Tri-z running problems

[Mosh]

Your jetting seams to be fine at 480 for your elevation and mods.

Is your K&N over oiled? I have seen a few that are just way to oiled and wont let them rev out. Also check the vacumm line at the base of the jug to the fuel pump and make sure it is not cracked or leaking vacuum , and it should have no fuel in it either. If so the pump is bad.

I may be swaying towards CR480R's post too. You may be getting into ignition issues at this point, since as you lean it, the blubber gets worse which leaner mixtures need more spark to ignite.
One of My Z's started acting much like yours at TF07. I went all over with the jetting, swapped CDI's etc. In the end the stator was shot and it busted up on the top end.
Z's are also inherantly known for the coil housing cracking and arching out on the frame. A shot of water poured over it, with the airbox plastic off, engine running, may reveal some arching on the frame from the coil. Check that also.

[Kart43]

Well it runs better. But still cuts out. I sprayed the coil and no arching. I did start it up and then I turned the fuel pump off. And it just keeps running. The engine won't die. It will idle a little faster but won't die. And the petcock is leaking just a little.

[El Camexican]

So sorry to hear that. Without the trike in hand I'm about out of ideas other than making sure that fuel system is 100%, but hopefully some of the long term Tri-Z guys like Mosh will be able to trace it for you. Good luck.

[tippmann]

I Presently have this exact problem with my 85 Z bugging at high rpm tested jet from 350 to 510 . but mine have port n polish shaved head v force dg tune and 38 mm flat mikuni.. im not an jetting expert but WOT with all the jet size and still having the bugging at hight rpm ,, Bough out a like new stator off ebay fully restored with all new part on it.. so i can probably make this option out.. my gaz pump is rebuilt too.. i want to try out direct gaz to carb with gravity. I still have to test out if coil spark on the frame... Manual shop say that resistance of coil should be 0.58 +- 10% im at 1 , 1.2 and the resistance coil + wire (spark cap) is 5900k Omh +- 15 % and im at 8k i think... but I dont think having more resistence in the coil can make the bike bugging like that at high rpm because like you if i release a little bit the throttle it clear out and it rev all good. im altmost out of idea for the moment. If you found out what was the problem let me know.
here link to the stator i bough http://www.ebay.com/itm/130477583293...witem=&vxp=mtr

[Bryan Raffa]

gonna bet its the stator crappin out like mosh said.. eric's big bore was crappin out in the dunes last year.. run good at the bottom but WOT it would break up. just like a jetting issue.. i had one do it also but there was moisture in the cover.. wich leads me to think something is up with my stator,,also

[TimSr]

I've had this problem a few times on a few machines. Usually one of a few causes.

1. Start the bike, and then apply water on the spark plug. If its spits and sputters really bad, buy a new NGK spark plug boot for about $6. Don't use a cheapo no name boot. While you are there, use the water to check the coil wire as well, but its almost always the boot.

2. Check for moisture under the stator cover. No matter how well its sealed, water will get in there. Allow to dry and hose down with WD40 before reinstalling cover. Long term fix, Drill a small hole in the bottom of the cover, install a nipple, and a vent hose.

3. Remove flywheel and clean everything up, and sand down any rust between flywheel and coil surfaces. Hose down with WD40. Rust particles and debris floating around in there between flywheel and coils actually cause scraping between those surfaces which you can feel by turning the flyweel very slowly by hand.

4. Take machine for a test run with flywheel cover removed. If problem got worse, its the flywheel side crank seal, and/or flywheel side crank bearing. You can check crank bearing for play by grabbing the flywheel and yanking shaft up and down checking for play.

5. The other cause I've seen is excess play lower rod bearings.

[Billy Golightly]

I Presently have this exact problem with my 85 Z bugging at high rpm tested jet from 350 to 510 . but mine have port n polish shaved head v force dg tune and 38 mm flat mikuni.. im not an jetting expert but WOT with all the jet size and still having the bugging at hight rpm ,, Bough out a like new stator off ebay fully restored with all new part on it.. so i can probably make this option out.. my gaz pump is rebuilt too.. i want to try out direct gaz to carb with gravity. I still have to test out if coil spark on the frame... Manual shop say that resistance of coil should be 0.58 +- 10% im at 1 , 1.2 and the resistance coil + wire (spark cap) is 5900k Omh +- 15 % and im at 8k i think... but I dont think having more resistence in the coil can make the bike bugging like that at high rpm because like you if i release a little bit the throttle it clear out and it rev all good. im altmost out of idea for the moment. If you found out what was the problem let me know.
here link to the stator i bough http://www.ebay.com/itm/130477583293?item=130477583293&viewitem=&vxp=mtr

Does it bog but not smoke, it just sort of "chokes"? Close the gap on your spark plug to .015 or .018, and I bet your problem will be solved. Weak ignition system somewhere is causing the fire to get blown out of the wide spark plug gap at higher RPMs.

[tippmann]

Ok im going to test out coil and cap with water right now ill update ya soon crank bearing and seal are all new stator is supposed to be ok i have my old one i can test it out too. with my mod and my 38mm mikuni should i stay within the range of 450 to 500 main?

[Kart43]

I bought a carb kit so I'm going to try to install it this weekend. If that doesn't fix it then I will to shorten the gap up on my spark plug and see if that helps

[tippmann]

Just swapped to my old stator and with 340 main it seem to be beter alot better

[tippmann]

Did some test again today and when i received my new carb there was a donut style piece around the Main jet that was connecting with the slow jet hole.. but i changed Needle well(not sure what the english tech term but its the part were the main jet screw) for a Q-0 i think ... well for the one they say in the wrench report.. BUT ! the new Needle well* was shorter so i couldnt not put the donut style thing.. So today i Opened my carb again and i realized that the donut part where holding the needle well* too and the fact that this same donut thing were link to the slow jet hole made me feel strange about the swap I did there. I Installed the stock needle + needle well* ( with the donut part) and i did a fast test who was looking Way better..sure my jetting is not good but ill try jet again tommorow and im 70% sure ill get it run right this time Ill keep ya update about this.

p.s Before removing the donut part in first time i asked some peaple about what this donut do and if its a must have in the carb and without seeing it they said it was a thing to limit wave in the bowl and i can bypass it. but with my last test im pretty sure this donut is important.

[Kart43]

Alright so back to work on my tri z. I cleaned everything up on the stator and wasn't any better. I had a 490 jet that I tried that didn't work and I even went down to a 450 jet and that didn't do anything. I'm still thinking it's ignition so what do you guys think? Should I buy a new source coil? Or should I just get a used stator on ebay? I've tried everything else. I've rebuilt the carb, set the float. I've checked the fuel pump and rebuilt it, I've checked the reeds and set the correct flapper distance. The last thing I have done is tried a different Cdi. I have the same problem no matter what.

[Rider414]

Did you check the output of the stator vs the service spec? You said you did the coil.

[Kart43]

I haven't checked the output. Another something I was thinking about it I have oil build up on my exhaust. Could the reeds be really weak and fluttering too much at high rpm? Do you know what the voltage output should be?

[muthey]

I had this problem and solved it. I replaced my voltage regulator and have had smooth sailing ever since give that a try why it can affect spark I'm not sure but it messed with mine and when I swapped it out with a new one all my problems were solved, also I would take the carb back to where it was when you got it. Let me know what results you have after changing voltage regulator.