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Beta 250cc reving our problems..


justjosh9
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It’s the 2017, throttle tube and cable seems to return fine when bike is off. We have had a look at the slide into the carb and it seems to be okay but the spring is a bit flimsy compared to other bikes? But it seems to rev out a lot at least once per trial and it always seems to be at near max revs and it’s pretty sketchy sometimes if I’m in a higher gear because it takes off for a bit... 

need help!! 

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Cable routing? Betas are a bit touchy if your body position is far forward. I know if I lean too far and press on the cable it’ll rev. A ripped or cracked carb boot will also cause what you describe so will a carb that isn’t mounted properly. Another thing that can hang the throttle is the closed end of the grip catching on the end of the bar. Usually happens after a fall or leaning the bar against a tree. Main advantage of running bar ends.

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At the wrong time i imagine a split second of extra gas could be very nasty, hope you get it sorted bud.

Take the carb off and open the throttle fully and check if the needle is bent and catching the nozzle guide. 

Gently check the needle is secure and cannot be lifted upwards into the carb slide, there is a retainer inside the slide that holds the needle and clip in position, if its not right the needle may be able to come up out of the nozzle tweak sideways and jam.

Carb slide jamming? Any dirt or damage. Seated on guides correctly?

Check cable route Start bike turn bars full left to right, any change in rpm? Check twist grip assy

Some 2t oils can emulsifiy in wet weather, only ever seen it happen on old 2t roadrace bikes with open carbs but maybe. White/yellow residue on carb slide

If it happens again clutch it and kill switch. Dont touch the twist grip as opening it again could relocate a rogue needle or stuck slide. take the carb off and have a look whats going on. 

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Thanks for th replies! That’s a great idea the next time It happens I’ll shut it down and see if I can figure it out. I’ve had the carb apart the slide seems fine but I’m not sure on anything else as I’m new to trials. 

Also when on full lock to the right it revs higher so the cable routing must be off. 

 

I hope I can sort it soon because I don’t feel very confident on the bike since this happens so often haha! 

Is this a problem with betas in particular? I’m not very impressed the bikes only 9 months old!! 

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I would be very surprised if it's a Beta problem, they do'nt make the carb, the cable or the twist grip.

If it only happens on say full lock turn in one direction, then suspect the cable routing, if it's just after you have twisted the throttle then suspect the carb assembly.

As its a new bike it's probably down to giving everything a good clean, not with a power washer !

 

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Betas in general don’t seem to have the best method of routing. Tighten the adjuster for immediate response and it will runup the engine in a turn. Make sure the end of the cable is properly seated in the carb top. Add a little slack to the adjuster and get used to that extra 5 degrees of rotation off idle.

For a real thrill catch the cable on a tree branch mid loop. Very exciting.

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