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Ossessionato
1979 P150X, 1983 P200E, 1987 PK125XL Elestart, 1988 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
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Location: Veria, Greece
 
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1979 P150X, 1983 P200E, 1987 PK125XL Elestart, 1988 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
Joined: UTC
Posts: 4310
Location: Veria, Greece
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Doing an overhaul on a friend's P2. Fuel in gear oil but no smoke. Crank's toast, can take it out by hand. Engine was assembled by someone else. Old crank was cut following some YT video. Kit is the old Malossi 210, was bought used on eBay, exhaust ported to its limits (53mm wide) and they went trough in one of the studs. They pressed in a tube to air leak "proof" it. It was running strong with a chrome SIP Road 2 and a SI24. He wants to go longstroke. Rotary looks untouched, only the angled drilling was cleaned up. Tried my old Polini, here's the timings...

Jack, any thoughts?? Should we be looking for another crank?? Maybe stay 57mm?? We want to keep the rest as is...

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Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4598
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4598
Location: London UK
UTC quote
Wheres the pictures of the Polini? 53mm wide on the Malossi is not too much and could still be used even with the stud open. Any other reason to change to Polini?

How much squish clearance in the head on the Polini? The 1.5mm above deck suggests you are planning to use a head gasket?
OP
@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
Jack221 wrote:
Wheres the pictures of the Polini? 53mm wide on the Malossi is not too much and could still be used even with the stud open. Any other reason to change to Polini?

How much squish clearance in the head on the Polini? The 1.5mm above deck suggests you are planning to use a head gasket?
The Polini is the one I had on my blue P with the pretty aggressive timing after TDC and which I also cut on the big end side. It's the one in the last pic which I took measurements with. As said, his crank is toast so we're looking if the Polini is OK or go to a different one…

Head is the "tourist" MMW, low compression, 1.2mm - 1.3mm squish…
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Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4598
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4598
Location: London UK
UTC quote
Ok I see it now. Use the 60mm crank. Set the deck to 0.8mm out the top. Will need approx 0.7mm (0.5+0.2mm) on the base and 0.5mm gasket on the head.
This will end up at 186/127/29. The guy tuned it so wanted it faster. This will need a strong upjet to keep the SI carb. That Chrome exhaust will be even louder after that.
OP
@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
Jack221 wrote:
Ok I see it now. Use the 60mm crank. Set the deck to 0.8mm out the top. Will need approx 0.7mm (0.5+0.2mm) on the base and 0.5mm gasket on the head.
This will end up at 186/127/29. The guy tuned it so wanted it faster. This will need a strong upjet to keep the SI carb. That Chrome exhaust will be even louder after that.
Thanks once again! As I understand it, rotary stays untouched. Also, I'm thinking in replacing the tailpipe to 20mm. Polini also did it on their Original Box cause they had some seizing issues with the 18mm pipe...
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Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4598
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4598
Location: London UK
UTC quote
Tail pipe will need 20mm minimum. Rotary 186 is ok. If ever planning an expansion exhaust another 10 degrees inlet would be better.
Will need big jets.
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