YZ167 feedback / opinions?

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11/4/2013 7:12 PM

I'm considering buying this kit from Maxpowerfor my 07yz125 .... does anyone own one? Is the power equivalent, or rather competitive to a stock 250f? Any setup issues? I posted this in the raceshop forum, but no replies ... thanks!

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11/4/2013 7:26 PM

PM sent

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11/4/2013 7:27 PM

I had the '06 yz125 made into a 144, actually liked it as a 125 better. We also have a '11 ktm 150, which is really a 144cc, and it has more hp than a 250f, but less torque. My son has holeshot 450's on it, not that that means anything, but it is fast. When you big-bore a motor, you usually lose rev, but I am not familiar personally with your deal.(maxpower)

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11/4/2013 7:31 PM

I'm sure there are many guys that are experts on this, but you need to have a stroker crank as well.

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11/4/2013 8:00 PM

we have a 56mm bore YZ125 (134cc)
retains the same overall characteristics but has more overall power

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11/4/2013 8:32 PM

I have the maxpower 167 kit. I bought it off a dentist in WY with about 5-10 hours on it. The thing rips. I must say the powerband is very wide. I run a 14/48 gearing and have a lectron Carb on the way. I think the 167 kit is the way to go. The bike revs great, wheelies 1st and 2nd gear, it just screams. I had a little trouble jetting, I live in So Cal and was running a 440 with 45 pilot middle clip position. I ordered a JD jetting kit and that definitely helped, but by doing some research I heard about lectron carbs and thought, if I have a 167 motor, why not get a great carb with it, I should have it on Thursday. I know the 167 kit is a little pricy I think the previous owner paid close to $2,000, he shipped them the motor, but with a YZ125, why not I am not planning on selling it and have a 2013 CRF450 as well, so once accustomed to a EFI jetting, a lectron carb for me was the way to go, do it no regrets.

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11/4/2013 9:02 PM

TheCRKid wrote:

we have a 56mm bore YZ125 (134cc)
retains the same overall characteristics but has more overall power

If I was going to big bore mine, I would go with the 134cc. IMO this is just the right size for the 125 motor.

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11/4/2013 9:07 PM

TheCRKid wrote:

we have a 56mm bore YZ125 (134cc)
retains the same overall characteristics but has more overall power

burn1986 wrote:

If I was going to big bore mine, I would go with the 134cc. IMO this is just the right size for the 125 motor.

As an old slow and somewhat fat person I would opt for the167 kit. As a small bore lover, I think that would just about be the perfect engine.wink

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11/4/2013 9:39 PM
Edited Date/Time: 11/4/2013 9:41 PM

I had a YZ167 that was done by Ric Peterson before maxpower bought him out and it is my favorite bike of all time. Great power and I was riding it in the vet pro class and even though I didn't get holeshots against 250s and 500s I was right in the mix on the start. On the rest of the track you could make up time in the corners and it was a blast to ride and race. No problems with it at all, just do a top end like I would have done if it were a 125. It cost $1250.00 to do the conversion and it was well worth the money.cool

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Ed Johnson

11/4/2013 9:47 PM
Edited Date/Time: 11/4/2013 9:49 PM

They also had a FMF pipe that was made for the YZ167 .

Photo

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Ed Johnson

11/4/2013 9:57 PM

YZ167
Photo

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Ed Johnson

11/5/2013 6:07 AM

I had a rpm cr167 back in 2001, was pretty badass. I think you will get close the the same hp as a 250f but still be down on torque

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11/5/2013 7:48 AM

The YZ167cc is awesome, I preferred racing one over a 250cc two stroke before I converted to all 4 stroke bikes. The 167 has good all around broad power. The 151cc kit is very fast and hits hard on top but not as much down low as the 167cc. I am not fast enough to ride the 151cc kit the way it needs to be so the 167cc kit was perfect for me.

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recmx.com

REC MX, JE Pistons, Wiseco, Rusk Racing, Yoshimura, Enzo Racing, Dubya Wheels, Asterisk, Rocket Performance, CCR Sport, & MMR

11/5/2013 7:51 AM

TheCRKid wrote:

we have a 56mm bore YZ125 (134cc)
retains the same overall characteristics but has more overall power

burn1986 wrote:

If I was going to big bore mine, I would go with the 134cc. IMO this is just the right size for the 125 motor.

have you tried a YZ139cc big bore? To me that is the perfect size, the 134cc is not much different and the 144cc takes away some of the over-rev, but the 139cc rips!

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recmx.com

REC MX, JE Pistons, Wiseco, Rusk Racing, Yoshimura, Enzo Racing, Dubya Wheels, Asterisk, Rocket Performance, CCR Sport, & MMR

11/5/2013 8:30 AM

What's the bore/stroke of the 167 kit? I'm assuming it's both?

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11/5/2013 8:43 AM

Why hasn't anyone taken on the idea of a short stroke 250 2 stroke? Or even a sleeved down 250? To say, a 220/200?

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2012 CRF250R #946



"Stop being a dipshit, and we'll both be less aggravated" - GuyB

11/5/2013 8:46 AM

I put a 167 kit on my 97 cr, loved it.

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11/5/2013 8:52 AM

TheCRKid wrote:

we have a 56mm bore YZ125 (134cc)
retains the same overall characteristics but has more overall power

burn1986 wrote:

If I was going to big bore mine, I would go with the 134cc. IMO this is just the right size for the 125 motor.

newmann wrote:

As an old slow and somewhat fat person I would opt for the167 kit. As a small bore lover, I think that would just about be the perfect engine.wink

Dang, newmann...I appreciate that post. I thought I was the only old and fat guy here! grin

I recently sold my Honda 450F just because it wasn't nearly as much fun to ride as I remember my small bores to be...and fun is all it's about to me any more. I'm looking at a 2005 YZ125 being sold locally on Craigslist and I might pickup the 167 kit. Sounds like a blast!

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11/5/2013 10:29 AM

moto314 wrote:

have you tried a YZ139cc big bore? To me that is the perfect size, the 134cc is not much different and the 144cc takes away some of the over-rev, but the 139cc rips!

No I haven't, but it sounds like you're right. 139 may just be the perfect size. Shoot, I would like to try all of them 134, 139, 151, and 167. That would make a nice ReVital project. I know GuyB is thinking the same thing. cool

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11/5/2013 11:10 AM

burn1986 wrote:

If I was going to big bore mine, I would go with the 134cc. IMO this is just the right size for the 125 motor.

moto314 wrote:

have you tried a YZ139cc big bore? To me that is the perfect size, the 134cc is not much different and the 144cc takes away some of the over-rev, but the 139cc rips!

burn1986 wrote:

No I haven't, but it sounds like you're right. 139 may just be the perfect size. Shoot, I would like to try all of them 134, 139, 151, and 167. That would make a nice ReVital project. I know GuyB is thinking the same thing. cool

I have tried them all, and got paid to do it! Best job I ever had.

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recmx.com

REC MX, JE Pistons, Wiseco, Rusk Racing, Yoshimura, Enzo Racing, Dubya Wheels, Asterisk, Rocket Performance, CCR Sport, & MMR

11/5/2013 11:59 AM
Edited Date/Time: 11/5/2013 3:06 PM

Socket946 wrote:

Why hasn't anyone taken on the idea of a short stroke 250 2 stroke? Or even a sleeved down 250? To say, a 220/200?

Why would you make a bigger bike that had more weight slower ? The idea is to make a lighter , smaller bike much faster.
Back when the first 125s were water-cooled the 100s were still air cooled so they would sleeve down the 125 so you could have a water cooled 100 or if you wanted to ride a Honda or Kawasaki in the 100 class you had to sleeve it because they didn't make a 100. They changed the rules and made the 105 class so you could run a 80cc bike that everyone made and modified out to a 105 and that pretty much ended the 100cc class that only Yamaha and Suzuki had bikes for anyway and because the smaller faster 80cc bikes were way faster as 105s than any 100 bike could be.

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Ed Johnson

11/5/2013 12:37 PM

We had a 151 from them and loved it! They get there with a bore and stroke job, lots of over rev!After a year of racing it sent the cly and head back to them. they did the 167 kit, still a great motor but lost some of the revs but more bottom end! Just remember the replacement pistons have to come from maxx power. They can get pricy doing them every 10 hours!

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11/5/2013 12:50 PM

Thumperyz,
Who did your 151 kit?

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11/5/2013 1:24 PM

I had to rebuild my 06 last year due to the main bearing taking a dump. I was just going to go 144, but Eric Gorr has a stroker crank in stock and it was only a bit more than a stock one, so I sent the cases to him and had him do the machine work on my cases, bore the cylinder and port it for more power everywhere. It ended up the 151 and I am going to send the cylinder back to him to change the porting to all mid and top. It just doesn't rev out enough for old, fat, and slow me!
A friend had the 167 kit on a 97/98 cr and it was all top and NO BOTTOM. Hard to ride, but it was FAST.

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11/5/2013 2:30 PM
Edited Date/Time: 11/5/2013 3:07 PM

The CR125s were not the best bike for a big bore neither were the RMs. Peterson said the YZ was the best engine for the 167 kit and he was even able to do away with the base spacer that you needed for the long stroke crank, On the YZs you could cut into the head and the piston would stick out above the cylinder when at TDC. You would lose a little top end on the YZ167 but when you put on the FMF spec pipe it ripped down low and on top. I paid $1250.00 and that was on a 96 model, dont know how much it goes for now. RPM had special pistons made so you had to order them from them, we found a polaris piston that was identical but the cost to buy from RPM was reasonable so I never tried anything else.

I was not planning on selling the bike but a local kid wanted it real bad, I told them that they could have their own done and they said they wanted mine because it was dialed in so I gave them a crazy price and they gave me cash. They could have bought a brand new YZ and had everything done that I had and still saved money. When they hand you that much cash for a used bike you take it pinch

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Ed Johnson

11/6/2013 6:07 PM

Joko wrote:

Thumperyz,
Who did your 151 kit?

Sorry been away a few days! Maxx power did our's!

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11/7/2013 9:01 AM

They have a website? Can't seem to find it on google.

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11/7/2013 9:54 AM

Flatliner wrote:

They have a website? Can't seem to find it on google.

http://www.maxrpms.com
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