Kitaco 12.2:1 piston and TB cam - anyone try this?
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Kitaco 12.2:1 piston and TB cam - anyone try this?

This is a discussion on Kitaco 12.2:1 piston and TB cam - anyone try this? within the Grom Performance forums, part of the Honda Grom Garage category; Just as the title states, I've got a TB cam in my motor right now and a 12.2:1 Kitaco ver.2 piston sitting on my workbench ...

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Thread: Kitaco 12.2:1 piston and TB cam - anyone try this?

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    Kitaco 12.2:1 piston and TB cam - anyone try this?

    Just as the title states, I've got a TB cam in my motor right now and a 12.2:1 Kitaco ver.2 piston sitting on my workbench with a fresh cylinder. Has anyone clayed the motor with this combination to save me some time?

    The Kitaco power kit is compatible with either Kitaco Type 1 or Type 2 cams, but I know those are fairly mild in terms of lift compared to the TB cam. From the research I've found here, the valve lift (not lobe lift) is as follows:

    Kitaco Type 2
    IN 5.39 EX 5.11

    TB Parts
    IN 6.29 EX 6.31

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    David's Avatar
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    I've done a few hundred miles on such a set up. It works without any problem.

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    Quote Originally Posted by mrsaturn7085 View Post
    Just as the title states, I've got a TB cam in my motor right now and a 12.2:1 Kitaco ver.2 piston sitting on my workbench with a fresh cylinder. Has anyone clayed the motor with this combination to save me some time? The Kitaco power kit is compatible with either Kitaco Type 1 or Type 2 cams, but I know those are fairly mild in terms of lift compared to the TB cam. From the research I've found here, the valve lift (not lobe lift) is as follows: Kitaco Type 2 IN 5.39 EX 5.11 TB Parts IN 6.29 EX 6.31
    As long as you're still running stock valves, you'll be fine... no issues with this setup.

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    Quote Originally Posted by David View Post
    I've done a few hundred miles on such a set up. It works without any problem.
    Performance-wise: what are your thoughts, compared to stock?

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    I imagine with the Kitaco cam, you'll get a little more low-end grunt, but with the TB cam, it'll be more of a screamer. The large overlap of the TB cam is definitely going to drop the effective compression.

    I dug into the tune of the Kitaco Power Pack kit and I plan to just set ignition timing to stock, run premium fuel, and adjust fueling accordingly.

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    You should do the dual valve springs. A ported stock valved head with TB cams, dual valve springs and a 34mm throttle body can make power up to 10K+ rpm. If you add in that high compression piston and an aggressive sprocket combo, the Grom is super fun to ride.
    Last edited by solidjohnny; 07-31-2019 at 08:21 PM.
    Quote Originally Posted by Paultergeist View Post
    It seems like there is always one more thing to buy, THEN I’ll really notice a difference in performance.

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    Installed the piston/cylinder, Koso throttle, PCX150, then quickly uninstalled the last two. Looking forward to tuning the bike over the next week, but the AFRs seem to be pretty close, as-is.

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    I have a grom running the finbro high compression piston, tb cam, ported head and throttle body, lightened flywheel, lightened spinner, and a few other things and its a screamer! I prefer to ride the high compression over my other built 143cc.

    Im using the finbro ecu and pdx150 injector on it, and haven't had a issue. I've never monitored afrs tho. Oil temp on my set up with no cooler is around 200-230.
    2015 Grom - High Compression 125 Build
    2018 Grom - 143cc BigBore
    1986 Spree - 70cc BigBore
    2017 DRZ400SM

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    I'm using Power Vision CX for tuning. Need to tweak my fueling a bit, but right now the AFR targets are 13.0:1 up to 6k, 12.8:1 to 8k, and 12.5:1 above 8k. I don't have the head ported and found out the hard way that slapping the 34mm throttle on the stock head is a dumb idea. It ran super lean and like garbage with the PCX150 injector. I realized the tuning time it would take to make it run stable would be a total waste without porting the head, so I put the stock throttle/injector back in place.

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    Reporting back now that I've got my gearing where I want it:

    Was able to just barely kiss the 4th gear limiter (9500) using 14/36 sprockets giving a 72 mph top speed with my 140 size rear tire.

    WOT AFRs are 13.1 until 6500, 12.8 until 8500, 12.5 to redline

    Relevant parts in my setup are:

    TB cam
    Kitaco 12.2 piston
    Uni filter (inner element only) directly on throttle
    Endurance/HRC exhaust
    Kitaco right-side engine cover (no spinner)
    3-row Kitaco cooler

    I don't want to push my luck on a new cylinder/piston, but I suspect I could hit 75-77 mph with a few free changes and 15/37 or 36 gearing including:

    2-4 deg ignition advance (running stock timing)
    12.8 AFR above 8500
    420 chain (running a 428 D.I.D. X-ring)

    My oil temp. hasn't exceeded 80 deg C since installing the cooler so I've got some headroom... but oil temp. isn't the same thing as piston temp.

    I also did some math and found that while the ramp angles and lift are more aggressive on the TB cam, the intake closing angle is almost identical between the TB cam and the Kitaco cams, meaning the dynamic compression of the setup is in the 11.4:1 range.
    Last edited by mrsaturn7085; 08-08-2019 at 11:03 AM.

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