Anyone interested in a YZ200?

[red_eye_righley]

Hey guys, I have found a YZ125 cheap. Its a long way to fetch it though and I was wondering, as it is a 2005 model, what differences are there between the 2005 and the 2009 model? I see the '05 also has the ali frame. any other changes that would make buying a newer one a better idea?

Cheers for any help! PS: has anyone got a yz125 motor out of the bike - I would greatly appreciate a size between the swingarm bearing "housings".

[avocasingletrack]

Why not a ktm200 ? Because the YZ125 handles so well . I had a KTM 200 (loved it) had a 300xc , Still have a YZ125 and YZ250 . I haven't found anything that handles better and instills more confidence than the YZ125 . You just have to keep moving on it, have to instantly pick good lines and maintain speed thru that line because it doesnt have half the bottom of a ktm 200 and like one fifth the bottom of the YZ 250 . You just gotta keep the YZ125 in the mids... stay smooth, drag clutch into corners and downshift whenever you even think you might have to ... It's alot of fun, just have to get used to it. Another thing is that if its a race with foot deep mud then the you just need a 250 ... you'll blow up the 125, lol . The YZ125 is 3 inches across the back of the engine where it slides between the swingarm and the 200 is like 4" . I was looking at both today on the bench . I dont know where that guy got the room to do it, you'd hafta take like 1/8" off each side of the case and and like 3/8" off each side of the swingarm ... I dont see the room there but it's possible, they guy did it.

A KTM 200 engine in a YZ125 would be the ultimate bike... imo The 200 has similar mid to top power as the yz125 but 2 or 3 times the bottom , yet still thrills like a 125 with a mean mid to top powerband . If somebody would make it, I'd buy it . I just cant "get along" with KTM susp/ergo's I could never understand why Yamaha doesnt offer the same YZ 125 chassis with a 175 or 200 engine in it ... it would be great

Edited March 13, 2012 by avocasingletrack

[joshua_inigo]

Hi guys,

As we all know, for woods/trail/enduro riding.... a 200 is a great motor to have. I am sure most have seen the YZ125 frame with the 200 KTM engine in it - sweet hey! Also, there is a YZ125 with a WR200 engine in it. And there are quite a few hybrids with a kx125 frmae and KDX engine....

I want to change things slightly, put a KDX200 engine into a YZ125....I think it will probably be the ultimate weapon with a little motor work.

There were also YZ125 WR made from ground-up by Yamaha Australia in the past, i think until 2004 ?

[joshua_inigo]

I could never understand why Yamaha doesnt offer the same YZ 125 chassis with a 175 or 200 engine in it ... it would be great

ABSOLUTELY! ?

It will go puuurfectly for my 143 lb, 5'7" frame ?

[Meister]

Here is a link to a NICE swap out!

http://www.pitracer.com/vbulletin/showthread.php?5496-RMZ-250-2010-frame-KTM-200-SX-motor&p=46746#post46746

[blueripps]

2005 and the 2009 model?

06+ has the upgraded suspension, SSS. I suppose the onetwofive also got the same rear shock upgrade as the 250, but not sure.

[H-B-R]

red_eye_righley - your name seems familiar, are you a member on kdxrider.net?

Maybe a year and a half ago I posted some pictures in the hybrid section of a YZ 125 I was considering turning into a hybrid with a KDX motor. The very first thing I looked at was the swingarm. The YZ swingarm is designed differently than a KX swingarm. That kept it from being a simple cut and bolt on deal. I would have had to take it to a machine shop for them to do some tig work. I didn't want to narrow the cases on the KDX motor.

Since I had no idea of what other issues I'd run into, I decided to not take the chance of ruining the YZ (it was in really nice shape). I went the more common route with using a KX.

[joshua_inigo]

Here is a link to a NICE swap out!

http://www.pitracer....46746#post46746

How about putting a nice any 1999 to 2010 YZ250 US-model engine into that RMZ250 frame or into a YZ125 alum-frame?

Or, even an Eric G 295 engine? ?

[Meister]

How about putting a nice any 1999 to 2010 YZ250 US-model engine into that RMZ250 frame or into a YZ125 alum-frame?

Or, even an Eric G 295 engine? ?

Dreamy. Just dreamy.

[FRECNDY]

The things that make a 125 lighter than a 250:

-narrower wheels

-smaller tires

-lighter engine

-maybe a smaller swingarm pivot bolt and bearings

-125 frame has a little less material and rises up under the 125 cases earlier than the 250 frame.

Other than that, they're pretty much the same. Putting a 250 in a 125 frame would require modifying the frame to turn it into a 250 frame. If you were willing to deal with the loss of traction, put the smaller tires on a 250 bike and call it a day, because that's what you'd end up with if you tried a 250-into-125 swap.

I'd really like to see the swingarm details worked out on the KDX-YZ swap. This looks like the thread where it was discussed:

http://kdxrider.net/...opic.php?t=7400 Seems H-B-R just took a look and decided it was too scary, rather than diving in and taming those sharks, giving them names. I figure you're doing some aluminum welding on the frame to get the mounts on it, and I've had plenty of aluminum welding done on my Husky already, I don't see the problem.

You would still have to drill/ream the KDX cases from 15 to 16mm for the YZ swingarm pivot bolt (at least that's the thread size on the end, per the manual). CRs have a 17m pivot bolt, so more driling/reaming there.

The CR swap works OK with an E motor, but those are all way old now and the KIPS is crap. An H motor has more durable KIPS, but it lives high on the front of the jug. The CR powervalve lives lower on the jug, so you end up having to carve up the CR frame to make room for the KIPS if you run an H motor in a CR frame. The YZ powervalve lives in the same general location as the H KIPS, so the frame is already relieved for it. There's a good chance it would fit a lot nicer without hacking up the frame.

People are finding that stock CR250 pipes actually work decently with the KDX motor. I guess 200 is close enough to 250. I figured I'd make an easy lathe part (a "pipe nipple") that would connect the female pipe connection on the KDX jug to the female pipe connection on a YZ250 pipe as a starting point, and the whole thing would be an easy plug-and-play connection. Would keep pipe replacements simple since the bike would use standard, unmodified parts.

I've been looking at gearing a lot, and it doesn't get the attention it should, but I'm convinced the magic of the KDX motor is at least half in the gearing. It has a close-ratio six-speed, so it's a little lower than a Yammie WR 4T first and maybe slightly higher than fifth. So compared to WR gears in a YZ250, you have another gear in about the same space. Always the right gear for whatever you're about to ride into/over/through. Would like to try this in a YZ125 AF.

I just took my TE610 on some singletrack for the first time on Sunday, and it was like riding an elephant. Kinda makes me think that awesome gearing and going back past my YZ250 to the other extreme in weight and nimbleness would make it hard to keep the shit-eating grin off my face.

Edited March 14, 2012 by FRECNDY

[H-B-R]

I'd really like to see the swingarm details worked out on the KDX-YZ swap. This looks like the thread where it was discussed:

http://kdxrider.net/...opic.php?t=7400

Good job finding that post, that is the one I was referring to.

Seems H-B-R just took a look and decided it was too scary, rather than diving in and taming those sharks, giving them names.

Easy to talk like that when it is someone else's money and bike.

Scary - no. Risky - yes. At the time, and even now, I wasn't in a position to start cutting up an almost mint bike and risk being left with parts I'd then have to sell.

I figure you're doing some aluminum welding on the frame to get the mounts on it, and I've had plenty of aluminum welding done on my Husky already, I don't see the problem.

Most people can't weld AL, I sure can't. I wanted something I could build myself instead of having a machine shop do most of it. Half the enjoyment I get out of riding my hybrid is knowing that I did it myself.

I'd be more than happy to start cutting up your YZ to see if I could get my KDX motor in it. ?

I've tried finding a YZ roller or a really cheap YZ to try this on but didn't have any luck. If nothing else, the 'one of a kind' factor would be there.

Edited March 14, 2012 by H-B-R

[MaxPower]

Here is a link to a NICE swap out!

http://www.pitracer....46746#post46746

If this keeps up there are going to be a lot of KTM200 with rolling frames for sale. That guy made himself a sweet bike

[joshua_inigo]

Dreamy. Just dreamy.

Well, i wrote the song i'm the king of wishful thinking ?

[Wideopen24_7]

YZ rear engine mounts seem to be the shortest of any motor so therefore the swingarm gap is the smallest also. They can easily be widened atleast 5/8" if not alittle more by pushing the inner bearings together and shaving the swingarm and the bushings. Its super easy, just look at the parts when they are all apart and take them to a machinist and tell them what you want done.

I believe what gives the aluminum framed yz 125 its super light feel is the compact and low slung motor. The KDX motors seem to be closer in size and weight to a 250 than a 125 with longer cases and vertical cylinder angle. The KTM 200 motor is 5 to 6 lbs. heavier than the new AF yz 125 motor and maybe 2 lbs. heavier than the steel framed 125 motor with a slightly higher center of gravity but matches the 125 frame very well. With the KTM 200 motor the tank is very close to the head.

The KTM 200 motor is a much better and lighter motor than the KDX 200 but I know that many loyal KDX owners love the 200 motor.

KTM chassis' are junk and have no real value.

[FRECNDY]

Easy to talk like that when it is someone else's money and bike.

I've cut up perfectly good vehicles to mod them with my own money. And if I do all the design, fabrication and parts fitup, having someone who's an artist with a TIG torch weld them for me is OK by me.

Anyway, here's some data relevant to the thread that I've collected. It's missing primary drive ratio data for most of the bikes, but still interesting.

As noted above, the KDX covers a wider range of ratios than a Yammie WR five-speed, but with six evenly-spaced ratios. Climb trees in first, wind it out down the straight in sixth.

The KTM has a first that's comparable to the KDX first, but the KTM sixth falls between fourth and fifth on the KDX. So you have plenty of ratios, but you've lost the dynamic range. Probably f'in awesome for really tight trail work, but isn't going to have legs on the top end. Not as versatile for singletrack, woods, desert if you want one bike that does everything really well.

As for the weight of the engine, the KDX started out as a 125. If you read KDX histories, it's mentioned that in the first couple years, I think of the E waterpumpers, some cheating cheaters who cheated on the amateur level bolted KDX motors into their KX125s and seemed to get away with it. Eventually, the KX evolved while the KDX basically stayed the same. So it's not as big and heavy as a 250, it's just as big and heavy as an old 125. Still pretty light and compact.

Edited March 15, 2012 by FRECNDY

[GCannon]

I think it would be cool, but for the work and money involved it might be easier to start with a yz 250 and work at tuning the motor to be more 200 like.

Before we start cutting Has anyone considered a 144 kit with a stroker crank? I would think even an offset crank pin and a 144 would get you close to 200CC and the longer stroke may even improve the bottom end power.

Maybe I am nuts but its fun to think about. This (i would think) would offer the best chasis geometry and weight distribution which is why you are starting with the 125 in the first place?

[Sheriff245]

Before we start cutting Has anyone considered a 144 kit with a stroker crank? I would think even an offset crank pin and a 144 would get you close to 200CC and the longer stroke may even improve the bottom end power.

Maybe I am nuts but its fun to think about. This (i would think) would offer the best chasis geometry and weight distribution which is why you are starting with the 125 in the first place?

The most you could get with a stroker crank is 58mm. That would make it a 155. You could go up to 167 with RPM's 60mm top end and 58mm stroker.

[Wideopen24_7]

I believe the RPM 167 is 60 bore 59 stroke and still won't get you the torque you want. The newer kx chassis handles great and looks good also without stickers on the tank like the yz. If you want to use a kdx 200 motor then the logical choice is a kx 125 chassis. Anybody got a weight on a kdx 200 motor?

Best 200's would be:

1. KTM 200 motor in any YZ 125 chassis from 97/98 on up

2. Modded KDX 200 motor in last year KX 125 frame

3. New style AF YZ motor bored and stroked in 02-04 chassis (I'm doing this one, less torque, lighter feel)

Edited March 15, 2012 by Wideopen24_7

[FRECNDY]

If you want to use a kdx 200 motor then the logical choice is a kx 125 chassis.

Why, because it's green? If the engines are totally different, there's nothing about the name on it being Kawasaki that makes it easier or more logical. For example, putting an LS motor in a C4 isn't any easier than it is in any other car that happens to have enough space. Nothing matches up, nothing is an easy bolt-together, even though it's the engine from the newer version of the same nameplate car. It's completely different.

If you read the threads in the hybrid forum over at kdxrider, it's apparent that the '02-07 CR125 frames are just as easy, if not easier to do the hybrid with. Things like the tank clearing the thermostat housing and radiator hoses that require pretty extensive rework on the KX are non-issues on the CR. I also think the YZ radiator hose routing is the best match of all for the KDX motor.

Best 200's would be:

1. KTM 200 motor in any YZ 125 chassis from 97/98 on up

2. Modded KDX 200 motor in last year KX 125 frame

3. New style AF YZ motor bored and stroked in 02-04 chassis (I'm doing this one, less torque, lighter feel)

Getting a 167 YZ built right is fairly expensive. If you have some fab and CL/fleabay skillz, you can put together a hybrid for a lot le$$, ending up with a lot more cc. You can take a KDX200 up to 220-225 with just jug work. Plus, you still have YZ gears with a YZ motor:

Edited March 16, 2012 by FRECNDY

[Wideopen24_7]

The AF YZ cradle is just too small for a KDX 200 motor, the motor won't lay forward near enough. The KTM 200 motor just barely fit and it didn't lay forward as much as it does in the KTM frame. Also the 'Y' where the exhaust comes through is really low on the YZ, once again the KTM 200 motor just barely cleared. Believe it or not but the steel framed YZ 125 has less room to work with.

The KX 125 conversion has been proven, is easy, and is a good chassis. Its more stable than a CR 125 but doesn't turn as good so it just depends on which type of handling you prefer. The CR should have lots of room since it can be modified for a CR 500 motor. The KX swingarm should not require machining and/or case machining.