Posts
51
Joined
1/5/2016
Location
GB
Ricky4071
4/12/2021 8:18am
4/12/2021 8:18am
Edited Date/Time
8/9/2022 3:32pm
Hi guys,
I have a 2020 YZ450f I bought brand new which has just over 40 hours on it. The other week it started making a what can only be described as chain slapping sound when putting it in second gear and felt like the clutch was slipping.
I changed the clutch with no luck, if you go 1st to third and so on it's perfect with no sound.
So now I'm putting it down to something inside the gear box. I know it's going to have to come apart regardless but is there any known faults with these?
Thanks.
I have a 2020 YZ450f I bought brand new which has just over 40 hours on it. The other week it started making a what can only be described as chain slapping sound when putting it in second gear and felt like the clutch was slipping.
I changed the clutch with no luck, if you go 1st to third and so on it's perfect with no sound.
So now I'm putting it down to something inside the gear box. I know it's going to have to come apart regardless but is there any known faults with these?
Thanks.
I'm a slow vet guy too... no jamming it in gear/always use the clutch/never even see the limiter.
The Shop
Is there any way to know by S/N if your bike is in the "fixed group?"
If I need to replace gears, I am going to have the transmission isotropic superfinished (ISF) and cryogenically treated before reassembly. I did this on an old Honda CRF450R- really nice mod.
I'm going to pull the engine out this week and take it to them so will update with what we find !
Thanks.
I looked up that isotropic finish... nice looking stuff. What does something like that run?
I heard a fast kid at my local track blew through his tranny in 9 hours! Same bike as mine. That to me seems crazy no matter how hard you are on the bike.
Put around 300 hours on a YZ250 trans as a faster younger guy, it finally started eating the dogs up and I replaced everything.
If this gear problem happens to me, I'll also be cryogenically treating the parts to improve strength and durability (in addition to the ISF). I plan to use these guys:
https://www.cryogenicsuperfinish.com/
I BOUGHT MY 2020 YZ450F BECAUSE THEY'RE BUILT LIKE A TANK ... FINGERS CROSSED ... PLEASE STAND BEHIND US YAMAHA!!!
We are now remachining all those gears on the milling machine and do an undercut to re-use them. 5 degr gives you enough holding ability to avoid jumping out of gear.
second gear cog and forth gear cog worn, shift fork worn..
Pit Row
If I knew this, I'd likely order some gears now and have them ready (+ isotopic superfinish (ISF) them).
Maybe KTM reacted to all the bike magazine idiots testing the bikes that complained year after year that a KTM is not as quick shifting as the japanese bikes. Now you got quick shifting but lost the safety of knowing the gear will never jump out just when you accelerate for that mighty step-up which is known as "do or die"
I would have bet a lot of $$$ that you would never have a single issue for the life of the motorcycle with the cryo and micro polish. Ever.
Do you think racing/full-power shifting contributed? Your profile pic looks faster than I will ever be ... by a looooong shot.
And 100%.
. I tried giving the jap bike a chance and it’s almost like the transmission just isn’t built for the micro polish, maybe just the cyro treatment.
I think by doing the micropolish it took off little pieces (I’m talking just deburring the corners and such for less friction) but the bike actually needs it with all the power and stress.
Hate me for this but I had a 19 450SXF before this bike and did 129 hard hours and never had to replace anything in the bottom end besides the rod at 100. So having these problems with the YZ just made me get another KTM lol.. very unfortunate but also not the only one with this issue.
Post a reply to: YZ450f gearbox issues :(