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I am convinced that the lack of increase in power at the top end is due to the cylinder head. I hear this over and over again about modded ET4.

I am planning to put on the 187cc Malossi. I already bought one.

The cylinder head channels are to be milled out to a bigger diameter and smoothed out.
As this is a 2 valve head compared to the 4 valve head of the GT 200 I maybe put in bigger valves as well....

The carb I am replacing with a 29 mm walbro from a GT 200 I already bought for only $20.

Anyone has an idea what I will gain? Laughing emoticon Laughing emoticon Laughing emoticon Laughing emoticon

Will it be similar to the power of the GT 200?
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@tfauch avatar
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Molto Verboso
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Location: Worcester, Ma USA
 
Molto Verboso
@tfauch avatar
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See: Piaggio Engines and look at the difference between 2 valve and 4 valve and air cooled and liquid cooled engines.

Tim
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Hooked
1962 Lambretta TV175, 2001 ET4, 1972 Honda CB350 1969 Honda CL350
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Location: Folsom, CA
 
Hooked
1962 Lambretta TV175, 2001 ET4, 1972 Honda CB350 1969 Honda CL350
Joined: UTC
Posts: 327
Location: Folsom, CA
UTC quote
My ET4 keeps up with stock GT's all day long and I didn't do any machining at all.
@orbit avatar
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Hooked
06' Vespa LX150, 73' Serveta Jet200, 64' Vespa GL150
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Posts: 125
Location: Clearwater, FL
 
Hooked
@orbit avatar
06' Vespa LX150, 73' Serveta Jet200, 64' Vespa GL150
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Location: Clearwater, FL
UTC quote
Not listed in the PDF that TFauch linked to, but the stats on Piaggio USA's site lists the FLY 150 as having a 150cc air-cooled 4-valve SOHC engine.

I believe that other than that, the LX/ET and the Fly have the same LEADER engine.
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UTC quote
You might want to consider making a GT200 airbox fit to go with that carb. Those carbs are very particular to incoming airflow, and those airboxes are designed very specifically for those carbs. I don't have any real experience with doing this mod, but it's one of the things that popped into my head.
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Peugeot Looxor
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Ossessionato
@bryce-o-rama avatar
Peugeot Looxor
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UTC quote
Orbit wrote:
Not listed in the PDF that TFauch linked to, but the stats on Piaggio USA's site lists the FLY 150 as having a 150cc air-cooled 4-valve SOHC engine.

I believe that other than that, the LX/ET and the Fly have the same LEADER engine.
I have a feeling that the 4-valve air cooled thing is a typo. The multi-valve layout is a large part of why the liquid cooled LEADER and QUASAR engines make more power than the air cooled ones. The cool thing about the 4 valve LEADER engines is that they still only use 2 rocker arms, and a two lobe camshaft. Someone enterprising and engineering savvy could potentially make an air cooled version of the 4-valve head, which would likely unleash more power from that engine. When I did the valve work on my engine, my friend and I looked at the head and realized there was a lot of flow work that could be done to open the ports and make them smooth. But it would cost a fair amount to get it done right. With other modifications, it could be useful, but I am not sure how effective it would be on its own.
@andrew avatar
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Molto Verboso
2006 Fly 150
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Location: Metro Detroit, MI
 
Molto Verboso
@andrew avatar
2006 Fly 150
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Location: Metro Detroit, MI
UTC quote
Bryce Ludwig wrote:
Orbit wrote:
Not listed in the PDF that TFauch linked to, but the stats on Piaggio USA's site lists the FLY 150 as having a 150cc air-cooled 4-valve SOHC engine.

I believe that other than that, the LX/ET and the Fly have the same LEADER engine.
I have a feeling that the 4-valve air cooled thing is a typo.
Yes, I'm fairly sure it is a typo (haven't taken my Fly apart enough to actually look), but the paper brochures state 2 valves, and the dealer said 2 valves. I sent an e-mail to Piaggio USA about correction their website a month ago but heard nothing back (big surprise).
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