Two Stroke Motocross
Two Stroke Motocross Forum => Technical => Topic started by: spencer.price3 on October 16, 2013, 01:47:04 AM
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Hey guys, so I am buying a 2001 YZ 125 on Saturday as a project. The bike is pretty beat so this should be pretty fun. Anyway, the bike needs a new cylinder, but the OEM cylinder is crazy expensive. What is your opinion on Athena's Big Bore Kit? I am looking at it, and it looks prett good. Any complaints or praises on Athena?
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I'm not shooting down the Athena kit idea (it would be pretty sweet), but is the OEM cylinder totally damaged beyond repair? Like did a rod go threw it or something? If not you should be able to re-plate it, re sleeve it at the worst for about $250 depending on where you go.
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Hey guys, so I am buying a 2001 YZ 125 on Saturday as a project. The bike is pretty beat so this should be pretty fun. Anyway, the bike needs a new cylinder, but the OEM cylinder is crazy expensive. What is your opinion on Athena's Big Bore Kit? I am looking at it, and it looks prett good. Any complaints or praises on Athena?
Heard rave reviews about the 134cc kit. You won't gain much peak HP but what you will end up with is a broader powerband with slight HP increases. But like I said the two guys I spoke to said they bought it for the powerband, not the power, and they well and truly got their moneys worth. For peak output you're better off going to 144 or 167. Note: Both people had latest gen YZ125s, not the older engine you're working with.
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I had a buddy who bought a grenaded YZ125. The cost of repairing the cylinder was more then the 125 Athena replacement kit. Bolted right on with no issues. It ran great for several years and then he drank the 4 stroke koolaid and it was sold.
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I have heard that when you install a Big Bore kit specifically on YZ125s that you need to modify the cases, does anyone know something about this?
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I have heard that when you install a Big Bore kit specifically on YZ125s that you need to modify the cases, does anyone know something about this?
I believe that is only if you go to a 144 (someone please correct if I am wrong). The 134 does not require modification.
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I have heard that when you install a Big Bore kit specifically on YZ125s that you need to modify the cases, does anyone know something about this?
I believe that is only if you go to a 144 (someone please correct if I am wrong). The 134 does not require modification.
x2 I THINK its with the 144 and its a little bit of clearance off hte crank cases. Definitely something to check though.
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Okay, so I think I have decided that I will order a used cylinder that comes with a powervalve already and send that off to Eric Gorr to bore out to a 144. I think it will be the cheapest option as the bike does not come with a cylinder and so I will need to buy the powervalve, which I priced out to buy brand new and is fairly expensive. So it is turning out that this bike will be pretty quick as I have heard nothing but good things of Eric Gorr's work.
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I've heard a couple of very bad things about eric gore but many good things aswell. If you talk to premixed he will most liekly call you an idiot for even considering eric gore
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Really...? What were these bad things? I guess I will have to do more research
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Things like cylinder head bolts not being shipped back and being asked to fork out money for hte bolts to be shipped back to you and still taking over a month. Dodgey bore jobs, stripped threads things like that. Although hte last one could have just been teh owner trying to pin his ****ty torque wrench or lack thereof on someone else.
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I have priced things out, and the Athena kit is a much better option as it comes with a brand new head, piston, ring, gaskets, and powervalve assembly. The kit comes with everything I need for the top end. So in the end this is cheaper. I am sure that the Eric Gorr option will give more power but I am only a novice rider, so I will focus more on suspension and stuff like that. I will keep you guys updated and hopefully have pictures of the bike up on Saturday. This will be my first rebuild of a bottom end, and I am rebuilding the crank myself, so that on its own should be interesting. I am more than open to tips, suggestions and comments
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I have priced things out, and the Athena kit is a much better option as it comes with a brand new head, piston, ring, gaskets, and powervalve assembly. The kit comes with everything I need for the top end. So in the end this is cheaper. I am sure that the Eric Gorr option will give more power but I am only a novice rider, so I will focus more on suspension and stuff like that. I will keep you guys updated and hopefully have pictures of the bike up on Saturday. This will be my first rebuild of a bottom end, and I am rebuilding the crank myself, so that on its own should be interesting. I am more than open to tips, suggestions and comments
Sounds like you've got your head screwed on right. Makes a nice change... YZ suspension components are typically very good stuff. It won't be up to snuff with the SSS equipment on todays YZ line, but its still very good. The Yaba kit on my 01 YZ250 was better than any jap stuff I've tried since, not set up either. Jap stuff excluding the SSS that is And they were lightyears ahead of the stock WP components...
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good thinking with the athena kit... no point spending money on ported gore cylinders if you dont need it
Just on a side note: I think that now Gore is part of Millenium Technologies (Nikasil Platers), You might see a present increase in service and reliability as Millenium are simply great.
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I have done some research on the Athena 144 kit, and it looks like there are quite a few complaints about the kit, and it also requires modifications to the cases, which I would not be comfortable doing myself, so that would mean I would have to pay the local Yamaha dealer 100 bucks an hour to do these small modifications. So I found that Athena makes a 125 kit, it comes with everything I need, so I will be keeping the bike a 125. I really do not mind because I am used to racing a stock cr125 which is apparently in no comparison to a YZ125 motor.
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I have done some research on the Athena 144 kit, and it looks like there are quite a few complaints about the kit, and it also requires modifications to the cases, which I would not be comfortable doing myself, so that would mean I would have to pay the local Yamaha dealer 100 bucks an hour to do these small modifications. So I found that Athena makes a 125 kit, it comes with everything I need, so I will be keeping the bike a 125. I really do not mind because I am used to racing a stock cr125 which is apparently in no comparison to a YZ125 motor.
Fair enough mate. Whatever way you slice it it'll be a blast to ride. Yes the CR motors weren't the best, but they could be brought up to speed. But that should have been done in Japan...
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So, today, well I guess yesterday, October 20, I went and picked up the YZ. As I suspected the thing was bagged. The bike was in pieces, the cylinder was missing, bottom end siezed, bolts were mismatched, fenders cut, tires bald, air filter was so old that the oil on it was dry, chain rusted, and the list goes on. One of the weirdest things I found was that the clutch perch was broken, so the owner had wired it together with chicken wire and then taped it with electrical tape. Anyways, looks like I have lots of work to do but I already got lots done today.
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So, today, well I guess yesterday, October 20, I went and picked up the YZ. As I suspected the thing was bagged. The bike was in pieces, the cylinder was missing, bottom end siezed, bolts were mismatched, fenders cut, tires bald, air filter was so old that the oil on it was dry, chain rusted, and the list goes on. One of the weirdest things I found was that the clutch perch was broken, so the owner had wired it together with chicken wire and then taped it with electrical tape. Anyways, looks like I have lots of work to do but I already got lots done today.
Thats upsetting... Although I'm not ashamed to admit I tacked a clutch perch back together with a 1200 mig welder in desperation to ride That was a great weld...
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So, today, well I guess yesterday, October 20, I went and picked up the YZ. As I suspected the thing was bagged. The bike was in pieces, the cylinder was missing, bottom end siezed, bolts were mismatched, fenders cut, tires bald, air filter was so old that the oil on it was dry, chain rusted, and the list goes on. One of the weirdest things I found was that the clutch perch was broken, so the owner had wired it together with chicken wire and then taped it with electrical tape. Anyways, looks like I have lots of work to do but I already got lots done today.
Thats upsetting... Although I'm not ashamed to admit I tacked a clutch perch back together with a 1200 mig welder in desperation to ride That was a great weld...
Ah the things we do just to get a ride in...
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So, today, well I guess yesterday, October 20, I went and picked up the YZ. As I suspected the thing was bagged. The bike was in pieces, the cylinder was missing, bottom end siezed, bolts were mismatched, fenders cut, tires bald, air filter was so old that the oil on it was dry, chain rusted, and the list goes on. One of the weirdest things I found was that the clutch perch was broken, so the owner had wired it together with chicken wire and then taped it with electrical tape. Anyways, looks like I have lots of work to do but I already got lots done today.
Sounds like you picked up my friends 125, this kid took it to the track with chicken wire holding the chain together, 9 teeth missing on the rear sprocket, and I don't think he had any bearings in tact. Great day Sounds like you got your work cut out for you though, have fun with the project
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I would post some pictures of the bike and the progress I am making, but I keep getting a message saying the file is too large, even when I only try one photo at a time
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make a photo bucket account, upload the photos to photobucket, copy and paste the [IMG] URL into the reply box and it should display the photo.
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make a photo bucket account, upload the photos to photobucket, copy and paste the [IMG] URL into the reply box and it should display the photo.
X2, pictures before, during and after are required. Failure to do so will be to forfiet the finished bike to the riders on this forum for a day on the track.
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http://s834.photobucket.com/user/spencerreidprice/media/IMG_00000129_zps57d18ae1.jpg.html?sort=3&o=0
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Oh dear... Better crank up the pressure washer mate.
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Pressure washer isn't needed The bike is all disassembled now, frame and subframe are getting ready to be sandblasted, then will be painted. Silencer has been painted, I was surprised as this was one of very few parts that was in good condition. Just waiting to go to the Montana border to pick up parts, then I can start re-assembling
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shes the DEVIL !
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shes the DEVIL !
Yeah haha, I will be getting the number replaced too
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That's one rough bike to start with.... which will make the build more rewarding.
I think you'll be happy in the end as '01 is a good year for the yz125.... I know I like mine an awful lot.
'01 is the last year they had a steel frame AND a 6-speed trans.... '02-'04 went to a 5 speed trans and '05 went to aluminum frame.
I also think you'll be happy having it stay a 125... once you go up in displacement, it loses a lot of its charm.
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That's one rough bike to start with.... which will make the build more rewarding.
I think you'll be happy in the end as '01 is a good year for the yz125.... I know I like mine an awful lot.
'01 is the last year they had a steel frame AND a 6-speed trans.... '02-'04 went to a 5 speed trans and '05 went to aluminum frame.
I also think you'll be happy having it stay a 125... once you go up in displacement, it loses a lot of its charm.
Yamaha went to a 5 speeder from 02 onwards? Really? As if the Hondas weren't enough of a failure.
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Yamaha went to a 5 speeder from 02 onwards? Really? As if the Hondas weren't enough of a failure.
Only the '02, '03 and '04 yz125 were 5 speeds. They still generally won the shootouts, though typically in spite of the 5 speed.
'05 onwards went back to a 6 speed trans, and they have aluminum frames (which are not my preference).
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So here comes the fun part, ordering parts! Woohoo! It is going to be a big bill, but I am doing this so that I can learn about motorcycle mechanics. However I really need your guys' help. I am trying to decide between a Hot Rods crank and a Wiseco crank. I had previously installed a Hot Rods crank professionally and it shredded to pieces after about 6 hours in my Honda, so I am very hesitant to go Hot Rods again. However I have heard many good things about Hot Rods, and that maybe I just had bad luck. What do you guys think?
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Or do you guys think that I should order the tools necessary to build the seized crank that I already have?
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Deinitely go a new crank but as for hot rods or wiseco, I've heard more bad things about wiseco. You're the second person on here that has had a hot rods seize in six hours on a honda. Was yours an 85?
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Nope, mine was a cr125, 2001.
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Pretty sure my 2001 CR125 had a hot rods in it that held up well to my (extreme) abuse.
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Okay, I guess I will give Hot Rods another try!
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check out partzilla.com first and see how much an oem crank is, I assure you it is better than both.
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Well, my parts came in, and it was like Christmas! Unfortunately I found that I have a few parts I still need to get, if anyone has YZ parts they would like to sell, let me know. Anyways, here are some pictures of the goodies.
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Oh! Also, how do you know if you need a new head, and where could I get one repaired, or even modified?
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i love christmas!
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Oh! Also, how do you know if you need a new head, and where could I get one repaired, or even modified?
Is there damage on your current head? Typically it will only need replaced/reworked if there is pitting in it from detonation. The pitting will create an initiation site for future detonation.
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Well, the cases are all apart, all the gears are there, but as I was inspecting everything I found that the transmission bearings were not the greatest, and that there was pieces of rust in many parts of the cases. Is it okay to put my cases in a parts washer if I can find one? How do I know if the bearings are okay? This is going to be a little more pricey than I thought already because I can not find any company that makes aftermarket transmission bearings, only crankshaft bearings. I am happy to say that things are coming along nicely, but there are definitely a few frustrations along the way. I guess there always will be when you rebuild a dirt bike.