Dell Orto PHBE 38 GD carb

[454MRW]

The 76 MC5 400 Penton that I just picked up has a Dell Orto 38MM carb on it. I'm disassembling and cleaning it and it looks good, but the bike acted like it ran out of gas both times I rode it for less than a minute, although it ran good up until that point, then acted like it ran out of gas, and since it sat for a while I thought maybe the float was gummed up. A new spark plug acted the same way. Does anyone have any experience or opinions about the Dell Orto carb, or should I just be putting a bing back on it?
It has a unique air boot in good shape, so it would be easier just to put it back on if opinions are favorable. Mike

[Bob Seymour]

Mike,
   Is the fuel tank vent working? Maybe try riding around with the cap loose and see what it does? Odd it would run fine then starve for gas. Just a thought.

[454MRW]

Bob, it's got a very nice plastic tank on it that is similar to a Clarke tank with a vent hose and a wide open vent. The fuel petcock flows freely. The carbs got a slightly different style choke without a tickler, so I would lean the bike over to overfill the fuel bowl when starting it, so I thought it might have just ran the fuel bowl dry then died. The needle has a rubber tip on it so I do need to order a new one.
Mike


Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978-1979 MX-6 175 & 250 KTM's
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[Steve Minor]

For what it's worth, I once had a 77 400 that would suck the float bowl dry on a long WFO straightaway...seems like we fiddled with the float bowl level to give it more fuel.

Steve Minor

[454MRW]

I'm almost certain it's all just lack of fuel since the float level look to be low and the needle valve rubber tip questionable. I ordered a gasket set a needle and seat and a couple smaller pilot Jets today and have to wait for UK delivery. The only reason I ordered a couple different smaller pilot Jets is the previous owner said it ran great but it was a little rich on the low end. He raced it at Unadilla and Mid Ohio. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978-1979 MX-6 175 & 250 KTM's
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[454MRW]

I got the carb kit from Eurocarb in the UK within 9 to 10 days, which I think is great. I replaced all the gaskets and seals, the needle valve and seat and set the float a little higher, and changed the Pilot down from 60 to 58, per the previous owners comment about the low speed being a little rich. Once the carb was back on the bike it started with the choke on and after a short one minute warm up, the bike ran great pulled strong, and did not miss, falter or die. The idle mixture screw is now at 1-1/2-2 turns versus the 4-1/2 turns it was at previously. Thanks everyone for all of your comments and suggestions. Mike