Lookin for a silver bullet....

[Guest]

Ok all you GS guru's out there - I've done many many searches and gotten myself so confused/overeducated that I don't know what I know and I'm about to either sell or commit GS homicide. I'm looking for a silver bullet that will solve my damm carb/jetting issues. I've done countless plug chops and made changes accordingly, only to find my changes (as dictated by the plug chops) to be incorrect.

84 Kat 750 (Same basic motor as the 83 GS750 and 85 GS700).
Airbox out and never going back in (it's just too painful).
Thusly, individual pod filters.
Jetted to hell and back with unsatisfactory results.
New intake o-rings.
Intake boots soft with no detectable cracks.
New carb o-rings.
Carbs cleaned. (CV's)
Bench synched, but not vacuum synched.
Diaphrams soft with no detectable cracks.
Valves adjusted.
Tested and functioning properly fuel valve.
135-145 compression on all 4.

I've returned it to stock configuration twice with the airbox, carb settings confirmed at www.katanacentral.co.uk with still no luck.

My last resort is to purchase a Dynojet kit as the instructions specifically say:

"Stage 1: For mildly tunes machines using the stock airbox, with stock or K&N filter.
Stage 3: For mildly tuned machines using individual filters or velocity stacks.
Both stages may also be used with a good aftermarket exhaust."

Direct quote from the instructions I downloaded off their website.

Soooo, does this mean that I can use this kit with stock exhaust? Sure sounds like it to me as "Both stages MAY also be used with a good aftermarket exhaust".

I'm tired of spending money to get this perfectly serviceable motorcycle to run. I'm tired of tearing it apart over and over and over to have my expected results change again and again. This CAN'T be this bloody difficult.
Here's what it's doing:
Idle: up to about 2k, then back down to almost and sometimes dying. Repeats this cycle over and over. Pull plugs they look rich.

Mid throttle: bucks and surges. Plug chop tells me it's rich, last time it was lean so I moved the needle half a notch and now its rich as ell.

WOT seems to be okay if a bit lean. I've gone up two steps in the inside 2, 1 step on the outside because the inside appeared to be much hotter than the outside. Now all 4 look uniformly white, where the two outside were running okay before. This may or may not be okay.

Air screws about 2-1/2 turns out.
This is about as good as its been so far for me.....

I'm leery of drilling the slides as DJ recommends in their instructions. Permanent alterations bother me (airbox aside).

Has anybody else done this, and were they happy or disappointed with the results?

Please help, I'm ready to blow the damm thing up. Or worse yet, sell it to someone and then find out it was a simple change.

[Billy Ricks]

A jet kit will take much of the headache out of the jetting process. Drilling the slides is no big deal, you just enlarge the existing hole with the bit that comes with the kit. If you use the DJ specs you'll be right in the ballpark. If you think you might go to a 4 into 1 later get the Stage 3. If you're going to keep the stock exhaust Stage 1 would probably be better for you. The surging seems weird. Even with the jetting off it should still idle well. Even with a kit the idle circuit screws don't get changed. You just do what you already did. Once you do the kit do as good a job as you can bench synching them. You can get the synch pretty close just using a piece of wire or drill bit between the throttle plates.

[TheCafeKid]

You replace your float valves? Double check your float levels? Check your petcock? Vaccum synch will smooth it out, the surging could simply be due to that. Give that a shot.

I duno much about the DJ kits as i havent used one yet, but I had been getting some mixed info on them myself. I was told, and was under the impression that when one buys the Stage 3 kit, all the ingredients for the Stage 1 kit are in there as well. If this is in fact the case, I would simply buy the stage three, incase future mods tickle your fancy...

[GQROD]

Did you originally have the stock size jets in the carb before you re-jetted?

My carbs don't have extra grooves to move the needle position they are twin CV's so I jetted my carb to stock and worked from there methodicly narrowing down my no start, high idle, no idle problems to the pilot jets being too small and my pilot air jets being too big.

In your case you know it is running rich and needs a vac sync so you may not be too far off.

You must do your tuning with all the parts you intend to run on the bike ie: air box on or off permanently otherwise you will not be able to tell where the problems are.

Don't mess with jets until you have solved the rich running by adjusting your needles, air jet screws etc. It could be that by tuning each circuit independantly you can solve multiple problems with one solution.

Hope this helps, we have all been where you are at.

[Billy Ricks]

You replace your float valves? Double check your float levels? Check your petcock? Vaccum synch will smooth it out, the surging could simply be due to that. Give that a shot.

I duno much about the DJ kits as i havent used one yet, but I had been getting some mixed info on them myself. I was told, and was under the impression that when one buys the Stage 3 kit, all the ingredients for the Stage 1 kit are in there as well. If this is in fact the case, I would simply buy the stage three, incase future mods tickle your fancy...

It's been years since I had my set of CVs taht I installed the DJ kit in. I seem to remember everything in the Stage 3 kit was there so you could go Stage 1. Don't quote me on that though. You can call DJ directly. They used to be real service oriented and if you needed additional jets they would send them gratis.

[Billy Ricks]

Are you telling us the needles have multiple grooves? If so someone already installed a jet kit. Float level does affect mixture greatly.

[Smokinapankake]

Thanks for all the replies.

Floats are set to spec. None leak, all float.
It has multiple needle settings. I think it came from the factory this way because it is a Japanese domestic model, i.e, never imported into the states. The air screws were not plugged off, either. But the needle doesn't look like the picture on the DJ website, and the main jets were standard issue Mikuni's, so I have no reason to think someone had already jetted it.
The DJ kit comes with parts for both stage 1 and 3.
I guess that I'm looking for some assurance from someone that if I spend the dough (130-ish) I will get some sort of return. In other words, will it improve my problem or will I just be unnecessarily spending more money?
I called DJ and of course, because they have no listing for an 84 GSX 750SE, they said I can't guarantee anything. The airbox may be different, the carbs may be different, blah blah blah. Not very helpful.

I'm bloody tired of fighting it.