Page 1 of 2 12 LastLast
Results 1 to 10 of 14

Thread: 400ex engine noise.

  1. #1
    Join Date
    Sep 2007
    Location
    NW, PA
    Posts
    2,171

    400ex engine noise.

    So in regards to my previous thread, i had my 400 rebuilt. 11:1 wiseco, stg2 hot came, crf timing chain, new valve-train. it runs, and runs good. But it makes a weird noise. not im not talking about the valve tick (which got louder from the stg 2 came. which i expected). its making a weird knock noise from the bottom end.

    at first i though it might either be a rod bearing or or a crank bearing, but it 1) doesnt do with when its cold, only after it warms up, and 2) if it was a crank or a rod bearing, i would expect it to get a lot worse as the motor climbed through the RPM's but it doesnt. i cant hear the noise anymore once its on the throttle.

    i embedded a video i took of the motor running. the noise that i feel as a knock is not as loud in person as it is in the video (taken with a galaxy note 3). I dont know if this noise was there before and its louder now because of the more aggressive cam? or it was there and now im just over analyzing any small noise cause i just rebuilt this. My builder checked the crank and doesnt think it was bad and thinks it cause of the more aggressive cam and because the jetting was lean.

    anyone else ever hear a noise like this?

    thanks for any input you guys can give me

    "Not all girls with tattoos are sluts, but every slut has a tattoo"

    2005 400ex / HMF Performance Slip on/ Uni with no lid / trail tech clamps with tusk fat bars /Cyrca hand guards/ ODI ruffian lock ons / Kenda Kutter XC's /DWT Rock'n'Lock fronts with DWT G2 rears/ Tusk fat peg nerfs / Bling Star Iron Cross/Jet Stealth shock conversion 450r front shocks/ gregs atv rear shock with gtt xc link/ CCP steering stabilizer/GTT swing arm skid

  2. #2
    Join Date
    Aug 2008
    Location
    Central NJ
    Posts
    11,326
    Yep, I had a similar sound awhile back.

    Turns out the cam was moving around in the head because oneof the dowel pins had had trouble going in and I had persuaded it slightly. Well turns out the hole was slightly out of round and the pin came out. Cam was rocking all around in there. Timing chain was also ruined and kinked like crazy. Id pull the valve cover and verify everything is good first.

    I also had a wicked vibration develop before or during the same time, quad would vibrate so much your hands would hurt after awhile. Crank was def on its way out.
    If it's stupid, and it works, it isn't stupid. - Murphy's Law
    2000 426EX,sold
    2004 450R WIP
    -Longtime A.A.D.S. (Accessory Acquisition Disorder Syndrome) sufferer.
    400EX Frequently Asked Questions, CHECK HERE FIRST!

  3. #3
    Join Date
    Sep 2007
    Location
    NW, PA
    Posts
    2,171
    Quote Originally Posted by CJM View Post
    Yep, I had a similar sound awhile back.

    Turns out the cam was moving around in the head because oneof the dowel pins had had trouble going in and I had persuaded it slightly. Well turns out the hole was slightly out of round and the pin came out. Cam was rocking all around in there. Timing chain was also ruined and kinked like crazy. Id pull the valve cover and verify everything is good first.

    I also had a wicked vibration develop before or during the same time, quad would vibrate so much your hands would hurt after awhile. Crank was def on its way out.

    so what did you do to check it mark? or how long did it take you to find out? and like cam was literally walking balk in forth in the cam journals? this sound doesnt come from the head though. it comes from the crank. but i can truly determine where at in the crank case it is coming from.
    "Not all girls with tattoos are sluts, but every slut has a tattoo"

    2005 400ex / HMF Performance Slip on/ Uni with no lid / trail tech clamps with tusk fat bars /Cyrca hand guards/ ODI ruffian lock ons / Kenda Kutter XC's /DWT Rock'n'Lock fronts with DWT G2 rears/ Tusk fat peg nerfs / Bling Star Iron Cross/Jet Stealth shock conversion 450r front shocks/ gregs atv rear shock with gtt xc link/ CCP steering stabilizer/GTT swing arm skid

  4. #4
    Join Date
    Aug 2008
    Location
    Central NJ
    Posts
    11,326
    Well the thing was I figured it was something related to going swimming in a lake with my 400 so I said F it and let it go ben. When I finally dug into it about 3 months later (it sat most of the winter) and found the timing chain bad and so forth. The cam was basically walking int he journals but surprisingly it didnt do any damage to anything. You could see slightly where the one pin had come out on that side and the cam made very minute marks but they were deep or bad.

    I too though that it was the bottom end, did the old screwdriver trick and found it in the head however. Noises can be deceiving ya know.

    Does it vibrate at all? Clearances were all good when assembled? Did you put it together or someone else? Crank bearings checked/seemed fine?

    I suppose overall I coulda looked into it earlier, but I didnt really care since I was mostly riding my 450.
    If it's stupid, and it works, it isn't stupid. - Murphy's Law
    2000 426EX,sold
    2004 450R WIP
    -Longtime A.A.D.S. (Accessory Acquisition Disorder Syndrome) sufferer.
    400EX Frequently Asked Questions, CHECK HERE FIRST!

  5. #5
    Join Date
    Jul 2013
    Posts
    366
    My 400 made a similar noise I just thought it was another special trait the came along with the 400ex motors
    2006 450r 24v Kickstart
    Ars-fx Exit Lonestar Precision Hmf Baldwin Web cams Rekluse
    Hiper Fasst flexx Cycra Prm Quad Tech Houser Gt thunder
    Bling star IMS Fluidine Rad Bare performance Streamline Gbc

    05 450r
    Hotcams Pro Armor Gt Thunder ArsFx Custom Axis Houser White Bros
    PRM Hiper Gbc Fasst Flexx IMS

  6. #6
    Join Date
    Sep 2007
    Location
    NW, PA
    Posts
    2,171
    Quote Originally Posted by CJM View Post
    Well the thing was I figured it was something related to going swimming in a lake with my 400 so I said F it and let it go ben. When I finally dug into it about 3 months later (it sat most of the winter) and found the timing chain bad and so forth. The cam was basically walking int he journals but surprisingly it didnt do any damage to anything. You could see slightly where the one pin had come out on that side and the cam made very minute marks but they were deep or bad.

    I too though that it was the bottom end, did the old screwdriver trick and found it in the head however. Noises can be deceiving ya know.

    Does it vibrate at all? Clearances were all good when assembled? Did you put it together or someone else? Crank bearings checked/seemed fine?

    I suppose overall I coulda looked into it earlier, but I didnt really care since I was mostly riding my 450.

    well i had someone else build the motor for me this time due to the cold and my lack of a heated garage. but the guys that built it are knowledgeable and have been building MX motors for awhile so.

    theres no vibration that i can tell of. i figured if it was a crank bearing, it'd be vibrating like a CR500 ro another big bore 2smoke. and the noise is not noticable as soon as you give it any RPM's past idle. When you start giving hte motor gas, all you can hear is the motor and the cam tick from the more aggressive came.

    been talking with the guys that did the motor. one of them is gonna look at it this weekend. we're wondering if it has anythign to do with the CRF cam chain being wider than the stock 400ex cam chain. we're also wondering if it has anything ot do wiht the break in period on the cam. The hot cam instructions state that it requires 30 mins of actual "ride" tiem break in time. i may have about 20 minutes total on the motor since its been put back together.

    the other idea we had is it may have somethign to do with teh cam chain tensioner since we didnt replace it during the build.

    either way, this weekend im gonna tear the head off and inspect teh cam/cam chain/cam journals/head dowels and see what i can come up with.
    "Not all girls with tattoos are sluts, but every slut has a tattoo"

    2005 400ex / HMF Performance Slip on/ Uni with no lid / trail tech clamps with tusk fat bars /Cyrca hand guards/ ODI ruffian lock ons / Kenda Kutter XC's /DWT Rock'n'Lock fronts with DWT G2 rears/ Tusk fat peg nerfs / Bling Star Iron Cross/Jet Stealth shock conversion 450r front shocks/ gregs atv rear shock with gtt xc link/ CCP steering stabilizer/GTT swing arm skid

  7. #7
    Join Date
    Sep 2007
    Location
    NW, PA
    Posts
    2,171
    Quote Originally Posted by LxMxL97 View Post
    My 400 made a similar noise I just thought it was another special trait the came along with the 400ex motors
    ever have any problems from it?


    see thats what i thought. i dont know if its been a noise thats always been a part of it and im just now noticing it and being a hypocondriac lol..or if its something new.
    "Not all girls with tattoos are sluts, but every slut has a tattoo"

    2005 400ex / HMF Performance Slip on/ Uni with no lid / trail tech clamps with tusk fat bars /Cyrca hand guards/ ODI ruffian lock ons / Kenda Kutter XC's /DWT Rock'n'Lock fronts with DWT G2 rears/ Tusk fat peg nerfs / Bling Star Iron Cross/Jet Stealth shock conversion 450r front shocks/ gregs atv rear shock with gtt xc link/ CCP steering stabilizer/GTT swing arm skid

  8. #8
    Join Date
    Nov 2010
    Posts
    1,657
    nothing on that vid sounds out of normal to me. I can't really hear it over the pipe though. the tick is louder than i like, i know everybody says these things tick ,but both my 400's i've been able to make quieter than what i'm hearing in your video. Many times when people say the tick is normal, there's often cases where it's adtually a tick from something like the cam chain, or the dowels like CJM mentioned. I would make sure your tensioner is working as well. What fuel are you running with the 11:1? You might want to consider going up to a higher octane if you're getting detonation it will knock.

  9. #9
    Join Date
    Jul 2013
    Posts
    366
    Quote Originally Posted by ben300 View Post
    ever have any problems from it?


    see thats what i thought. i dont know if its been a noise thats always been a part of it and im just now noticing it and being a hypocondriac lol..or if its something new.
    I only had the motor for about 35-40hrs of total ride time but it ran great and pulled strong never had a problem I say pull the valve cover since it's very easy check the dowels make sure they are there but I wouldn't go any deeper in the motor I would just run it how it is
    2006 450r 24v Kickstart
    Ars-fx Exit Lonestar Precision Hmf Baldwin Web cams Rekluse
    Hiper Fasst flexx Cycra Prm Quad Tech Houser Gt thunder
    Bling star IMS Fluidine Rad Bare performance Streamline Gbc

    05 450r
    Hotcams Pro Armor Gt Thunder ArsFx Custom Axis Houser White Bros
    PRM Hiper Gbc Fasst Flexx IMS

  10. #10
    Join Date
    Sep 2007
    Location
    NW, PA
    Posts
    2,171
    Quote Originally Posted by 2001400exrida View Post
    nothing on that vid sounds out of normal to me. I can't really hear it over the pipe though. the tick is louder than i like, i know everybody says these things tick ,but both my 400's i've been able to make quieter than what i'm hearing in your video. Many times when people say the tick is normal, there's often cases where it's adtually a tick from something like the cam chain, or the dowels like CJM mentioned. I would make sure your tensioner is working as well. What fuel are you running with the 11:1? You might want to consider going up to a higher octane if you're getting detonation it will knock.

    ya, the tick is a little loud, but i attribute that to three things 1)crf cam chain, 2) the stage 2 cam, and 3) the valves need to be readjusted after break in (which i planned on doing)


    im gonna check the tensioner and the dowl pins. liek i said. the knock or the "boop boop boop boop" as my buddy calls it doesnt get louder, adn its actually louder in the video than it is in real life.



    and as for fuel. when i initially fired it up, i was running some bad gas and i believe i was having some detonation. yesterday i drained the tank completely and put in a mixuture of 2.5 gallons of vp 110 and sunnoco 93 (both sold at a gas station owned by guys that run big block mods). i calculated it gives me in the ball park of 102 octane which i feel confident running at 11:1 compression.

    my builder says he wants me to see what it sounds like with a larger pilot jet in it and that it might be to lean. it probably was. i ahve not changed jetting yet and am running a 40 pilot.

    so its like, if i can find anything in the head, do i do what LxMxL97 says and just not worry bout it till something actually happens? which something may never happen?
    "Not all girls with tattoos are sluts, but every slut has a tattoo"

    2005 400ex / HMF Performance Slip on/ Uni with no lid / trail tech clamps with tusk fat bars /Cyrca hand guards/ ODI ruffian lock ons / Kenda Kutter XC's /DWT Rock'n'Lock fronts with DWT G2 rears/ Tusk fat peg nerfs / Bling Star Iron Cross/Jet Stealth shock conversion 450r front shocks/ gregs atv rear shock with gtt xc link/ CCP steering stabilizer/GTT swing arm skid

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •