How do Mini-4-Strokes Compare with Each Other?

By Jerry Matta

If you haven't ridden many mini 4-strokes you can't assume bigger is better. It's not like comparing a 125 to a 250 where the technology is of the modern age. All mini 4-stokes built today are based on 20-30 year old technology and the design is chosen by whatever is on the shelf and in decent supply at the time. Also, you can't use dyno numbers from different dynos, they all measure differently. Why, I don't know. For instance I know that the BBR dyno measures a bit higher than the dyno we use down here, which isn't bad, but you can't say mine dynoed at 12hp up here and yours dynoed at 10 hp down there so your sucks; you just can't compare the numbers. What dynos are best at is saying,"this is the stock curve and this is the modified curve and we did X amount better.". Then there's torque, where the power is along the curve etc. But that's a whole other story.

Here are the numbers from the same dyno:

• Stock CRF150 -- 9.5 hp

• Mod CRF 150 w/ 170kit, cam, valves -- 10.8 hp

• My 120cc -- 10.9 hp

• TTR150 -- never tried

• XR200 in miniframe - everytime we dyno the bike always runs like crap, so I'll get some numbers later.

Real life on the track:

• Stock CRF150 - real smooth, electric feeling power, no hit, feels like a 120cc XR100 with no work other than big bore kit. Mainly, because the compression ratio is something 9.0 or 9.5 -1

• Modified CRF150: Way more of everything, pulls harder, more hit, Very smooth, feels pretty good. Good overall power.

• TTR150: Kind of the same as a modified CRF150, but less, smooth power, seems to have more bottom than a XR120cc, but less overall power, which is mainly noticable on uphills such as Glen Helen.

• Fully Modified XR100: nice hit, decent power, tons of rev, but needs to be wide open to keep up with a modified CRF150.

• Modified XR200 in CR80 frame or CRF150 frame: Tons and tons of torque, big hit, capable of third gear starts. The 6 speed is capable of incredible speed, not much rev needs to be short shifted, but basically unfair.

• CRF230 in mini frame: never ridden, but I hear it's like real good XR200, but comes with an electric, which is almost worth it just for that. (Kevin Windham wished he had one at Glen Helen)

• YZF250 in BBR Frame: Haven't ridden, but I imagine it would be like taken a 5000hp funny car to pick up groceries.

I'm comparing these because people have misconceptions about all these bikes. Mainly because when I was selling my bike people email me and say they could get a CRF150 or TTR125 since their faster, when in fact my bike has 2hp more than a stock 150 and out pulls a fully modified TTR150 on uphills. And it's impossible to argue with anybody, but for example if you look at the TTR125 exhaust port you'll know what I mean. If all the motors were built to the same specs flow wise, with ti valves etc. like a mini 450f bigger would be better, but with these little bikes it doesn't work that way. Until a company (probably Yamaha) comes out with full race mini four stroke we have to put up with all this.