Husky TX300 38mm & 40mm PWK STIC Review

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5/30/2018 7:51 PM
Edited Date/Time: 5/30/2018 8:43 PM

The purpose of this post is to review the STIC Metering Block for Keihin PWK carburetors, particularly in the application of my 2017 Husqvarna TX300.

BLUF: If you don't want to read the long of it, all you need to know is the STIC metering block is 100% legit. It does exactly what it claims to do. I can tell you with 100% certainly that there is not a single pipe, head, reed cage, or any other type of engine mod out there that can increase power like the STIC does, especially at the price of $295. For the record, nobody gave me one of these to test for free. I paid out of pocket for it. I am not affiliated with the inventor, George Boswell, or any of the dealers of this product.





Background: In general, the TX300 is one of, if not THE best bike I have ever owned (and I have owned many). Even with the Mikuni woes, this is a very good bike out of the box for a multitude of applications. I use mine primarily in the high-desert of New Mexico, but also use it in the mountains from time to time, and it handles both with ease. I have an insatiable urge to tinker and make things better, even when they are already very good. To that end, I have thrown the book at this bike in terms of modifications. Every single modification I have made to this bike has made the bike a bit better, with the exception of the Lectron carburetor. For the purposes of this thread, we'll just discuss the carburetor mods.

The JD jetting kit for the Mikuni worked well, but, given my nature, I decided to try the Lectron. In the words of my friend, it "makes old man power". He was right. I hated the characteristics the Lectron brought, so I sold it after two rides on it and bought a Keihin 38mm PWK short body from JD, with his jetting kit. Night and day better. It was crisper everywhere and just ran better in general. I landed on a 38 pilot, JD Red Clip 3, 170 main, 1.5 AS for my conditions (5200', 75 degrees at the time).



Again, being that I can't leave well enough alone, I decided to give the STIC a try. I purchased it from Derek at HP Race Development originally. It came with a .115 needle jet. I gave it a shot and couldn't get the bike to run right. It would load up really bad off the bottom, then clean out and hit really hard in the midrange, then flatten out up top. I ended up contacting the inventor, George Boswell, directly about the issues I was having and that I needed a smaller needle jet. Mr. Boswell contacted me within an hour of my email and explained to me the interworkings of the STIC system. He sent me, on good faith, an entire new STIC with the correct .114 needle jet, a 50 pilot and a 182 main jet installed, and only asked that I return the one I originally bought from Derek to him when I received the new one. Unbelievable customer service, and my hat is off to him.



I installed the STIC into my Keihin with the supplied jets and went out for a test run after work. Atmospherics and initial settings were as follows:



5200'/90 degrees F

50 Pilot

JD 2 Scribe Red Needle, Clip 3

182 main

3.5 AS



Right off the bat, it was abundantly clear that the bike was making more power everywhere. It ran MUCH cleaner with the .114 needle jet installed. The best way I can describe the power the TX is putting down with the STIC installed is that it has the bottom and midrange of a 300 on crack, and a top end that pulls like a 250 on crack, and it revs out much further where before, it would flatten out on the top end. It seems to just keep pulling and pulling.

The only spot that felt like it might be running a bit rich was on the main, and I figured I might as well try one step smaller on the pilot as well. To be clear, even with overly rich settings, it still ran really well. I installed a 48 pilot and a 180 main, and left the other settings the same. The bike ran cleaner on the main, but didn't seem to want to pull as hard (however, slightly) as it did before. I reinstalled the 50 pilot and kept the 180 main and everything felt perfect. The spot I rode today is full of deep, power robbing sand, big whoops and very steep sandhills. I found the steepest, sandiest hill out there and made a go at it with little to no running start at it. Not only did the bike make it, but it accelerated the whole way up and I was actually able to upshift and continue accelerating. I wouldn't have made it previously, without the STIC installed. I couldn't believe it, honestly.



I will be doing more testing with this system, but again, I am more than impressed and I can say with full confidence that its legit. I need to start saving money for rear tires smile

More to follow.

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5/30/2018 10:31 PM

Very cool, the fact the STIC exists is the only reason I'd go through the trouble to take the Mikuni off on my 250sx.

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5/31/2018 5:26 AM
Edited Date/Time: 5/31/2018 5:33 AM

seth505 wrote:

Very cool, the fact the STIC exists is the only reason I'd go through the trouble to take the Mikuni off on my 250sx.

I don't think the Mikuni is as bad as everyone on the forums makes it out to be. Frankly, I think the knowledge of how to tune a carburetor is slowly going the way of the buffalo. As others have noted on here, correcting the squish with the new line of Husky and KTM 2 strokes really goes a long way in cleaning up the jetting, but its only a piece of the puzzle.

You can definitely tune it to run good enough, but the difference between the Mikuni and the Keihin PWK is significant. Add the STIC in the mix, and you have an absolute animal of a bike. If you ride any sort of motocross or fast off-road/WORCS and you ride a 2 stroke, you NEED this mod. Period.

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5/31/2018 5:43 AM

Nice review. Haven't seen any bad reports yet.

Did you lose any top end or over rev with the Keihin vs Mikuni (before STIC)?

What other mods do you have on your TX? Would be interested to see mods and your impressions.

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5/31/2018 5:56 AM
Edited Date/Time: 5/31/2018 6:07 AM

erik_94COBRA wrote:

Nice review. Haven't seen any bad reports yet.

Did you lose any top end or over rev with the Keihin vs Mikuni (before STIC)?
...more

I personally didn't note a loss in top end or over rev with the Keihin over the Mikuni. Regarless, that has been my complaint overall with the 300 is the lack of top end, and over rev. My mods are as follows:

- RK Tek Head (Unsure of squish measurement or PSI)

- PC Works Pipe/Factory Sound Silencer: This increased power everywhere and I gained some overrev with this system)

- VForce4 Reeds: I didn't notice much of a gain with these, although my stock ones were warped from the factory.

- SX CDI and one step colder plug (BR8EIX)

- Cut out pretty much the entire right side of the airbox

- 38mm Keihin PWK Short Body, now with the STIC

- Running a 50/50 mix of 91 Pump/VP 110, Amsoil Dominator at a 50:1 mixture

The head probably made the biggest difference out off all the mods, outside of the STIC. Outside of engine stuff, I had Factory Connection revalve my suspension, install a bladder kit and Xtrig on the shock. After having my FX450 done with their AER performance kit and updated 2018 parts, I'll be sending the TX suspension back for an update. Its very good. Running a Scotts damper with their HD cradle setup. I have another set of wheels coming from FasterUSA (Excel A60/Bulldog Spokes/FasterUSA Hubs). Once those come in, it'll be getting some new Starcross 5 shoes and nitromousses. I installed an IMS tank since this thing is pretty thirsty in the dez.

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5/31/2018 10:59 AM
Edited Date/Time: 5/31/2018 11:00 AM

erik_94COBRA wrote:

Nice review. Haven't seen any bad reports yet.

Did you lose any top end or over rev with the Keihin vs Mikuni (before STIC)?
...more

CSAR FE wrote:

I personally didn't note a loss in top end or over rev with the Keihin over the Mikuni. Regarless, that has been my complaint ...more

About a month ago I had Factory Connection fix the low-speed harshness in my AER's with their performance mod and revalve. SO MUCH BETTER! Makes these air fork compliant in braking bumps, roots and rocks. They did the shock bladder mod too with revalve.

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5/31/2018 12:28 PM

erik_94COBRA wrote:

Nice review. Haven't seen any bad reports yet.

Did you lose any top end or over rev with the Keihin vs Mikuni (before STIC)?
...more

CSAR FE wrote:

I personally didn't note a loss in top end or over rev with the Keihin over the Mikuni. Regarless, that has been my complaint ...more

Thanks for the reply.

I had a ported 300 kit on my TC250 for about 10 hours. Will make a separate post on it at some point. The 300 kit was very nice for the more open tracks or softer tracks (MX only for me) I ride at, but changed the riding style more than I wanted (more 450 like, less 250 2-stroke like).

Having correct squish and the PC exhaust were also very worthwhile as a 250 and 300. Still mulling springing for the PWK and STIC for the 250.

Also to note, I have a set of Starcross 5 soft on my my TC250 and I like them a lot. Traction is 85-90%+ of the MX3S and they are wearing very well so far (better than MX3S).

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5/31/2018 1:14 PM

erik_94COBRA wrote:

Nice review. Haven't seen any bad reports yet.

Did you lose any top end or over rev with the Keihin vs Mikuni (before STIC)?
...more

CSAR FE wrote:

I personally didn't note a loss in top end or over rev with the Keihin over the Mikuni. Regarless, that has been my complaint ...more

erik_94COBRA wrote:

Thanks for the reply.

I had a ported 300 kit on my TC250 for about 10 hours. Will make a separate post on it at some point. ...more

With the STIC installed, you could honestly ride the 300 like a 450 or a 250. Tons of low end and midrange on tap and very responsive, but the top end and overrev is there now if you need it. Straight up dude, don't mull it over anymore. If you have the cash, buy a PWK and a STIC.

The only other thing I'm going to do to this motor is have it ported by HP Race Development. I think after that, it'll be pretty much the perfect 2 stroke, or damn close to it.

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5/31/2018 5:18 PM

Can tell you one thing.....the PWK 38mm along with the STIC mod from Derek , woke up my Husky 125 like nobodies business! First test ride was yesterday , and I kept thinking about how hard that 125 was pulling yesterday. For a 125 , it pulls like a mule! OP aint kidding! Thinking real serious about getting another one for my RM 250 once I get her back up and running.

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And there goes Jeffro. One of God's own prototypes. A super high-powered mutant of some kind never even considered for mass production. Too weird to live, and too rare to die.

Pimpin' Ho's , Rollin' fatty's......drinkin' beers , beers , beers!! ~ Ja

5/31/2018 5:28 PM

A STIC is my next purchase for my freshly built 04 YZ 250. It took me a year finally get it together and I love it. I have talked to Keith at KP Racing a lot about the STIC. I can't wait to get one.

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6/9/2018 7:52 PM
Edited Date/Time: 6/9/2018 8:01 PM

Sorry its been a bit since I've last posted about the STIC. I decided to try the N3EJ needle out of a YZ250 to see how the bike performed. I got the bike out for a quick ride Friday afternoon, after work. I was pretty tired after completing a gnarly memorial workout for some brothers we lost in Afghanistan 8 years ago, and it was over 100 degrees out, so I just did one short loop and packed up before I had a heat stroke. Friday's environmental factors and jetting specs:

102 degrees F
5200'
11% Humidity, aka dry as a bone

.114 Needle Jet
50 Pilot
N3EJ, 3rd Clip
182 Main
3.5 AS

I found the N3EJ needle to be crisper from idle to about 1/2 throttle than the JD Red two scribe needle, but it didn't seem to want to pull as hard past that as it did with the previous settings. I didn't get a chance to swap the 180 main back into it for more testing on this ride.

I do find the bike to be much better at pulling itself through the deep sand and getting on top of it with the STIC, where before it really struggled to get back going when you slowed down. For that reason, I preferred to run my FX450 in very sandy areas, but the STIC makes the 300 a viable option for these conditions. Here is a quick clip of how the bike runs/sounds on my ride Friday:

&t=2s

I went out this morning for about an hour's worth of seat time, before it got too hot. Today's environmentals/jetting specs:

80-85 degrees F
5000'
10% humidity

YZ250 N3EJ Needle, 3rd Clip
50 Pilot
180 MJ
AS 3.75

Dropping to the 180 main brought back the top end and overrev that I lost when I moved over to the N3EJ needle/182 main combo. Unbelievable power from this thing. I purposely started at the base of several steep, sandy hills, going much slower than I was comfortable attempting these climbs with and the bike didn't seem to care; it just chugged its way up like it was nothing. With the power the bike makes, it can really save your tail on those nasty hills that come right after a turn, where if you don't carry your speed and execute the turn with good technique, you would be hosed otherwise. The same goes for those types of jumps, for those of you that stay on the track... Which brings up another item of note for those who are planning on running a STIC: be very careful hitting jumps after first installing this thing, whether they are on the track or trail. It is very easy to over jump them now (as I did today, and almost wadded it up). Take your time getting used to the power.

I am going to try raising the needle one clip next. I am very close to what I feel is perfect jetting.


Although this review is on an off-road oriented bike, it is still very applicable for motocross bikes, as Jeffro has shown. I would highly recommend it for those of you with a new 250SX/TC250, but it will work on pretty much any bike you can throw a Keihin PWK on.

Both the Keihin short body and screw top variants are available directly from STIC headquarters, for $274, plus $295 for the STIC metering block itself. It’s a good savings over ordering it from JD, if you don’t care to use his needles or extended Air screw.

STIC headquarters: 715-479-7822
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6/10/2018 2:24 PM

Great review, I'm currently on a 200 and would love to trade up to a newer 300 in the near future. I'd probably do much of what you've done to yours, sounds like it runs like it should now. I got some work done to my head and it really woke my bike up along with a NECJ needle out of an RM250 it lugs great down low and pulls like an MX bike up top. Maybe I need to add a STIC to my setup. Thanks for the heads up.

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21.5 350 XC-F
96' XR600r

6/10/2018 8:31 PM

Here's my final review of the STIC/38mm Keihin PWK combo:

&t=2s

Hopefully I can get it on the track to test soon.
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6/17/2018 5:56 PM

Very nice info. Currently on a 250sx 2017. Looking to do the 300 conversion like I did on my 13, but don't want to loose the over rev that the 250 has. But man I want some more roll on torque.

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6/18/2018 3:27 AM

Markee wrote:

Very nice info. Currently on a 250sx 2017. Looking to do the 300 conversion like I did on my 13, but don't want to loose the ...more

With the STIC and a PC exhaust, I don’t think you’d have any complaints about lacking overrev.

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6/18/2018 9:01 AM

Markee wrote:

Very nice info. Currently on a 250sx 2017. Looking to do the 300 conversion like I did on my 13, but don't want to loose the ...more

CSAR FE wrote:

With the STIC and a PC exhaust, I don’t think you’d have any complaints about lacking overrev.

Got the PC exhaust. What power valve spring and turns are you using?

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6/18/2018 9:09 AM

Markee wrote:

Very nice info. Currently on a 250sx 2017. Looking to do the 300 conversion like I did on my 13, but don't want to loose the ...more

CSAR FE wrote:

With the STIC and a PC exhaust, I don’t think you’d have any complaints about lacking overrev.

Markee wrote:

Got the PC exhaust. What power valve spring and turns are you using?

Red spring, flush with the housing.

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6/18/2018 5:01 PM

Did George tell you it works better with the air screw more open?

I thought it did from my testing, but KP said no.

I still run it at 2.5 to 3 turns out with a size bigger pilot because I think it runs better that way.

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6/18/2018 5:22 PM
Edited Date/Time: 6/18/2018 5:32 PM

Mr. Robinson wrote:

Did George tell you it works better with the air screw more open?

I thought it did from my testing, but KP said no.

I ...more

Yes, that was the direction I received from him when I contacted him for help initially.

The STIC system needs a lot of air from the air screw, and a big pilot for it to work as intended. What is your application, and what size pilot are you using? Altitude and temps?

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6/18/2018 5:55 PM

I'm running it in a YZ250 with X mods.

I've been running a 52 pilot, 3 turns out and a 188 main. Typically 0 to 1000' @ about 85F right now.

I got one of the first 5 KP shipped out for sale, so I've had it for some time now. It was obvious to me from the beginning that the system pulled air from the pilot circuit and the air screw had a big effect on it. I was told other wise, but after going back to his recommended settings that mine worked better. So, I just ignored him and did my own thing since it ran even better.

I've never talked to George about it, so I was just wondering what he had to say.

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6/18/2018 6:08 PM

Mr. Robinson wrote:

I'm running it in a YZ250 with X mods.

I've been running a 52 pilot, 3 turns out and a 188 main. Typically 0 to 1000' @ ...more

That sounds about right. What needle are you using?

I will be trying out even larger pilots, hopefully this week, to see what happens.

I wouldn't hesitate to contact George if you have any questions. He's very friendly and a wealth of information.

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6/18/2018 6:19 PM

I run the stock N3EJ - 2.

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6/19/2018 1:07 PM

Mr. Robinson wrote:

I run the stock N3EJ - 2.

I've found this needle to work very well with the STIC. There is another user who is running the N3EJ needle in a KTM 250 and is having excellent results. Do you know what size needle jet you have installed?

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6/19/2018 2:15 PM

Honestly, I don't. I'd have to dg through the emails from when I bought it to see if it was ever mentioned.

From what I was told a lot of the development work was done with the YZ250, so that may have something to do with the N3EJ working so well.

I haven't messed with the jetting a whole lot, because it dialed in pretty quick and worked as advertised. So, I've very happy with it and haven't found the need to mess with it much.

When I have, I just end up back where I am. Even from winter to summer there seems to be very little need to mess with the jetting. I can normally bring it in with just the pilot jet.

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6/19/2018 3:34 PM

Mr. Robinson wrote:

Honestly, I don't. I'd have to dg through the emails from when I bought it to see if it was ever mentioned.

From what I was ...more

Well boys, its time to go big, or go home. Dad always said if you can't run with the big dogs, then stay on the porch. I will be testing the 40mm Keihin PWK short body, fitted with the STIC metering block, on my 2017 Husqvarna TX300. Yes, you read that right: 40mm.

George was gracious enough to send me this carburetor for testing and evaluation. We believe there are even more gains to be had on this motor with the STIC, and a larger carburetor bore. The STIC has proven to be excellent at substantially increased fuel delivery and vaporization, so it only makes sense to see what we stand to gain when we are able to flow more air. 

Testing will be completed with both the .114 and .115 needle jets. I plan on starting out rich in all circuits and tuning from there, most likely a 185 main, somewhere in the vicinity of a 55 pilot, and either the JD blue or red needle (I haven't decided which yet). The carb comes in Thursday, and testing should begin Saturday. 



For those who want to take the plunge into the STIC, but still need a Keihin, you can purchase both from STIC Headquarters.



More to follow. Photo
Photo

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6/19/2018 4:28 PM

Congratulations, that should be badass on a 300.

Is the air screw port hogged out? Looks bigger than normal.

BTW, I wouldn't waste time with the JD needles. I'd just go with the N3EJ.

JD stuff is a whole other way of thinking from this.

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6/19/2018 5:12 PM

Mr. Robinson wrote:

Congratulations, that should be badass on a 300.

Is the air screw port hogged out? Looks bigger than normal.

BTW, I ...more

I believe it just appears so as the air screw isn't present in that picture.

Perhaps I'll start with the N3EJ, then.

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6/23/2018 8:16 PM
Edited Date/Time: 6/23/2018 8:21 PM

I completed the initial round of testing with the 40mm Keihin PWK/STIC combo. I tried to get some footage today, but my helmet cam is giving me fits. I suspect the SD card may be corrupted. If I can get it to work, I will post another video. The day started out at about 80 degrees in the morning and was up to 95 when I finished, with 5% humidity. The specs I finished with by the end of the day:



58 Pilot

AS 3.75

YZ250 N3EJ needle, clip 3

.114 Needle Jet

190 Main



As you can see, this carb needs big jets. I went to my usual spot that you all have seen, if you watched the previous two videos I posted with the 38mm Keihin/STIC testing. What I noticed up front: the midrange, top end, and overrev all increased significantly with the 40mm/STIC combo, which I didn't think was possible with how much power the bike made with the 38mm variant. It feels like the bike never wants to stop revving out. This makes the bike much more forgiving with missed shifts, or sections on a track/trail where there isn't enough room to shift up and get back in the meat of the power in time to clear that jump, or make it up that hill. The bike pulls out very far, instead of going flat on top like a stock 300. That has been my biggest complaint with this engine, and the STIC not only fixes the issue of top end/overrev, but actually makes it a strength. I believe I can go up to a 195 main jet and achieve even better results. I will also be testing with the .115 needle jet in the 40mm. This carb needs a lot of fuel to work with how much more air it is flowing.



The bottom end feels softer than it did on the 38mm variant, but still worked well. As you can see in the photos in posted above, the vortex generators, aka "air wings", have been mostly removed in this carb. I will be testing a variant with the "air wings" still present, along with some other components coming from STIC headquarters. This is just the beginning with the 40mm. Again, more posts to follow. 



If you don't believe the STIC is doing something very different from typical fueling, and is increasing fuel vaporization and availability at a rate not previously thought possible, just consider the size of the jets I am running in the bike, and the environmental conditions. Try sticking a 58 pilot and a 190 main jet in your 250 or 300 at 5500' and 95 degrees, and see what happens. Hell, try it in the winter too. Your plug would be sopping wet and there would be spooge dripping all over the swingarm, if you could even get the bike started. To put it in perspective, I was running a 38 pilot and a 170 main before the STIC. The hype is real, folks. This is not snake oil, this is actual engineering, and years of R&D, at work.

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6/23/2018 9:23 PM

Hmm, I wonder if it's worth it to consider the 40mm for a 250cc. Did he mention that it's only a good bet with the 300?

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6/24/2018 12:26 PM

seth505 wrote:

Hmm, I wonder if it's worth it to consider the 40mm for a 250cc. Did he mention that it's only a good bet with the 300?

George has used 40mm carbs in 125’s on up with great success.

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