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vomitbomb

2010 YZ 450 troubles

18 posts in this topic

Hi all,

I've posted on here before with a few of my troubles but I thought I'd make a list of them and see if anyone can tell me what my underlying issue is.

  • Burning oil - about 100-150ml every 60-80kms
  • Backfiring on decel a lot - I put a new exhaust on after these problems started but it never backfired as much as now.
  • Very hard to start when hot, a bit hard when cold.
  • Won't idle - The idles as far as it goes. strange thing is it seems to drop randomly and stall and then sometimes it sounds too high.
  • Sometimes the kick starter seems to 'skip' teeth.

Things that might give clues:

  • All started shortly after the bike was drowned (it had water coming out the exhaust when I tried to start it.) Not sure if that's just a coincidence or not.
  • The mechanic said the timing was slightly off (the cam markers didn't line up exactly)

Things I have done:

  • Had the valves adjusted - no difference. One of front valves (I think exhaust?) was tight so it was loosened up.

I just spent around $300 having the valves done and a service which made no difference at all so I'm a bit hesitant to take it to the dealers to spend more money for nothing, even if they do have the correct tools that may help them find the problem.

It is still ridable but very frustrating so I'm not getting out and enjoying it much any more. It seems to run smoothly when it's moving and the power loss I feel may just be in my head. Went out on an organised ride last weekend and it turned out to be mostly tight single track so it was difficult to keep the thing from stalling.

I guess what I want is some good idea's where I can narrow down the cause. I fear that if I go to the dealer with my crack pot thoughts they'll end up doing something drastic and unwarranted that doesn't fix the problem. To me the oil burning seems to point to a pretty major issue and doesn't seem like it could be related to the starting problems, but that's just my crazy theories. Is it normal for these things to burn oil at all? I had a 2008 WR450 that never burnt a drop.

Thanks in advance.

- Shane

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I assume it was runnng ingested water and shut off????

It could have some damage, bend rod, damaged rings...who knows. I'd be curious to see the results of a cylinder leakage test.

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Isent there selfdiagnosis on these new fi models? Iam thinkin some kind of electric problem....

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I assume it was runnng ingested water and shut off????

It could have some damage, bend rod, damaged rings...who knows. I'd be curious to see the results of a cylinder leakage test.

Yeah it was still running when it sucked in the water.

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When you had the valves adjusted at the shop did they do a leakdown test on the motor? If so what were the readings?

Burning oil do to piston rings or who knows what due to submerging will deff. cause starting and runability issues.

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burning oil is either rings or valve stem seals. i had problems with the valve stem seals.

Valve stem seals hey? Sounds like that may be worth investigating.

When you had the valves adjusted at the shop did they do a leakdown test on the motor? If so what were the readings?

Burning oil do to piston rings or who knows what due to submerging will deff. cause starting and runability issues.

They didn't do a leakdown test while it was in the shop.

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I drown my bike once , and i to make sure i didn`t get sand , or something in the motor i removed the head , and cyinder. Put in new rings , and flushed the bottom end many times. That was 3 years ago , and have no problems with my bike to date. If i were you i would start their.

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Went out riding on the weekend and the engine had locked up when I went to start it again. Tried to roll start it down a hill and it eventually came loose, made some clunking noises then took off. After that the idling issue seemed disappear but it still wouldn't kick start.

Something to do with auto comp?

I reckon I'll be taking it to the dealership tomorrow.

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i am in the auto salvage business and we sell a lot of new motors for cars that are still under warranty and thats because they suck in a water. 90 percent of the time they bend vlaves and a lot of times they bend rods. in my opinion your bike wouldn't run with a bent rod but it will run like crap with bent valve and all of you symptoms seem to agree with bent valves. good luck

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Hi all,

I've posted on here before with a few of my troubles but I thought I'd make a list of them and see if anyone can tell me what my underlying issue is.

  • Burning oil - about 100-150ml every 60-80kms
    If there are no leaks, then the rings or the valve seals could be at fault here.
  • Backfiring on decel a lot - I put a new exhaust on after these problems started but it never backfired as much as now.
    Did you use a new gasket? Did you torque the exhaust bolts before and after a couple of rides? Leaks in the exhaust system can cause backfiring.
  • Very hard to start when hot, a bit hard when cold.
    Do you pull the cold start knob out when starting the bike when it's warm? I know that sounds backwards but the cold start assist knob functions as a hot start as well, and works well when done.
  • Won't idle - The idles as far as it goes. strange thing is it seems to drop randomly and stall and then sometimes it sounds too high.
    Classic symptoms of an intake leak, if you've had headwork done or whatnot it's possible that they did not torque the head properly, the intake boot is not on properly. There could be a crack in the boot, who knows, but sounds like some kind of air leak at or past the throttle body.
  • Sometimes the kick starter seems to 'skip' teeth.

Things that might give clues:

  • All started shortly after the bike was drowned (it had water coming out the exhaust when I tried to start it.) Not sure if that's just a coincidence or not.
  • The mechanic said the timing was slightly off (the cam markers didn't line up exactly)

Things I have done:

  • Had the valves adjusted - no difference. One of front valves (I think exhaust?) was tight so it was loosened up.
    AIr filter neglect, and/or a bad seal on the filter will cause un-filtered air to enter the engine. WHen dirt hits a valve, it grinds it away, the valve seal and/or valve starts to wear, and tolerances for the valve tighten up.

I just spent around $300 having the valves done and a service which made no difference at all so I'm a bit hesitant to take it to the dealers to spend more money for nothing, even if they do have the correct tools that may help them find the problem.

It is still ridable but very frustrating so I'm not getting out and enjoying it much any more. It seems to run smoothly when it's moving and the power loss I feel may just be in my head. Went out on an organised ride last weekend and it turned out to be mostly tight single track so it was difficult to keep the thing from stalling.

I guess what I want is some good idea's where I can narrow down the cause. I fear that if I go to the dealer with my crack pot thoughts they'll end up doing something drastic and unwarranted that doesn't fix the problem. To me the oil burning seems to point to a pretty major issue and doesn't seem like it could be related to the starting problems, but that's just my crazy theories. Is it normal for these things to burn oil at all? I had a 2008 WR450 that never burnt a drop.

Thanks in advance.

IMO, if you are not able to do the work yourself, find a better mechanic. Sounds like he/she isn't doing too great of a job narrowing things down for you. When you bring a bike in, and pay money for service, you should see results, not a bill and a big ? mark with the words "Can't figure out" scribbled in crayon at the bottom.

- Shane

brent

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Hi all,

Well the bikes all fixed up now and running like new, that is, after $3.5k was spent on it. I hadn't realised how much power I had lost!

When I was looking through the forums for threads about similar issues, finding one with an actual conclusion was far and few between so I thought I'd add it here. It'd also be nice to get an opinion or two on the work that was carried out and whether it was warranted or not.

Anyway, I took the bike to a reputable dealership. I thought that if I'm going to have the engine pulled apart I may as well get it done somewhere that does quality work and has a good rep. Whether or not that'll carry over in resale I don't know.

I got a call from the shop saying the engine looked like it had done an enormous amount of hours (I'd roughly estimate it at around 50 or so hours) and that considering what they'd seen in the top end they wanted to pull apart the bottom end as well. I asked them to put the old parts aside for me, more out of curiousity than anything else as I'm definitely lacking on mechanical knowledge.

I asked them to show me the parts that were worn and if they could, how it happend and why it's a problem. So I have some pictures of the olds parts focusing on the bits I was told were worn.

Timing chain

The first thing they noticed was the badly stretched timing chain. My previous mechanic had thought this was "still OK". Maybe it got worse between now and then. The shop did say they couldn't get it started at all after I dropped it off. To me that sounds like it would explain a fair few of my symptoms. no picture of that, I don't think it'd add any value just being a chain and all.

Cylinder

The cylinder head was completely replaced. I was told it had a 'ridge' on the top part of the cylinder which is caused by the piston not quite making it up to the top. It's kinda hard to see but I can feel the ridge with my fingers. I was expecting to see scratches or score marks but there was none of that. This pic was done with the phone so it's not very good quality. You shouldn't have any issues making out the ridges in it though.

image3wp.th.jpg

Crank Shaft

I was told it was wearing on the bottom which you can see in the picture below. Two large bearings were also replaced (sorry I don't know what they're called). They spin fine but I was told they have movement in them. When I check I can feel the inside ring moving slightly sideways against the outside ring, if that makes sense.

img3665o.th.jpg

He didn't actually say that this part was worn but it looks similar to what is seen on the other parts so I thought I'd post it too. It's the bit that holds the piston to the crankshaft.

img3659wj.th.jpg

Valves

The mechanic pointed out the edge where there was a small amount of wear. Mainly the thin strip between the edge of the valve and that first ridge towards the stem.

Valve 1

img3655p.th.jpg

Valve 2

img3658o.th.jpg

Here's the piston covered in crud:

img3660s.th.jpg

They measured the clearances between the side bits in the below photograph and said it was worn beyond it's tolerances.

img3663h.th.jpg

I'm pretty sure the wear is a result of the bike being drowned a fair while ago and compounded with poor maintenance. I replaced the oil every second or third ride, but my air filter maintenance was lacking. Eitherway it was a lesson learnt, albeit an expensive one.

Are these bikes that sensitive to this kind of wear? Considering the symptoms I had I figured the engine would have something broken and perhaps rattling around inside or at least some scratches or gouge marks somewhere. Something your average joe could look at and say "well there's ya problem" and not just a combination of worn and degraded parts.

Any thoughts or advise would be great. I can take and upload some more photo's if anyones interested.

And thanks to all the people who posted on here too. I appreciate the help.

Edited by vomitbomb

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Your problems sounds like its from the drowning but I'm curious what engine oil and what air filter oil you were using?

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Yes, they ARE THAT SENSITIVE. Anytime unfiltered / poorly filtered air gets into the engine, you are eroding metal. Ingesting water is as damaging, if not more so. Esp if the waster is laden with sediment.

It is possible the cam chain stretched when the initial stall happened in water, but the other problems (worn valve faces, worn rings, worn cylinder) would have manifested too. Glad to hear you are up and running again. :smirk:

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