125-200cc 167 kit... can hurt people apparently...

I had Christmas last night. My 167 Kit arrived from George at Uptite. Very nice work and all the pieces are first rate, especially the forged Mahle piston kit. Between 12 hour work days and relatives visiting, it will be Sunday night before I can get it mounted up. I just had to start a thread because this is very cool stuff. I will take pics of the parts and install for posting later. OBTW, there is one damned big hole in the Pre-08 CR 125 cylinder, I expect this to be a torque motor that will rule on the trails.

I am going to change to 13X49 gearing right off the bat as I was already changed to the stock 13X50 gearing for the 144. Wish I had picked up a 48T rear when I was at MotoTech instead of the 49T that I was going to change to whenever I wore out the stocker.

More as I progress,
Walt

I'm on pins and needles, waiting for your report!

Is that all bore and no stroke ?

Yup!

Yes. This is not going to be turning 12000 rpm like the 144/125 does. I so seldom rev the crap out of my 144(love the breadth of this little motor), that I have always been very interested in the 167 kit. I personally like to ride a gear high and carry more speed and be able to stay on the gas longer and get back faster riding the bottom and middle. I just don't have the talent or fitness to ride on the pipe continually. My conversations with George really lead me to believe that my issue will be getting it geared high enough for the torque output and not worrying about getting it to rev. I could easily see this motor never seeing the other side of 10000 rpm.

Great thing is the speculation will be answered in the near future as long as I don't screw it up.

Walt

Now it this works... I'll need to keep my 300 a little longer for George to get my barrel done... (have to let She who must be obeyed know this)

I hope it runs well. Curious about the torque vs. rev of the motor. I have to admit I really enjoy riding on the pipe with the 125 (soon 144).

On the other hand, boosting the torque on this little bike, without increasing the change of overheating would make the bike climb anything.

Does the 167 still have a powervalve?

JS

Man what a thread teaser! I too can't wait for your ride reports. Happy for ya and I have no doubt you will get it installed correctly. Good question on the powervalve JS.

Subscribed!

Wow!
No stroker crank?

That barrel must have some meat if it can punched out that far. I bet it still revs out decent since its not stroked. Plus you're not changing the rod angle, which I think is a good thing.

Rock on!

It should be about the same bore and stroke as a KTM 170 (200 barrel on a 125). I hear that motor works really well.

So, this is a pre-'08 cylinder? The newer cylinders don't have enough meat to bore this far? Do I have this right?

Thats what I remember reading. I think he used an 06 for the project. LOL if it works good it will be a mad rush for old cylinders.

Yep, the newer ones are pretty maxed out at 144 from what I understand.

Note that bore/stroke changes are a bit different on a two stroke than a four. Unlike a four stroke a short stroke/big bore doesn't necessarily mean a high-rpm motor nor does a long-ish stroke relative to bore mean a low rpm, torque motor.

For example, look at a KDX200, its way oversqure by two stroke standards and is pretty low-mid oriented. A 250cc two stroke MX'er has a super-long stroke, but still revs out pretty high (of course porting etc all makes a bit difference too).

I always wanted another 175 cc bike - I wonder if they could come close with a stroked 167 cc kit? We'll need a long range report also to see how the bottom end holds up.

The kit still retains the power valves. The major concern for the kit is how well the bottom end will hold together if you rev it to the nuts all the time. Obviously when you install a 62 mm piston on a bottom end that was designed for a 54 mm piston the added weight is going to stress things if you are going to turn it above 10,000 rpms a great deal. I would be surprised if it lost the ability to turn high rpms, it just isn't what I require from a motor. If I want to spend a lot of time on the pipe I will just re-install the 144 kit. One thing that George was saying is that if you have any issues with the bottom end installing the kit will bring them to the surface. My take on that is that if I had a thousand hours on the bottom end, I would probably tear it all down and replace all the bottom end bearings and rod before I installed the kit. JMO.

When I looked at the pictures of Kelly's 144 kit cylinder, it sure looked like they eliminated the shallow areas in the cylinder sleeve that were preventing using the newer cylinder for more than 58mm bores. I will definitely take a lot of pics, before, after, EG 144, and all the various parts. I can hardly wait for Sunday.

Walt

Looking forward to the step by step photos and the ride reports Walt. I bet you cant wait to tear into it.

Walt, just rev it a few times for the rest of us guys who want to install the kit and blow out the bottom end racing (I mean beating) all the open class bikes.

JS

If you get a chance maybe put both pistons on a scale. It'd be really interesting to see what the weight difference is. Sometimes big bore pistons aren't much heavier, sometimes not any heavier if they find places to save weight along the way with different designs or materials (if the pins are different weigh those too).