2018 YZ450F Starter Clutch... Yes another one.

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12/30/2018 2:29 PM

Hey guys i will try to make this short and to the point. So about a week ago i was loading my bike to go to the local track and i bumped the electric start for a moment with the exhaust plug in( im not sure if this has any significance) and when i unloaded the bike and went to start it all the bike did was make a loud high pitched whining noise like the starter was just spinning and not cranking the motor. I had heard that these bikes have been having issues with the starter so i just went ahead and bump started the bike. 2 laps in and i stall the bike in the back track and think to myself shit now i have to try and bumpstart this thing in soft sand so as a last ditch effort i hit the start button and the bike fired right up to my amazement. It continued to start the rest of the day and then i tried it multiple times over the next couple days and it worked everytime. Now of course when i go to ride on friday i unload the bike and the starter wont crank the motor again. I bump start it and go ride but this time the starter doesnt work at all for the whole day.

That brings me to yesterday where i decided to go ahead and pull the starter clutch out myself since yamaha and the dealer want to act like this isnt a known problem with these bikes. (the guy i talked on the phone with at yamaha actually said to me that he didnt know what a yz450f was, unbelievable). Anyways i pulled the clutch and everything and when i pulled the holder for the damper assy and the starter clutch the washer that is supposed to hold on the starter clutch fell onto the ground. Turns out it is supposed to be held in by a circlip which is no where to be found on my bike ( i did find a couple small metal fragments inside my oil screen located next to the oil sight glass). So that was my first issue, no circlip. When i went ahead and tested the starter clutch like the manual says, clockwise it should spin freely and counter clockwise it should engage, it seemed to do exactly that. I inspected the damper assy as well and everything seemed fine. So i went up to the local dealer and tried to get a circlip that i was missing and of course you cant buy it , you have to buy the whole starter clutch. Lucky for me i have known the service tech there for a while and she went and pulled a valve retainer for an older 1700 road warrior and told me it would work for what i needed it for.

So this morning i go ahead and reassemble the whole bike but this time with the circlip in place. Once its back together i go ahead and try to start the bike (fingers crossed) and it does the same thing again, starter is spinning freely but not cranking the motor. I bump start the bike to make sure everything else is fine and it runs great. I shut it off and try to start it again and the starter cranks the motor over right away(WTF). I shut it off to try one more time and the starter is spinning freely once again.

I say screw this, pull the starter motor as well and everything seems to check out there as well. So now i am completely stumped. But as i start thinking about it i remember that whenever i would try to start the bike and the starter would spin freely, as the starter would almost come to a stop you could hear the starter clutch engage (almost the same sound when you bump the starter really quick where you can just hear all the moving parts lock together compared to the whining sound of the starter just spinning freely)

So my question is, Did i fail to properly test the starter clutch? Maybe when i was spinning it counter clockwise and it was engaging i just wasnt putting it under the amount of torque that it would take to actually crank the motor over, and that is why it sounds like it is engaging as the starter motor comes to a stop? Also has anyone heard of the circlips breaking off of the end of the starter clutch shaft like that?

Im really hoping its the starter clutch and i just didnt test it properly. Thank you for reading and i hope you can help smile Bike has ~33 hours on it.




12/31/2018 9:19 AM

80 views and no one has any ideas ?unsure


12/31/2018 4:51 PM

Check all connections, try taking starter apart and check contacts


12/31/2018 8:51 PM

Im not familiar with those things. However if you can hear the starter motor just spinning without turning the motor over, your starter clutch is bad. I think thats a safe bet. Its a common issue on these bikes.

I hope someone whos done some of these chimes in before you order a new one. Im sure they arent cheap


1/1/2019 5:18 AM

Common problem on this model. The 19 has an updated starter system, but not sure if it would change over.


Take it to the limit, one more time!

1/1/2019 7:53 AM

I thought for sure the starter clutch as well but like i said when i spun it counter clockwise to test it , it engaged. I just wasnt sure it i was putting it under enough torque to really test it. All the manual says is to make sure it engages. I still have the starter motor off the bike so in a few minutes im going to tear down the starter motor and see what i can find. Im really hoping thats the culprit so i dont have to pull the starter clutch again. I will report back guys. Thank you for the replies.


1/1/2019 8:16 AM

They’re seriously junk. There’s a reason the 19 has an updated part. The updated starter clutch from the 19 will fit your 18. It’s comical Yamaha claims they know nothing about it meanwhile they’ve covered some folks for the updated part, and others they say they have zero idea.


1/1/2019 12:30 PM
Edited Date/Time: 1/1/2019 12:35 PM

I like Yamaha but their customer service is about as shitty as it gets. My brother was in the service overseas at the time & bought a brand new 2011 yz250f. Came home a few months later, rode it a handful of times(with good maintenance & proper cleaning, etc). Went to have the suspension serviced about 5hrs in & the fork cap was stuck into the fork leg so badly it couldn't be removed by anything in a safe manner without risk of damage, suspension tuner tried, dealer tried, everything was tried. Called yamaha time & time again. Dealer, regional rep, customer service, anyone he could get ahold of. Every single one told him to get fucked, it wasn't their problem & he should figure it out or buy new forks. Not only that but when he called the regional rep personally, he told him to stop wasting his time, he already gave the dealer the answer & then called the dealer threatening to pull yamaha from them like a complete douche over their fuck up from the factory. That & the rest of the horror customer service stories I hear with yamaha is why I will now never buy a new one again. I think any new bike I buy will likely be a ktm for the fact that they go above & behind to keep people happy, even at times when it was their own fault. Also had other problems on that same bike right from new but I dont feel like typing any further lol. Good luck


7/4/2019 6:18 AM

I have the same exact issue. Clutch does engage when turning by hand but spinns when pressing the starter. Have tried everything but nothing really works. Sometimes it starts and "engages" but only for a milisec.

Did buying the new starter clutch solve the issue for you?



7/8/2019 7:05 AM

Sundberg29 wrote:

I have the same exact issue. Clutch does engage when turning by hand but spinns when pressing the starter. Have tried ...more

Yes i replaced the starter clutch on mine and havent had an issue with it since. Have put around 20 hours on new starter clutch and it hasnt missed a beat. Still disappointed that i had to come out of my own pocket for it but oh well.