Branny Posted December 16, 2023 Report Share Posted December 16, 2023 Hi just wondering if anyone can help I have a beta 125 2004 trials I went out today and revs stuck on full and I pulled kill switch no joy still didn’t cut out so had to put ht cap off checked carb and throttle in fine not stuck not nicks in cable slider hits bottom carb fine soon as I start it just revs up full any ideas thanks Quote Link to comment Share on other sites More sharing options...
tony27 Posted December 16, 2023 Report Share Posted December 16, 2023 Ignition side crank seal is a possibility although I wouldn't expect the revs to go sky high instantly Quote Link to comment Share on other sites More sharing options...
Branny Posted December 16, 2023 Author Report Share Posted December 16, 2023 Okay will try new seal thanks pal Quote Link to comment Share on other sites More sharing options...
lineaway Posted December 17, 2023 Report Share Posted December 17, 2023 Is the cable holder in the top of the slide missing, out of place letting the needle to move freely? Quote Link to comment Share on other sites More sharing options...
feetupfun Posted December 17, 2023 Report Share Posted December 17, 2023 The rubber carby mount piece (between the carby and the reed cage) are known to crack and let air in 1 Quote Link to comment Share on other sites More sharing options...
Branny Posted December 17, 2023 Author Report Share Posted December 17, 2023 Will check these things thanks Quote Link to comment Share on other sites More sharing options...
Branny Posted December 17, 2023 Author Report Share Posted December 17, 2023 Spoiler Quote Link to comment Share on other sites More sharing options...
lineaway Posted December 17, 2023 Report Share Posted December 17, 2023 First off that is not the stock carb. That vent line, does it have a hole in the middle? If not cut iy in half, its not venting. Take the carb apart and blow contact cleaner threw that hole to verify. Quote Link to comment Share on other sites More sharing options...
Branny Posted December 17, 2023 Author Report Share Posted December 17, 2023 Hi thanks for reply I did search the internet and said was stock carb ? I’ve cleaned the carb throttle nice responsive everything working good nice and clean now just unsure if there is ment to be screw in the hole with threads thanks Quote Link to comment Share on other sites More sharing options...
Branny Posted December 17, 2023 Author Report Share Posted December 17, 2023 Hi thanks for reply I did search the internet and said was stock carb ? I’ve cleaned the carb throttle nice responsive everything working good nice and clean now just unsure if there is ment to be screw in the hole with threads thanks and the vent line has hole cut Quote Link to comment Share on other sites More sharing options...
arthritic Posted December 18, 2023 Report Share Posted December 18, 2023 Happened to us when two events combined. That is, a faulty carb. float needle combined with the petrol tap being left on overnight. Fuel seeped into the crankcase causing immediate high revs when it started. Quote Link to comment Share on other sites More sharing options...
Tr1AL Posted December 18, 2023 Report Share Posted December 18, 2023 20 hours ago, Branny said: Hi thanks for reply I did search the internet and said was stock carb ? I’ve cleaned the carb throttle nice responsive everything working good nice and clean now just unsure if there is ment to be screw in the hole with threads thanks and the vent line has hole cut @Branny Beta OEM is usually a Mikuni carburettor. you cannot go wrong with blanking that hole on the VHST carb you have fitted to your Beta as it is only for use with bikes that have the exhaust mid box on the right hand side of the bike for example a GasGas.. just plug it with something . Quote Link to comment Share on other sites More sharing options...
lineaway Posted December 19, 2023 Report Share Posted December 19, 2023 I have given 4 suggestions. And you cannot even figure out its the wrong carb. Good luck, find a friend. Quote Link to comment Share on other sites More sharing options...
djr Posted December 19, 2023 Report Share Posted December 19, 2023 Only from experience, I would say it does sound like an air leak , which could be a crank seal or cracked inlet manifold (as already mentioned) or a gasket etc. Although that carb may well not be original, if it's been running fine previously with that carb, then you don't necessarily need to change it for an original carb - just find out if it is a fault with the carb that can be repaired - like the missing blanking screw that has been suggested. If it is an air leak you are looking for, it won't be massive, I once had a Yamaha that did the same , and the air leak was so tiny you wouldn't think it could have allowed enough air through to make it rev highly, but it did Quote Link to comment Share on other sites More sharing options...
Branny Posted December 19, 2023 Author Report Share Posted December 19, 2023 Thank you all for reply’s will give it all good going through this weekend Quote Link to comment Share on other sites More sharing options...
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