flat spot in power on 83gs550es

[reem98]

Hi I am working on a 83gs550es trying to get it tuned right. I have a 4into1 exhaust a K&N air filter and a K&N Stage 1 jet kit. It runs good on the low end and top end but in the middle as I go under full throttle from like 4k up it hesitates and studders up around 6-7k then does fine after that.
would this be my neadle position or my main jets.
Thanks

[Carter Turk]

What kind of exhaust? I think its partly the pipes fault. They tend to compromise the power somewhere in the rev range. You could always try a washer under the needle .5mm or raising the mains 2.5 sizes depending on the plug color.

[reem98]

Is there a place I can find or does anyone know what size mains come with an old K&N Jet kit for an 83 Gs550es.
Thanks

[Nerobro]

Yup, they are DJ 114 and 116 jets. Which are different than mikuni numbers. However... the problem you're running into a needle issue. :-) Time to raise them a little. You may also wanna opening up the pilot screws a little.

[reem98]

Mine actually read 98 for the mains. Do you have a jet kit in your GS550es??

[Nerobro]

98? Sounds right for a stage 1 jet kit. the 114 and 116's are for stage 3. It reallys sounds like you need to raise your needles a little.

[reem98]

hey thanks for the help
I was also wondering if you remember did you delete that nylon spacer above the needle when you put in the jet kit in the gs550e and do you have any idea what that 98 dyno jet size is in Muniki jets.
Thanks

[reem98]

I was wondering what this might mean if I hold the throttle steady at like 6k and then punch it it stumbles. but if I go up from like idle under load it is fine.
why might is stumble when I punch it if its already revd up.
thanks

[Carter Turk]

I would guess the 98 DJ are 95 mikuni. Aren't stock 92.5?

Have you raised the needle with a washer yet. You should be able to do this w/o removing the carbs. Just take the tank off.

It sounds like your getting on the mains from down low and sort of bypassing the needle, when introducing a lot of throttle, but when your at a cruising state you're probably on the needle.

Not scientific, just a guess

[Nerobro]

Don't guess. The numbers DO NOT directly relate. In fact the numbers get further from each other in a exponential manner. DJ numbers are diameter. Mikuni numbers are flow. say a dj 50 and a dj100 jet... the dj 100 jet will flow four times as much fuel as the 50. A mikuni 50 will flow 50cc's a minute. A mikuni 100 jet will flow 100cc's.

[KEITH KRAUSE]

A DJ 98 should be either a 90 or 92.5 Mikuni.

[Carter Turk]

Guess what. I'm allowed to guess if I like. My guessing got you to respond, but you failed to tell him what jet size he has in Mikuni world.

[KEITH KRAUSE]

Guess what. I'm allowed to guess if I like. My guessing got you to respond, but you failed to tell him what jet size he has in Mikuni world.

:-? Not sure what you're saying.....to me? I'm just guessing too. I think it's an accurate guess though. A 98 DJ should be equal to either a 90 or 92.5 Mikuni.

[pano]

When I jetted my 1100e with individual filters and 4-1 exhaust I had a flat spot at 4-5 k. I raised the needle. I then had a sputter at 4-5k so I raised the needle again. It runs smooth now throughout.

[Carter Turk]

Keith,

I was refering to the nerobro post.

Curious though, wouldn't DJ stage one main jet be at least 2.5 bigger than stock, assuming stock is 92.5? I wonder if the jet came from a GS 450 stage one kit.