Tri-z running problems

[Kart43]

I have a 85 z that is all stock minus a k+n filter. It was at all the factory settings. At wot it blubbers and if I let out of the throttle just a little it clears out. So I put a 480 jet in it and it got better but still blubbers at wot. So I went to a 490 and it got worse. So what do you guys think? Could it be the float set wrong or is it something else?

[El Camexican]

A 480 jet???:wondering I think the stock main jet is a 137.5 Put it back in and test it as it was. Then try raising the clip on the needle one slot at a time (you want to raise the needle to let more fuel in) If raising it all the way to the top makes it run better but not great, put in a 140 and start all over again with the needle. That said don't put blinders on, it may run better with a smaller jet, or a lower needle position as the higher velocity you are likley getting with that filter may now be pulling more fuel up through the stock jet. Test and tune are your words for the day.

[Kart43]

The stock jet is a 470 for a 85 tri-z. That's what was in it when I got it. And the manual I have stars the same. From what I've read I didn't think the needle highth mattered at wot?

[Addicted]

470??????????

[El Camexican]

The stock jet is a 470 for a 85 tri-z. That's what was in it when I got it. And the manual I have stars the same. From what I've read I didn't think the needle highth mattered at wot?

I just looked it up on a parts diagram. Stock main is a 137.5. No offence, but are you sure your messing with the main jet? Are you sure its a stock carb? As far as the effect of the needle on your performance it takes you right up to WOT and to a minor extent is still blocking the orfice slightly when you are wide open. It may not have much effect after you are WOT for a few seconds, but of your main is off it will give you indications as to which way you need to go. i.e. a perfectly jetted main will usualy run best with clip set in the middle position. If you are running better in the upper midrange with the clip at either extream your main jet is likley off a bit.

[Kart43]

The manual I have says stock jet is 470. That's what was in it when I got

[ceaserthethird]

Check what brand carb it is ?

[El Camexican]

470??????????

Check this out. http://yambits.co.uk/470-mikuni-main-jet-p-2223.html Go figure. Anyway the test and tune advice stands. Put the 480 in and play with the needle.

[Kart43]

You're fine. No offense yes it is a main jet. It is a mikuni carb. I have a ytz250n service owners manual and that's what it tells me as far as a stock jet. Is that the wrong manual. It came with the bike

[Addicted]

470? you might be running a TAD bit rich.... try like 145, my 250r would do the EXACT same thing then i leaned it out. ran PERFECT. try using the search bar up top. its awesome!

[Mosh]

The 85 Z was suggested between a 470-490 main, but they ran rich at that setting anyway.
The 86 Z ran a smaller main down around 360 if I recall correctly. But dont quote me on that. 86 carb was designed different so they leaned the main.
Mikuni carbs run significantly higher numbers than Kheins or PWK's.
If you try to put some obnixously low number main in a stock Z carb, you will have a nice new ashtray for your shop once the piston melts.

What jet did you start with? Did it run good then just start acting up?
How old is the K&N

[Kart43]

I just bought the bike two weeks ago. It had a 470 in it to start. As far as how old the k+n is I don't know. It did it the first time I rode it. And has been doing it since. I could take the filter off for a pass down the road and see if it helps

[El Camexican]

http://www.ozebook.com/compendium/t500_files/mikuni.pdf
http://www.triumphrat.net/hinckley-classic-triples/121732-good-chart-on-keihin-vs-mikuni-jet-sizes.html

A couple of good sites if about jets. Keep in mind mikuni uses two types of main jets, hex (amal style) and slot, or "round" I suspect the chart on the second link showes the round jets which are not typicaly used in our trikes.

[Kart43]

Ok so I went from the second needle clip to the third and it didn't make much difference. So then I took the airfilter off and it got way worse. So with the air filter off it getting a bunch more air whichbis making it leaner obviously. So I will try another clip. Any other sugestions?

[El Camexican]

Ok so I went from the second needle clip to the third and it didn't make much difference. So then I took the airfilter off and it got way worse. So with the air filter off it getting a bunch more air whichbis making it leaner obviously. So I will try another clip. Any other sugestions?

Third from the top, or third from the bottom? Also, please don't run your engine without a filter. Snowmobiles can get away with it (no dust) but you will ruin your engine doing that in the summer.

[Xpress]

470? you might be running a TAD bit rich.... try like 145, my 250r would do the EXACT same thing then i leaned it out. ran PERFECT. try using the search bar up top. its awesome!

That may be true for Keihin jets... But Mikuni uses different size numbers.

[Kart43]

Third from the top. I just tried putting it in fourth from the top and no luck either. I took it off for one pass down my street and I put my filter back on. So it's all good. I checked my compression. After three good kicks it's at 150. If I keep kicking it will go to 180. After that I tried putting a 460 main jet in it and it got way worse. I think my next steps are putting a 500 main het in it and then checking the float hight

[MTS]

Whats the spark plug looking like..? Is it the same one that came with the bike?.... Slide opening all the way...needle isnt jumping around? What kind of fuel are you running?

[zzmegad]

im running a 490-500 in my 85 Z which is stock other than oversize bore and DG exhaust. so far so good ;)

[Kart43]

The plug looks real good. The insulater is cocoa brown and and it isn't wet. I changed the plug from when I got it. The plug that was in it was real black. But he was running yamalube at 20:1. So that explaines the black plug. I'm running 92 octane. Klotz suprtechniplate at 32:1.

I did check the float Hight. It was pretty high. I lowered it. Hopefully I can run the bike tomorrow and see if it helps

[cr480r]

i doubt the float was too high unless it was puking fuel on the ground... if the main circuit seems to be the only problematic throttle range, and it is unresponsive to jet changes i would then suspect ignition troubles....

[El Camexican]

Third from the top. I just tried putting it in fourth from the top and no luck either. I took it off for one pass down my street and I put my filter back on. So it's all good. I checked my compression. After three good kicks it's at 150. If I keep kicking it will go to 180. After that I tried putting a 460 main jet in it and it got way worse. I think my next steps are putting a 500 main het in it and then checking the float hight

OK, so 460 does not work and correct me if I'm wrong but all this recent needle playing was done with the stock 470, right? If so, put a 480 in and "drop" the needle (put it on the clip nearest to the top of the needle) and try it. Regardless of how it runs like that pull it and drop the clip another notch (raise the needle). Keep going until you find the best spot. If that spot happens to be at the lowest position and it still does not seem right go to a 490 and repeat. If this does not make things better we'll have to look at other things. Do you happen to know what the alttitude is in your area? Also how was the trike running before you put this filter on? I'm starting to wonder about your fuel pump/filter as well.

[Kart43]

i doubt the float was too high unless it was puking fuel on the ground... if the main circuit seems to be the only problematic throttle range, and it is unresponsive to jet changes i would then suspect ignition troubles....

The measurement from the base of the carb to the top of the float was too long. So that would make the bowl level low right? So I shortened the distance to spec which will put more fuel in the bowl

[Kart43]

OK, so 460 does not work and correct me if I'm wrong but all this recent needle playing was done with the stock 470, right? If so, put a 480 in and "drop" the needle (put it on the clip nearest to the top of the needle) and try it. Regardless of how it runs like that pull it and drop the clip another notch (raise the needle). Keep going until you find the best spot. If that spot happens to be at the lowest position and it still does not seem right go to a 490 and repeat. If this does not make things better we'll have to look at other things. Do you happen to know what the alttitude is in your area? Also how was the trike running before you put this filter on? I'm starting to wonder about your fuel pump/filter as well.

The recent needle clip position changes were done with the 480 jet. The altitude in my area is 1200 to 1300 ft. Also the k+n filter was on the bike when I got it. And I'm not sure if this makes a difference but the air box cover is gone as well

[cr480r]

OK, so 460 does not work and correct me if I'm wrong but all this recent needle playing was done with the stock 470, right? If so, put a 480 in and "drop" the needle (put it on the clip nearest to the top of the needle) and try it. Regardless of how it runs like that pull it and drop the clip another notch (raise the needle). Keep going until you find the best spot. If that spot happens to be at the lowest position and it still does not seem right go to a 490 and repeat.

i disagree with this method. The needle and main are separate circuits. While the needle taper and length will have an effect on the final main jet size, the main jet should not effect the needle clip position. I recommend getting the needle position set and leaving it. Make one change at a time. Because of the overlapping effects of the circuits jet from TOP TO BOTTOM. Pilot, needle, then main.


I'm starting to wonder about your fuel pump/filter as well.

i wondered about this too until he said smaller jets worsened his condition

[El Camexican]

For CR480r

With respect to the main and needle relationship my reasoning for this method is that if you aren't sure about the main jet size you need you can figure out which way it needs to go (up or down) based on how the engine reacts to the much easier to change needle clip position as they overlap/work together, or whatever you want to call it until near max. RPM. As I think I said earlier if you are getting the best performance with your clip set at either of the extreme positions on the needle you should likley change the main jet so that you can put the clip nearer to the center position. I'll add that the end of the needle is still obstructing the fuel at WOT so it still has some effect. As far as which way to start jetting I find the right main jet before deciding on the best needle position. It's been a long time since I've looked in a carb book, maybe time I brushed up before I add anything else (I hate eating my words)

About the smaller jet/fuel pump I was not consitering the jet size as a factor, but the fact that he can't seem to get it to run right with in the 460-480 range which makes me wonder if he's getting enough fuel. If there is a pump or filter problem I doubt a smaller or bigger jet would make much difference at WOT. I'm not saying he needs that 460 jet, but if he's starved for fuel at WOT a smaller main would make it worse in theory as it further restricts fuel flow.

That all said I was under the impression he started with a perfectly good stock trike and started having problems when he added a different filter. Sounds like he bought it that way and has no stock air box, so there is no base line to go back to. If this 490 main dosen't work I'd suggest he get the carb well cleaned, check that the reeds aren't damaged and then the fuel pump. After that I don't know what could be causing problems only at WOT. I hope the 490 works.

[Kart43]

Well I've checked the reeds. They look good. And I've already had a 490 jet in already. But I'm going to ride when I get home and see if changing te float height made difference. I'll let you guys know what I figure out. Thanks for all the help

[El Camexican]

Well I've checked the reeds. They look good. And I've already had a 490 jet in already. But I'm going to ride when I get home and see if changing the float height made difference. I'll let you guys know what I figure out. Thanks for all the help

Do you still have metal reeds in it? Just wondering as a bad set of fiber reeds could perhaps "flutter" excessivly at high RPM and cause the problem. When your inside that carb, remove and take a good look at the Nozzle Jet (The one the Main screws into) and make sure all the holes are clean if you haven't done that already. They get plugged fairly easily when fuel is left sitting, or crud gets in there bowl.

Do you know how to set the float height? If not ask, but all you are trying to do at this point (as your problem is strictly WOT related, right?) is to make sure the needle/seat assy is opening enought to allow max fuel flow when the float is sitting at the bottom of the bowl. I guess what Im saying is don't get too agressive with that adjustment unless you think you bent something when you were in there before. If everything is stock it be darn close to where it needs to be already.

I'll recommend that if this adjustment does not change things that you start thinking about rigging up a drip bottle to gravity feed that carb on one of your test runs. This is the best way I can think of to eliminate your fuel pump from the possible problems list. I guess you could also just disconnect the fuel line, shut the ignition off and kick the engine over to see how much fuel comes out of the line. I can't tell you an amount, but based on what I've seen on my clear lines when I was first filling my carb it looked like at least 3 or 4 inches of fuel moved through the unobstructed line with each kick. It may not be as much fun as going 60MPH with a jug of gas hanging from your neck, but it seems a lot safer. Maybe some other guys here know a better way? I guess you could drive at an RPM just below that bog for an extended distance and see if the point at which the bog starts becomes lower over time as that would indicate a fuel shortage too. If it is your pump, don't panic, rebuilt kits are cheap and plentyful.

[Kart43]

The reeds felt like plastic. They weren't bowed or anything they were laying pretty flat. I just looked in my service manual to see where to set the float. I did a little research online before. But what I did was measure from the base if the carb to the top of te float. My manual says it should be 1.23 in +or- .004 inches. I had to bend the tab quite a bit to get it there. So that means that the float level was really low. So when I get home I'm going to ride it and see if it made a difference. And if it doesn't then I'm just going to order a fuel pump rebuild kit

[El Camexican]

good reading

http://www.iwt.com.au/mikunicarb.htm

http://www.dansmc.com/carbs2.htm

[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:wondering 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.:beer

[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?item=130477583293&viewitem=&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 (http://rover.ebay.com/rover/1/711-53200-19255-0/1?campid=5336526073&toolid=10001&mpre=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.

[Kart43]

What happens if I just remove the regulator. I assume it will blow out my headlights. What else could happen?

[muthey]

I wouldn't just remove the regulator, as your headlights will more than likely blow, but it might also be damaging to the stator as well. Also they are fairly cheap, you can get one for a 80's model or early 90's model banshee and they are the same connections. That is what I swapped mine out with.

[Kart43]

I unplugged the regulator and it revs right up. Thanks man for all of your help.

[muthey]

your welcome, I don't know why it affects it unless they fault, and surge back into the stator, mine went right after I added in a horn and swapped out the rear tail light for a led tail/brake light. took the horn off but left the led lighting and replaced the voltage regulator and haven't had a problem since.

[Kart43]

I've been trying to fix this thing for a long time. I can't believe that's what it was.

[Kart43]

Does your kick start slip every now and then? How do you fix it.

[Rider414]

Wow regulator eh? I just got a Tri Z and it has a miss on the top end.

[Kart43]

I haven't rode it yet, so there is no load on the motor yet. I just ordered a regulator. As soon as I get it I'm going to go ride it. What I did was just unhooked my regulator and turned my lights off that way it wouldn't blow the bulbs out.

[muthey]

mine wasn't quite that bad yet I could rev it with no load but under load it would sputter at wot