125-200cc Uptite 167

Walt,

Thanx for the input. You've really did some homework on this mod. I don't blame you for not messing with the ports. Why mess a good thing up. I was just curious to see if I could get some more top out of it for the straights. Nothing worse than picking some riders off in the woods then they pass you on a long straight.

Can't wait till you do the comparison with all three (125,144,167).

Í think the 144cc will be the winner

Here is my dyno run from today with the 144. Last week when we did the 167 at a certain point the rear end was really hopping and the map was a flat jiggly line from there. We didn't try doing anything about it. The same thing happened today at virtually the same place on the curve. We went back and put two guys on the rear end and the curve smoothed out and jumped a little over a hp. When I am all done I am going to go back and do the 167 over again. I expect peak hp will be very similar between the two. For now here is the two curves layed over themselves.

One thing you are going to notice when you compare my 144 curve to the TBM curve produced with the WR150 is that mine has much better bottom/mid. This is a direct result of significantly modified power valves, the CR ignition, and the higher compression of the EG head/CR Honda 58 mm piston. I hope to get some valves over to Ryan(rpmguy) so he can build a program to cnc valves for people with little expense. I will be sending him the ones in this test as soon as I am done with all the dyno testing.

Walt
Do you change the ignition timing from one setup to the next ? Are you running the 09 digital CDI or JD now?

Walt,

Looking good!

I don't change anything other than slight jetting changes for the different cylinders. I am running the JD ignition with the general dirt map. There isn't a huge difference between it and the 09 map, maybe a bit more mid.

When I plotted the new curve over the 167 curve I found a mistake I made in drawing the first one. The curves came out meeting at about 6800 rpm when their sheet showing them both doesn't have them meeting until 8600 rpm. They virtually parallel each other the entire way until the rear wheel hop/spin kicked in at ~8500 rpm. I had made the stupid plotting error.

I think it is going to be interesting to see the 167 tied down like you did with the 144.

Can't wait to see the new results.

My guess you'll go couple HP's over the 144 yet.

Walt,

Any updates coming. I think I read you bolted on a 125 Cyl?

Haven't made it to Missoula yet. I was out cutting down "bad" trees yesterday and hauling them off. Today I have a nasty cold. I had planned on going today. It is only open couple of days a week so I will need to make it tomorrow or wait another week. The 125 is definitely down everywhere compared to the other two. Especially on the bottom/mid although it isn't really fair to compare the stock pv grind to the other two.

Walt,

Sounds great! I think everyone is getting that cold recently.

That's good to know about the 125 power.

Hope ya get better!

Darin

Yeah it's pretty bad when the Dr is sick. Hope you feel better soon Walt!

I have been sucking zinc in hopes of avoiding it moving down but if I am going to be sick now is the time.

Walt,

We thought you were silently working in the background, turning it into a 200!

So what does your thinking tell you? What is your favorite, as it stands now?

144?

167?

125 (Which I think we know the answer to this one)?

Well I personally can't wait to bolt the 167 back on, but I am a low to mid rider who only uses the pipe when necessary or when I want to haul the mail until I endo. 35 years ago I would go with the 144 as it revs faster on top and thats where I rode. For your son re-plate the 144, for you ??? While it runs far,far,far better as a CR 125 than it ever did as a WR 125, I can't imagine any circumstances where that displacement would be better than the 144.

Well,I guess I'm finally a member of the 167 club just finished the install tonight. A few heat cycles tomorrow or by the weekend and then I can wait out the weather and log some time on it.

I dyno'd the stock CR 125 motor today. Very interesting results. The 125 made almost the same hp as the 144 but at 1000 rpm higher. Power band was significantly narrower and low end/mid was significantly less. The 144 and 125 curves are compatible as we had the rear end tied down. I am going to re-run the 167 in the next week or so with a tied down rear end as it was hopping and significantly spinning the first time. Live and learn.

They had a curve from an un-corked 09 WR250F that they did on Tuesday. It had peak hp of only 3/4 hp more than the 144 peaked. Torque was virtually equal but the 4T has a broader, fatter curve for both.

Interesting stuff

It sure is! Great stuff!

Thanx, your efforts are great and I know that your doing alot of work to post this!

That's good to know that the 144 is close, compatible with the 09 WR250F.