Rebuilding 2015 YZ450F

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1/26/2019 5:57 AM

Hey everyone,

Im looking to rebuild my 2015 YZ450F. It currently runs great but has around 100 hours on the motor. Im thinking of just doing the timing chain and top end. This will be my first time tearing down a 4 stroke motor myself. Im fairly good with a wrench and have all the tools just have not done this before. Just wondering if anyone has links to some good videos, guides, tips on when it comes to doing a top end rebuild.

Thanks!

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1/26/2019 8:23 AM

Rockymtn should have some diy vids on their site...Tusk flywheel puller , OEM gaskets , OEM timing chain and your choice of any reputable piston should be fine. Ive done my share and they are very straight forward...I actually enjoy doing them...lol. If the cylinder still looks/measures good just clean it up with some scotchbrite/wd40 and be on your way. Id check valve clearances before disassembling and if any adjustments are necessary just do them on the bench instead of in the bike.Be a good time to check clutch plates/ assembly also.

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1/27/2019 7:27 PM
Edited Date/Time: 1/27/2019 7:28 PM

One thing about your bike. Make sure it is super clean around the intake area before disassembling. It's like a funnel right into the throttle body. Also take your motor out of the frame if possible. It's easier to do the angle torquing and overall topend work.

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1/27/2019 7:47 PM

hod928 wrote:

Hey everyone,

Im looking to rebuild my 2015 YZ450F. It currently runs great but has around 100 hours on the motor. Im thinking of just doing the timing chain and top end. This will be my first time tearing down a 4 stroke motor myself. Im fairly good with a wrench and have all the tools just have not done this before. Just wondering if anyone has links to some good videos, guides, tips on when it comes to doing a top end rebuild.

Thanks!

When you say top end do you mean piston, rings, gaskets, wrist pin, circlips, valve seals, valves, shims, camchain and sliders?

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1/28/2019 11:42 AM

Change the rod NOW. Do not pass go.
The small end WILL break thru the oil hole.
Had it happen at 75 hours.
The 2019 rod doesn’t have oil holes in the pin end.
The ‘15 rod was supposed to be worse than later years as well.
Had to part ours out after it sawed the motor in half.
KC
Photo

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1/28/2019 11:44 AM

And the valves and springs.

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1/28/2019 12:57 PM

I would definitely do the crank also. New piston could put too much stress on the old crank which means KABOOM!

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2017 RMZ450
2005 YZ250-sold :,(
1998 YZ250
2005 KX250F

80% of the time it works every time
IG @2HRacing
Thanks to : Factory Effex, N2Dirt, Acerbis, DT1, Fasthouse, Matix, FMF, ASV, 100% & Mika Metals

1/29/2019 9:35 AM

hod928 wrote:

Hey everyone,

Im looking to rebuild my 2015 YZ450F. It currently runs great but has around 100 hours on the motor. Im thinking of just doing the timing chain and top end. This will be my first time tearing down a 4 stroke motor myself. Im fairly good with a wrench and have all the tools just have not done this before. Just wondering if anyone has links to some good videos, guides, tips on when it comes to doing a top end rebuild.

Thanks!

I would look into getting a carillo rod standard length, i think you should do that, replate cylinder do cp-piston rings, standard oem yamaha piston, valves and springs, possibly cut the seats, depending on how you do air filter changes and what fuel your running, good luck, also on the timing chain side of things i have had the plastic timing chain guides crack in half and drop to bottom of motor when surpassed 100 hours. Just be safe, and only trust so many people, opinions are always gonna be oppinions but the manual stayes FACTS. follow the manual.

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2/5/2019 9:21 AM

Definetly do the head...At 100 hrs I would just plan on putting new valves in and having the seats cut along with new guides, seals and a timing chain paired with a fresh Con Rod and a forged piston

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2/5/2019 10:41 AM

It all depends on how you ride the bike. If you are a weekend rider only and say trail ride the bike you could go longer with the bottom end and slap a top end in it as long as clearances check out. If you ride track and ring it out and what not, I would fully rebuild it especially if it has been raced a few times in those 100hrs.

I will say BUY THE RIGHT TOOLS for the job if you are doing it yourself. Yes, tools are expensive (at least some) but trust me, it will save you money on having to buy more parts because of that one bearing you smashed in with a socket and hammer.

All you should need is a small propane torch, flywheel puller, clutch holder tool or impact, bearing press and puller tools, and a torque wrench. Some things to make life easier would be a pen magnet, circlip pliers and whatever else you want.

Good luck!

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