Craigslist Find: Brand-New in Box 83-85 200X Cobra Aluminum Exhaust

[Jack G]

Thanks Ironchop!

Per request, I have included more tables of the exhaust data with conditional formatting. This table shows the color gradient that makes it easier to determine how an exhaust compares to the others along the whole power band.


Next, a table that is conditioned to highlight the cell GREEN if HP is greater than stock, YELLOW if HP is the same as stock, or RED if HP is less than stock exhaust.


Lastly, since I will be putting a SuperTrapp exhaust on my 200X soon, I wanted to see what the dyno graphs looked like in comparison to the stock exhaust. I think I will end up using 10 discs to get an exhaust that doesn't drop off as much in the mid-range but still gives good low and top-end.


I'd be happy to post the graphs of the other exhausts if anyone is curious, just let me know which ones you wanna see. If I have them all on one graph, it's too cluttered.

[ironchop]

This is the most useful 1st Gen ATC200X exhaust thread I've ever seen on here.

Again Jack, thanks.

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[Arky-X]

Interesting analysis.
Seems like the stock exhaust was best around the 6500-8500 RPM for the most part. Most all of them gave more in the lower RPM range.
Looks like Krause really hit the lower RPM range while CRF and Curtis Sparks shifted the band to about 5000-8000.

Thanks!

[Scootertrash]

Just found this thread. Interesting charts, I may have to mess with the disc count in my 200S.

[Shawn Powell]

I wonder if this account for jetting. Seems like .3 of a hp at peak is not a lot. I know there only 16 to begin with but still. I don’t own a machine that small but I will tell you I can feel a significant gain from my stock 350x to jetted and supertrapped one. Different engine I know just saying the old butt dyno doesn’t lie.


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[Jack G]

I wonder if this account for jetting. Seems like .3 of a hp at peak is not a lot. I know there only 16 to begin with but still. I don’t own a machine that small but I will tell you I can feel a significant gain from my stock 350x to jetted and supertrapped one. Different engine I know just saying the old butt dyno doesn’t lie.


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On the second page of the article (page 63) they state that the main jet was bumped up from the stock 108 to 110. They used that jetting for all of the tests. The airbox lid was also removed during testing.

Another good point they make is that the results only reflect the performance with a stock engine. With a built/modified engine, the exhausts would perform differently. Maybe the Yoshimura really shines when paired with other performance mods (i.e. cam, carb, air filter, larger bore, and/or hi-compression piston), and just not the stock engine.

TLDR: This data is not the be-all-end-all to declare which exhaust is best for every 200X, just the stock ones. My guess is this data does not apply once other performance mods are added to the equation.

[Shawn Powell]

On the second page of the article (page 63) they state that the main jet was bumped up from the stock 108 to 110. They used that jetting for all of the tests. The airbox lid was also removed during testing.

Another good point they make is that the results only reflect the performance with a stock engine. With a built/modified engine, the exhausts would perform differently. Maybe the Yoshimura really shines when paired with other performance mods (i.e. cam, carb, air filter, larger bore, and/or hi-compression piston), and just not the stock engine.

TLDR: This data is not the be-all-end-all to declare which exhaust is best for every 200X, just the stock ones. My guess is this data does not apply once other performance mods are added to the equation.

That makes a lot of sense. Also you have to jet for each exhaust, and again being unfamiliar with the 200x a 108 to 110 doesn’t even seem like enough , unless the OEM exhaust wasn’t very restrictive in the first place. Good read either way.


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