rotax rpm problem

phil feigel · Guest

need help have rotax that will not rev past 13,000 on sprint track even gearing 12/84. i know the powerband should be kept in the 12,5 area but most of the fast guys are twisting 14,2 the motor has 10 hours on it,i have changed,parts with a good motor turning 14,2 ie; carb,coil,pipe,checked power valve,what are the effects of bad reeds??? any help out there please thanks phil

Nick Weil · Posted: Sun Aug 18, 2002 7:35 pm Post subject: rotax rpm problem

Phil,

Some days we have a real problem turning those high revs on the big tracks as well. The sure way to do it is to draft. The other option is to keep leaning out the main jet. But be warned, lean is mean, right up to the point where your crankshaft and you rod see fit to part ways. If you are running the same gearing as the other guys try a few things...

1. Disconnect ALL electrical connections. Clean well with electrical contact cleaner and reconnect.

2. Try swapping batteries with someone who is turning the high revs for a session. Same with the coil.

3. Remove your crank sensor, clean and reinstall.

I got lots more, but try those for starters...

Nick Weil
SpeedQuest

phil feigel · Guest

thanks nick and i'll be talking to you tomorrow, need to order some parts,but we tried jetting 98 degrees out had a 160,went to 162 everybody else 165 and went slower,it's like it wants a 158 but i know that is too lean, thats why i think it's the reeds maybe,tried the battery thing also. crank sensor yes if it was full of metal?? all connection clean and dry,the motor must be a lame kangaroo

Bob Schabel · Posted: Mon Aug 19, 2002 3:15 am Post subject: rotax rpm problem

Phil, Take a look at your power valve. Make sure it's not in upside-down. Believe me it happens

The bevel side should be down. the flat side up. This will cause your lake of top end RPM.

phil feigel · Guest

yes bob i checked that also and it's in right,thanks for the reply

Alan Macfarlane · Joined: 19 Feb 2002 Posts: 4 Location: west vancouver

I recently ran at a race where 150 and 152 jets were required by some. The corrected elevation there was as high as 4200 ft. What is the elevation and if you have it the corrected elevation at your track?
Can you run full throttle at 10000RPM?