Hi All,

Does anyone know if a different carb (other than the standard) will fit on a Beta 50 Trials, air cooled?  I have just bought a new Dellorto but it's no good, can't get it running right and these carbs are shockingly built.  I know everything else is fine as it's just had a full engine rebuild - all seals/gaskets have been check for leaks.  Pulling my hair out with this thing so any help would be great.  Carb size is 15mm internal bore.

Thanks

I bought it from Eurocarbs and told them what it was for.  I still have the old one and it does the same.  It's not a cheap copy but it keeps sucking air through the top of the carb.  When it revs high I can stall it by spraying GT85 at the carb top.  I have eliminated all other air leaks.

Came with a 68 main. Not sure if this is standard but it shouldn't cause the issues I have I don't think.....

 

No.  It wouldn't tick over correctly.  Took it to a shop and they said it was the left hand seal gone, replaced, still didn't run correctly.  They took the head off and said there was play in the big end which was throwing the timing out. Full rebuild and still not running right - not sure this was the issue though.  The original main jet was a 60 but I have never seen the bike run correctly on this.  Carb I bought new had a 68.  I have changed this back but still the same issue.  I can hold a nice low rev off the throttle but not off the carb...I can get it very 'crisp' off the throttle but it wont tick over.  It either revs its nuts off or stalls...this is killing me and it doesn't help my 6 year old asking every two minutes if I have fixed it yet

 

This carb doesn't have a fuel mixture screw, it's the most crude carb I have ever seen.  I can raise the needle via the idle screw but it doesn't seem to have much of an impact, it either doesn't tick over or it revs high.  I can hold a steady low idle by using the throttle though which is odd. 

It's a plastic slide held in place within the carb body and a spring angled at 45deg pushes down on it.  Dellorto SHA 15/15

 

I have an old carb, same model with a metal slide.  I've cleaned this up and used that but still the same.  I've almost run out of ideas..thanks for your help though

I have been thinking along those lines.  I have seen a carb for a KTM 50 SX as it's the same engine but I'm not sure if it will fit in the frame.  Also concerned as I need to keep the smaller inside diameter (15mm) for torque.  The KTM one s 19mm so not sure.  I'll have a look at the TY one, thanks

http://www.ebay.co.uk/itm/272159783246?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT