Jetting??

I just bought a 1983 Kz750 Twin, put straight pipes and pod filters on it. Before I did this it ran perfectly, now it starts and idles fine, but once I get on the throttle it bogs down and wants to stall. If i roll on the throttle really slow I can get it to higher RPM's. This makes me think that I need bigger jets, currently the main jet is a 115. Anyone have any thoughts, jet problem?? Tank, petcock, and carbs. are all super clean. Thanks anyone for your much needed help!!!

What brand of pipes? Homemade?

What make of pods? Hopefully, not homemade.

Youv'e deffinately leaned things out a bunch, and will probaally require a complete re-jet.

Homemade pipes yes, store bought pods! Yea figured I am probably way lean. How high of a jump should I make with the jets??

dajmartin wrote:

I just bought a 1983 Kz750 Twin, put straight pipes and pod filters on it. Before I did this it ran perfectly, now it starts and idles fine, but once I get on the throttle it bogs down and wants to stall. If i roll on the throttle really slow I can get it to higher RPM's. This makes me think that I need bigger jets, currently the main jet is a 115. Anyone have any thoughts, jet problem?? Tank, petcock, and carbs. are all super clean. Thanks anyone for your much needed help!!!

I am not sure which carbs you have. My '79 750 twin has the BS-38 carbs which came stock with 125 main jets. 115 sounds kind of small. The mains used to be available up to 140 but I don't think anybody sells the tiny main jets any more for the BS-38 carbs. Stock pilot jets are 45, I would go up to 50 on those. They are still available, I think they are BS30/96 jets if I remember correctly.

IMO, straight pipes will never run right across the full range because the needle taper won't match the flow.

dajmartin wrote:

Homemade pipes yes, store bought pods! Yea figured I am probably way lean. How high of a jump should I make with the jets??

Jetting is a whole big can of worms that is going to teach you alot about your carburetion, believe me.

You can work with that straight pipe, it will still run ok, just probly have a flat spot like mine. (between 2000 - 3500...rpm's) but playing with the pilot mixture can help this alot.

Take your pilot and main jets out and start making some phone calls. You should be able to find someone with knowledge who can give you an idea of what you'll need.

Or just search this forum/filebase for more jetting size info...

Good Luck. I've found jetting to be like a pendelum, it just gets better, or worse.