06 yz450f troubleshooting help

Yamaha YZ450F 2006

15 replies to this topic
  • wet_willy05

Posted April 01, 2013 - 10:54 AM

#1

Hi guys thanks for the help heres my problem,

06 yz450f
maybe 10-15 hrs on cylinder/rings/piston/timing chain
pretty low overall hrs on bike
jd jetting 48 168 3000ft elevation 2 turns out

About a month ago i was trail riding my bike and didnt realize for a duration of the ride that i was losing coolant through an o-ring under my y- tube. I run a boyeseen oversize cover/impellor which was keeping my bike cool before i ran it close to dry. My bike started acting like it was hot and a little boggy but still o.k. on power...what i also noticed while i limped her a small ways to the truck was a noticeable whirring sound like i was losing compression somewhere. My bike immediately died when i slowed down to a slow speed. Tried starting up after a coolant refill and she would start for a second, idle then die again. The bike kicked over fine and never siezed but was very hot.........Wouldnt idle

Had a leak down test done by a local shop and they said i had a 30% roughly compression loss through intake valves.(this taking for granted the guy knew about the auto decompression)

I had kept the valves in spec but decided that on a bike of this year (06) time to get my valves done
- had kibblewhite valves and spring set installed

got everything back and installed the head, set timing and set my valve lashes in spec, cleaned the carburetor including jet orifices
and inspected my piston and cylinder. Looked good (approx 15 hs on new piston/rings/cylinder) cross hatching still evident etc...

Buttoned the bike up completely and tried kicking her over: same problem as before! Bike idled for a second or two then die, and i got the rpm's high enough for her not to die and i rode it up the driveway....sounded pretty rough in spots and when i got back to the garage it died again at that low rpm :banghead:

I did notice on reinstallation that if i torqued the cam caps per manual order that upon torquing the last bolt, my cams would budge/spin even at tdc..... this was not the case before but i figured my caps got a little warped because of heating...i torqued them in a little different sequence to get them to spin freely

Also noticed that when i had my head cover off and spark plug still in that when i built up compression with the kick start, i could hear air escaping somewhere and oil or coolant bubbling... Also there was a few drips of cooland leaking through the weep hole under water pump cover so perhaps i need new seals or i burnt up my water pump? Could this cause electrical error? Im not super experienced with symptoms after getting a bike really hot because ussually i make a habit of keeping fluids CORRECT.

Any input would rock especially from grey
thanks guys
Will from Montana

  • slothman

Posted April 01, 2013 - 01:42 PM

#2

sounds like the water pump is shot, overheating the engine causing it to stall. Do NOT run the engine anymore until you pull the pump and inspect.

  • grayracer513

Posted April 02, 2013 - 06:37 AM

#3

The air yoiu hear inside the cam box is normal. It's going past the rings into the crankcase.

Running otherwise OK for a couple seconds then shutting down sounds like a stator problem. The water pump needs to be resealed.

  • wet_willy05

Posted April 02, 2013 - 09:14 AM

#4

Im going to redo my water pump seals and check the stator , would these explain the slight whirring sound and what would seem like a compression or air loss at low rpm? the bike will run rough if i get the rpms above idle for as long as i keep rpms up then die immediately if they get low again regardless of being in gear or neutral. could any of this be a bottom end issue, it never seized up but did about get ran dry on coolant. also quick question what is that hole on the kick starter side of the head...its centered on the side of the head. its not threaded but looks like it is pretty deep. Also is it typical for a stator to malfunction after getting a bike hot? Did notice a very slight rattle when i kick the bike over "sometimes"- i hope my connecting rod/bearings are ok

  • slothman

Posted April 02, 2013 - 11:59 AM

#5

the bike will run rough if i get the rpms above idle for as long as i keep rpms up then die immediately if they get low again regardless of being in gear or neutral.


This sounds like a fuel issue. Have you done any carb work? The jets could be clogged, which is why it only runs when you are giving it gas.

  • wet_willy05

Posted April 02, 2013 - 02:17 PM

#6

Took the carb apart and the jets were clear. Me running the bike low on coolant caused the problem ....I'm going to check the stator and flywheel tomorrow but it really seems like a compression issue as my bottom end seems to turn over ok. Would a slight leak in a water pump seal cause a bike not to idle/run? I wouldn't think so

  • slothman

Posted April 03, 2013 - 11:52 AM

#7

Took the carb apart and the jets were clear. Me running the bike low on coolant caused the problem ....I'm going to check the stator and flywheel tomorrow but it really seems like a compression issue as my bottom end seems to turn over ok. Would a slight leak in a water pump seal cause a bike not to idle/run? I wouldn't think so


The jet holes are super small..did you clean them out ? Also, do you have the correct jetting for your altitude and mods? If it's not jetted right it will run piss poor.
The water pump needs to be fixed but I don't think it's related to the idle. If you havn't cleaned the jets, that would be the next step. It doesn't take much to clog them.

  • wweagleflyer

Posted April 03, 2013 - 03:23 PM

#8

The small, deep, unthreaded hole you asked about on the head is a drain port for the sparkplug tunnel. If any water gets past your dust boot below the coil, it will drain out there. The hole is also very useful to blow compressed air through when you want to get loose dirt out of the spark plug tunnel before removing the spark plug.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • wet_willy05

Posted April 03, 2013 - 06:10 PM

#9

Cool thanks because the manual basically just shows it for what it is......a hole.

Update: pulled the ig cover and inspected stator/flywheel. There were three or four small flakes of metal on the inside of the rotor that seemed to give the stator excessive wear on the coils. These little shavings and some sticky oil inside the flywheel looked like it blew the stator out.

I don't have a voltmeter so just ordered a new stator from Steahly. It will be here Friday I'm hoping this has to do with the intermittent spark.. as to the few metal shavings I have NO IDEA . I'm gonna change the oil early and keep an eye on it

  • wweagleflyer

Posted April 04, 2013 - 05:40 AM

#10

I also have an 06 yz450f, and like you I found metal flakes stuck to my flywheel magnets. I then found small metal ball bearing balls in the cavity near the oil sump. After you drain all the oil, and if you have the left hand (magneto) cover off you will be able to lookin into the center of the crank case below the sump pickup. That is were I noticed the small ball bearing balls. It turned out to all be from my detent wheel bearing was shot. The metal flakes on the flywheel were pieces of the bearing cage material. I ended up splitting the cases to inspect damage from the ball bearing balls, and to be sure to get them all out. Damage turned out to be minimal, but that was the only way I could be sure I got all the balls out since I couldn't find all of them according to the number that are supposed to be in the bearing.

At a minimum, I would recommend looking real closely through the oil drain window between the center of the crankcase and the left hand side.

  • wet_willy05

Posted April 04, 2013 - 09:25 AM

#11

Ok thanks for the tip ill look real close. Where is That detent wheel bearing at and is that all u had to do on your bottom end? I'm hoping its part of my clutch assembly because of some new tusk friction and steels I put in before this prob occurred....

  • wweagleflyer

Posted April 04, 2013 - 10:22 AM

#12

The detent is item 6 shown in post 19 of the link below. You have to remove the clutch and right hand side outer case to get to it.


http://www.thumperta...0f-index-lever/

See also this thread to see pictures of minor gear damage that occured on my machine.

http://www.thumperta...mage-questions/

  • wet_willy05

Posted April 07, 2013 - 09:09 PM

#13

so i replaced my stator and was getting good spark when i grounded the plug and kicked. my bike would fire up but only for a sec.....not idle, upon trying to give it gas it would kill it right away(quicker). i think maybe i timed one of my camshafts a tooth off. i need to check my decompression assembly when i pull my head cover again and re-time. i swore both dots were perfect :banghead: . my cylinder/piston/rings/valves are straight!

any other advice/options other than taking it to a shop and having them check my electrical? my timing chain has less than 10 hrs so i dont think it slipped when i got the bike hot

  • wet_willy05

Posted April 09, 2013 - 06:20 PM

#14

So....rechecked my timing and am 90% sure its timed right. the dots line up perfect and the timing chain is fairly new

What i noticed earlier about my cams not spinning freely.. I think is the problem!

If i tighten ONLY the back left cam cap bolt for the exhaust cam to 7ft/lbs my cam WILL NOT BUDGE.
this tells me that the journal to cam cap clearance is dam near a negative number! Dont have plastiguage to check but pretty sure if i torque my cam caps on correctly they should spin freely....Like my front tire..... Right now i can get my intake cam to spin easier than the ex but its still not spinning super smooth.

Im thinking that since this bike has been heated up a few times, and i ran it low as hell on coolant i warped my cam caps or my cams grew fatter???

I think why my bike is dying at start and low rpm is because the cams arent spinning completely free. Anyone have this happen? Advice/Ideas???

  • f150jokerstyle

Posted April 09, 2013 - 10:13 PM

#15

So....rechecked my timing and am 90% sure its timed right. the dots line up perfect and the timing chain is fairly new

What i noticed earlier about my cams not spinning freely.. I think is the problem!

If i tighten ONLY the back left cam cap bolt for the exhaust cam to 7ft/lbs my cam WILL NOT BUDGE.
this tells me that the journal to cam cap clearance is dam near a negative number! Dont have plastiguage to check but pretty sure if i torque my cam caps on correctly they should spin freely....Like my front tire..... Right now i can get my intake cam to spin easier than the ex but its still not spinning super smooth.

Im thinking that since this bike has been heated up a few times, and i ran it low as hell on coolant i warped my cam caps or my cams grew fatter???

I think why my bike is dying at start and low rpm is because the cams arent spinning completely free. Anyone have this happen? Advice/Ideas???


Or your head is warped???? I would think that would happen before the caps would warp just due to the fact they are not that beefy and if they were tweaked I would think they would sort of spring back. Also you can check the run out on the cam bearing surface. Set up something to spin the cam in and use a dial indicator with a mag base and spin it and look for high spots as you move over the dial indicator a 1/16 of an inch at a time or so.

  • grayracer513

Posted April 10, 2013 - 07:12 AM

#16

Why on Earth would you tighten one cam cap bolt to its full torque and not the rest? I don't know how you could expect it not to distort under those conditions.

The exhaust cam typically does turn stiffly in a lot of YZF's with the head cold. Get some Plasti-Gage and check it. When torquing the cam caps, reduce the torque from the specified 7.2 ft/lb (86 in/lb) to 6.2 (75 in/lb), and tighten the bolts to that spec in at least 3 steps, say 35, 60, and 75 in/lb. Be absolutely sure that the mating surfaces of the cap and head are clean, and that the cap is completely seated against the head BEFORE tightening any bolt.





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