June 23, 201115 yr Hi , Just recently got back into trials and enjoying immensley, now ride with my son who as just purchased a new Beta Evo 4t 300. problem he is encountering is a loud backfire often , (almost every time he gets past half revs. ) had back to shop who have sealed exhaust but problem still persists, will be taking back and shop very heplful, just wondered if any other beta 4t evo owner encountered same problem, many thanks Mike.
June 23, 201115 yr Yes mine does same if I've been above 3/4 revs for more than 30 seconds and drop the revs off quickly usually on a road section think it's just excess fuel burning off ??? Doesn't seem to have any side effects just makes you jump now and again lol
June 23, 201115 yr see here..... http://www.trialscentral.com/forums/topic/23670-beta-evo-4t-250300/page__hl__evo4t__st__30 Nothing to worry about - common with large capacity 'thumpers' and twins. Its the ignition of excess unburnt fuel introduced when doing what you describe (and sometimes made worse by an air leak into the exhaust system - like if you had the system apart then didn't seal it properly) My BMW R1150GS was a bugger for it - scared the bejeesus out of many a blue rinse waiting at the bus stop. Found one to watch with this bike though. The engine breather exits into the bottom of the air box. After a big off and the bike being upside down - then going down a steep hill, my bike began popping and farting all over the place. I later discovered the engine had spat some oil out of the breather into the bottom of the airbox and this must have then been pulled / poured through the carb when going downhill causing the popping and banging. Worth checking if ever you have a big off.
June 24, 201115 yr Author Many thanks for your replies , i will pass this info on to my son who was concerned, seems its quite the norm so he will be pleased to hear it . Thanks again Mike.
June 24, 201115 yr Many thanks for your replies , i will pass this info on to my son who was concerned, seems its quite the norm so he will be pleased to hear it . Thanks again Mike. Interesting feedback. I had the Rev4T 250cc bike for about 18 months, and never experienced such a problem. Always ran clean and quiet.
June 24, 201115 yr Yes I had a 250cc 08 4 stroke and never had it happen its only when I've moved to the 300cc that it's started
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