99wr400f engine lock-up


14 replies to this topic
  • haimesyboi

Posted May 04, 2006 - 06:27 AM

#1

bike ran great all day, then there where a couple small jerks from the bike, but kept running normally, then a minute later, in first gear the engine completely stopped. i thought whoops ive stalled :crazy: , but i went to kick her over agen as usual and, the starter was rock solid, it is possible to force the piston through the whole cycle, as one of my "friends" kindly showed me by stamping on the starter :ride: there is not a particular hard spot which stands out in the cycle, also ive found the allen bolts on the cam cover were nicely rounded out by the previous owner, whats the best thing i can do about this?? im kinda hoping its somethin to do with the camchain/tensioner, as i doubt it has ever been replaced, im just hoping its not a buggered piston/cylinder/head/valves :ride: any ideas????????? thanks

  • 5valve

Posted May 05, 2006 - 12:24 PM

#2

Open up and inspect.

  • OlaGB

Posted May 05, 2006 - 01:24 PM

#3

You have to take of the top end, inspect, and then pull the cylinder if nothings wrong on the top end..

My guess is that it has something to do with the piston..

Easy fix, not so expensive either.. Cost a little if the cylinder has to be changed out though..

Pull it to pieces, to inspect..

  • 1rkcooper

Posted May 05, 2006 - 08:38 PM

#4

When you get the head off check and see if the valves are seating. You can fill the intake port with clean solvent and see if it leaks through the valves, do the same on the exhaust port side. If they don't leak then it must be lower down, rings & piston.

Good luck

  • bluebike1999

Posted May 06, 2006 - 02:57 AM

#5

please keep us informed as to what it is.
you may notice there is two almost identical posts regarding 400's locking up.
hope this isnt a trend developing.

  • haimesyboi

Posted May 07, 2006 - 09:11 AM

#6

pulled the cam cover, both cams appear to be fine, cam chain looks fine, putting in a new one anyway, when i pull the head and check for the seating of the valves, does it matter if the cams are not in place?? if my piston is shot, is it worth buying a high comp one, what are the benefits over standard? thinkin about a hotcam aswell while im hear with auto-decomp yay what u reckon? im hoping to see perfect valves, a shot piston, but a reusable cylinder, what do u reckon my chances are :crazy:

  • OlaGB

Posted May 07, 2006 - 10:50 AM

#7

It takes you approx 0.5 hours to find it out yourself, without having to guess whats wrong..

To inspect the valve sealing, the camshafts dont have to be mounted :crazy:

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  • 1rkcooper

Posted May 07, 2006 - 03:15 PM

#8

When my 400 locked up it made a rattling noise and died, dead, locked up, absolutely no movement. I was so scared of what I was going to find that I didn't take it apart for a week. One of the valve heads broke off and bent all the rest of the valves as well as wrecking the piston, head and the torque actually twisted the rod. The only part that wasn't damaged was the cylinder and I don't know how it wasn't. One big mess of the motor.
I hope yours isn't that bad.

You still have movement so that is a good sign.

Good luck

  • flatnacker

Posted May 07, 2006 - 03:40 PM

#9

Did it still run after this happened? Sounds exactly like what happens to my bike at least once every ride-it stalls and locks solid, have to put all my weight on the starter and wait for the pressure to gradually decrease, then I can kick her over as per normal and she runs fine. Kinda had me scared at first but its been doing it for over a year now with no ill effects-Im guessing its some wierd compression lock or something?

  • haimesyboi

Posted May 09, 2006 - 08:28 AM

#10

ok, i pulled the head, nothing was wrong so i was like oh the piston must be mashed up,,,, nope the cylinder popped right off, piston was nice n shiny perfect condition, oh dear, the con rod is locked kinda stifly to the camshaft, i have a little play but then it locks right up. is this simply the big end bearing is destroyed? is there anywhere i can buy the new bearing on its own, which will post to the uk? or do i have to buy a connecting rod kit with the bearing in it? how easy is it to change the bearing in the crank? or do i have to take it to a workshop to be replaced? :crazy: gonna start splitting the engine i guess.......

  • 5valve

Posted May 09, 2006 - 10:09 AM

#11

Yes, splitting cases, replacing both cranck bearings, conrod bearing-worshop job absolutely
note, that con rod connects to cranckshaft, not camshaft.

  • OlaGB

Posted May 09, 2006 - 10:15 AM

#12

:ride: That sucks :ride:

My small end bearing in the rod was the problem in my bike (no not similar problem, but sort of interesting for you to know?)

I checked up the rod and rod bearing prices, and cost of work to take apart the crank to change the rod, and calibrate the crank again.. I ended up changing the complete crank.. The crank costs around 300$.. Plus another 60 or so for the main bearings since you already are splitting...

The rod should probably be changed out anyway since you had serious problems there.. And its easyer to just change out the complete crank, than sending it to a workshop with a bag of parts along with it.. Who knows, perhaps the guy that`s going to do the work (pressing, calibrating etc) was up late last night, drinking :crazy:

To look for parts costs, take a look here:

http://www.yamahaaccy.com/parts.aspx

  • chancho196

Posted May 09, 2006 - 01:01 PM

#13

Let us know how you get on. Better keep an eye on mine!!

  • bluebike1999

Posted May 09, 2006 - 02:18 PM

#14

make sure you get a quote here before you part with$

http://www.jp-parts.com/index.html

all genuine, direct from japan at about half dealer costs.
good luck

  • 2wheels-drz

Posted May 14, 2006 - 01:48 PM

#15

Did it still run after this happened? Sounds exactly like what happens to my bike at least once every ride-it stalls and locks solid, have to put all my weight on the starter and wait for the pressure to gradually decrease, then I can kick her over as per normal and she runs fine. Kinda had me scared at first but its been doing it for over a year now with no ill effects-Im guessing its some wierd compression lock or something?



not using ur decompression lever? or else theres a problem with the decompression mechanism on your bike.




 
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