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My 2004 YZ144 Woods Bike\Build\Rambling

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Got back into racing dirt last year after coming from Trials. Went from a 2001 KTM 300exc that was a great "open area" bike. Not so great for our tighter Harescrambles (my opinion). Swapped that for a 2004 YZ250F thinking the 4T power would be great for racing. Raced Indy Endurocross on that and then decided that I wanted to go back to 2T. I wanted something that felt like my trials bike. Something I didn't think twice about what I was doing in the woods. 125 2T it was. Unfortunately I traded my bike for a POS 2004 YZ125. Would have been fine had the original owner(s) taken care of it, but alas.....they did not. I'll post up here what I've done\will do to make it my competitive machine. I'll be competing in D17 Harescramble Series B class.

Be forewarned that while I do occasionally take pictures of what I do on the bike....I don't always, and when doing general maintenance\things like that....I generally don't take pictures due to not wanting to get grease\crap on my camera. I also find that while out riding I do a horrible job of taking pictures. I now have my own GoPro, so there will be testing\tuning\practice video.

Enough chit-chat; onto things.

The bike I got rid of for the 125:


The 125 after a bit of elbow grease:


Everything seems fine, but right off the bat, I notice some issues. *For one, the forks aren't in the greatest shape, the steering feels notchy, the tires are shot, and the frame is unusually rusty. **** have I gotten myself into? *And why the crap did I trade an essentially pristine YZ250F for this thing? (I'll spare the 4T vs 2T battle for the track)

Day before my first time out on the bike, I decide to pull the triples and am greeted with the following:


Ok. *No biggy. *Needed to ride that weekend, so went to a local dealer and swapped them out. *Killed some hearing in my left ear while pounding the races out. *Wear hearing protection kids!

Finally got to do a real shakedown of the bike @ KI Tracks in Oregon, IL. *Oddly enough, I don't have any pictures of me there. *I do have this brief video ( hopefully ya'll can see the thing) from my buddies cam. *He's on a KTM 250SX. *I show up around the 2:30 mark. VIDEO

Things I learned from that ride: *1.Forks were toast. *2. Don't ride in muddyish conditions with a half-assed rear fender...spend the 25$ on a new one!

Now I know that I'm a bit big for stock suspension @ 190 pounds without my gear, but I know the bike shouldn't so easily bottom out purely under breaking. *The power of the bike felt quite nice, and the Shinko 520 tires hooked up very well in the tacky soil. *Unfortunately towards the end of the day, I heard what I presumed to be piston slap. *I shook it off as me "hearing things.

Enter suspension rebuild. *Pulled fork tubes and found the following:


Both fork tubes pitting nicely. *From what I gather, it's rust from beneath the coating coming out, because it wasn't localized to where rocks would hit the tubes. *I busted out some fine grit sand paper, smoothed them out, and got on with the project:


I got the bike all put back together, and it was time for a shakedown at some local trails. *Again, I don't have pictures of this, but the bike felt incredibly planted while riding. *I was able to ride all out with complete ease, and was able to take greater hits on the front without bottoming out the fork. *The bike felt like a complete winner (in a good sense) after that shakedown. *Unfortunately, I was for sure hearing piston slap and decided to pull the top-end.

Big surprise, the cylinder was out of round. *More so at the bottom of the bore than the top. *I figured why risk things....Lets get a big bore!

Enter Eric Gorr. *Eric is about an hour and a half North of me, so I pulled the engine and loaded up that and the wife and headed north!


Dropped off the motor and went to do some mall browsing with my Wife and kill some time before picking up the fresh engine from Eric. *I headed back to pick up the engine, to be informed of the bad news. *Mr. Crank was Mr. Toasted! *haha. *Well I wanted to ride in 2 days, so it was time for some over-nighting of parts (from Japan?) and some quick handy rebuild work. (Sorry, not a single pic of the rebuild. *I guess I was focused. haha) *At this point, I also tossed on a 14T front sprocket as suggested on Thumpertalk. *Apparently the 144 has the extra giddyup to take care of the taller sprocket, so I did it to it.



Things were looking great. *Bike got back together in very little time. *Engine rebuild was super smooth. *I felt confident that the bike would kick right over....sure enough it did. *All the better, I was ready to ride for that Saturday. *Originally had planned to go back to KI Tracks when my neighbor walked over while I was loading up the bikes. *Would I like to ride at their track 5 minutes from my house.....Why yes I would! *Off to the track!


The bike needed proper breaking in. *So MotoMan Break-In it was. *If you think he's wrong...I don't care. *He know's what's up, and that lil 144 had some scoot. *Unfortunately I decided to man-up and hit one of the doubles on the track. *Now don't get me wrong. *I've jumped plenty of jumps that were longer in distance than this one, but the track was more SX style with steeper\taller face that was a bit intimidating. *I decided to not wait for my friend to get on his bike to "pull me" through the jump and instead pegged the bike in 2nd. *Sigh. *I didn't slip the clutch enough coming out of the turn and part way in the air knew that I was doomed.


Obviously I came up a bit short on the jump. *I didn't have 100% commitment and just didn't do things right. *Thankfully I didn't get hurt from this. *I didn't fall. *Just came up short, cased, and exploded my rear shock & linkage into quite a few pieces:


Earlier that day, I managed to tweak my knee. *I had messed it up practicing on the YZ250F earlier in the year, but apparently this day just aggravated things and I ended up not being able to walk by the end of the night. *I'll spare you the racy photos of my bare legs and just share the link to the following MRI\x-Rays of my knee. *Doctor drained plenty of blood & gave me a piece of crap "knee brace". *Thank goodness for having Insurance!

Fubard Knee

I managed to score a replacement shock\linkage off eBay for a handsomely 40$. *Not a bad gig. *Unfortunately, I was still on the edge of "being able to ride". *Winter decided to set in, and I figured that to help protect myself even more, I would pull my bike apart, sand blast the frame, powder coat it white, and toss the darn thing back together. *I did this for a couple reasons. *My frame was rusty. *I have a large enough sand blaster to blast my frame. *And I have a friend who can Powder Coat stuff the size of a car who happens to be storing a bike in my garage.....So it cost all of Free99 + my time.

So my frame went from looking like this rust bucket:


To looking like this work de art (disregard the pile of CR below the frame):


And as such the bike went back together ever so nicely:


I will continue on this later, but figured I would give a precursor. *I'll list out the things I have done, things I'm doing, and attempt to put whatever full specs I can up about my rig. *In the meantime, feel free to check my site for other info: www.AndrewGore.net



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Only quick other things I have right now are rather trivial. Ok, so one of them isn't. The following was delivered to me today:


I'm usually a "ride it as it is" type of guy. My suspension is at stock settings. I run stock exhausts. I don't fool around too much with stuff on the bike. My standard feeling is that I should be able to ride around a "problem" on the bike and still be fast. This is why the auto-clutch was such a rough purchase for me. I know how to use the clutch. Trials will teach you to properly use clutch\brakes very quickly. There is a difference though. Trials event you are kicking it in a section for no more than 60-90 seconds. Harescrambles, you're in there for 2 hours. I don't care who you are, or how fit you are. At that 2 hour mark, you'll feel like the devil is sucking your heart out through your knee caps. The Dyna Ring was picked up to help make that 2 hours just a bit easier on myself. I'll weigh in on how I feel on it. I have a feeling I will like it, due to retaining standard clutch operation.

As far as counter-shaft sprocket. The 144 handles it just fine. Since doing the main rebuild I have ridden the bike once on the ice, once in the uber deep snow in the UP, and last weekend @ Racine Indoor MX. On the ice, the sprocket setup was just dandy. With the tires I had, it could have handled going up to a 15T front sprocket and been fine. Had I of had grippier tires, the 14T woulda been perfect. In the UP, it was fine, but in all honesty, the bike sucked. It just isn't meant for trying to plow through thigh deep snow. No way around that.

Now as far as the 14T cs Sprocket @ Racine Indoor MX, it gets a little more complicated. I had kept my jetting at the following:

MJ: 440

PJ: 40

AS: 1.5 turns out

Needle: Position 4

I had it up uber rich for riding in the UP. It was around 0 degrees & I knew I was gonna be in snow. Problem is that I had essentially 0 Low end. The bike felt pretty strong up top, but still nothing to really write home about. I am now going to the following jetting:

MJ: 420

PJ: 40

AS: 1.5 turns out

Needle: Position 3

I rode with this jetting just after I did the 144 (day I cased the double) and it felt to pack a plenty good punch.

Last week at Racine Indoor with the 440 jetting, the bike felt like a stock 2001 CR125 (only other "modern" 125 2T I can compare to right now). The bike felt like a turd down low, but if you slip a bit and get on the pipe, it would be all rocketship on you. So to put it simply. Even with a poorly jetted bike on a smaller SX style track and with the 14T CS Sprocket, the bike still had what it needed to move my large rear around the track at an ok pace.

Reference (Yes, I know I'm slow and have poor corner speed. I'll blame the frozen soil 😏 ):

I will update more as I can think of it.


ps. Should be installing Revloc Dyna Ring tonight.

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Well apparently my friend who was assisting in the 144 rebuild was on the picture taking job. If you use these pics as reference in rebuilding your motor.....you're probably doing it wrong🤣


Want some organization? Feh


Then I guess this CR showed up and worked some magic:


As I began pulling trans apart:


I gather that's all we got. I'll admit. I probably looked a bit like this while buttoning things up:


But it all got done and I was more like:



Dyna Ring installed tonight. Took a whopping 20-30 minutes. No pics, as I was trying to get everything done before my wife finished baking some Calzones.

Remove rear brake. Remove clutch cover. Swap clutch plates (pre-soaked mine in ATF...yes I use ATF). Re-Assemble everything. Find out that my current clutch cable is max stretched, requiring the internal spacer on the clutch Throw-Out bearing. Eat Calzone. Repeat steps above. Test ride...And we're rolling


I will note that I raised my idle a little as well. I'm used to running my idle basically where there is no idle (trials thing again). Kicked it up a bit (I'll look tomorrow what it is set at) and giddyup it felt sweet. Kick in gear & twist the throttle.

Time for some Newcastle Brown Ale


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The bike is a 2004 Yamaha YZ125(144)



Pro-Taper YZ Hi Bars

Pro-Taper Dampened Top Triple Clamps

Moose Pro Contour Hand Guards

Pro-Taper Pillow block grips

MSR\Moose Grip Levers


Shinko 520 Front (12psi) 80/100-21

Shinko 520 Rear (10psi) 110/90-19

Standard tubes with Stans-No-Tubes inside.

14/49 Gearing

Random non o-ring chain


Front - Stock. Compression\Rebound @ Stock settings

Rear - Shock off a 2002 YZ125. Using 2004 Stock Clicker settings.


Eric Gorr YZ144 setup. I believe #3 setup (Just more overall power). Pump Gas

Revloc Dyna Ring Auto-Clutch. Stock Spring configuration

OEM Pipe

OEM Silencer with "yoshimura" sticker on it from previous owner.


OEM Plastics

Acerbis Rear Fender (will not buy again). UFO Replacement waiting to be installed


Moose Front\Rear Tugger Straps

Moose Skid Plate

Soon to add:

Acerbis Over-Sized Tank

Race-Tech Springs .46kg/mm Front

Race-Tech Springs 4.8kg/mm Rear

FMF Q Silencer

FMF Pipe (if deal on eBay)

Replacement Forks (YZ250?)

Jetting to follow.....

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YZ Year: 2004

YZ engine size: 144

Carb mods(PowerNow, Wings, JDJetting, ect..): OEM

Air Filter: (stock?) No-Toil

Main jet: 420

Pilot Jet: 40

Needle model/Clip position: Stock Needle - 3

Air screw: 1.5 out

Altitude where you ride: 0-1000ft Above Sea-Level

Reeds: OEM

Pipe/silencer: OEM

Head mod: OEM (nothing)

Other mods(FWW, ect.): Revloc Dyna-Ring

Type of fuel: Illinois Crap "93" "premium"

Type of Premix/Ratio: Amsoil Interceptor or Amsoil Dominator 40:1

Type of Trans oil: ATF

Type of riding(MX, trails/technical, desert ect): Tech Trails - MX or trails for practice

Where in the powerband do you ride (Lugger/Bottom End, or Wide Open - Top End): It's a 125...Revvin to the moon!

Rear Tire: Shinko 520 110/90-19 (10psi)

Gearing (sprockets): 14/49

Degree of satisfaction: 8. Could handle some bottom end crisping up

And finally: how much spooge 1) none, 2) little, 3) medium, 4) lots: 1

Notes: So far so good. Will report back in after practice Friday.

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yeah andrew this thread is pretty awesome. Its nice to know im not the only person that tends to go through things sometimes and then have that oh sh** moment, guess I need to replace that too. I've been into my bottom end more times than id like to admit. Just sent my cylinder out to Eric Gorr myself for a weld and re-plate. Freaking rips now.

The thing I hate most about the yz's is that adjusting the idle is such a process. I wish i could adjust it with a twist but no, you need to attack it with an 8mm and a small phillips. Anyways good luck with everything and I enjoy reading your build/re-build/ whatever you wanna call it.


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Ok so it wasn't the first official ride with the Revloc Dyna Ring. First ride with the Dyna Ring was in my neighborhood....riding 2-up with my wife. Showed her all she had to do was twist the throttle and off we went :rant:

So while that was more than likely an amusing test for the neighbors, it wasn't a proper flogging that I felt I needed to give it. Unfortunately, while the weather has been turning here in the MidcraptasticWest, the local trails I ride at aren't completely snow free. So I just had to force myself to go up to the local Racine Indoor Motocross. Not the woods I'll be racing, but a good place to feel it out.

As seen before, the track is a smaller SX style track. The bike is setup as stated above. Under-Sprung & "Under-powered" for my physique,🤣 The Dyna Ring has the "stock" number of springs for RPM engagement. I figured I would try it as supplied, and then make any tweaks from there. For reference, the engagement is plenty low. Also, I raised my idle a bit higher than I normally run. When clicked into 1st, the revs drop a bit and I wanted the bike to be essentially stall-proof. I will check actual engagement RPM next time I ride the thing.

Onto the actual riding. I kicked over the bike, and let it warm up. A grin grew under my helmet as I had my hand at my side and popped the bike into gear. Rolling up to the track entry I couldn't contain myself. It took all I could to hold myself back on my first warm-up laps. After the bike and I got loosened up, I gave it all I had.

Holy crap I felt like I was cheating. I essentially kept my bike in 2nd gear for the entire track and just rolled with it. If I flowed through the turns as I should on the 144 2T, the bike would be on the pipe right at the exit, and launch me over the following jumps. If I botched a turn, or took a tighter inside line, a quick stab of the clutch was all that was needed to get the bike right back on the pipe. This was exactly what I wanted. Just enough to let me float around on the bike without having to destroy my left arm over total race time.

I put 2 hours of actual track time on the Dyna Ring, and it just continued to get better and better as I rode it more. I felt more comfortable with blasting into the whoops section. Sure, that could be just me loosening up with more riding, but not having to think about the clutch in the whoops was a blessing.

Braking in the air was also a totally different ball game. With the bike being so under-sprung, I really need to put a bit of body english in to clear over the doubles at this track. When I'd normally need to brake\clutch in the air, all that was needed was a stab of the brake, and then back on the gas as I would land. One thing I did notice was that if I over-corrected with rear brake, it took a fraction of a second longer for the rear wheel to spool up after throttle input. This can be attributed to not doing the equivalent of straight up dumping the clutch in the air. Not an issue at all, but an observation.

I was less fatigued after 2 hours of riding, and more confident in my overall riding. This is going to be a HUGE benefit for Harescrambles, and will not hesitate to put one of these on any future race bikes I own. I've also warned friends to not ride my bike, as they will want to be lightening their wallet in short order. Long story short, it's a great bit of kit 😏

Here's a video from earlier on in Fridays riding session:


PS If anyone has any specific questions on any of the bike, including the Dyna Ring, feel free to ask.

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  • 2 weeks later...

I haven't gotten to ride since the 18th there. I was supposed to change the oil on the bike this past weekend, but I got distracted by a local bike dealer and ended up buying another bike. lol.

I'll have a better idea of the bike this weekend anyways. I tossed on some forks off a 2004 YZ450F. Gave me proper spring rate for my weight and gave me some good condition forks. I also tossed on a rear spring for my weight. Just sitting on the bike in the garage, it feels much better.

I'm tempted to toss the 13T front sprocket back on to see what I get, but I'm kinda eyeing up testing the new bike at the track a bit more than the 144. I'll keep posted.


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very cool! i had a 04 yz125 too, good bikes.....i see your in D17, did you or will you race the team race at lincoln trail? Its a 2.5 hourrace with a team up to 3 riders thats 20% mx, 70% woods, and a little open field racing too, if you havent done it before it a very fun race and lots of ppl enter, about 15 minutes a lap and it non-stop for 2.5 hours, good times!

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I haven't heard of it. I'll have to check it out for this year. You know if they let anyone do it solo? Nothing like a little self torture 👍

edit: Should note. I rode the local indoor track for a couple hours this past weekend with the new suspenders. I'm not sure if it was that, or it being 35-40 degrees in the place, but my body felt like it was being thrashed. I'm assuming it's the cold, but dang. I had more confidence in the turns & the jumps with the new suspension. It kinda has a nice balance between super stiff & trials bike squish.


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  • 4 weeks later...

Figured I'd do some sort of update here. I've got 10.8 Hours on my 144 as of right now. When I rebuilt the engine, I knew the shift stopper would need to be replaced, but knew it could hold out until I pulled the motor again. Last night I got to work.

Eric-Gorr recommends doing fresh ring on the 144 every 10 hours, so I figured why not pull the thing apart. My next ride will be on my bigger bike, so this can sit for a few days out of service.

30 minutes in and the engine is pulled:


Top End is removed:


Bore shot:


Nothing really in the crank area:


Slight scoring on front of piston (exhaust port bridge)...Any input?:


Head looks as fresh as it did when I installed it:


I didn't bother with hopping into the shift stopper yet. I need to grab the clutch tool from a friend and go from there.

Anyone have any info on that slight scoring on the front of the piston? I figure it should be fine. I feel nothing on the cylinder bore, and assume it's just due to the exhaust port bridge.

The bike has been on the following jetting\settings:


Trans oil changed every other ride (approx every 2-4 hours). Air filter has been changed the same.

Bike has been feeling extremely great. These tires are continuing to impress me, although they are showing some signs of knobs wanting to tear off. I attribute this to riding in the cold temps.


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looks like the port bridge could have been relieved a little more. It will wear, so should be ok just warm it nicely before riding.

Put your used ring in the cylinder and holdit up to the light. You will be surprised how much wear is on the ring in the exhaust bridge area. You will see the gap where the exhaust bridge has worn the ring.

This is why you change 125 rings often. If you dont the rings will eventually catch in the exhaust and...............ouch

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I didn't bother with hopping into the shift stopper yet. I need to grab the clutch tool from a friend and go from there.

Are you working on stop lever because there is a problem or because of the reported problems with it on this forum?

If it is because of reported problem, those problems only exist in the 2005-2006 yz125 engines not the 2004 yz125 and older.

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