2018 YZ450F Skipped Timing

Dude im exhausted from just reading about your problems. Fuckin wise up and cut your loss and buy another brand.

kb228 wrote:

Dude im exhausted from just reading about your problems. Fuckin wise up and cut your loss and buy another brand.

I have one on order.

It is easy to "dump it" when you didn't spend $11K on the bike plus $3-4 thousand in suspension and parts, plus the $2400 for the new motor, plus all the other BS. Trust me, I looked at getting rid of it months ago and it was like whipping my ass with 7-8 thousand dollar bill and throwing it down the flush.

With a trashed motor at 6 hours or whatever that was, the dealer should be covering that completely. In streetbike/car terms, 6 hours is 360 miles if you think of highway speeds. Its brand spankin new. I get theres a lot of money but i dont think anyone here thinks you should be in that deep in the first place.

But to answer your question, bad cam chain tensioners and bad guides cause it to skip teeth. Poor maintenance and being hard on the engine cause this. And regards to your oil, its time to change it when its not a clear amber color anymore. That can be 2 hours or 10 hours depending on the bike and rider. Dark oil means theres debris in your motor. That leads to bad valves and problems everywhere else. It truly is unbelievable youve gone thru 2 motors on a bike thats brand new and continue to have issues.

kb228 wrote:

With a trashed motor at 6 hours or whatever that was, the dealer should be covering that completely. In streetbike/car terms, 6 hours is 360 miles if you think of highway speeds. Its brand spankin new. I get theres a lot of money but i dont think anyone here thinks you should be in that deep in the first place.

But to answer your question, bad cam chain tensioners and bad guides cause it to skip teeth. Poor maintenance and being hard on the engine cause this. And regards to your oil, its time to change it when its not a clear amber color anymore. That can be 2 hours or 10 hours depending on the bike and rider. Dark oil means theres debris in your motor. That leads to bad valves and problems everywhere else. It truly is unbelievable youve gone thru 2 motors on a bike thats brand new and continue to have issues.

Trust me man we did everything possible with this goddamn thing. “Competition” bikes have no warrenty the day they leave in the back of your truck. Not sure if corporation are easier to deal with in the States or not but Yamaha Canada was horrible to deal with. My local dealer really did bend over backwards to help. It was just a mess from the get go.

I would agree with stating that I run this more like a 250f than a 450 but certainly no Barcia.

I should have looked into this more when we first noticed the oil was changing quickly. The bike itself felt like it was running fine and with all the other problems that had happened I just wanted to ride my damn bike.

I have had a lot of bikes man...almost a new big wheel bike every season since 08 between Yamis and Suzukis. Combining all those bikes together the problems I’ve had with this stand alone can’t even compare. This has to be a pure lemon because I do not see other people having the same issues I have been having (with the exception of the starter). Thanks for your input again my man and I can tell you I won’t be back with another Yamaha problem.

I personally would tear it apart down to the bottom end and fix it. I assume the crank will be ok and all lower end bearings. If you have to send the head out to pro 1 heads and buy new oem valve if damaged. Easy fun project. Sucks it's a new bike. Only thing in my opinion that can't be fixed is when the frame cracks like my yammi did

That’s very unfortunate. I’ve heard of bikes skipping timing from be restarted on landing after stalling in air, but none from bump starting on ground.

It sounds like it was something else that caused it to skip timing.

so odd, bike has to be a lemon. In the northeast a ton of people on the new yz450s. People swear by them because of the durability.

The oil would get dark on my 17 until about 12 hours.

The cam chain is completely worn out causing it to jump the timing. It never hurt the cam sprockets or tensioners however which is weird. It looks as though the valves are fine and didn’t hit the head or bend the valves. Piston and rings need to be replaced (which was expected). Cylinder had some weird ware on the exhaust valve side. Not too bad though...should clean up fine. Crank was tight and looked good. Parts will be in end of the week and hopefully put back together over the weekend. Heres hoping this solves the problem.

The timing chain shouldnt even be close to being roached in 25 hours. Neither should your piston and cylinder.

kb228 wrote:

The timing chain shouldnt even be close to being roached in 25 hours. Neither should your piston and cylinder.

Absolutely agree with you on the timing chain and cylinder. The cylinder should be fine though. Piston and rings I believe say in the manual to do every 10-15 hours. This probably gets over looked by a lot of people. We did mine on both my 16 and 17 YZ250F around 25 hours just to refresh but they still had lots of life still in them. This one though is toast.

I had some weird thing happen on my 18 250F that I've never seen before. I had sight glasses in both master cylinders fall out/ break . Front at 15 hours, rear at 42. Changed pistons and cam chains every 25 hours max religiously and had weird things.
First piston- had cracked the bottom above the wrist pin on the bottom of the piston dome at 18 hours, (first piston was pulled due to compression loss of 10 psi after one ride.)
Second piston-sound of "knocking" at 19 hours, 37 hours on bike total, (piston had side to side play creating a "knock")
Third Piston- just came apart and skirt went everywhere at 14.6 hours on piston 51.6 hours total
Fourth Piston -had no issues was changed at 25 hours on piston at 76.6 hours total.

I had a bunch of other odds and ends like the weld around the radiater spout leak, cam chain tensioner on the second piston failed, bar mount lower broke, cranked frame, bolts would not stay tight with locktight added after on most every bolt.
Just lots of little things that made no sense, it was a good bike but just needed to be looked after and torn down often and bolts checked every ride.

Man, my buddy's 2018 has been nothing but problems too. He's a smooth A rider that is meticulous with maintenance, doesn't ride the thing hard for how fast he's going.

On the 2nd or 3rd ride the OEM chain snapped on him after he landed and lucky didn't wreck or break the cases. The starter clutch went at 5 hours and Yamaha wouldn't cover it. At 8 hours the output shaft seal started leaking.

The bike would run like shit half way through a moto because it would fill the airbox with dirt, which his 2015 didn't do. It got so bad that he'd be doing filters between motos and would still have the bike die on him at the end of a moto while braking. We talked to the Factoy Yamaha mechanics at Unadilla to see how the pros bikes make it through and they said it's not a problem... Then I saw this airbox mod they do to prevent dirt from getting in lol.



At 20 hours the thing ended up locking up on him. The piston squirter clearly fatigued and broke off, which made the bike lose oil pressure. It looked like a casting flaw that propigated until it fell off from vibration to me. Every bearing in the engine is junk, the upper rod bearing siezed and turned the piston sideways in the bore (away from the oil squirter, nothing made contact with it). Cams, buckets, cam, bearings are all badly worn. The piston damaged the valves when it turned sideways. Timing chain wore so far that you could jump teeth by hand.

Yamaha said it is from running out of oil and lack of maintenance. I was pretty shocked at how little the dealership or Yamaha cared when we went there. He was told by the dealer that the piston and cam chain are 15-20 hour items on a 450 haha.

At this point he's been without a bike for 4 months, and Yamaha finally just said they'll help him with some of the parts. Looks like it is still going to cost about $1500 on a $9000 bike with 20 hours on it. Pretty shitty deal.

More shots of the airbox mod, maybe it will help someone who has the same problem. I asked the mechanic who made the part and he wasn't sure.

And heres some engine gore

foreman52 wrote:

The cam chain is completely worn out causing it to jump the timing. It never hurt the cam sprockets or tensioners however which is weird. It looks as though the valves are fine and didn’t hit the head or bend the valves. Piston and rings need to be replaced (which was expected). Cylinder had some weird ware on the exhaust valve side. Not too bad though...should clean up fine. Crank was tight and looked good. Parts will be in end of the week and hopefully put back together over the weekend. Heres hoping this solves the problem.

The stories I could tell! Yes, those Yamaha 450's will stretch the cam chain and skip 2 teeth without bending the valves.
I had one guy tell me he fixed the timing at the track and still rode, it jumped again and he brought it to me. I couldn't believe it did not bend a valve.
Sorry, but most of the Yamaha 450's looked ridden hard and put away wet. It wasn't like the three or four I seen do that had any maintenance whatsoever. You can hear when the chain starts to go, it makes noise at idle that will disappear at revs, if someone is doing valve adjustments it should be caught then also. 25 hours hard 450 riding and the cam chain could be toast. Are you fast, are you throttle king? The aftermarket cam chains might have a stronger tensile strength?

everyone gets a lemon at some point...Get it back together, off it & move on.... My then new 2006 yz450f was such a piece of shit, I went back to 2 strokes for a few years ....

I learned my lesson back in 2000 when I got the first YZ250F to hit Southeast Texas. It was a pretty amazing pile of shit in the end. People keep telling me that I should have expected a first year bike to shit the bed and how much better they have gotten since then. Yet we always keep seeing these threads pop up 20 years later in the Yamaha thumper camp.

Wanted to chime in on the oil getting dark... in all my YZFs the oil has gotten fairly dark in one ride and I have never had a problem with them. I was thrown off on my current 250F (so much so that I was doing oil and filters after every ride). Yamahas are typically bulletproof, sucks that you got a lemon and the dealership hasn't helped you out. I'd sell it and get a fresh one, save yourself more time, $$ and headache.

I’ll chime in on the lemon. In California there is a Lemon law in regards to automobiles, not sure in regards to motorcycles. It’s a pretty sweet law that refunds the entire cost of the lemon.

Jbulz wrote:

Man, my buddy's 2018 has been nothing but problems too. He's a smooth A rider that is meticulous with maintenance, doesn't ride the thing hard for how fast he's going.

On the 2nd or 3rd ride the OEM chain snapped on him after he landed and lucky didn't wreck or break the cases. The starter clutch went at 5 hours and Yamaha wouldn't cover it. At 8 hours the output shaft seal started leaking.

The bike would run like shit half way through a moto because it would fill the airbox with dirt, which his 2015 didn't do. It got so bad that he'd be doing filters between motos and would still have the bike die on him at the end of a moto while braking. We talked to the Factoy Yamaha mechanics at Unadilla to see how the pros bikes make it through and they said it's not a problem... Then I saw this airbox mod they do to prevent dirt from getting in lol.



At 20 hours the thing ended up locking up on him. The piston squirter clearly fatigued and broke off, which made the bike lose oil pressure. It looked like a casting flaw that propigated until it fell off from vibration to me. Every bearing in the engine is junk, the upper rod bearing siezed and turned the piston sideways in the bore (away from the oil squirter, nothing made contact with it). Cams, buckets, cam, bearings are all badly worn. The piston damaged the valves when it turned sideways. Timing chain wore so far that you could jump teeth by hand.

Yamaha said it is from running out of oil and lack of maintenance. I was pretty shocked at how little the dealership or Yamaha cared when we went there. He was told by the dealer that the piston and cam chain are 15-20 hour items on a 450 haha.

At this point he's been without a bike for 4 months, and Yamaha finally just said they'll help him with some of the parts. Looks like it is still going to cost about $1500 on a $9000 bike with 20 hours on it. Pretty shitty deal.

I've been toying with the idea of running a piece foam in those intakes. Not sure if it will affect the performance or not.

Jbulz wrote:

Man, my buddy's 2018 has been nothing but problems too. He's a smooth A rider that is meticulous with maintenance, doesn't ride the thing hard for how fast he's going.

On the 2nd or 3rd ride the OEM chain snapped on him after he landed and lucky didn't wreck or break the cases. The starter clutch went at 5 hours and Yamaha wouldn't cover it. At 8 hours the output shaft seal started leaking.

The bike would run like shit half way through a moto because it would fill the airbox with dirt, which his 2015 didn't do. It got so bad that he'd be doing filters between motos and would still have the bike die on him at the end of a moto while braking. We talked to the Factoy Yamaha mechanics at Unadilla to see how the pros bikes make it through and they said it's not a problem... Then I saw this airbox mod they do to prevent dirt from getting in lol.



At 20 hours the thing ended up locking up on him. The piston squirter clearly fatigued and broke off, which made the bike lose oil pressure. It looked like a casting flaw that propigated until it fell off from vibration to me. Every bearing in the engine is junk, the upper rod bearing siezed and turned the piston sideways in the bore (away from the oil squirter, nothing made contact with it). Cams, buckets, cam, bearings are all badly worn. The piston damaged the valves when it turned sideways. Timing chain wore so far that you could jump teeth by hand.

Yamaha said it is from running out of oil and lack of maintenance. I was pretty shocked at how little the dealership or Yamaha cared when we went there. He was told by the dealer that the piston and cam chain are 15-20 hour items on a 450 haha.

At this point he's been without a bike for 4 months, and Yamaha finally just said they'll help him with some of the parts. Looks like it is still going to cost about $1500 on a $9000 bike with 20 hours on it. Pretty shitty deal.

49weasel wrote:

I've been toying with the idea of running a piece foam in those intakes. Not sure if it will affect the performance or not.

I know he tried that and said it killed power. I'm not sure what type of foam he used though

https://www.rockymountainatvmc.com/p/734/45426/PC-Racing-Flo-Shroud-Air-Filters

I just ordered some of these. If those don't work I will run window screen.

49weasel wrote:

https://www.rockymountainatvmc.com/p/734/45426/PC-Racing-Flo-Shroud-Air-Filters

I just ordered some of these. If those don't work I will run window screen.

i run the same ones in my 17. No power difference and the filters stay WAY cleaner. There's a few open spots behind the filter housing that lets enough air in.

I cannot speak to the amount of problems you've had, and god bless you for the amount of money you've kissed goodbye.

I believe that there is an underlying problem with valve train in the newest generation yamaha's. I have a couple friends whose new yz250f's and yz450's cannot keep the valves in spec. Most event was a 2018 yz250f that needed new valves are 5 hours.

NJKawi913 wrote:

I cannot speak to the amount of problems you've had, and god bless you for the amount of money you've kissed goodbye.

I believe that there is an underlying problem with valve train in the newest generation yamaha's. I have a couple friends whose new yz250f's and yz450's cannot keep the valves in spec. Most event was a 2018 yz250f that needed new valves are 5 hours.

Yup! You wouldn't believe some of the 16's and 17's down here having valve troubles. I never heard anything on the 18's though and 14's and 15's were solid.

49weasel wrote:

https://www.rockymountainatvmc.com/p/734/45426/PC-Racing-Flo-Shroud-Air-Filters

I just ordered some of these. If those don't work I will run window screen.

Might have to order myself some of those, thanks for the link.

Had to report this.

I was browsing the facebook mx classifieds in my area. I saw 2 separate 2018 yz450fs for sale. both claimed to have new motors replaced by Yamaha. On bike claimed 17 chassis hours and the other one 20 hours. Weird they wouldn't cover yous

Ladies and gentlemen, your 2019 shootout winner. Haha