Rev 3 250 - 2003 Low Power - Is This How They Are? Help!

[davllan123]

Recently bought an 03 rev 3 and have replaced main bearings, piston, plug, oil. Carb is totally clean. Bike starts first kick and runs like a watch. However, compared to my old gasgas and my son's sherco, this thing feels seriously down on power. It's as though the flywheel weight is fitted (it's not just checked) it's slow to rev compared to what I'm used to. Have fitted a fast action throttle which has helped a little. I also took the back exhaust box off and ran it without the air filter but no change. Is this how they are? Any suggestions would be much appreciated.

[lineaway]

I`ve had quite a few rev 3`s and the `03 was a lame duck in the power dept. Never had a liking for that bike.

[dan williams]

Beta's do tend to alternate between "perky" and "smooth" from year to year. When you say you checked for the flywheel weight do you mean the one on the primary side or the ignition side? Beta's have two primary crank gear options based on what year and engine size. Typically pre-'07 a primary side weight was on the 270 but it's possible you have one. You can see the difference from the exploded diagrams on the Beta site.

http://www.betamotor.com/system/attachment...t_04_motore.pdf

This is the '04 diagram but it shows the weight. Curiously it doesn't show the non-weight option.

Other possibilities are ignition timing slightly retarded. More advance gives more "pop" also harder starting and rougher running but that's the price you pay. Of course jetting can be off slightly. I assume this is a Mikuni carb. If your reed valves are damaged it will greatly soften the power on the bottom.

Probably the only way to really tell if your bike is significantly down on power though is to try a similar one.

[davllan123]

Thanks Dan, I checked on the ignition side. Can't quite make out a weight on the primary side from the diagrams but will keep looking. I'm sure the penny'll drop soon. My son's sherco and my old gasser ripped your arms out of your sockets and are great for jumping off something. This is beatifully smooth but there's such a delay when you crack the throttle open. Will check the ignition timing soon . Thanks you again for your assistance.

[dan williams]

Yeah my '05 has the primary weight and took some clutch work to get it to hit hard. the '08 doesn't have the primary weight and jumps like a scalded cat when you whack the throttle. Simple enough to spot if you have the weight. if you look through the tranny fluid sight glass and can see a flat piece of metal inboard of the glass you have the flywheel. Unfortunately I don't think it's removeable. Probably could be machined down.

[worldtrialchamp]

its yellow!

[stork955]

Gday, Clean the front exhaust sections. It will need it at its current age. Also check ignition timing. Using a Timing Light is the best way.

Cheers,

Stork

Edited February 24, 2010 by Stork955

[davllan123]

Thanks, a friend of mine suggested pouring petrol into the pipe and then setting it alight with a piece of lit paper! Any better suggestions? Thank you all

[nzralphy]

i'd do the same but i live out in the country side so there are fewer smoke issues. Point the pipe up so it acts like a chimberly (sp?). It will get WELL hot! when the fire dies put an old speedo cable into an electric drill and the flailing cable will knock off the carbon. Check your timing and reeds!

Ralph

[dan williams]

Did that with a mid muffler once. Quite the smoker. Let it go for an hour or so and watched as the liquid goo drained out. Decided I'd better stop after a before the fire brigade arrived. Not sure it ran any different but it's always fun to play with fire.

[davllan123]

Did my first trial on this bike today (Old man white route). My scores were as good as they have ever been, not bad for a first outing. I have never experienced such traction. Smooth gradual power and, to be honest, I never thought "I wish I had more power" I'm really starting to look at this bike in a different light, if it wasn't for that bloody left hand kick start!