carbs are 2.5 richer 122.5 vs. 120 for 1 & 4, so maybe bring down those inners to 105 and see what happens.

Nerobro, thanks for clarifying jet sizes between Dyno and stock. i'm currently in possesion of jets from 92.5-160.

Again it could be the flat spot the header makes somewhere in the rev range.

Just today I changed my pilot jets back to stock after many years believing the guy at Aurora Suzuki saying "trust me you need to go up on the pilots" to find I eliminated most of a stumble I have at 3000 rpms or minute throttle openings.

[KEITH KRAUSE]

Ok heres what I have found I took out the DJ 98's (dynojets) on the mains, cause around 7k it would sputter bad
I put in 102.5 outers and 107.5 inner mains. not it had power up to redline but sputtered alittle around 6-7k so I dropped the needle from 5 to position 3. Well it got really bad had no pickup (way to rich) I went to positon 6 it lost the sputter but didn't have good power up around 10k. So I went between 5 and 6 on the needles it has alittle sputter around 6-7 and decent power up to redline.
Can someone please explain how I can get rid of the mid sputter and still have good top end.
Thanks

You've kind of lost me with the above description.
You "dropped the needle from 5 to 3.....it got really bad, way to rich".(?) Dropping the needle 2 positions would lean it out quite a bit, unless it was super rich at the initial position to begin with. What position are the e-clips at now (from the top of the jet needles?) What "base settings" did the jet kit suggest for the e-clips?
You need to give throttle positions to describe performance, not rpm's. Too confusing.
You then need to give us plug reads at specific throttle positions. 1/3, full throttle positions and then minimal throttle openings. Tape and mark your throttle housing/grip, chop off and read.
Just to re-cap this thread, you have a stage 1 kit, a 4-1 pipe and a K&N filter in a stock airbox WITH the lid still on, correct?
What jets sizes/parts come with your kit? Have you positively determined what size mains, etc, your bike uses as stock? Trying to re-read this thread and it sounds like there's some confusion here.
I read a ways back that you had a question about re-using the factory plastic spacer(s) that come in the jet needle assembly. Yes, you must re-install in exact order, the factory spacer(s) with the new jet kit needles. Did you?
Also, have you prepared the bike for re-jetting? Good compression...valve clearances good...ignition timing correct...good blue/white spark...K&N filter oiled correctly... airbox seals good...petcock/fuel flow good...carbs clean....floats adjusted...vacuum synched...mixture screws set for best idle...new gaskets for the new pipe...?