STIC Carb Metering insert for Keihin PWK38, PWK36 and PWK28, fits both screw top and electronic Powerjet types, Short Body non electronic types
This STIC metering block for keihin carbs is a shocker in both our dyno and field testing. Great gains in power, throttle response, acceleration, and overall performance.
Please allow 5-10 business days for product shipment. We build our blocks to order and undergo a QC process on each one to ensure your product is how it should be! We suggest the 38mm for nearly all applications. The E type is the short body carb, found on yamaha's, ktm's and many other bikes. The M type is the long body carb, usually found on older model bikes and cr500's. Please allow around 2 weeks for shipment, the shop has been busy and inventory has been coming in sporadically. Email harrisperformance@gmail.com for any additional info or fitment questions. Carb Machining Stage 2 Modifications We also have stage 2 modification for the Keihin carb, which includes extensively developed bore work, shaping, and jetting set to be used in conjunction with the STIC insert. This modification is worth around 1hp.. We modify the electronic power-jet circuit as well. It's a perfect mate for the STIC system - making use of the superior fuel atomization and coupling it with drastically improved flow and signal, while allowing additional volume for space taken up by fuel converted to vapor. It's an incredible value for the power. Powerjet Type - $200 USD Non Powerjet Type - $150 USD 85CC and Supermini Carb Bore/HP mod- $150USD |
Our Independent Dyno Testing Results![]()
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Consumer Reviews
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STIC Block COMBO Kit, "E" Type 36 and 38mm JD Kit, thumb adjustable air screw
Included in COMBO is
STIC Block "E" Type
1 Needle Jet for application
JD Jetting Kit with 2 needles, 2 extra pilots and 2 extra main jets.
Longer air screw and spring set up for hand/finger adjustment
For short body style Keihin PWK carbs, found on later gen KTM's, Current Yamaha's and others. Great gains in power, acceleration, throttle response, and performance. Unlock the hidden potential!
Thumb Adjustable Air Screw for keihin pwk
Longer Air Screw and longer spring (sold as a unit)
Allows hand adjustments to air screw
STIC DVI Keihin Metering Block 38PWK 36PWK "E" Type
Fits NON screw top PWK38mm - Common to KX250, RM250, YZ250, KTM 125, KTM150, KTM250, KTM300, and PWK called "short body"
Great Dyno proven gains, incredible throttle response, improved performance in all conditions.
Enter Proper Bike and Details, we will ship suggested needle jet
How To: Video instructables on Installation and Needle Jet
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Frequently asked Questions:
What fuel do I need?
We recommend a minimum of 98 octane combined rating ((RON)+(MON))/2, one fuel that meets this requirement is VP MS98, or a 50% percent blend of VP C12 and 91 Pump gas. The consistency of pure race fuels is also very good compared to pump gas as an added tuning benefit. Another option we highly suggest is Avgas 100LL mixed 4.5 gallons to .5 gallons of pump gas for those on a tighter budget. We have found on the KTM models, pump gas is sufficient as well as the stock honda models, beta, gas gas, and sherco.
Why do I need higher octane rating?
Most production motorcycles are highly developed from the manufacturer to run right up to the limit if 89-91 pump gas as long as they are jetted a little too rich for max performance. Sadly most OEM development was done on two strokes before pump gas changed formulation to the ethanol/oxygenated blend we have now making many two strokes incapable of running pump gas stock unless grossly rich. The compression ratio selected by the OEM is right up the limit before detonation. When increasing power, the dynamic compression ratio increases, and total heat production increases (piston engines are heat pumps - converting heat into power). Due to this - a higher grade fuel is necessary - or a reduction in compression ratio. We have found if you know what you are doing, most ktm's have no issue with pump gas. But on yamaha, you need to make sure you listen for detonation when getting optimal set up.
Will my engine life be affected?
The engine must be in good mechanical order prior to any increase in power, from any modification. Outside of this, no. The engine life will be the same as it was before as long tuning is correct.
What jetting is suggested?
The STIC has gone through a few changes since inception, and we now have a wonderful installation sheet included with it.
That said, 250-300 we prefer the needle jets as detailed with a 38mm carb.
.113A for offroad
.113 B for MX
And with 125 and 150's we prefer a
114A for offroad
.114B for MX
A good starting point for all bikes is
200 main
50-52 pilot
When dialing in for maximum performance with proper fuel and tune up, we have found down to 185 main in some applications.
And we offer a JD needle kit with 2 options
The stock yz250 needle is also a good starting point for many users - you can check out our video's on some needle mods we do.
On 36mm carbs all settings are smaller
42-45 pilot
170-180 main