Beta rev 3 125 carb issues

[reghusky]

Hello, I wonder if anyone can help please? My son has a rev 3 125 2006 with the dellorto VHST 26 carb. I have taken the carb out to clean it and check jets, it has a threaded hole here which leads straight into the carb bore, should this be blanked off? I can't believe it's right to let unfiltered air straight into the engine?! Also does anyone know the standard jets/needle position for the dellorto? Thank you.

[konrad]

I'm used to the PHBL, but your VHST looks like this photo: https://www.speed-parts.nl/carburateur-dellorto-vhst-26-mm-bd-flat-slide.html

The casting probably was made that way so it could have mixture and idle screws on either side.  You could test with compressed air.

 

 

[reghusky]

Yes, I agree it looks like the casting is made for both. It definitely goes from outside to inside, I thought the unused side would be blocked or capped. I wondered if anyone had the 125 and could confirm or deny?

[konrad]

5 hours ago, reghusky said:

I thought the unused side would be blocked or capped.

Typically, the unused side would not have been machined.  If it was like that from Day-1, the engine would have had a massive air leak and never worked properly.

[reghusky]

Yep, that's what I think Konrad, I wonder if it was meant to have a blanking plug in it which has fell out. It was running but idle was erratic. Piston, rings and crank seals have all been done.

[konrad]

I don't see that you have anything to lose by plugging a hole that should not exist.  Personally, I would try something quick and dirty like hot-melt glue.  If that was successful, I'd use epoxy.