All Things Moto! Dirtbike Forums

Go Back   All Things Moto! Dirtbike Forums > Dirt Bike - ATV - Suspension Forums > 4-Stroke Dirt Bike Bike Forums > 4-Stroke Dirt Bikes - Yamaha

Reply
 
LinkBack Thread Tools
  #1  
Old 07-17-2016, 05:29 AM
Welcome To ATM
 
Join Date: Jul 2016
Last Online: 08-03-2016 04:32 AM
Location: Alaska
Posts: 3
Default 1999 YZ400F Seized, freed up, seized again

     

Okay, so i bought a 1999 yz400f without knowing what it was for one, because the owner told me it was 250f, it was a very solid bike, good compression, strong bottom end, only had 4 gears? dont know why but i didnt question it, ran perfect(only small flaw was the exhaust clamp wasnt on, so between the header and muffler it pushed black exhaust out of the jug and leaked but i didnt think anything of it because it ran good), never even got to making my first oil change on it which i regret doing as soon as i got it, i rode this bad boy around for about 2-4 weeks straight everyday (yes yes i know dumb idea without maintenance) but i was in love, it beat everyone elses 450f's, and was the baddest bike of them all, truly was the thump heard around the world. However, my love for this bike is not what we the people are here to discuss, i was riding one day to my friends house,(15 and this is how i commute), and all of a sudden i lose power and my rear tire locks up, i roll to the nearest gas station on the side of the road, and attempt to kick it over again not knowing what the heck just happened. kicks over 3 or 4 times then locked up completely. so i had my buddy bring it back to my house in the back of his truck, i let it sit around in my shed for a week due to me pricing out parts for this 400f(dont get mad, was my first dirtbike that i bought so i didnt know how to tell what was what), i guess i was blessed and bought a very healthy very rare bike, the 1999 YZ400F. thats right, not the problem-filled 1998 version, the stronger more improved 1999! i go look at the bike a week later and am playing with the kick starter, and it freely moves again, i was shocked, i was filled with joy and could not believe my eyes, i hopped on it and attempted to kick it over about 125-150 times before it finally started, i rode it up and down my street(it had all the power it did before it seized) and rode good for about an hour, i rode over to my friends house again to show them so i could prove i wasnt dreaming, but then the second time i started it, rode it out of my friends driveway, i heard a big *clunk* coming from the back lower end of my engine, i continued to drive thinking it was a rock or something hitting my frame or another piece of metal on my bike, and i was already late to get home, and next thing you know i pull in the clutch, lose power, and it seized up again, i waited another 30 minutes of walking this heavy monstrosity down the trail towards my house, and it kicks over again! what the heck right? i got it to start once more, then it did the same thing, i gave up and got home and put it in the shed to hopefully never look at it again, i was so frustrated, i now moved into a new house so it had some time to sit, still locked up, i looked in the oil fill and there is metal shavings, 2 months later it still will not kick over, i drained the oil and saw how clogged the filter was, along with the air filter, mind you this was my first ever time doing any sort of maintenance to the yz, i dont want to go ripping out the engine without anything to look for, i cant not find anyone with the same problem for my bike, and hard to find rebuild kits, seems like my only options are buying a whole new engine ($1350 on ebay) or buying a whole bottom end ($400-600) on ebay for the bike and swapping the damaged parts, i need outside knowledge if anyone has had this happen to them or can lead me in the right direction on to what happened.
Reply With Quote
  #2  
Old 07-17-2016, 05:39 AM
ATM! Pro Class
 
Join Date: Jul 2011
Last Online: Yesterday 07:42 PM
Location: Benton, LA
Posts: 4,925
Default

Most likely thing is the crank/rod bearings have seized due to poor lubrication. If that is the case you will find other damaged parts as well when you tear it down. There will most likely be cam journal damage, which will require a new head. You are looking at a very expensive rebuild.

Paw Paw
Reply With Quote
  #3  
Old 07-17-2016, 05:10 PM
Welcome To ATM
 
Join Date: Jul 2016
Last Online: 08-03-2016 04:32 AM
Location: Alaska
Posts: 3
Default

well, i appreciate your knowledge and help. I most likely am going to buy the new engine so i dont have to spend hours and hours and money to replace the damaged parts and hope it runs again, any guesses why it only had 4 gears? its mind boggling to me
Reply With Quote
  #4  
Old 07-17-2016, 07:24 PM
ATM! Pro Class
 
Join Date: Jul 2011
Last Online: Yesterday 07:42 PM
Location: Benton, LA
Posts: 4,925
Default

It was a 5 speed from the factory, but maybe something in the drive train failed.

Paw Paw
Reply With Quote
  #5  
Old 07-18-2016, 03:22 AM
Intermediate Class
 
Join Date: Sep 2009
Last Online: 01-08-2018 02:50 AM
Location: Greece
Posts: 198
Default

yup as PawPaw said it looks from the schematics to be 5speed.

anyhow now it is late but you must always check before every ride that the oil level is right. on your new engine after the first full tank change the engine oil & filter.
Reply With Quote
  #6  
Old 07-18-2016, 09:11 AM
cowboyona426's Avatar
JOATMON
 
Join Date: Feb 2003
Last Online: 11-15-2018 11:27 AM
Location: Newport, WA, USA
Posts: 9,495
Default

The reason it was locking up was probably a bad lower rod bearing, but with metal shavings in the oil and only 4 gears you definitely have other issues going on. Keep in mind if you buy a used engine, you may not be any better off than where you started to begin with. My suggestion would be to buy a good service manual, tear it down and see what is going on for yourself and learn how to rebuild what you have so you know what's going on inside there.
Reply With Quote
  #7  
Old 07-18-2016, 09:15 AM
ATM! Pro Class
 
Join Date: Jul 2011
Last Online: Yesterday 07:42 PM
Location: Benton, LA
Posts: 4,925
Default

Quote:
Originally Posted by cowboyona426 View Post
The reason it was locking up was probably a bad lower rod bearing, but with metal shavings in the oil and only 4 gears you definitely have other issues going on. Keep in mind if you buy a used engine, you may not be any better off than where you started to begin with. My suggestion would be to buy a good service manual, tear it down and see what is going on for yourself and learn how to rebuild what you have so you know what's going on inside there.
X2

Paw Paw
Reply With Quote
  #8  
Old 07-22-2016, 03:10 AM
Welcome To ATM
 
Join Date: Jul 2016
Last Online: 08-03-2016 04:32 AM
Location: Alaska
Posts: 3
Default

UPDATE: ran the vin, it is a 03 450f, which came with 4 gears from the factory, i pulled the engine from the bike, one intake valve was loose, cam chain did not move, so im still thinking crank seized. no metal shavings came out in the oil, i saw very few at the bottom of the case with a flashlight, i was debating buying a case splitter online, or letting a shop rebuild it, hot rod crank, rod, namura piston, hot rod stage 2 cams, good gaskets, any reason the crank seized? cylinder wall looks good with no scratches, valves are black along with top of piston and spark plug, but looks cleanable, gears still shift, can anyone lead me in the right direction on what to do with it? rebuild? if so what parts? only new crank bearings?
Reply With Quote
  #9  
Old 07-22-2016, 07:39 AM
arnego2's Avatar
Expert Class
 
Join Date: Mar 2008
Last Online: 01-09-2018 03:14 PM
Location: Porlamar
Posts: 762
Default

I'd go for a rod kit, both crank bearings, piston and maybe a gasket kit for the topend, plus the case splitter No one works better on your bike than yourself, with a few exceptions.
Reply With Quote
  #10  
Old 07-25-2016, 10:30 AM
cowboyona426's Avatar
JOATMON
 
Join Date: Feb 2003
Last Online: 11-15-2018 11:27 AM
Location: Newport, WA, USA
Posts: 9,495
Default

So is it actually an 03, or did someone put an 03 motor in the 99 frame?
If the lower rod bearing is locking up, the crank will not move and that's why the cam chain will not move either. Crank issues are not very common on the Yamaha's. Stop trying to guess and split the cases and find out for sure, I still stay lower rod bearing.
Splitting the cases can be done without a case splitter, but the splitter will make life easier. On the Yamaha they have little tabs on the crank case you can use to help coax the case halves apart, but it's tedious and time consuming. The splitter is a good investement, I bought the Tusk one and have no complaints. You can all use an automotive steering wheel or harmonic dampener puller, usually can be had a bit cheaper.
Reply With Quote
Reply

  All Things Moto! Dirtbike Forums > Dirt Bike - ATV - Suspension Forums > 4-Stroke Dirt Bike Bike Forums > 4-Stroke Dirt Bikes - Yamaha


Thread Tools


Similar Threads for: 1999 YZ400F Seized, freed up, seized again
Thread Thread Starter Forum Replies Last Post
02 yz 250 seized not sure what I want to do with it sammittrue 2-Stroke Dirt Bikes - Yamaha 13 08-30-2015 09:44 AM
CR 250 Seized!!! DH32 2-Stroke Dirt Bikes - Honda 6 08-05-2010 01:28 PM
Rm 125 seized need help...... hoytproshooter 2-Stroke Dirt Bikes - Suzuki 5 12-15-2007 05:47 PM
YZ 125 seized? mbogosia 2-Stroke Dirt Bikes - Yamaha 33 08-17-2007 02:17 PM
Seized... SirFallsALot243 General Discussion 44 04-08-2004 09:29 PM


All times are GMT -6. The time now is 06:59 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright ©2002-2017, JDub Consulting, Inc. All Right Reserved.