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@jozzze2000 avatar
UTC

Member
Vespa PK 50
Joined: UTC
Posts: 37
Location: Slovenia
 
Member
@jozzze2000 avatar
Vespa PK 50
Joined: UTC
Posts: 37
Location: Slovenia
UTC quote
I leak tested the engine at 1 bar of pressure, and observed a decrease to 0.5 bar within five minutes, indicating two leaks.

The first leak is located at the junction between the cylinder and the engine block, and the second is found where the carburetor pipe meets the engine block.

I guess this isn't main issue causing no start.

Additionally, I'm noticing that the engine turns freely via the flywheel, almost as if there's no compression resistance. Is this normal?
@safis avatar
UTC

Ossessionato
1979 P150X, 1983 P200E, 1987 PK125XL Elestart, 1988 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
Joined: UTC
Posts: 4310
Location: Veria, Greece
 
Ossessionato
@safis avatar
1979 P150X, 1983 P200E, 1987 PK125XL Elestart, 1988 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
Joined: UTC
Posts: 4310
Location: Veria, Greece
UTC quote
Is it a new kit?? If yes, was the piston installed correctly?? If not, the no compression symptom is probably piston / rings related…
OP
@jozzze2000 avatar
UTC

Member
Vespa PK 50
Joined: UTC
Posts: 37
Location: Slovenia
 
Member
@jozzze2000 avatar
Vespa PK 50
Joined: UTC
Posts: 37
Location: Slovenia
UTC quote
The kit has been in operation for 14 years, and the total mileage it has accumulated has slipped my mind.
@safis avatar
UTC

Ossessionato
1979 P150X, 1983 P200E, 1987 PK125XL Elestart, 1988 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
Joined: UTC
Posts: 4310
Location: Veria, Greece
 
Ossessionato
@safis avatar
1979 P150X, 1983 P200E, 1987 PK125XL Elestart, 1988 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
Joined: UTC
Posts: 4310
Location: Veria, Greece
UTC quote
First check the seal, flywheel side, they tend to fail over time. Then, probably rings, I'd take the cylinder out and inspect for wear…
UTC

Addicted
Joined: UTC
Posts: 952
Location: Planet Earth
 
Addicted
Joined: UTC
Posts: 952
Location: Planet Earth
UTC quote
14 years on a DR smallbore seems like you have had your monies worth. Id think of two things here if this were mine, change the 75 to the DR102, jetting wise four or five points over what youve got and make sure the base gaskets are decent on cylinder, also use high melt point silicon on the carb slots that go on the manifold to rule out the most common point for air leaks.
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