2017 rmz450 engine noise at 45hrs??

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12/16/2018 10:18 PM

Alright so I'll start off by saying I change the oil and filter on this bike every 3hrs. Same with cleaning the air filter. About a month ago I took it around my track and didn't even get 300yrds down the track and the rear tire locked up. I gassed it and it bogged and died. I went to kick it and it stuck. The 2nd attempt it turned over. And 3rd kick it fired back up surprisingly. It had very subtle motor noise.

I ride it up to where we sit and my buddy says he hears nothing and takes it around the track. Half way around it starts knocking hard. Hard enough at 150yrds we could all hear it. He rode it back up and gave it a steady throttle and it stayed the same loud knock.

Long story short I took it too a mechanic that's we've known for years and does great work. He ran every test he could without pulling it apart and couldnt find anything. Only 3% leak down on the valves after 45hrs! He told me to take and ride it and see what happened. So the first time I ride it it sounds like normal no noise. The second time out it starts in again with the subtle knock and I can feel it through the pegs.

Were both at a loss but I dont wanna split it just yet incase anyone else has had issues with these rmz's and can point me in a direction. I'm thinking rod bearing but idk. It's only got 45hrs and I ride it considerably hard as in on the limiter alot on the track but I wouldnt think itd go at 45hrs either. If anyone knows or has had one act up or maybe some info on what it sounds like any help would be appreciated before I scatter the bottom end on the bench.

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12/17/2018 1:09 AM

Knock could be many things. Timing chain, valve chain, worn piston, worn crank..

Youre at 45 hours and ride the bike hard. Open the top end and take a look. Or gamble it and lose some engine cases.

Without a video its hard to say. You can localize the noise with a mechanics stethoscope. Harbor freight sells them for $3.

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12/17/2018 3:13 AM

Engine mounts all tight? Swingarm pivot tight?

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12/17/2018 5:03 AM

yz133rider wrote:

Engine mounts all tight? Swingarm pivot tight?

Yes everything is tight. And torqued to spec

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12/17/2018 6:31 PM

kb228 wrote:

Knock could be many things. Timing chain, valve chain, worn piston, worn crank..

Youre at 45 hours and ride the bike hard. Open the top end and take a look. Or gamble it and lose some engine cases.

Without a video its hard to say. You can localize the noise with a mechanics stethoscope. Harbor freight sells them for $3.

Well the mechanic I took it too done that and didn't find anything and said it looked good. I'm more than likely gonna take it apart and split the cases because I have a feeling its rod bearing the way it sounds. I just found it odd the bike would roast the rod bearing at 45hrs. Given the kindve life its lived on the track it wouldnt suprise me though.

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12/17/2018 6:34 PM

Dis he verify it didn't jump timing?

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12/17/2018 9:40 PM

coastlinecascot wrote:

Dis he verify it didn't jump timing?

Yes he did. Cam chain tensioner and all were fine. That was his first thought but turned out it wasnt and he ran every test and looked at what he could without tearing apart the whole motor for now. More than likely I'm gonna have too anyways

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12/18/2018 10:54 AM

Could be many things. Might have been a bit of valve guide breaking off and rattling around in the combustion chamber before getting spat out - that would explain the temporary lock up. Have a look in your exhaust for any metal particles. Also take the oil filter out and cut it in half to inspect for any debris which might give an indication of the rod bearing failing. Could also be the timing chain tensioner sticking and not maintaining tension. If it was mine, and I heard any metallic noise whatsoever, the head would be getting pulled for inspection.

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12/19/2018 6:54 AM

Those engines have been known to be hard on cam chains. Maybe replace that and the tensioner first

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12/19/2018 7:40 AM

A friend of mine raced RMZ450 in the past years and he had several crank pin failures, usually always at 50 hour mark.

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12/19/2018 7:27 PM

needforspeed78 wrote:

A friend of mine raced RMZ450 in the past years and he had several crank pin failures, usually always at 50 hour mark.

We’re these OEM cranks/pins? Never heard that issue before I’m curious

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12/19/2018 7:43 PM
Edited Date/Time: 12/19/2018 7:46 PM

needforspeed78 wrote:

A friend of mine raced RMZ450 in the past years and he had several crank pin failures, usually always at 50 hour mark.

That's interesting. Never heard anything on it before but from the sounds of it and the way its acting I'm almost certain is a crank/crank pin or bearing issue. It runs fine but now clings in the motor. I'm gonna take the top end off and see if it's a rod bearing if not I'll be splitting cases either way. We ran about every possible thing you could do without completely disasselmbing the motor just in case it was something minor like a cam chain tensioner but looks like I'm gonna have to bite into this one. I just didn't think itd do it at 46hrs.

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12/19/2018 7:47 PM

kb228 wrote:

Knock could be many things. Timing chain, valve chain, worn piston, worn crank..

Youre at 45 hours and ride the bike hard. Open the top end and take a look. Or gamble it and lose some engine cases.

Without a video its hard to say. You can localize the noise with a mechanics stethoscope. Harbor freight sells them for $3.

I'll try that. More than likely the top ends coming off but I'll try that first to get me pointed in a direction.

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12/19/2018 9:34 PM

needforspeed78 wrote:

A friend of mine raced RMZ450 in the past years and he had several crank pin failures, usually always at 50 hour mark.

colvin227 wrote:

We’re these OEM cranks/pins? Never heard that issue before I’m curious

Yes, they were OEM cranks. He usually rode 3-4 bikes per year and get a fresh one after 50-60h mark and he had at least two crank failures where the lower bearing and pin was shot.

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12/22/2018 1:14 PM
Edited Date/Time: 12/22/2018 1:14 PM

How did the oil strainer by the gear shifter look?

Sounds like crank to me as well, just unlucky as these things are normally bulletproof. They are a noisy engine but safer to split the case's and find nothing than go the other direction. Might just end up costing you some gaskets and seals fingers crossed.

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12/23/2018 5:16 AM

The piston may be toasted. 45 hours is not unreasonable for a four stroke top end. I cracked my yz450 piston at 50. Don’t believe the majority of people on vital who say they get 200+ hours without doing a thing. Bikes don’t wear out when you don’t break 4K rpms. You said you ride the bike hard so this isn’t an unreasonable assumption.

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12/23/2018 6:54 PM

Had a intermittent knock CRF450R. Guessed it was the crank. Took it apart and the bearing seemed okay until the new OEM unit showed up. The old bearing had worn on one side of the pin. The new crank had noticeable tighter tolerances.
If you took the old rod and really used a lot of pressure it was possible to feel it rocking on the pin, hence the noise.
The new crank/rod had zero movement as far as rocking. Grab that rod and see if you can get it to rock side to side, not up and down.

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12/24/2018 2:22 PM

The crank went on my 2014 RMZ450 around 50 hours, seemed to run fine but had a chatter. Tear it down and check everything out. No way I would keep riding it.

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12/24/2018 2:55 PM

gristle568 wrote:

The crank went on my 2014 RMZ450 around 50 hours, seemed to run fine but had a chatter. Tear it down and check everything out. No way I would keep riding it.

That's what I'm thinking. I've had some tell me too run it to find out and I cant do that. I'd rather pull it apart and fix it for $300 or so then $1000+ in a whole top end. It's doing the same thing. Runs fine but you can hear it chatter. And I'm not gonna blow the top off of it for a weekend worth of work.

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12/24/2018 5:50 PM

Had a clutch make crank sounding noise.

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12/25/2018 8:47 AM

gearbox?

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12/25/2018 11:17 AM

cody41 wrote:

The piston may be toasted. 45 hours is not unreasonable for a four stroke top end. I cracked my yz450 piston at 50. Don’t believe the majority of people on vital who say they get 200+ hours without doing a thing. Bikes don’t wear out when you don’t break 4K rpms. You said you ride the bike hard so this isn’t an unreasonable assumption.

I've had plenty of bikes and had them go and it's pretty usual at least symptom wise. This one though isn't making any noise to make me think the top ends going out but more bottom end crank sound. I just didn't think a rmz would roast one before 50hrs and figured I'd see if anyone else with a rmz had farther info if itd ever happened to them. I'm not completely surprised though because it gets rode outdoors mainly and is on the rev limiter quite a bit lol. I'll pull it apart and split the cases and get to the bottom of it. I'd rather not have it lock up coming up the face of a jump. And since its winter I'm not riding it every minute so nows the time to do it.

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12/25/2018 2:19 PM

I have a buddy with 2 rmz 450’s 12 and 17, and he had one of the main bearing retainer screws walk out on both bikes. Had to rebuild both. I could see maybe it would be ok before it warmed up and everything cold and tight no noise, and then after everything warms its loose and rattling around. I think you are on the tear down train man!

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12/25/2018 2:22 PM
Edited Date/Time: 12/25/2018 2:22 PM

cody41 wrote:

The piston may be toasted. 45 hours is not unreasonable for a four stroke top end. I cracked my yz450 piston at 50. Don’t believe the majority of people on vital who say they get 200+ hours without doing a thing. Bikes don’t wear out when you don’t break 4K rpms. You said you ride the bike hard so this isn’t an unreasonable assumption.

Mocaby_24 wrote:

I've had plenty of bikes and had them go and it's pretty usual at least symptom wise. This one though isn't making any noise to make me think the top ends going out but more bottom end crank sound. I just didn't think a rmz would roast one before 50hrs and figured I'd see if anyone else with a rmz had farther info if itd ever happened to them. I'm not completely surprised though because it gets rode outdoors mainly and is on the rev limiter quite a bit lol. I'll pull it apart and split the cases and get to the bottom of it. I'd rather not have it lock up coming up the face of a jump. And since its winter I'm not riding it every minute so nows the time to do it.

Yeah man you said it you ride it hard “on the limiter” outdoors so it wouldn’t be out of the relm of possible for it to need crank service at 50 hrs of that kind of riding, seems like normal maintenance for your riding ability and style

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12/27/2018 5:52 PM

nick610s wrote:

I have a buddy with 2 rmz 450’s 12 and 17, and he had one of the main bearing retainer screws walk out on both bikes. Had to rebuild both. I could see maybe it would be ok before it warmed up and everything cold and tight no noise, and then after everything warms its loose and rattling around. I think you are on the tear down train man!

This happened to my 12 crf450 sad

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