Yes....jetting. Toss out the DynoJet kit?

[scott-s]

 Working on fitting a 2000 GSX750-F engine into a 1980 GS550E frame. 

 

 Going on recommendations here, I picked up a set of '95 BST-36 carbs and had them professionally rebuilt to stock specs. 

 I have a Dyno Jet Stage 3 kit that I got for a good price but have since seen all the differing opinions on DJ. luckily, I have NOT installed it yet, so nothing is drilled out, etc.

 

I ended up using BST-36 carbs , Bandit 1200 mainfolds and rubber velocity stacks and RamAir filters. I'm told this should be easier to tune than the stock carbs.

 

 I slotted the timing advancer so I can play with that. I have the stock header and a Yoshimura RS-3 pipe/muffler.

 

 Before I go about installing the dynoJet kit, should I just try shimming the needles and getting a few sizes of main jets to try?  I know I have a bit of a bastard combo here. I just want to try to make it run best I can and would like to avoid any known pitfalls if possible.

 

[scott-s]

 FWIW, after getting some feedback from a member here and talking to my buddy who runs a shop up in North Carolina (and has generally favorable experiences with DJ), I went ahead with a "75% install" of the DynoJet kit.

 

 Meaning I adjusted the mixture screws per their recommendation (plugs were already drilled out), used the 140 DynoJet mains (middle of the "rich" jets, I can still go up and down) and used their adjustable needles.

 

 What I did NOT do is drill and tap the slides for the correctors. Both guys told me not to bother with that. Even DJ mentions that one of the two (per slide) can be removed. We'll see where this gets me.....someday.

[Gixer1460]

Good - you had the kit and so you'll find out for yourself whether it works or not. I like DJ kits and I acknowledge not everyone feels the same way but I only offer my experience, that they work for me, 'out of the box'. If I wanted to spend hours taking carbs off and on, thrashing up and down roads and repeating - then yeah i'd go the stock jets and needles route. All I know is that i've fitted a stg 3 kit to a GSXR 1186L motor with K&N's and bespoke 4-2-1 V&M Supersport exhaust - everything as DJ instructions and it took one jet change and 1/2 hr on the dyno to be perfect. And that kit came with needles and emulsion tubes which if they did wear (which they will) are covered by DJ's lifetime warranty for no-cost replacement!

[Lachie04]

On 6/13/2019 at 7:52 AM, scott-s said:

 

 What I did NOT do is drill and tap the slides for the correctors. Both guys told me not to bother with that. Even DJ mentions that one of the two (per slide) can be removed. We'll see where this gets me.....someday.

Drilling the slides has little to do with the jetting

The volume of air flowing through the carb is governed by the buttery fly

When you open the throttle the velocity of the air increases

as the air flows over the holes in the slide it draws air out of the diaphragm by the venturi effect.

This causes the slide to lift

The drilling of the holes is supposedly to allow the air to be removed from the diaphragm quicker thus increasing the speed the slide lifts and theoretically quicker acceleration.

IDK it may also effect the height the slide sits at constant throttle equilibrium 

Another way I have heard to get the slide to lift quicker is to cut a couple of turns off the spring so there is less force on the slide but this can cause issues of the slide not dropping either quick enough or insufficient force to close the slide

Edited June 15, 2019 by Lachie04

[scott-s]

 I should clarify. The slides ALREADY have two holes on either side of the needle. The DJ kit says to drill and tap them and install some threaded plugs that are included in the kit. The instructions say that, for tuning purposes, one of the plugs can be removed.

 

 A member here and my shop owner buddy both recommended leaving the slides stock and just using the adjustable needles and the jets.

[scott-s]

 So...this bike is "finished" but not on the road yet. I have very few miles on it, riding it (illegally) around the back roads near my house.

 

 It definitely needs some tuning down low. I can feel it surging or hunting at part throttle. Runs like a raped ape up top.  It can be a little difficult to get cranked if I let it sit for a few weeks. Not having made it to the dyno yet, or even pulled a plug, those things hint to me at being lean on the bottom end. 

 

 If I remember correctly, the mixture screws are on the engine side, so they meter fuel and not air. Think there's anything I can do with them to help? Or just wait for the dyno runs and see exactly what I need to do? The DynoJet kit didn't come with any pilot jets that I remember.

[Pastyman]

On my stage 3 DJ kit I had to go one size up on pilot jet to get it to run correct

[alboo]

just been through this and after a lot of advice i went for the dj kit stage 3 followed the instructions to the letter including drilling the slides and air jet 

runs nice and revs like a banshee .gsx1100f engine kn filters and a harris exaust.