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Discussion Starter #1
Listen to what this guy says about his experience with an aftermarket cam.

Grom build

He confirmed the reason why I run the stock cam.
 

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Well you (or he) is comparing a stock cam to a TB cam which is really a high RPM cam. I tried it and didn't like it at all, thought it was gutless below 7K and really took off from there.
You could try a Yoshimura ST1 or Kitaco Type 1 cam. I run the ST1 on the 125 and I love it, it's basically stronger everywhere. It doesn't have the TB high end but makes up for it in the low and mid range, it will pull any gear from really low in the RPM range. I'd say with the ST1 it feels like a stock engine, just bigger and a bit angrier.
 

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The video you linked... "...93 [octane fuel] is just gonna burn through gas faster...".

Credibility = gone.

Taking advice about building your motor from a guy that doesn't understand octane rating or spark plug heat range isn't a great idea.

That said, the TB cam is a screamer and the stock cam is junk, even for low- or mid-range as it has no lift. If you want low- or mid-range power the Yosh or Kitaco cams mentioned above are fine.

One important thing to note - if you bump compression up significantly (11.8+), you'll probably have issues with the stock cam as it doesn't reduce dynamic compression enough to be safe.
 

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Discussion Starter #5
The TB cam is a screamer and the stock cam is junk, even for low- or mid-range as it has no lift. If you want low- or mid-range power the Yosh or Kitaco cams mentioned above are fine.

One important thing to note - if you bump compression up significantly (11.8+), you'll probably have issues with the stock cam as it doesn't reduce dynamic compression enough to be safe.
Thanks for the info. :)
I'll never raise the compression as I like the freedom of running on cheap regular gas. And I actually like the stock cam as I run the engine most between 3,000 and 6,000 rpms because the oversized tires raise the gearing up by 5%.
86318
 

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I have the Yosh ST-1M cam in my 2019 grom and love it. Like others have said, it pulls great at all RPMs and feels like having a bigger motor. It may not have the very top end punch, but I would want that for track use and not running around town where I use lots of low and mid RPMs. The ST-1M cam also matches my Yosh RS2 loop (loop designed for midrange power/torque), and the dinger mid intake (also midrange power/torque). Matching your components is important, for sure. The ST-1M cam is more $$$ than many others, though.

-S1930
 

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Ive built and tuned many groms with different setups. The power you "lose" down low with a Tbolt cam is hardly anything to cry about. I ran the DCR R1 Cam on my 125 with aracer and to this day (im 4v 181 now) it was my favorite setup. it screamed and the power loss down low was really nothing. Your mind will play games with you. Ask the modded airbox guys that claim to notice a huge difference on a stock ecu :p
 

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Agreed, if you want low end, bore it out. If you want low end and top speed, add a 5th gear.

My 125 cc motor felt best with a TB cam, 12.2:1 piston, and throttle body with a foam filter stuck directly on it. My 181 cc feels like it should come this way stock, and my 33 mm throttle is still a little undersized.
 
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