From Briggs Jr to Rotax Jr

Kim Zobbe-Hogdal · Posted: Tue Aug 27, 2002 2:41 am Post subject: From Briggs Jr to Rotax Jr

My 14 year old has done well this year in Briggs Jr and would like to get a Rotax Jr for next year. It will be a new class for our club, so we haven't even seen a Rotax Jr on the track. Is this a huge jump? Would she be better off going to Yamaha Jr first then Rotax?
Kim

Beat the Boys

Chaz Clover · Joined: 18 Jul 2001 Posts: 879

The Rotax Max engine, including the Jr configuration is a much different beast than the Jr Briggs you're running now.

At least double, and possibly triple the horsepower your driver is currently using. That means a lot more speed.

Your driver will have to get used to the difference in how 2 cycle engines behave at low rpms. Unlike 4 cycles, Rotax Max engines don't like the lower RPM ranges and lack power there. They simply won't pull out of the bottom like a Briggs engine will. They like to be run in the power band or "on the pipe" as it's sometimes referred to. Rotax engines seem particularly sensitive to running at low rpms, and will load up and foul out relatively quickly if run too long in the low end. So your driver will have to get used to not only running at higher speeds, but also keeping engine revs up as close to the power band as possible in cornering, etc.

The engines power may also be a bit more "explosive" than your driver is accustomed to.

If you're thinking a Yamaha first, I'd suggest finding someone who will let your driver give a jr yamaha a really good test - not just a few laps. An unrestricted piped kart might not be bad either as it gets closer to the hp a Rotax jr develops. One thing to keep in mind is that many yamaha clutches are set to lock at much higher RPM than a Rotax (my old motor was set to lock in around 10k rpm's).

If your driver likes the power and adapts easily to the engine differences, then I'd say go with the Rotax rather than the KT100. Less engine maintenance, longer engine life, etc.

Good luck.

Chaz http://www.kartmonster.com

quote:
Originally posted by Kim Zobbe-Hogdal:
My 14 year old has done well this year in Briggs Jr and would like to get a Rotax Jr for next year. It will be a new class for our club, so we haven't even seen a Rotax Jr on the track. Is this a huge jump? Would she be better off going to Yamaha Jr first then Rotax?
Kim

Beat the Boys

George Durdin · Joined: 23 Jul 2001 Posts: 177

Kim,
We've had seven Junior Max's in our IKF regional program this season,most of them have come up from our Super Jr.II Briggs class.From our experience I believe the Max Junior is a natural progression from the Briggs Junior classes.The horsepower on the bottom end is smooth and progressive and the top end isn't over powering to a youngster with at least a full season of experience in an entry level class.It is still a clutch class that will continue to teach them the leasons of driving a good clean line with added horsepower.
The Max Junior is reliable and cost effective........if cared for properly it will more than likely outlive its big brother the FR 125.
It is definitely not an entry level engine package for a youngster with no previous experience.

Pete Van Ginkel · Posted: Tue Aug 27, 2002 10:44 pm Post subject: From Briggs Jr to Rotax Jr

Kim,
I think the Briggs classes are the perfect training ground for Rotax JR. My son went straight from Briggs to Rotax JR. and kicked butt his first time in it. This was at a SoCal MyChron race. There were only two Jrs. that first race, so they put them in with the Masters class and started them a half lap back. He lapped the entire field except for the top two Masters finishers.
She`ll do fine.