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joeprunc

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About joeprunc

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    TT Silver Member

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  • Location
    California
  • Interests
    Dirt Biking, 4X4ing, surfing, snowboarding, water skiing

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  1. joeprunc

    NO START after Rebuild - YZ250F

    Bike ran great.
  2. joeprunc

    NO START after Rebuild - YZ250F

    Final Update... got her running: Didn't check the neutral switch. A friend talked me into re visiting the fuel system (the injector in particular). So a last ditch effort, I pulled the injector off, and you can hold the nozzle and housing together and turn the motor over by hand, I was getting a good mist of fuel each kick. I then revisited the throttle body as a whole. I cleaned the injector seating hole, pulled the are pressure sensor and the air bypass hole. In anticipation of kicking the bike for days, or trying to bump start it, I had a friend come over. Sure enough just as I'm finishing putting it back together, he jumps on the bike and second kick it turns over.....what the hell!. So either there was something with the fuel/air delivery that I magically cleaned, or my friend had a fresh leg, and use to kicking a 450. Either way, a few hot cycles last night, then another one today and I'll go out and break her in ;). Thank you for all the help everyone!
  3. joeprunc

    NO START after Rebuild - YZ250F

    Pulled the flywheel, everything was installed properly before. Carefully put it back together...still nothing. I'll check the neutral switch Close to throwing in the towel.
  4. joeprunc

    NO START after Rebuild - YZ250F

    So I got my bundle of parts in last night. @William1 I'm sure you are doing this right now..... I checked the entire wiring harness, and all the pins in every connector, they all appear to be good with a visual check. Swapped the Stator & crank sensor...nothing no difference in spark either Swapped the condenser and ECU, nothing. @beezer Thank you for the video, I did swap back my old coil, and made sure the connections are good and tight. Checked the timing again. Kicked the bike over with the valve cover off, and the counted the # of rotations of the cam, they rotated 1 to 1.5 times, which means I should be getting at least 2-3 sparks per kick. I'm not, I'm only getting one....and at the very bottom of the stroke of the kickstarter. In my frustration and again failure last night I found this post The one component that I did touch during the top end, that I haven't touched since is the flywheel. If he was having a hard time getting spark because of the woodruff key not allowing the flywheel to seat, its worth a check. So I also have a brand new flywheel....should I put a new one in, or just pull the old, inspect and reinstall?
  5. joeprunc

    NO START after Rebuild - YZ250F

    Thank you for your advice, I remember having an issue many moons ago with jetting my 2003 YZ250F and you help was right on. The parts I have coming are...free. From Yamaha the stator could be supplying just enough to charge the condenser (which then powers the fuel pump), but not provide sufficient voltage to the ECU or Coil to generate sufficient spark. Yes the bike was running and starting perfectly before the rebuild. I am only getting one big blue spark per kick of the kickstarter...I am thinking the same thing as you it really should be 3-5 sparks....not 1. It seems like the spark usually happens when the kickstarter makes contact with the foot peg....I'm not sure if this is a coincidence with the way I'm at TDC when I kick, or if it is a grounding issue. The motor should be grounded to the frame via the engine mounts, and the electronics grounded via the ground off the ECU which I checked all mounts, and the ground wire (am I missing something there)? I have been through the ignition "No Spark" trouble shooting portion of the manual (the Yamaha manuals are actually quite good) and checked all the steps and sensors (except for the crank sensor were it connects with the wiring harness. Mine appears to go directly into the wiring harness, but after looking at drawings and replacement parts, this connector must be somewhere else). From Yamaha there have also been issues where the Stator tests good with Ohms, but the required voltage isn't sufficient. And I don't have a multimeter that can record peak voltage output to test that. I tested the kill switch, connector, and wiring to/from, and currently have it completely disconnected right now. Again I truly respect and appreciate these comments, I'm at an utter loss right now. I will go back tonight or tomorrow and check again all the connectors and sensors.
  6. joeprunc

    NO START after Rebuild - YZ250F

    I agree its an electrical problem, but couldn't find anything with grounds or connections....I guess if the stator doesn't work, I'll look at replacing the whole wiring harness.
  7. joeprunc

    NO START after Rebuild - YZ250F

    Update: Pulled the ground (the one up near the right radiator) and traced it back to the wiring harness, looks good as it probably was off the factory line. Tried my ECU on a running bike, it fired up the other bike first kick...so the ECU isn't the problem. I have a new stator and crank position sensor coming Friday, hope that's the issue. Are there other grounds that I am missing? Looking at the manual, it looks like this is the only one.
  8. joeprunc

    NO START after Rebuild - YZ250F

    So I've been also talking with Yamaha. I just got off the phone with a possible diagnosis. So one thing I left out in my detailed initial report was the spark I am getting is one spark per kick, usually at the end of the stroke. I tried doing research to see if this was normal or not. It made sense that kicking the bike the piston does one/two revolutions, and at lower RPMs (the initial part of the kick) there weren't enough Rs to generate spark. Hence the one spark. However Yamaha said there should be multiple sparks when kicking, as the motor should rotate several times with the kick starter gear reduction. SO he said, check the ECU with another bike....put my ECU on a running bike. This will check the ECU. If not swap the Stator and crank position sensor. I'll let you know with more updates.
  9. joeprunc

    NO START after Rebuild - YZ250F

    Funny, I thought about that too on day three of working on the bike, but since then I have pulled the boot several times and checked. You can also hear air sucking into the cylinder as the newer YZFs are louder than most other bikes when kicking over. I've also pulled the air filter off.
  10. I have done a lot of reading, research, trouble shooting, and work before I posted this. I apologize for how long this post is, but wanted to include all the details of what I've done to keep the thread in the right direction. So, I am having issues with my bike, and have done a ton of trouble shooting. Let me start of by saying I have checked my timing about 13 times, and have three other people verify it as well….I don’t think timing is an issue. I’ve also disconnected the kill switch. I’ve also rebuilt 4 top ends on various YZ250Fs in the past, however this is my first FI bike. My Bike: 2014 YZ250F GYTR head, FMF Ti Exhaust, 51 hours. Primarily ride track and race C Class (8-10 events per year). Work performed this time on the bike: Timing chain, a new 2015 stock piston, wrist pin, rings, and wristpin oil spray. Verify valve clearance after install, and rotation. I checked the cylinder, piston, rings, for clearance and tolerances. I checked the crank for tolerance as well. The piston has the F mark towards the front of the bike (which correlates with the intake valves, larger sized) (NO SPARK ISSUE): I put the bike back together and it would not start, no sputter, no burp, nothing. I diagnosed it as a no spark. I checked the timing and valve clearance (its dead on, and yes I know the exhaust valves go towards the rear of the bike), I checked the chain tension as well. I was trying to ground the plug to the valve screw and or the frame. I Disconnected and inspected all connections off the wiring harness, and checked for any fraying especially up around the radiators/frame area (all looked good). I followed the manual checking resistance on the kill switch, primary and secondary coil, spark plug cap, crankshaft position sensor, stator, checked ground, spark plug resistance and gap (also a new spark plug). I made sure the ECU was in the upright position. However, I was a retard and measured the secondary resistance of the coil including the cap…so it was 9k ohms over. I thought this was the issue, so I purchased and installed a new coil…but found this mistake after I already installed it. I pulled the clutch in and kicked the bike and Finally got spark!! My neutral switch is directly hardwired into the harness, so I could not pull it to check resistance. And for some bizarre reason, I get spark every time with or without the clutch pulled in. So the no spark issue should be cured....I think (see last few paragraphs). (I'm only able to see the spark when the spark plug is grounded to the frame, I don’t have the tool to inspect what happens when its installed in the head. I still am having trouble with a no start (next step CHECK FUEL SYSTEM) With spark figured out I’m still not getting a start, a sputter, any sign of life. I checked the timing again (its dead on). I checked the woodruff key on the flywheel, and can shine a light down the keyway and see the woodruff key in the keyway. I also checked that TDC is actually the same as what is marked on the flywheel by putting a long screwdriver in the spark plug hole and rotate the motor to see its highest position. I checked the timing again (its dead on). I dug deeper into the electrical system. I checked that I get voltage spikes from the stator, rectifier, and condenser. Unfortunately, my multimeter is just a handyman’s so it doesn’t hold the peak voltage, and takes the RMA so the spikes are lower than expected. However, I do see a spike in voltage for each of the electrical components listed above. I grabbed a GYTR programmer and connected it to the bike, No trouble codes showed. I checked the timing again (its still dead on). I continued looking into the fuel system. I set up a system to clean the injector with brake cleaner and a 9 volt battery, spraying cleaner into the fuel nipple and pulsing the injector. It sprays a large good mist, and did from the first spray. I then pulled the tank and connected the 9 volt battery to the fuel pump and can hear it spin. Checked the TPS with the GYTR programmer and shows no errors (throttle 5 deg at 0 and 88 deg at open I know I can adjust this better, but should not be a no start issue). I kicked 150 or so times. Variation of throttle open, closed, mid, Cold start open, closed….nothing. I pulled the plug and the plug shows only a little wet residue on the furthest parts from the electrode. The piston has a sheen of fuel when you shine a light down. The fuel line is not pinched, and you cannot squeeze the line, which is telling me the fuel pump is working, and the injector is spraying fuel. I also disconnected the fuel to injector connection and fuel sprayed like it was under a significant amount of pressure. As I was using compressed air (about 50 psi) to blow out the residual fuel from the top off the piston, I noticed air blowing out the exhaust. I rotated the motor to TDC, checked the timing, and blew again, still a bit of leak by…..ahhh leaky valves causing leak by and not allowing spark. I verified the valve clearance and it was still right in spec. Phase 2 So I pulled the head off to pull apart the valves. I found a bit of carbon buildup on the valves, and assume that during the cleaning, some of the carbon deposits were removed, and others weren’t which masked the valve clearance and sealing. Looking at my head, it needs seats to be cut and new valves. Fortunately, I know someone at Yamaha, and I had a spare GYTR head sitting in a box with 0 hours on it.....same part number as my existing one. I assembled the head, checked the valve clearance and timing. Rotated the motor lightly, and checked the timing and valve clearance again and chain tension. I kicked the motor over a few times, and checked the timing and valve clearance again. I also checked the timing chain tension, and the tensioner is doing its job. Assembled everything back together…….and still no spark…..WHAT the hell!!??!?! Checked the spark, and I still have spark. I tried spraying starter fluid in the intake and kicking….nothing. Sprayed starter fluid in the spark plug hole and then install the spark plug, still nothing. I checked the timing again, still dead nuts on. Had two other people verify the timing. I tried bump starting it, it sounded like bump starting a 2T with a fouled plug, just bog, bog, bog, wheel lock. Since there was absolutely no sputter, or sound of life with starter fluid, I’m thinking that it’s a electrical issue or a spark issue when the spark plug is attached to the motor. Thinking it might be a grounding issue, I pulled the ground wire off the frame (it looks as clean as the day it was installed), and reinstalled it. Still nothing. I am getting a fairly bright blue spark when grounded to the frame. I double checked the gap, and also tried a new plug....still nothing. I am now at a loss and feel like a retard. I really want to get back and ride some moto. I have talked with Yamaha on the phone a few times, and have helped me thus far. They have been great, but I'm a stubborn engineer, and would prefer to fix this on my own. I'm thinking the next steps are pulling the fly wheel and check the key (although I would think that verifying that TDC with the location of the mark on the fly wheel would prove this is accurate). Then replacing the Condenser, Stator, and/or ECU, then cam position sensor. I apologize for the extra long post, and have read and searched here and Vital (yes I saw the TPS thread on the 2015 YZ250F). Are there any other directions I should try, any other things I'm missing?…or should I give up and send it into a shop/dealer to diagnose? Thank you Joe
  11. joeprunc

    MSR NXT Riding Gear

    I'm an average Joe. I primarily ride/race motocross 30+ C class, but still enjoy getting out in the woods with the right crew. I wear Astricks knee braces, so maybe I'm a bit harsher on my gear. I only buy clearance gear, and currently have MSR, Troy Lee, Fox, One, and KLIM gear. I have a pair of MSR NXT gear from 2009 that I love and still wear. Its actually been so good that in 2015 I was looking for some new stylish gear, and bought another pair of MSR NXT pants and jersey. I have maybe 5 rides and two races on the gear. There are holes in both leather inner patches so large I can fit a baseball through them. I only cold wash, and air dry all pants and gloves. My old pair of NXT pants probably have seen 60 hours of riding have been washed atleast 30 times, they have been through the ringer and still do not have any holes, hell even the stitching is holding together (for the most part). They do fit great, not big a baggy like ONE, not too tight like Fox, they fit me (5'-8" 160 lbs) perfectly. But they fell apart so quickly that unless given a new model to try from MSR, I will not be purchasing anything from them. Sorry to be a bumper to the review, and hopefully it was just one bad batch. Photo: First few rides on it...Zaca Station
  12. joeprunc

    Anderson and altitude

    Was doing some research on racing the Mammoth MX next year, and I have heard that it takes 3 weeks to properly acclimate to the altitude. Most people have stated that showing up a day or two before the race is better than being in the altitude for 6-10 days. As 6+ days later your body is trying to acclimate, and does not normalize until a few weeks in.
  13. joeprunc

    The wrench tossed into the chapionship.

    Now the question is where would the chase series have had to start to have a good battle for the championship at Vegas?....I don't know the answer myself, but figured someone here might have already looked at that.
  14. joeprunc

    New supercross format.

    I like the long show....I usually drag it out over the next work week, get to watch a little at a time. If I do watch it live, I am sure I have a can or three of Monster, helps with snoozing
  15. joeprunc

    Is the 2016 GYTR Yamaha YZ450F too fast?

    I agree a GYTR setup for a 450F is a bit overkill. But I race a 250F against 450F, so having the additional power is nice. The cams are different which allow more power at the higher RPMs which are easier to get to on a 250F. I had a 2010 with and without a GYTR head and can tell you the head added a bit of extra seat of the pants hp (or maybe it was the FMF sticker i put on the rear fender). I'm now on a 2014 YZ250F and have the GYTR head and love it, even more power than the 2010, plus the FI is nice. I've ridden my brothers 2015 YZ450F, and it is stupid fast. I just got to ride a 2016 YZ250F with all the GYTR goodies, and its significantly more powerful than my bike.
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