MNSBR: Yz250F - Rebuild Or Part Out? - MNSBR

Jump to content

Page 1 of 1
  • You cannot start a new topic
  • You cannot reply to this topic

Yz250F - Rebuild Or Part Out? Plus some other "I blew my shit up" questions

#1 User is offline   wotan Icon

  • Shot out of a cannon > squeezed out of a tube.
  • PipPipPipPipPipPipPipPip
  • Group: Member
  • Posts: 2,436
  • Joined: 12-May 05
  • Location:hud-town, wisconsin
  • Ride:Aprilia RSV

Posted 02 May 2016 - 09:14 AM

I bought this 2005 YZ250F last year for a song. It was pretty beat but since it was my first bike and I'm fairly handy, I thought I'd start there. I rebuilt the carb and cleaned it up and fixed some little issues here and there. It's impossible to start, though. Once running and warm it was riding OK, but I would kill it on the trail and spend the next hour either kicking it or pushing it up hill to bump start it. Total nightmare.

Last weekend it died and I ended up pushing it for an hour. It was running really, really hot. When I got home, I opened the drain on the water pump and all that came out was oil (black, good looking oil.... not frothy or contaminated at all!) Any thoughts on what this means or what I blew?

I compression tested it and after seeing only 60lbs decided I better start tearing it down for a rebuild. Now I realize that with the auto-decomp it might be possible that I was seeing correct compression after all? Is there a way to accurately compression test these?

Last question -- I'm not into this bike for much and I'm ready to just ditch it and buy one that I know will be reliable. Is it going to be better financially to rebuild it and sell it -- or should I just part it out?
0

#2 User is offline   miweber929 Icon

  • Runnin' with the devil
  • PipPipPipPipPipPipPipPipPipPip
  • Group: Member
  • Posts: 3,308
  • Joined: 28-September 06
  • Gender:Male
  • Location:Woodbury
  • Ride:'14 Thruxton, '14 CBR650F, '13 Kymco Super 8 150, '11 Sprint GT, '04 WR450F

Posted 02 May 2016 - 09:33 AM

Personal opinion here but little 4 stroke motocrossers get the shit beat out of them so if you are looking at buying another used one I would simply rebuild yours instead as you then know what you got. If everything else works for you and is solid, with a nice big bore and a new water pump (my guess is your seal is shot from your description) you'll have a nice bike.
0

#3 User is offline   TLRSKUNK Icon

  • I Should really edit this.
  • PipPipPipPipPipPipPipPipPipPipPip
  • Group: Member
  • Posts: 4,935
  • Joined: 29-April 08
  • Gender:Male
  • Location:Lakeville, MN
  • Ride:16 R1 60th Anniversary, 2010 YZ450 Sumo/dirt, 15 Grom

Posted 02 May 2016 - 09:41 AM

only way to test due to auto decompression is a Leak down test. (from what i was told on my 2010 YZ450.
I was reading 60 on kick as well. and according to a friend that was considered in the normal range.
0

#4 User is offline   slopoke Icon

  • I Should really edit this.
  • PipPipPipPipPipPipPipPipPipPipPip
  • Group: Member
  • Posts: 4,758
  • Joined: 31-December 07
  • Gender:Male
  • Interests:takin it slo because I loves you girl
  • Ride:segway to the lrt

Posted 02 May 2016 - 10:17 AM

adjust your valves. my built 07 260 will be for sale soon. motor has about 30 hours on it from full rebuild, brand newish clutch basket(recluse), inner hub(gytr), springs(wiesco), plate(OEM Yamaha) and fibers(wiesco). oil coming out the radiator drain could mean seal between the pump going(i might be wrong there).
0

#5 User is offline   Vrooom Icon

  • Its coming rite at me!!!!!!
  • PipPipPipPipPipPipPipPipPipPip
  • Group: Member
  • Posts: 3,002
  • Joined: 22-August 06
  • Gender:Male
  • Location:Hastings ,mn
  • Ride:sold !2012 Gsxr 750,sold!2011 Ninja 1000 Sport tour thang"sold" ,09 Ktm 690 SMC Vrooom Vrooom!!! 06 Red GSXR 750 Sold!!!, 11 YzF 450 SuperTard/Mx

Posted 02 May 2016 - 10:36 AM

Valves Also . One of my exhaust ones got tight and it would not start at all.
0

#6 User is offline   wotan Icon

  • Shot out of a cannon > squeezed out of a tube.
  • PipPipPipPipPipPipPipPip
  • Group: Member
  • Posts: 2,436
  • Joined: 12-May 05
  • Location:hud-town, wisconsin
  • Ride:Aprilia RSV

Posted 02 May 2016 - 12:03 PM

View Postslopoke, on 02 May 2016 - 10:17 AM, said:

adjust your valves. my built 07 260 will be for sale soon. motor has about 30 hours on it from full rebuild, brand newish clutch basket(recluse), inner hub(gytr), springs(wiesco), plate(OEM Yamaha) and fibers(wiesco). oil coming out the radiator drain could mean seal between the pump going(i might be wrong there).


What are you thinking for price?
0

#7 User is offline   slopoke Icon

  • I Should really edit this.
  • PipPipPipPipPipPipPipPipPipPipPip
  • Group: Member
  • Posts: 4,758
  • Joined: 31-December 07
  • Gender:Male
  • Interests:takin it slo because I loves you girl
  • Ride:segway to the lrt

Posted 02 May 2016 - 12:28 PM

around 3 with spares, bodywork, rear wheel, exhaust, a stack of tires. I just did the valves, starts first-3rd kick. crank up built motor by PDR performance, newer tires, brakes, new right radiator, devol rad guards, devol skid plate, freshly repacked FMF power bomb header, custom jetted for 260 kit.
0

#8 User is offline   cb186 Icon

  • Zach "i'll crash yours too" Hughes
  • PipPipPipPipPipPipPipPipPipPipPipPipPip
  • Group: Member
  • Posts: 6,277
  • Joined: 13-September 04
  • Gender:Male
  • Location:Ham Lake
  • Ride:04 R6 racebike

Posted 02 May 2016 - 03:14 PM

View Postwotan, on 02 May 2016 - 09:14 AM, said:

I bought this 2005 YZ250F last year for a song. It was pretty beat but since it was my first bike and I'm fairly handy, I thought I'd start there. I rebuilt the carb and cleaned it up and fixed some little issues here and there. It's impossible to start, though. Once running and warm it was riding OK, but I would kill it on the trail and spend the next hour either kicking it or pushing it up hill to bump start it. Total nightmare.

Last weekend it died and I ended up pushing it for an hour. It was running really, really hot. When I got home, I opened the drain on the water pump and all that came out was oil (black, good looking oil.... not frothy or contaminated at all!) Any thoughts on what this means or what I blew?

I compression tested it and after seeing only 60lbs decided I better start tearing it down for a rebuild. Now I realize that with the auto-decomp it might be possible that I was seeing correct compression after all? Is there a way to accurately compression test these?

Last question -- I'm not into this bike for much and I'm ready to just ditch it and buy one that I know will be reliable. Is it going to be better financially to rebuild it and sell it -- or should I just part it out?


If you decide to sell ad is, let me know, I may be interested.
0

#9 User is offline   miweber929 Icon

  • Runnin' with the devil
  • PipPipPipPipPipPipPipPipPipPip
  • Group: Member
  • Posts: 3,308
  • Joined: 28-September 06
  • Gender:Male
  • Location:Woodbury
  • Ride:'14 Thruxton, '14 CBR650F, '13 Kymco Super 8 150, '11 Sprint GT, '04 WR450F

Posted 02 May 2016 - 05:52 PM

How do out of adjustment valves cause oil to come out the waterpump drain plug? I agree the valves are probably causing hard starting but there seem to be other problems with this bike, especially with the cooling system seals.
0

#10 User is offline   wotan Icon

  • Shot out of a cannon > squeezed out of a tube.
  • PipPipPipPipPipPipPipPip
  • Group: Member
  • Posts: 2,436
  • Joined: 12-May 05
  • Location:hud-town, wisconsin
  • Ride:Aprilia RSV

Posted 03 May 2016 - 09:48 AM

Tore it down last night and the damage is far worse edit: better! than I was expecting. Head gasket was blown to shit but the cylinder looks brand new and the piston/rings were in good shape. Going to throw some new rings in it and get the valves properly adjusted and see where I stand.

I also found a crack in the coolant pipe between the head and the radiator hose. This explains where all my coolant went -- and then once that was gone, oil was pushed out the bad head gasket and into the water pump. Should be easy enough to replace that coolant pipe and then button it back up. Hoping it starts reliably once I get it back together. Parts are on the way.
0

#11 User is offline   wotan Icon

  • Shot out of a cannon > squeezed out of a tube.
  • PipPipPipPipPipPipPipPip
  • Group: Member
  • Posts: 2,436
  • Joined: 12-May 05
  • Location:hud-town, wisconsin
  • Ride:Aprilia RSV

Posted 04 May 2016 - 09:16 AM

Decided I'd have the head and valve train gone through -- anyone know a local shop that does these for a fair price? I talked to headwerks in bloomington and he quoted me $400 + parts!!
0

#12 User is offline   slopoke Icon

  • I Should really edit this.
  • PipPipPipPipPipPipPipPipPipPipPip
  • Group: Member
  • Posts: 4,758
  • Joined: 31-December 07
  • Gender:Male
  • Interests:takin it slo because I loves you girl
  • Ride:segway to the lrt

Posted 04 May 2016 - 02:25 PM

I had PDR performance in andover do my motor. Looks like you are in WI (?) theres a guy who works out of Arkansas MX park that does motor work. I've read good things on Thumper talk
0

Share this topic:


Page 1 of 1
  • You cannot start a new topic
  • You cannot reply to this topic

1 User(s) are reading this topic
0 members, 1 guests, 0 anonymous users