03 yz450 no first gear??


5 replies to this topic
  • sdunshee

Posted December 04, 2008 - 08:16 AM

#1

My buddy has a 03 yz450 that has no first gear. Take off in first and it clanks and neutrals out and then slams back into gear. I haven't ridden it but other people can verify it. Anyways....he brought the bike to my house he pulled the motor and tore it down. Only thing he saw was a nut that had come loose on the gear that is turns the clutch basket gear. He is determined that was the problem I told him it might have had something to do with his knocking noise but not the trans. Didn't see anything wrong with the tans gears(stripped teeth) so after doing some searching it sounds like a shift fork problem. Does this seem correct?? Where is the 1st gear set located in the trans?? I will look at it tonight for signs of wear on the gears/dogs from slamming in/out gear. My buddy is still dead set on the loose gear causing the problem, I respectfully disagree though. Any thoughts?? Also need to locate a good used RH case(the one the clutch cover bolts to) as the loose gear damaged it pretty good if anyone has one layn around.

  • 426 NOOB

Posted December 04, 2008 - 10:15 AM

#2

My buddy has a 03 yz450 that has no first gear. Take off in first and it clanks and neutrals out and then slams back into gear. I haven't ridden it but other people can verify it. Anyways....he brought the bike to my house he pulled the motor and tore it down. Only thing he saw was a nut that had come loose on the gear that is turns the clutch basket gear. He is determined that was the problem I told him it might have had something to do with his knocking noise but not the trans. Didn't see anything wrong with the tans gears(stripped teeth) so after doing some searching it sounds like a shift fork problem. Does this seem correct?? Where is the 1st gear set located in the trans?? I will look at it tonight for signs of wear on the gears/dogs from slamming in/out gear. My buddy is still dead set on the loose gear causing the problem, I respectfully disagree though. Any thoughts?? Also need to locate a good used RH case(the one the clutch cover bolts to) as the loose gear damaged it pretty good if anyone has one layn around.


That is definitely the problem. The forks and dogs are most likely worn and possibly the gears. I know that if you replace one gear you also have to replace the gear that is on the same shaft or something like that. Like 1st and 3rd. Dont quote me though. Grayracer will know exactly what gears need to be replaced together. This is not an uncommon problem.

  • grayracer513

Posted December 04, 2008 - 11:32 PM

#3

You're right, your buddy's wrong.

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  • sdunshee

Posted December 05, 2008 - 05:31 AM

#4

Thats what I figured, now I have to convince him to purchase the right parts. Would it be best just to do both shift forks since the motor is apart anyways? Exactly what gears need replacement? Thanks again

  • black_dog

Posted December 05, 2008 - 05:41 AM

#5

Thats what I figured, now I have to convince him to purchase the right parts. Would it be best just to do both shift forks since the motor is apart anyways? Exactly what gears need replacement? Thanks again


Does sound like worn dogs. 1st gear is made up of the smallest cog in the input shaft and the largest cog on the output shaft.
One of those will have a sliding dog which engages into it. It is those two components which will need replacing.
Worn dogs that are jumping usually bends the respective selector fork too so you'll need that as well.:thumbsup:

  • sdunshee

Posted December 05, 2008 - 07:25 AM

#6

Cool. Thanks for all the help guys.





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