Having some trouble dialing in my bike. I just put a dynojet stage 1 kit in, did the float vent mod and put a slip on pipe on it. Great under load but won't stay even when I try and keep it at a steady rpm. I keep turning the idle up so that it won't die and it works for a while but then it just wants to die when I come to a stop. I synced the carbs also. Any ideas before I tear down the carbs completely? 1997 ZX750r constant velocity carbs. Thanks

 

What clip setting is the needles on ? Main jet size ? Did you pinch the diaphragms in the top of the carbs causing
a vacuum leak ? Is the bike stumbling on cruise power ? How is full throttle acceleration ?


Did you also folow directions completly ? Stock air filter or high flow like a K & N filter ?

 

Clip is on #4 as per dynajets instructions, as for acceleration it's fine but if I hold it at say 4000rpm it sounds like it's sputtering. Stock air filter, don't think I picnched the seals. Jets are 138 outers and 136 inners.

 

did you try the starting fluid trick to see if the intake gaskets are sealed properly ?

 

I will try that. One other thing I noticed is that it looks like it's running rich, judging from the sooty looking stuff in the exhaust pipe. I have the ari/fuels at 2 1/2 turns out. Do you think backing them out more would help?

 

it wouldnt hurt to try it but if the intakes not sealing it might make the bike not want to run at all. when i blew out my intake gasket it would sputter bad and only run above 4000 rpm. made taking off at the lights fun.

 

First you can not judge you mixture buy the exaust tip because of todays fuel additves . Each brand burns diffrent and leaves diffrent residues.

You have a lean condition at part throttle / cruise . First remove the top caps accesing the needles . Leave on the 4th clip but take
one of the two washers on top of the needle and place it under the clip giving you a half step postion .
This will richen up your mixture at part / cruise throttle postion . If it gets better but not completly gone go back in and place the clip on postion #5 and place both washers back on top .

Go have a dyno run done that has A/F probe ( AIR FUEL RATIO ) about 30 to 60 dollars for 3 pulls at most shops . Post your dyno chart and I will read it for you and show you were to make changes to improve your tune on the bike .

 

THIS IS NORMAL. For a 96 and newer zx7r, its impossible to get the correct jetting. If you jet the bike it will run better, if you do the float bowl mod, then it will run ever better in the top end but then it just like you said, very jumpy when trying to hold a steady rpm. i've moved the eclips around and found that if you move them down a slot it makes the midrange and lowend awesome, but the topend litteraly has way to much fuel and runs like ***. leaving the clip on number 4 is the correct setting. if you reverse just the float bowl mod, the bike will run fine and holding it at a certian rpms will be much smoother. but you will tell a top end difference when you do it, b/c the bike will accelerate smooth, but you can feel it wanting to do more. I've just had to learn to deal with it. what size jets are you running b/c the kit comes with 2 sets. From all my experiences, the larger jets, the 134outer,136 inner are still too small. I bet if i ran something in like the 140's it would run better.

the zx7r is a awesome track bike for its time, but jetitng it sux.

also it says in the jet kit that anything under 4k the bike runs like ***.

 

Your bike does not run on the needles after 75% throtle opening it is all main jet after 75% so by sugesting the the e clip affects TOP END is a false statement .

You may speak with DYNOJET direct by there Tech # if you chose to not belive my statement above . They will agree .

Nothing is impossible . I tune Dorey Racings 3 drag bikes 99 ZRX 1100 First 1100 in the ZRXOA to be under 10 seconds with no big bore 1109 Kit . 9.81 @ 137 mph 1.51 60' They said a 1100 would never break into the 9's with stock cylinder bore .

Take your time in tuning your machine and read up on it as much as you can if you want TOP PERFORMANCE. Dont follow into
what works for this guy should be exactly right for your bike . Good luck and hope you get it sorted out .

 

i've done the research on tuning a zx7, on the 7's only they put this crappy emmision thing on that changes the pressure of the bloatbowls from that of the airbox and it required these huge stock jets of 190 to run right. when you rejett your supposed to remove this system and change to much lower jets. ie why the dynojet kit comes with 130,132,134,136 jets. when i changed my clips to #5 i was runnign so rich i would fuel was coming out my airbox and down into the little oil tube that hangs down. it was doing that so much that i couldn't ride more than 5 miles without it overflowing if i was in the higher rpms, in low rpms it wouldn't do it, i changed the needle back to #4 and it fixed it. also forwhatever reason dynojet has you run smaller jets on the outside and larger on the inside for some reason. I have no idea why and when I asked dynojet they just said b/c.