So at the young age of 45, I have decided to start riding with my buddies at some local motocross tracks. It also gives my wife a chance to hang out and watch me ride, I usually ride single track and trail ride, so hard for her to tag a long. I have been riding since I was 11, so this is no where near a new sport to me. But my riding has always consisted of single and trail riding. I have 3 good buddies I ride with and they pretty much ride tracks only and luckily enough for me one of them is a really great rider and gives me a lot of good advice!
So, we picked up a 2004 YZ125. It's a one owner, really clean and all original bike. I know, it's only a 125, but I am comfortable on smaller 2-stroke bikes and I like that it is not crazy powerful like a 250 2-stroke. I also think it will make me a better rider learning on a bike like this. The bike is in really good condition and I plan on spending most of my build money on suspension, I think that will be the most beneficial upgrade. I will still take it out once in a while single track riding, but 70% will be at the track. So I want to focus my build directed towards track, without making it completely useless out on some single track. I know that might be asking a lot, but I am hoping you guys can help me build a great bike that can keep me smiling on both!
So my build plans and where I need advice from you guys....
Suspension, I will be dropping it off at Future Shox in Phoenix, so that is covered
Clarke desert tank that I will be installing for days where we ride long single track and I plan on not filling it up completely on track days to keep weight down
Pro Taper Cr Hi contour 1 1/8 bars
Acerbis handguards, not wrap around
New plastics & graphics... Restyle kit or 04 plastics?
Gripper seat cover
New chain
Sprockets, what size?
Biggest question I have, keep exhaust stock or upgrade? Is it worth it? Exhaust is like new and no damage!
It has a brand new Michelin Starcross rear tire, so that should be good to go for awhile
New Shinko front tire, I will see how that performs
Anything else that you guys would recommend? Not trying to spend a ton right away, I want to make sure I like riding track and make sure this is a bike that will last me for a while.
Thanks in advance!
So here are a few pictures of what the bike look like when we picked it up today, minus the pro taper bars I had already installed.
I would take the stock exhaust off and put it away. Looks good on the bike when you sell it.
Toss the stock chain n sprockets for new.
Frame guards skid plate rad guards or braces.
Yamaha uses a bearing on the bottom of the shock check and grease it. If it's not all ready been neglected.
Oh yea and take off replace the swingarm chain slider and replace it with a tm design. Bare minimum put something between it and the swingarm. The Yamaha floating design will wear a groove into the arm if you don't.
Enjoy I had an 02 new
Thanks, exactly the kind of advice I was looking for.
It has Devol radiator guards on it already, I will order TM chain guards. I also ordered a 50 & 51 tooth rear sprockets & RK gold chain.
dump the suspension and buy 2006 onwards shock and forks with the corresponding front axle and brake system- best upgrade u can do to your suspension.
i had a brand new 2004 YZ125- biggest downfall is the 5 speed gearbox- it ll benefit from a good exhaust system- i had good results with DEP Pipes, i tried FMF and i wasnt that impressed.
I personally never had issues with the oem chain block and slider- as long as they are oem the are good quality.
If you go single track the tm designworks rear block is an advantage as it doesnt use the alloy cage wich can easily get bend by hitting a rock.
Make sure u replace your piston in time- otherwhise the cylinder will wear out fast
The Shop
Luxon 4-Post Bar Mounts
$189.95 - $239.95
Free shipping: VITALMX
So I ordered a few parts last night....
Polisport Restyle kit
50 & 51 tooth rear sprocket
Gripper seat cover
Factory effex graphics
Acerbis handguards
I also bought a used like new Clarke desert tank for $80
Can't wait to get the build started and take it out!
make sure the axle adjusters are not frozen. If they move run them in and out with a light coating of anti-seize.
I'd say given your intents, budget and skills, you are exactly on the right track. Me personally, I'd save my money for now, run the stock pipe and replace it when it gets too dented.
Yeah, I thought that would be the best move. Thanks!
Congrats on a super clean find! I agree you're on the right track with what you're planning. I would add a V-Force reed valve and most importantly upgrade to SSS forks. Another cheap/easy upgrade is finding a newer CRF front brake. The whole thing bolts right on and it is a massive improvement.
I ran the stock pipe, a PC pipe, and an FMF pipe. I actually preferred the stock pipe until I put the 144 kit on, then the FMF seemed to work best.
Here's a link to my '04 build in case you see anything you have questions about. Happy to help!
https://www.vitalmx.com/forums/Bike-Builds,46/2004-YZ125-Build,1334911?…
Your bike turned out great!
If I come across a set of SSS forks for a good deal, I will definitely upgrade! What year and model CRF front brake works?
Thanks
Got the restyle kit and graphics installed. Still waiting for my custom number plates and the fender graphics.
Before and after pictures. I kind of like the clean look of not a ton of graphics on it.
Pretty sure the one I'm running came off a 2009 CRF250R. The stock 04 YZ brake felt downright dangerous to me haha.
Installed the seat cover and hand guards today.
I think I want to upgrade the pipe & silencer, what would you guys recommend? I want more low end power, but smooth throughout.
Installed a new 51 tooth sprocket and gold RK chain today.
Very tasteful build!
Took the 125 out this morning with a couple friends, bike runs great!!
Pit Row
Dude that bike is so clean! I have an 04 as well. The simple look of the stock graphics with the restyle kit gives it a modern upgrade.
Picked up some UFO frame guards today, not my favorite guards but definitely will protect the frame from anymore where really cleans it up.
What kind of seat cover is that? I'm getting an 01 and am gonna need a seat cover sooner or later.
Neutron gripper seat from Rocky Mountain ATV.
I recently had a 2004 yz250 but back in 04 i raced a yz125.
This is what i had done to my 04 yz125 (in 2004):
get aftermarker pipe and silencer. I always liked FMF, PC was always a little to pipey(top end) for me.
vforce reeds
send the cylinder to a reputable motor guy to have ported polished, (you can also do big bore kits)
This is the upgrades i made to an 04 yz250 a few years ago:
a CR/CRF master cylinder will easily swap, its litterally just unbolt the brake line and reinstall. I would rebuild any used MC also 2009+ yz/yzf MC are a huge improvement over the 04. also rebuilt the calipers as well, as even though it may be low hour, the rubber seals are 18 yrs old.
get as seat from 2006 model and up, the 2006 bikes and newer had a taller seat which get you on top of the bike vs in it and will help with handling.
the rear shock from 04 was really good but the biggest issue will be the fork as they use an old open bath design, it was hard to to keep them from being harsh feeling even after a revalve compared to any fork after 2005 stock. if you can buy SSS forks then all the better
My wife got me a matching stand for Christmas, now I need to order the matching mat!
She also picked me up a set of blue folding shorty levers. They are the cheap MZS Amazon levers, but they definitely don't feel or look like they are cheap quality!
you have done a brilliant job of that buddy, looks clean and trick, i have a 2003 i have owned from new, there a great bike, super fun to ride, i had mine revalved when i got it as i was only 9 stone back then and it made the suspension as good as any of the modern stuff of today, i run 13 front and 49/50 rear, with the 5 speed box i find there the 2 most used sprockets for me over the years, ive upgraded a lot on mine over the last decade, and added all the extras which most of us older guys do lol im just replacing all my bolts over the next couple of months for titanium, due to me attempting to nickel plate my original ones and im just not happy with them
Do you still have those plastics and graphics laying around? I might be interested in buying them for my ‘04.
I do.
So I pulled the spark plug after 2 1/2 hours on the bike, here’s a few pictures of it, what do you guys think? Does it look like it’s running rich, lean? When I first got the bike the motor had just been rebuilt within less than an hour of ride time and the gentleman was running 40:1 with motorex 2-stroke oil. The first time out there was some spooge out of the exhaust and I started to run 32:1 motorex and the spooge went away.
I think it looks fine. What jets do you use? In my 04 I ended up with 420 main and 40 pilot and stock needle in middle position.
Post a reply to: 2004 YZ125 Build... Need Advice!