Put in new jets...bike won't start =(

  • JonGPZ750
  • JonGPZ750's Avatar Topic Author
  • Offline
  • User
  • Posts: 8
  • Thanks: 0

Re: Put in new jets...bike won't start =(

12 Jan 2015 16:40
#658521
Thanks everyone for all the advice!
heres where I stand now, the bike starts with I have 117.5 main jets and 37.5 pilots however when the bike warms up it high revs a lot just idling...what can I do to lower the revs also I back out the idle screws still high rev.
thanks again everyone

Please Log in or Create an account to join the conversation.

  • Tyrell Corp
  • Tyrell Corp's Avatar
  • Offline
  • User
  • "You were made as well as we could make you"
  • Posts: 1650
  • Thanks: 261

Re: Put in new jets...bike won't start =(

12 Jan 2015 17:59 - 12 Jan 2015 18:02
#658530
These GPz were always cold-blooded, and it takes a mile before they will run cleanly off choke.

The chokes on full often race a cold engine too high, if you open the throttle on a cold start it bypasses the 'choke' (enrichment circuit' on a CV carb).

Maybe you need to set the idle by the adjuster when it is hot firstly, then balance the carbs. If youcan't balance them then bench synch them with a drill bit. Check your fuel height too. The 'idle' screws are actually your pilot airscrews on top of the covers, generally around 1.5 -2.5 turns out.

I like pod filters, but they can take some setting up. More info on what jetting you started and finished at might be informative. Unless you are way too big, I suspect maybe something like fuel height, needle position or carb balance has been unintentionally altered when rejetting.
1980 Gpz550 D1, 1981 GPz550 D1. 1982 GPz750R1. 1983 z1000R R2. all four aces
Last edit: 12 Jan 2015 18:02 by Tyrell Corp.
The following user(s) said Thank You: JonGPZ750

Please Log in or Create an account to join the conversation.

  • JonGPZ750
  • JonGPZ750's Avatar Topic Author
  • Offline
  • User
  • Posts: 8
  • Thanks: 0

Re: Put in new jets...bike won't start =(

12 Jan 2015 19:52
#658545
Alright so here are the changes I have made its not much because I have gone back and forth.
Airbox before Now pod filters
main jet before 115 now 117.5
Pilot jet 37.5... I do have 40
new Sparkplugs
Bike Runs and idles at like 5rpm :(

Please Log in or Create an account to join the conversation.

  • Tyrell Corp
  • Tyrell Corp's Avatar
  • Offline
  • User
  • "You were made as well as we could make you"
  • Posts: 1650
  • Thanks: 261

Re: Put in new jets...bike won't start =(

13 Jan 2015 10:18
#658593
5k rpm off the choke I think would take more air/fuel than the idle circuit can provide - your throttle plates should all be about 99 percent closed on idle. Even if your throttle grip is shut, if your throttles are partly open too far then the 'choke' enrichment circuit is bypassed.

Adjust this idle with the adjuster knob on the carbs when hot, if the carbs are far out of balance you won't gt a smooth idle.
1980 Gpz550 D1, 1981 GPz550 D1. 1982 GPz750R1. 1983 z1000R R2. all four aces

Please Log in or Create an account to join the conversation.

  • bountyhunter
  • bountyhunter's Avatar
  • Offline
  • User
  • Posts: 7246
  • Thanks: 338

Re: Put in new jets...bike won't start =(

13 Jan 2015 12:37
#658607
JonGPZ750 wrote: Bike Runs and idles at like 5rpm :(
That is the classic symptom of a vacuum leak.
1979 KZ-750 Twin

Please Log in or Create an account to join the conversation.

  • tachrev
  • tachrev's Avatar
  • Offline
  • User
  • Rubber Side Goes Down
  • Posts: 343
  • Thanks: 11

Re: Put in new jets...bike won't start =(

13 Jan 2015 13:00
#658608
bountyhunter wrote:
JonGPZ750 wrote: Bike Runs and idles at like 5rpm :(
That is the classic symptom of a vacuum leak.

I second this. Sounds like you have a leak.
1977 Kawasaki KZ1000 : Street/Strip
Build Thread

Please Log in or Create an account to join the conversation.

  • Tyrell Corp
  • Tyrell Corp's Avatar
  • Offline
  • User
  • "You were made as well as we could make you"
  • Posts: 1650
  • Thanks: 261

Re: Put in new jets...bike won't start =(

13 Jan 2015 17:56
#658632
..also bypassing the enrichment circuit hence the starting and hot idle problems.

When they are leaking just a bit they won't idle evenly. Also cracks in the rubber manifolds from heat and aging aren't always apparent until you take them off and squeeze them.
1980 Gpz550 D1, 1981 GPz550 D1. 1982 GPz750R1. 1983 z1000R R2. all four aces

Please Log in or Create an account to join the conversation.

  • JonGPZ750
  • JonGPZ750's Avatar Topic Author
  • Offline
  • User
  • Posts: 8
  • Thanks: 0

Re: Put in new jets...bike won't start =(

18 Jun 2015 13:36
#677165
Sorry for the late update, been busy.

I Got It up and running ! B) Everyone's advice was pretty much all right. It was a combination of getting the right jet combination.
Finding and eliminating vacuum leaks. Turns out all 4 of the Corroborator boots when completely destroyed.

Thanks all

Please Log in or Create an account to join the conversation.

  • Randombeat
  • Randombeat's Avatar
  • Offline
  • User
  • 0 to 100 real quick...
  • Posts: 274
  • Thanks: 23

Re: Put in new jets...bike won't start =(

20 Jun 2015 07:29
#677399
So what size jets did you end up with?
1980 KZ750H LTD-- pods-- vance & hines 4-1 --speedo/tach/blinker/switch deletes -- brat style

Please Log in or Create an account to join the conversation.

Powered by Kunena Forum