NEW OS21 XM MAX ver.2

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tom galdys

Well-Known Member
Joined
Sep 30, 2009
Messages
1,176
Ok, I got my new motor and tore it down along with another one. For 150.00 or so you are not getting much for your money. Everything mic'd out identical to a stock OS. You do get a better con rod and a beefier piston around the wrist pin. The lower is identical down to the hole for the water pick up(with no pick up). The only thing you need to have the same engine is the extension for the muffler. Can someone explain to me why a hotter running(just guessing on that) engine and a longer exhaust chamber will make the motor better? Tell me the 150.00 was well spent. With the expanded muffler,will an increase in exhaust duration help this motor? Thanks Tom Galdys
 
Tom, I believe that the extension on the muffler will help get the motor into its "power band" sooner, and even make it broader. As far as the rest, I really cant help you there.
 
Heat makes power. Untill the engine ceases to function mechanically anyway.
 
tom galdys said:
Ok, I got my new motor and tore it down along with another one. For 150.00 or so you are not getting much for your money. Everything mic'd out identical to a stock OS. You do get a better con rod and a beefier piston around the wrist pin. The lower is identical down to the hole for the water pick up(with no pick up). The only thing you need to have the same engine is the extension for the muffler. Can someone explain to me why a hotter running(just guessing on that) engine and a longer exhaust chamber will make the motor better? Tell me the 150.00 was well spent. With the expanded muffler,will an increase in exhaust duration help this motor? Thanks Tom Galdys
Click to expand...
I've posted the results of running my Ver.II before, but my VS1 is faster with the Ver. II. I have a feeling the air cooled head is providing a larger part of the performance increase. I don't plan to try running with just the new head and then then just the muffler. I've got better things to do, not sure what the "better things" are, however.

Is faster worth $150?? That's an individual decision.

JD
 
Jerry Dunlap said:
tom galdys said:
Ok, I got my new motor and tore it down along with another one. For 150.00 or so you are not getting much for your money. Everything mic'd out identical to a stock OS. You do get a better con rod and a beefier piston around the wrist pin. The lower is identical down to the hole for the water pick up(with no pick up). The only thing you need to have the same engine is the extension for the muffler. Can someone explain to me why a hotter running(just guessing on that) engine and a longer exhaust chamber will make the motor better? Tell me the 150.00 was well spent. With the expanded muffler,will an increase in exhaust duration help this motor? Thanks Tom Galdys
Click to expand...
I've posted the results of running my Ver.II before, but my VS1 is faster with the Ver. II. I have a feeling the air cooled head is providing a larger part of the performance increase. I don't plan to try running with just the new head and then then just the muffler. I've got better things to do, not sure what the "better things" are, however.

Is faster worth $150?? That's an individual decision.

JD
Click to expand...
Do you remember how much fatter the needle was??
 
kroggs said:
Jerry Dunlap said:
tom galdys said:
Ok, I got my new motor and tore it down along with another one. For 150.00 or so you are not getting much for your money. Everything mic'd out identical to a stock OS. You do get a better con rod and a beefier piston around the wrist pin. The lower is identical down to the hole for the water pick up(with no pick up). The only thing you need to have the same engine is the extension for the muffler. Can someone explain to me why a hotter running(just guessing on that) engine and a longer exhaust chamber will make the motor better? Tell me the 150.00 was well spent. With the expanded muffler,will an increase in exhaust duration help this motor? Thanks Tom Galdys
Click to expand...
I've posted the results of running my Ver.II before, but my VS1 is faster with the Ver. II. I have a feeling the air cooled head is providing a larger part of the performance increase. I don't plan to try running with just the new head and then then just the muffler. I've got better things to do, not sure what the "better things" are, however.

Is faster worth $150?? That's an individual decision.

JD
Click to expand...
Do you remember how much fatter the needle was??
Click to expand...
I don't know if the needle is fatter than the Ver. I . I never even thought about a difference.

JD
 
Tom,

Thanks for doing the comparison and measuring everything to make sure. Guess the head and pipe really are the only performance boost this engine has. The expansion chanber incresases the pipe volume and converts the stock muffler into more of a tuned pipe.
 
I also never thought to check out the carb. They are identical. the needles are both .014 thick and the same length. The rest of carb is the same also. Tom
 

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