TheProtoSmith

We did it boys. Finally passed at round ten. 105 jet on the primary, 5dbtdc, and a whole bunch of fine tuning later, Cesar the 720 can finally be registered.

alirght jet is replaced now running a 92 and a 150, So definitley a bit lean but i'm ok with it. Car is running great now. I gotta do valve lash next but I'm gonna make another run at emmissions after work today. wish me luck

Welp lol that jet was sheared on mine and all I've got on hand today is a 150. So I'll use that to make a pass at emissions.

O. Is my face red. I'll swap that out right away. Just to confirm secondary jet is on the left?.

Maybe I installed backwards?

So rebuild carb? Or is it there a way to just blow out the secondary. That jet was sheared when I replaced them

Smooth but non linear Torque curve. Rises steady, until 80% throttle after that throttle input does nothing. Sounds like too lean to me but I'm definitely learning a lot about these Nissan 4 bangers. Is jetting the only way to tune air mix for non idle conditions.... Seems a bit coarse to really dial in a machine

Same result.. a little less obvious though

I should have been more specific, it runs and sounds fine, but there is like very little power. Atleast at low rpm, high rpm feels comparable to both coils firing There is also the chance that I have the car too far leaned out and it is just low in power.

Hmm, ok, so maybe I should look at the base timing. I know vacuum is good and based off your description of the timing adjust system; it shouldn't be activated under full throttle load. This issue is persistent across even low rpm so that would negate the mechanical advance as the issue aswell. Since my ignition system is all fresh (plugs, rotor, cap,and wire), it should rule out faulty ignition, guess I just gotta bite the bullet and pick up a timing light instead of just tuning by ear. In my conceptual understanding of the system if I want to effectively set the base timing, I should disconnect the vac advance, and the secondary ignition coil, and then add those systems back in after the 5d BTDC has been calibrated. Sound good?

Hmm, I thought changes in timing were all handled by vacuum on my year, and I'm not sure if this helps but brand new cap and rotor.

Alright old jets are out one was cracked, both were too big. Like #200 ish mix screw now makes a difference wooo. Did a 92 and 97 on the new jets. Now I gotta tune this carb in. Runs pretty well when both coils are on and like ass when you full throttle. Which should mean the system it too far retarded right? (Because of the full throttle second coil shut off circuit?(

ok Cool so i think i found generic motorcycle carb jets. that are metric which should line up with it being a japanese carb. but they are for like 150cc motors so i'm a bit confused on that. unless i'm mistaken (because i haven't been able to take the carb apart today. it should be an M5. x .8 thread with a #100 diameter nozzle. although i might just run it even leaner than that given my insane numbers. also thinking of dialing back the pilot too to probably be the 107 instead of the larger bore. But thats just a thought right now. Ill lay off from drilling out the plug and see if i can get there with the jets if these parts look right some sort of confirmation would be great. Cheers, Smith https://www.amazon.com/gp/product/B07JZM493B/ref=crt_ewc_img_huc_2?ie=UTF8&psc=1&smid=A23MTL1LIY6YXM https://www.amazon.com/gp/product/B07SL2JH4T/ref=crt_ewc_img_dp_1?ie=UTF8&psc=1&smid=AAQI0AA583SPQ

Any chance I can get a link? I don't do motorcycles but I'm sure there are different types of jets. It seems to really match the diagrams of the carb in my service manual . I just think it's missing the window but I'm no expert. Could also be a fully rebuilt ebay one. I opened the top off the carb and it def has something that interfaces with valve at the bottom

Ok so continuing to dig I was able to find the fuel air mix solenoid. But it's behind a Welch plug. I plan to drill that out and adjust it tomorrow. Hopefully that will offer me more options in terms of tuning... Any one say that this is a terrible idea? It's this part even adjustable? Diagrams are not as detailed as I would like. If it's not electrically controlled how is this actuated?