Jetting help please

Discussion in 'Motor, Transmission, Electrical, Intake & Exhaust' started by Erik6061, Apr 17, 2019.

Yamaha Raptor 350 & Warrior Forum

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  1. Apr 17, 2019 #1

    Erik6061

    Erik6061

    Erik6061

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    So I got a basically free warrior. Was a basket case, someone didn't tighten the cam gear bolt tight enough and it sheared the shoulder where it rides on the cam off. So I bought a cheap cam, timing gear, and top end gasket set. Cam said it was a "performance cam" but at $18 I seriously doubt it. Anyways, while I had everything apart I'd cleaned everything up, lapped the valves, and removed quite a bit of material from exhaust port and a good bit from intake port. Left the material of the head with plenty of thickness tho. Reassembled everything, and since I was too impatient to wait on a clymer manual, Googled valve lash, .06ish on intake and .03 on exhaust ( yes I know too tight now, dug deeper and found sum info with about .10 intake and .20 exhaust, please correct me if I'm wrong cause it's loud). Wither way, I rebuilt the carb 3 different times, cleaned the Jets real good, couldn't get the jet that looks like it needs the accelerator pump out but ran a piece of wire through it and it's flowing free. Starts and idles awesome, if u punch it it boggs badly. If I ease into throttle it'll revv fine till just over half throttle. Loosening valve lash improved it a good bit as I suspect the valves we're floating. It'll pull the front wheels and go fine till maybe 3/4ish throttle then falls on it's face.
    There is a slip on exhaust on it, exsound or exosound , something close to that. Carb looks like a newer kehien, has butterfly and a slide. I'm not totally sure what the year if this thing is either. So I'm at at a point thinking it has to be jetting, now I have no clue what jetting to use , I'm at 1400 ft elevation. Also have a cheap air filter in the stock box. Any help would be awesome, I really really wanna get this thing running right so I can put it all back together and stretch it's legs on the trail and see what it does. I'm going to recheck the timing tomorrow and see if maybe I didn't keep enough tension on left side of chain while I did it. Kinda grabbing at strings right now so anyone who has a clue please let me know. I'm a certified mechanic but I'm kinda new to small engines!
     
  2. Apr 17, 2019 #2

    Erik6061

    Erik6061

    Erik6061

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    So after reading a bit more, I think I have realized I have a idea of what my issue is. I pulled on the accelerator pump "arm" and tried to pull it apart , but it didn't pull out of the bowl so I didn't mess with it any farther and it seemed to pump correctly so I figured it was good enough. What I did notice was where the arm gets pushed by the throttle linkage , throttle had to be open halfway or more to activate the pump. So I assume the pump spring is worn out , which probably has a bunch to do with the mid-range bog I have. I'm going to pull it apart and clean and sand the pump hole and stem out so it moves completely free and either replace or stretch spring. I still assume I'm going to need to jet this bike too and would like a place to start so I'm not running blind.
     
  3. Apr 22, 2019 #3

    Angie

    Angie

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    I hope you get it fixed.
     
  4. Apr 23, 2019 #4

    Erik6061

    Erik6061

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    Not alot of activity on this forum it seems, I will have new Jets tomorrow ( stage 1-5 with shims) so I will have to start fresh and try and dial it in. Fixed the accelerator pump and drastically improved the mid range too. Unfortunantly I have kind of lost some interest in the little warrior now that I put a new transmission chain in my 500 scrambler ( heavily modded, dynoed at 58hp to the wheels), poor Lil warrior feels like a snail in reverse! The manual shift still makes it fun , hope when I get it jetted correctly it'll get more power , I really want to WANT to ride it as I'm sure it's a blast in the trails.
     
  5. Apr 25, 2019 #5

    Erik6061

    Erik6061

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    So, ended up buying a complete jet kit ( stage 1-5) . The best I have had it running so far with a 150 main jet and a 42.5 slow jet, with needle on slot 3 ( closest to the pointed end) with a single spacer washer under that (basically slot 4) and air/fuel mix screw 2 1/2 out. Have stock airbox, do not want to cut it as I end up in alot of wet conditions. Still have a few backfires on deacceleration , should be able to fix that with air/fuel screw I think. Anyways , figured I'd post an update, in case it helps someone out in the future. The problem was also a mis-adjusted float, was starving for fuel too, I put a new spring in my accelerator pump also. Didn't fix the float before I ended up with the current Jets tho so I am going to try a few other Jets also before I finalize it and put everything back on it. I still am not sure if valve clearances, It is loud up top so definantly want to get that corrected before the plastics go back on.
     

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