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DeadBattery

What jets should I run on my trx440ex

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I recently rebuilt my top end and put a big bore 440 on it, I'm also running a stage 2 hot cam, but I'm wondering what kind of jets I should use, and what I adjust it to.

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14 minutes ago, DeadBattery said:

It's an NGK DPR8Z

 

Not sure if you understood Derf , he meant to read the condition of your spark plug against a spark plug chart , after running it in the engine , you can tell if the carb is too lean or too rich ----post a pic of your plug 

 

image.png

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Hi DeadBattery , almost forgot , welcome to the forums !!!  440 Big Bore EX , you need to meet @SlammedRanger he is the EX Guru

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Just now, Fishfiles said:

 

Not sure if you understood Derf , he meant to read the condition of your spark plug against a spark plug chart , after running it in the engine , you can tell if the carb is too lean or too rich ----post a pic of your plug 

 

image.png

Yeah that's my bad, I didn't know what derf meant, but here's a picture of it. And thank you.

168546158098574277395201175523.jpg

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Just now, DeadBattery said:

Yeah that's my bad, I didn't know what derf meant, but here's a picture of it. And thank you.

168546158098574277395201175523.jpg

Do another pic , looking down on the plug like in the plug chart !!! 

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I would say it is running too rich --- how long / much time  after the rebuild is it now ?  Is it smoking any ? 

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It's been maybe a month or two, but it still hasn't ran, it ran only two times, but then stopped, I redid the timing like 8 times, tested my cdi box, replaced the stator, but all I can think is the carb, and no it doesn't smoke when I turn it over.

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It was a Chinese carb, and just threw it on there, which wasn't smart of me, since I just tried to take the pilot out, and it was bottomed out along with all the other jets, so I'm gonna throw it on there, and see if it will run, and see if that's the problem. It has a 42 and a 140

Edited by DeadBattery

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How about some more history. I take it has never run right since rebuilt ?   And it has only ran twice for short periods  ?   Did it rev up ok? Idle ok? 
 

Do you have a compression tester.  Test the compression , you might find timing is 180 degrees out. Quick test that tells a lot.  

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19 minutes ago, Fishfiles said:

How about some more history. I take it has never run right since rebuilt ?   And it has only ran twice for short periods  ?   Did it rev up ok? Idle ok? 
 

Do you have a compression tester.  Test the compression , you might find timing is 180 degrees out. Quick test that tells a lot.  

So a couple months back I rebuilt it, since the cam chain tension failed and came off, and when I opened it metal chunks everywhere, some gasket maker, that wasn't even on correctly, so I put the cases in degreaser and water, dried them, I did new valve, put a stage 2 cam, then had a big bore for it, put it all back together. First startup and it ran, but there was valve tick, so I adjusted them, the next day it was gone, but I never drove it or let it run, and the next day I go to ride it, and it didn't start. I then tested the cdi box, some of the terminals were shorted, I replaced it still didn't run, put a new stator on there, since my lights were dim prior to this, and the stator was going bad, I put a new wiring harness on, and a new starter, I also put a Chinese carb, that I never adjusted, until now, and I come to find out the timing was off a couple teeth, so I'll try flipping the cam 180 like you said, and see if that works or not, but if it doesn't it is most likely not getting enough air, or too much gas, since you earlier said it's running too rich, but that was the old spark plug, so I'm gonna run to the store soon and get another spark plug, just to freshen it up.

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SlammedRanger checking in lol. Ok so since rebuild it started with a valve tick. Then stopped. You said it was timed a few teeth off. Thats very scary. These are interference engines. Meaning valves will hit piston very very easily. (Few teeth off). You may have gotten lucky with that. 110 psi compression is also scary low. But valves being adjusted too tight could cause that. Also could be a bent valve. Were gunna hope for the best on that aswell. When you timed it did you have the cam lobes facing up or down with piston at top dead center? (On the |T mark on the flywheel.) The carb is also jetted not even close. Your gunna be a 45 pilot jet minimum. Possibly a 48. And somewhere in the 180-190 range on main jets. With the 440 kit. Did you ever confirm where the metal inside the engine came from? Thats scary aswell. Usually metal shavings on these engines are crank failure.

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I timed it with all the cams facing down, and made sure the lines on the sprocket stay lined up, the metal shavings coming the cam chain constantly grinding against the wall of the valve cover and all the way down to the head and the cylinder, but I replaced the cylinder, and cleaned most of the shavings up. When it first ran it was idling ok with a 38 and a 170 jet, but I'll get new jets for it, and a new spark plug, since that spark plug it the old one I ran.

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Ok lobes facing down was right. Did you confirm the piston was all the way up? 4 stroke engine so you will see the |T at bottom dead and top dead center. If piston wasnt up at top you would have it timed 180 out. But it would have never ran at all that way. When its timed 180 out it will pop every single revolution and not start period. Not a bad idea to confirm 100% but if it ran i would bet its not that. My bet is the jetting is whats causing you trouble. I was running a 45 pilot when my quad was only a 416 with a cam. It wouldnt even run on a 42 no matter how hard i tried. Just like your having happen.

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I'll try and get some jets for it, if you have any suggestions for what kind of jets I should get and what brand. I also flipped the cam back the way it originally was, when it first started, and if it's still not starting I'm gonna send it to a buddy of my brother, and see what's if they can diagnose the problem. This is my 2nd ever quad, since I started out on a blaster for beginners, then I got a 400ex, and I've been learning on the way.

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DeadBattery , looks like your in good hands now and got a new friend that shares the same likes as you " SPEED " , I am just a old " mud guy " >>>> in the end we are all Brother Bikers 

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@DeadBattery i us jetsRus. They will have everything you need. If you had the oem carb i could tell you exactly what jets it has. But china carbs can be all over the place. You will have to remove the jets and take pictures.

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I had a Kei-hin carb on there, but it really just needed some new screws and a seriously good cleaning, but I used the jets in that one, and they fit in the Chinese one I have, but I'll order some and see.

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Yep keihin would have been the oem carb more than likely. But even that isnt a guarantee anymore. China carbs have been selling with keihin and mikuni castings on them now. The only way to know for sure now is to go off the part numbers on the side if the carb body.

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Yeah I wasn't sure, the jets had keihin on them too, but yeah I'll try to find a store near me that has jets, I'll try and run a 50-55 and I have a 170 already in the carb, but I'll try going up on the jets. But I think it might be the timing honestly, or it's just not enough compression, since i sprayed starter fluid in the intake manifold, and still wouldn't start, I heard niche is unreliable, but I don't think they would be so bad that you can't even get your engine started only after two starts.

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On 5/31/2023 at 5:11 PM, DeadBattery said:

Yeah I wasn't sure, the jets had keihin on them too, but yeah I'll try to find a store near me that has jets, I'll try and run a 50-55 and I have a 170 already in the carb, but I'll try going up on the jets. But I think it might be the timing honestly, or it's just not enough compression, since i sprayed starter fluid in the intake manifold, and still wouldn't start, I heard niche is unreliable, but I don't think they would be so bad that you can't even get your engine started only after two starts.

If the jets had the K on them its a very good chance that is the oem carb. China carbs dont come with jets with the K on them or atleast not that i have seen. Niche is cheap. But i had a buddy that we put the piston and jug from a niche kit on his quad and it ran no problem at all for about 3 years. Now the concern would be if they sent you the wrong size piston or something. Not matched for the bore size maybe? We mic'd everything and ours was close. We did end up running a hone through the jug a few times as it was a tiny bit too tight for our liking. But would have ran im sure no problem.

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I'm gonna try and go to my other house tomorrow, and try and put the new jets on and put a new spark plug in there, since I'm in the process of moving and the garage is cluttered with boxed and stuff as of right now, so I've been trying to make time between my job and moving. Also, if I spray starter fluid into the manifold should it run for a little, since it still didn't start when I did that, and so I'm leaning towards not enough compression since, but the last time I did a test and it read out 120, but it's either compression, spark, or timing, but I triple checked timing and I think I can knock it off, but is there anything electrical that can prevent it from starting that I should check, since I checked the cdi and the ignition coil, but I have no idea what I'm looking for on the ignition coil, so if you or somebody can tell me what I'm looking for on it that would help a lot.

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