Any YZ125 Gurus out there?

chuckie108
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chuckie108
Edited Date/Time 6/3/2017 4:20am
Looking at picking up an '89 YZ125(what can I say, I'm a Yamaha guy). Looked at one today and the guy says it has a ported '87 cylinder- which was the good play back in the day. Anyone know if there is any truth to this? I know that gen YZ125's are notoriously slow, so I'm trying to access what I'm getting myself into.

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MaxPower
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MaxPower 5/20/2017 12:55pm
5/20/2017 12:55pm
Unless I know who did the work I would not be comfortable with buying a ported cylinder. I might be stubborn, but a grinder and big holes doesn't mean a fast bike.,
chuckie108
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chuckie108 5/20/2017 8:29pm
5/20/2017 8:29pm
MaxPower wrote:
Unless I know who did the work I would not be comfortable with buying a ported cylinder. I might be stubborn, but a grinder and big...
Unless I know who did the work I would not be comfortable with buying a ported cylinder. I might be stubborn, but a grinder and big holes doesn't mean a fast bike.,
You're not stubborn, your just tuned into the fact that most "tuners" don't know much! LOL. The price is right, so I think I'm going to pull the trigger. I think I'd rather have a later gen nicasil cylinder anyways. Thanks for the input!
mark_swart
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mark_swart 5/21/2017 12:01pm
5/21/2017 12:01pm
89 wasn't slow! It wasn't as fast as the Honda, but it had a nice midrange punch and was still faster than green and yellow that year. I raced that bike for two years when it was new - with reeds and a pipe it was just fine - plenty of holeshots on that bike. I don't know who would put an 87 cylinder on an 89. 87 was all bottom end like a trail bike.
Russ14
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Russ14 5/22/2017 5:08pm
5/22/2017 5:08pm
I'm building one of them now also, I've been told the 90 model cylinder is the way to go. Clutch outer cover off of 90 model also helps the creeping of the 89 clutch is the info I'm getting.

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chuckie108
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chuckie108 5/22/2017 10:54pm
5/22/2017 10:54pm
Pulled the trigger! Runs(actually barks HARD on the stand!), shifts, new plastics, new Renthals, Perfect PC pipe, has all the parts and some sapres. Love YZ's of this area, couldn't pass it up for the money. Can't wait to tear into it!!!


toomey706
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toomey706 5/24/2017 11:04am
5/24/2017 11:04am
It's actually really good motor. TUF racing ported a motor for me back in the day and was one of my favorite bikes ever. 89 and 90 head really good Motors the 91 fell off a little bit and needed a lot of work to get going fast. I'm on the hunt for a 1991 YZ125 now and they are almost impossible to find.
cvm
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cvm 5/25/2017 3:18am
5/25/2017 3:18am Edited Date/Time 5/25/2017 3:20am
toomey706 wrote:
It's actually really good motor. TUF racing ported a motor for me back in the day and was one of my favorite bikes ever. 89 and...
It's actually really good motor. TUF racing ported a motor for me back in the day and was one of my favorite bikes ever. 89 and 90 head really good Motors the 91 fell off a little bit and needed a lot of work to get going fast. I'm on the hunt for a 1991 YZ125 now and they are almost impossible to find.
You think finding the bike is bad, wait till you need a powervalve. I bought a whole 93 just for the powervalve Smile
Ya I think the 90 cyl/head was the ticket, that's the big change. 90 heads dime a dozen. Here's a not so great pic of her so far, keep on looking. The stares youll get goin thru pits on a pink antique are worth it haha. All the new EVO graphics in wrappers (race-trim) waiting for owner to remember how to ride after 30 yr layoff. Jetting is a bit conservative on rich side intentionally, but pulls like a freight train. Lotta fun.
Slammed a 12t on it to make 2nd gear turns instead of 1st (for my slow old ass) & She is quite perky. Was a box of bolts 9 mos ago.


Its a race bike, not a show piece so save it.
cvm
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cvm 5/25/2017 3:27am
5/25/2017 3:27am
chuckie108 wrote:
Pulled the trigger! Runs(actually barks HARD on the stand!), shifts, new plastics, new Renthals, Perfect PC pipe, has all the parts and some sapres. Love YZ's...
Pulled the trigger! Runs(actually barks HARD on the stand!), shifts, new plastics, new Renthals, Perfect PC pipe, has all the parts and some sapres. Love YZ's of this area, couldn't pass it up for the money. Can't wait to tear into it!!!


Awesome! Congrats, Ya I'm jealous Smile
Could ya post up at some time how the fit is on the PC pipe? Mine came w/ a FMF which seems to work fine, & not leak, but the install, & the clearance around the water pump outlet tube -up to the Y fitting is just way too tight. Pipe to frame clearance @ ft of airbox area not correct either. But It Works!!!
Thanx
Dekon
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Dekon 5/25/2017 7:15am
5/25/2017 7:15am
Nice looking bike. I just picked up an '89 also. Literally a total basket case. But, for $100, I couldn't pass it up. Saved me the work of stripping it to the frame. Are you going to do a build thread for it?
RyanLester761
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RyanLester761 5/25/2017 2:34pm
5/25/2017 2:34pm
Nice score by the way. I like those YZs too!
chuckie108
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chuckie108 5/25/2017 10:43pm
5/25/2017 10:43pm
cvm wrote:
Awesome! Congrats, Ya I'm jealous :) Could ya post up at some time how the fit is on the PC pipe? Mine came w/ a FMF...
Awesome! Congrats, Ya I'm jealous Smile
Could ya post up at some time how the fit is on the PC pipe? Mine came w/ a FMF which seems to work fine, & not leak, but the install, & the clearance around the water pump outlet tube -up to the Y fitting is just way too tight. Pipe to frame clearance @ ft of airbox area not correct either. But It Works!!!
Thanx
Your bike looks great! I'll try and take some pics for you. Give me a couple of days.

chuckie108
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chuckie108 5/25/2017 10:52pm
5/25/2017 10:52pm
Dekon wrote:
Nice looking bike. I just picked up an '89 also. Literally a total basket case. But, for $100, I couldn't pass it up. Saved me the...
Nice looking bike. I just picked up an '89 also. Literally a total basket case. But, for $100, I couldn't pass it up. Saved me the work of stripping it to the frame. Are you going to do a build thread for it?
I was in the same boat! LOL Mines pretty rough overall, but all the important stuff is there. I'll definitely do a build thread, I'm just trying get my YZ400 done first(been waiting for months now on my cylinder port job). Plus I'm currently rebuilding my modern bike. I'll probably try and do a "budget" build on this one. Going to try and force myself to reuse parts as much as possible, source good used stuff, etc... We'll see if I can restrain myself! Hahaha
chuckie108
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chuckie108 5/25/2017 10:55pm
5/25/2017 10:55pm
RyanLester761 wrote:
I have a 1989 yz125 cylinder core, if anyone needs it. It's on Ebay
Ryan, is your cylinder Nicasil? Or steel liner? Apparently this bike I got has been bored, so it's not Nic'ed. I'd prefer Nicasil cylinder, and I wouldn't mind getting a good core that I could have ported/repaired.
RyanLester761
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RyanLester761 5/31/2017 10:16am
5/31/2017 10:16am Edited Date/Time 6/2/2017 8:49pm
chuckie108 wrote:
Ryan, is your cylinder Nicasil? Or steel liner? Apparently this bike I got has been bored, so it's not Nic'ed. I'd prefer Nicasil cylinder, and I...
Ryan, is your cylinder Nicasil? Or steel liner? Apparently this bike I got has been bored, so it's not Nic'ed. I'd prefer Nicasil cylinder, and I wouldn't mind getting a good core that I could have ported/repaired.
I think it is Nicasil plated but I'll have to double check. Sorry for the slow reply. I just checked this...
RyanLester761
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RyanLester761 6/2/2017 8:49pm
6/2/2017 8:49pm
chuckie108 wrote:
Ryan, is your cylinder Nicasil? Or steel liner? Apparently this bike I got has been bored, so it's not Nic'ed. I'd prefer Nicasil cylinder, and I...
Ryan, is your cylinder Nicasil? Or steel liner? Apparently this bike I got has been bored, so it's not Nic'ed. I'd prefer Nicasil cylinder, and I wouldn't mind getting a good core that I could have ported/repaired.
Yep. It's plated. Not sleeved.

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Admoe68
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Admoe68 6/2/2017 9:17pm
6/2/2017 9:17pm
My brother holeshot his quali at Washougal National in 1990 on a bone stock yz125. That thing was quick unlike mxa's opinion at the time.

Can anyone offer advice on what year cranks are compatible for the 93? I'm having a real hard time finding anything for it. I heard 89 to 93 are the same? Maybe someone on here has a good condition one laying around?
cvm
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cvm 6/3/2017 4:19am
6/3/2017 4:19am
Admoe68 wrote:
My brother holeshot his quali at Washougal National in 1990 on a bone stock yz125. That thing was quick unlike mxa's opinion at the time. Can...
My brother holeshot his quali at Washougal National in 1990 on a bone stock yz125. That thing was quick unlike mxa's opinion at the time.

Can anyone offer advice on what year cranks are compatible for the 93? I'm having a real hard time finding anything for it. I heard 89 to 93 are the same? Maybe someone on here has a good condition one laying around?
Partzilla ( or any one else for reference) is your friend. Pull up 93 in a window, 92 in another, etc & compare part #'s. w/o looking I checked that and (were the same) put the crank off my 93 into my 92. I think youre good back to 89 w/o looking at #'s. The big 93 changes were chassis not motor I think. I'm dyin to know how many of these years I could x-ref power valves w/ a little creative dremel, heinekin and epoxy. the bearing #'s are the same for many years. Good Luck fix it. I should be at Unidilla rite now but my comeback is taking time so I'm goin to 2 track days this weekend.
lumpy790
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lumpy790 6/4/2017 1:07pm
6/4/2017 1:07pm
I believe Eric Gorr did the porting for TUF at that time

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