2023 Yamaha YZ250F engine rebuild; Part 1
HTML-код
- Опубликовано: 11 июл 2023
- 2023 Yamaha YZ250F Engine Rebuild. Engine was damaged during a national enduro woods race. This is the disassembly and cleaning of the top end parts.
#yamaha #yz250f #yz250fx #enginework #dirtbike #motorcycle #mxracing #shopwork
Thank you so much for the video! Doing a total rebuild on my 2021 YZ250F and this video answers so many questions!
Wouldn't cleaning the titanium valves remove the coating on then
Unfortunately most OEM titanium valves are not Ti-Ni coated. So the vapor hone running the crushed glass and water slurry is not aggressive enough to cause any damage.
man, you know your shit around these bikes! As an experienced mechanic, which motocross bike would you say has lowest running costs and best reliability in long term perspective?
Thank you, I appreciate it.
My personal bikes are from the KTM group, I love the 350SXF and the 300SX, but they require more maintenance than other brands. I was the mechanic for Rachel Gutish when she raced the GasGas 350 in GNCC, National Enduro and Endurocross. So I didn’t mind working on those bikes every week as we kept her race bikes maintained throughout the few years.
The Sherco 300SEF four stroke she is racing now isn’t bad, but I prefer the MX platform more then enduro based bikes because it’s easier to make power out of a MX style engine, even when adding a wide ratio transmission and flywheel weight. The Sherco builds power differently by design and it’s not something I know a ton of information on since we have only had the bikes since January. Although Rachel did get on the podium at Coker GNCC in WXC pro with a 3rd place. So she definitely likes the bike.
As for a brand I’m familiar with and find to be reliable, it’s hard to beat the Yamaha YZ250F/YZ250FX model. I just finished rebuilding the GNCC WXC pro bike (2024 YZ250FX) of Kayla O’Neil after Camp Coker this past weekend. That bike had over 60 hours in it and was still running strong. It was just a good time to rebuild it with the break in the schedule.
Last week I rebuilt two YZ250F engines, one a race bike and the other a practice bike for a National Enduro and GNCC rider. Other than a melted stator wire from a crash with another bike, those bikes just needed normal maintenance.
No big surprises on the Yamahas. They handle well, come with good suspension parts, make decent power in stock form. They are louder then some other bikes, and the air intake being up front makes weird noises, but you get use to it.
Wow! That's some answer :) I am glad you mentioned KTM. They get a demonized for being unreliable by most riders. I ride street bikes for couple years now, and I am considering to give it a shot with an MX bike. I am Hesitant between YZ125 / YZ250F / SX125 / SX-F 250 (I would buy brand new) I like the Yamaha most but I may get a very good deal on new KTM since I work in company that has a partnership with KTM.
I actually like the SX125 most but I have seen some horror stories online about bike breaking down after literally couple of hours on it. What would be your recommendation mate?@@ThomasStire517
If it sucked dirt in, did you check the crank?
Everything gets checked. Showing every detail would be a 5hr video.
Hi there can you please tell me the dimensions for the wooden stand that your motor is sitting on as I would love to make one up as ive got a bike build wr450 2018 engine it need full top end done also if you have any good tips on installing timing chain cylinder and head
Sure, this is the small one, it’s outside dimensions are 10.5” x 10.5” I also have a medium sized one that is 12.5”
X 12” and it works well for the larger engines like a 450.
Engine stand is best, but it had an engine on it already. So I used the wood as a base to stabilize the engine. We use to build them with the wooden stands all the time.
Timing chain is not too bad, have both cams in, pulled towards the side of the head so you can tilt them down. Start with the exhaust cam first, wrap the chain around the gear with the marks lined up for tdc, then the intake and rock them into place.
There is a part 2 video when I installed the cylinder and head.
Thanks so much for your reply’
I’ve just made the wooden stand up for now and I’ve also purchased a ballards engine stand from mx store but there on back order here in Australia
I’ve Got a few more questions for you to answer if you can please answer them it would be most appreciated’
I have a wr450 2018
It had around 76 hours on her only road ridden but I wanted to pull it down and put a new timing chain and piston rings gaskets etc I’ve had the cylinder diamond honed to put the cross hatching back into the cylinder so the rings seat as there nikalsil plated electorsil here in Australia did that as they are the best cylinder shop here in Australia for nikalsil cylinders
Anyways I’m up to where I’m checking my
ring end gaps
The first ring is the ring that has a bevel at top and bottom edges correct it also has a T and that faces upwards correct?
And in the service manual it says the
1st ring end gap should be 0.20mm 0.30mm
I’ve put the ring in the cylinder about 10mm down with the old piston witch I left the old second ring still on the piston so when I push the piston down the second ring stops it from going down past the approximately 10mm mark
and I then put a fila gauge in the 1st ring end gap and I’ve got slight drag at 0.20mm
Is this ok?
Ok on the second ring gap it says in service manual
0.35mm 0.50mm and I get slight drag at 0.35 is this also ok ?
Should I also check the two bottom oil rings I was also told they don’t need to checked ?
Also should I use permatex assemble lube like you did when installing the piston in the cylinder
or use mineral oil
I was told the rings won’t seat if I use assembly lube but I’ve seen you use it and I don’t think you would use it if it was going to not let the rings seat
When torquing the head in service manual it says to use Molybdenum Disulfide Grease on the head bolts and washes
And also Molybdenum Disulfide Grease on cam lobes in your video I seen you use assembly grease what’s better in your opinion
Should I follow the manual on this one or you ?
Also what’s the best method of running in the motor after everything is installed like how many heat cycles what fuel should I use should use a standard NGK Plug
Or a iridium NGk plug
I’ve purchased motul mineral oil for break in as I was told this is the best way to run it in ?
Since the bike was new after mineral oil break in it has always run motul 300v 10w-40w
Any tips of other good weights of oils you might no of
Sorry about all the questions it’s my first time doing a 4 stroke engine
I’ve have done 2 strokes before but the machine shop did all the ring end gaps and stuff like that for me but I wanna learn from someone like your self
I found your video because I have some oil leaking between the blue valve cover and the head. Hoping its just the gasket, is it best to pull the whole motor, or can you just take the tank off and get to the valve cover
@@JoeyWashburn you can replace the valve cover gasket without removing the engine. Just remove the fuel tank and you will be able to replace it.
What’s the year and size of your bike? The 2023 Yamaha YZ250F valve cover part number is 1SM-11193-00-00 and is about $20 from Rocky Mountain ATV/MC.
If you have Instagram send me a DM at tlstire517 and I’ll send you the gasket if it’s the same part number for your bike.
It’s a 2022 yz250f