gpz750 stage 1 vs stage 3

For my racer, I ordered a Dj stage 1 kit, and received the wrong one (stage 3)...

I do not want to run individual filters, that was the idea behind getting the stage 1 kit.. In the past i noticed the loss of 1 or 2 horsepower is worth the reliability and drivability of keeping the airbox...

should i get the stage 1 kit, or use this stage 3 kit with the airbox?

You didn't mention other mods on this "race bike". What type racing? Internal engine mods? Pipes? The stock airbox isn't a bad idea...

The Dynajet kit IS a bad idea. The bike will be easier to tune and run better with the stock jet needle. The jet needle they gave you is the same one used on a zillion other models using BS34 carbs and the profile doesn't suit a lot of the needle jets. I have about 50 sets of those DJ jet needles folks couldn't make work bwhahahaha

Anyway, stick the stock jet needles in. Use some #40 pilots and bump the mains according to other mods on the bike; especially the pipes. The GPz 34s are a bit lean so you can easily go with low #120 mains if you are wanting to see redline quickly based on the other factors I asked about. The little stubby jet needles with little taper will provide plenty of gas in the mid range and it doesn't effect the air/fuel mixture much to shim them. I have some sets of the same jet needles that have clip positions and I believe you can still buy them from Kaw Canada if you would like to tune the mid-range... or you can shim the jet needles using Mikuni shims which are precision ground .5mm thickness and two shims = 1 clip slot.

basically the bike will have about .030 off the head (hasnt been sent out yet) 3 angle valve job, and a 4-2-1 hindle exhaust (thanks hindle!). No other mods. road racing of course..

i had awesome success with dynojet kit in my carby R6 back when i raced that in 2000/01.. so i figured... *ahem*

ok lets scrap that plan...

right now the carbies have 37.5 pilots and 110 mains and the clips in the middle on the needle.

advice to stay with the stock needles its a great idea, any more info would be awesome...

Like I mentioned, the off idle transitions out of slow curves will be easier to tune for with a size large pilot jets. If you are running colder plugs, just keep an eye on the plugs if you have a slow track... The #40 pilot jets are a bit richer. The stock #110 mains are a shade on the small side, even on a stock GPz. Your bike hasn't much in the way of mods except for the pipes so I suggest you will need around a #120 set of mains (just guessing as I haven't ever had any feedback on the Hindle pipes) but a good set of scavaging 4 into 1s CAN NOT pull redline with the #110 mains. The little 750 engine is on the peaky side and you will want to run in the middle of the power band as the engine is somewhat anemic otherwise... The slightly higher compression won't make a great deal of difference I think.

Once you get to a track, run the bike to redline and if it acts like it is running out of gas at a slightly lower rpm, it will be either rich or lean... a trial by pulling the choke out will confirm which. the lean issue will ease off as the choke ain't a choke... it is an enrichener and you will be adding a small amount of addition gas via the enrichener circuit indicating the #120 mains I suggested are small. If your bike runs worse, then they are too big. The #120s should be fairly close but again, no direct experience with that fancy set of pipes. If I were racing a 750, I would consider some aftermarket cams as the 750 cams are on the mild side and not all that perky... I don't know much about this bike except I have ridden it and it doesn't have a big kick when then cams come in as a Z1 or KZ900 does... this tells me that the cam profiles are on the mild side but I would get with the racer types for more valid opinions.

holy... amazing help!

Im going to forgoe milling the head because i just dont have the time to wait for it at the machinists and then have to degree the cams..

I will def pick up a bunch of jets and give that a go.. thanks alot! should i go much higher on the pilots or leave them at 40?

The #40 pilots should be about right. Larger with the stock airbox and you may foul plugs in a tight track situation.

I know this is way off topic but George I checked out your website and I was admiring the bike pictured in the header. Can you tell me where I can find a small fairing like that? Is that a Maier or Shoei? Thanks, John

It is a Maier GPz replica. I don't ever use it as it puts an airblast right in the middle of your face with upright bars. The bike pictured is one of our carb testing bikes.

The picture above is from a '84-'86 GPz550(L to R). Stock 4A10 Needle, K&N Stage 1 & 3 Needle, and Factory Pro Needle. Could you do a little explaining on what the differences in the profiles would do?

Thanks.

with the 120 mains theres alot of poop coming out of the exhaust if i mildly rev it while in the driveway...
its got stock airbox and filter and 4-1 MAC pipe.

the plugs are BLACK.. i know to run these air cooled motors rich, but is that normal? im just interested in throttle response and top end, so i dont care what is flying out the back since it will be someone else smelling it

I believe black plugs could be an ignition problem.

Also interested, I just saw my carbs professionally cleaned this year -- how did you do it. Just interested, because it took ALOT of time/effort/special tools to do mine. My driveway/garage dip and clean did NOTHING compared to what had to be done.