2018 YZ450F 3rd Gear Slipping

The engagement dogs are rounded off in 3rd gear you can send the trans to R&D performance and have it made better than new

What oil is in it? I can for certain feel slipping with a certain brand on mine. And it happens to be my favorite and did not cause slipping with my previous years husqvarna

swtwtwtw wrote:

What oil is in it? I can for certain feel slipping with a certain brand on mine. And it happens to be my favorite and did not cause slipping with my previous years husqvarna

X2

Paw Paw

Paw Paw and swtwtwtw, can you guys elaborate on what oil would cause slipping? I have heard about it before however never had any problems myself, looking to buy a Yamaha soon and would be nice to know.

If you have a 3rd gear shiftfork bent and it's rounded off the gears, then changing to a different oil won't fix it. Now if it's the clutch, it might.

Yamalube 10W40...same stuff I have been running for years. I am certain it is not an oil or clutch related.

Once you shift into third gear and get on the gas hard it slips. It feels as if something is not catching. I'm pretty positive this is a transmission issue, but I just wanted to see if anyone has had this issue yet.

foreman52 wrote:

Yamalube 10W40...same stuff I have been running for years. I am certain it is not an oil or clutch related.

Once you shift into third gear and get on the gas hard it slips. It feels as if something is not catching. I'm pretty positive this is a transmission issue, but I just wanted to see if anyone has had this issue yet.

Slips? When my YZ lost third year it didn't slip. It would hit a false neutral or just jump out of gear. There was no doubt what was going on. My third year has went out three times. I finally sent the internals of the entire transmission and had them cryo-rem treated. No worries since.

foreman52 wrote:

Yamalube 10W40...same stuff I have been running for years. I am certain it is not an oil or clutch related.

Once you shift into third gear and get on the gas hard it slips. It feels as if something is not catching. I'm pretty positive this is a transmission issue, but I just wanted to see if anyone has had this issue yet.

Harry Backmon wrote:

Slips? When my YZ lost third year it didn't slip. It would hit a false neutral or just jump out of gear. There was no doubt what was going on. My third year has went out three times. I finally sent the internals of the entire transmission and had them cryo-rem treated. No worries since.

This happened on my yz 250

Yams lube is good. However, when a gear goes the trans hits a false neutral. If I overrev this bike it falls flat on its face, anything above 8000 rpm with the Preston map. That alone feels like clutch slippage.

I've seen gears go and like the above posters said, "it's like a false neutral". I've also had them go out where it felt like a very loose chain jumping over the sprocket teeth. This happens when the "dogs" on the gears are rounded off which usually is accompanied with a bent shift fork.

swtwtwtw wrote:

Yams lube is good. However, when a gear goes the trans hits a false neutral. If I overrev this bike it falls flat on its face, anything above 8000 rpm with the Preston map. That alone feels like clutch slippage.

This would be the best explanation to what I've been experiencing thus far.

I wouldn't say it's exactly like "hitting false neutral" because when that happens we almost go over the bars, but it's certainly a feeling like that. It looses power when hitting a high RPM and than it corrects itself and you almost whisky throttle over backwards because all of a sudden the power hits of all at once

mx317 wrote:

I've seen gears go and like the above posters said, "it's like a false neutral". I've also had them go out where it felt like a very loose chain jumping over the sprocket teeth. This happens when the "dogs" on the gears are rounded off which usually is accompanied with a bent shift fork.

Now would you see metal shavings in the oil if this was the case? There was no signs of anything in the oil.

FWIW, 3rd gear seems to provide the most power on all the bikes ive ridden. Its quite possible you need stiffer clutch springs from hinson or something.

Also maxima and amsoil full synthetic dirtbike oil is the only one that prevents slipping - in my experience.

mx317 wrote:

I've seen gears go and like the above posters said, "it's like a false neutral". I've also had them go out where it felt like a very loose chain jumping over the sprocket teeth. This happens when the "dogs" on the gears are rounded off which usually is accompanied with a bent shift fork.

foreman52 wrote:

Now would you see metal shavings in the oil if this was the case? There was no signs of anything in the oil.

Then it's probably not that.

mx317 wrote:

I've seen gears go and like the above posters said, "it's like a false neutral". I've also had them go out where it felt like a very loose chain jumping over the sprocket teeth. This happens when the "dogs" on the gears are rounded off which usually is accompanied with a bent shift fork.

foreman52 wrote:

Now would you see metal shavings in the oil if this was the case? There was no signs of anything in the oil.

mx317 wrote:

Then it's probably not that.

Thanks for your input. I will post the solution once we open it up! Some of the smartest people I know are scratching their heads. A few think it's what you mentioned and than the others are saying the complete opposite. It's a mystery I wish I never had!

Still no updates. Bike has been at the Yamaha dealership for two days. They have tried multiple solutions including putting a whole new computer in the bike. The motor has not been taken out yet, but Yamaha does not believe it's an issue with the transmission.

kb228 wrote:

FWIW, 3rd gear seems to provide the most power on all the bikes ive ridden. Its quite possible you need stiffer clutch springs from hinson or something.

Also maxima and amsoil full synthetic dirtbike oil is the only one that prevents slipping - in my experience.

I like this advice.

Also, I suggest buying a magnetic drain plug. All three times my YZ tranny went out there was not a lot of stuff on the magnetic drain plug, but there was more than usual. Or, you could filter the oil through cheese cloth and see what you get. Maybe you're doing these things already and I'm just not able to parse it out of your posts, but those are a couple of suggestions.

Kb is right about third gear too. That's where my YZ 250 makes the most power, and it has always been the gear the dogs round off on. I don't know about the four strokes, but it takes hardly any wear on my smoker's 3rd gear dogs for it to start jumping into a false neutral. In fact, the first time I took it apart I looked at them and thought they were fine. Put it back together and the same problem immediately (that was a painful lesson for sure). Anyhow, once I got the new third gear and saw the difference in the dog ears it was noticeable, but still not very much had worn. Like I said, it doesn't take much. Good luck to you, motobro.

Lost 3rd gear twice on my 05 kx250f and it's like hitting a false neutral. Bike wouldn't move at all if I shifted into 3rd, just felt as though the chain was skipping teeth on the sprocket like someone else had said. Had to run 2nd and shift to 4th. You'd know if it was 3rd gear going out. Hope they figure the issue out quick

We're two weeks in here now and nothing has been resolved. My local dealer has bent over backwards trying to get it fixed. The service from Yamaha has been completely unacceptable. This is my third Yamaha in three years...my 2016 YZ250F needed the valves replaced twice (both at 20 hours), my 2017 YZ250F needed the valves done at 30 hours, and now I am having this issue with my new 18. My faith with Yamaha has gone completely out the window. I can't deny that it is a powerful and good feeling bike but my god watching my buddies on other brands not having to worry about issues like this makes you think.

What rpm range is it breaking down?

Sounds electrical but I have never see a CDI controle unit go bad it is typically something feeding it the info that goes bad.

What have they tried from the simple end? Check all connections and Electrical grease in all connections? Would assume Spark plug has been tried? Spark plug cap? Thermo unit? Neutral switch Assembly? Engine controle unit?

I would get the bike back and find someone that has the 18 and swap out the parts till you find the culprit

Every electrical component has been swapped off another brand new bike in the showroom. The issue is still persisting. This now eliminates anything electrical, which almost everyone thought it was. Looks like we will be opening the motor up now...Hopefully I will be back in a week with an update.

Well, here’s to the solution. Mine is better now at 30 hrs than ever. I have been testing Rock Oil synthetic and my clutch performance is better than with my favorite synthetic.

Ok i will as again ....
What rpm range is it breaking down?

lumpy790 wrote:

Ok i will as again ....
What rpm range is it breaking down?

Get it home while it's raining of course so pavement is wet. Here is an idea of what it's doing. I wish I could get a video opening it up more. You can hear/see as soon as I get on the throttle hard it "skips".

foreman52 wrote:

Get it home while it's raining of course so pavement is wet. Here is an idea of what it's doing. I wish I could get a video opening it up more. You can hear/see as soon as I get on the throttle hard it "skips".

Sounds like 3rd gear is blown to me. Doesn't sound like a clutch, clutch would be more of a progressive slip and electrical I think would cut out instead of "skip"

lumpy790 wrote:

Ok i will as again ....
What rpm range is it breaking down?

foreman52 wrote:

Get it home while it's raining of course so pavement is wet. Here is an idea of what it's doing. I wish I could get a video opening it up more. You can hear/see as soon as I get on the throttle hard it "skips".

Hondas4Life3 wrote:

Sounds like 3rd gear is blown to me. Doesn't sound like a clutch, clutch would be more of a progressive slip and electrical I think would cut out instead of "skip"

Yep. Mechanical issue. Shift fork or the gears themselves. Very small possibility the shift drum has a problem.

Did you take the time to tear the right side apart? That star thing on the drum could be worn out. Or if its pre-rounded as previously mentioned, the tensioner spring might be too weak to hold it.

Any metal in the oil filter? Trans would leave metal shrapnel. Oil pump filter?