Large Swamp Runner Kit (18-23hp)

From: $749.00

Our 18-23hp Large kit is perfect for marsh skiffs, bateaus, and jon boats 14 to 16 feet.

Kit Weight: 75 lbs.

The Vanguard 627cc (23hp), Predator 670 (22hp), and Honda GX630 & GX690 are the popular engines used.

SKU: 40kt00v Category:

Our Large Swamp Runner Kit includes every part needed to build a longtail motor except for the engine.

Each kit includes:
  • Coupler Assembly
  • Tethered Kill Switch Assembly & Adapter
  • Tiller Handle
  • Duckbill Throttle Assembly & Grip
  • Heavy Duty 100" Shaft Assembly
  • Two Aluminum Surface Piercing Propellers, 9" & 9.5"
  • Engine Base Mounting Bracket
  • Transom Bracket
  • All hardware required for assembly
  • Owner's Manual for assembly instructions and other information
Additional Info

You can view performance stats submitted by verified Large Swamp Runner Kit owners at the link below.
Customer Performance Stats -
This will show the engine sizes the large kit was installed on, the type of boat, along with the weight, speed, propeller, and RPMs reached.

Most people put the SPS Swamp Runner Large Kit (75lbs) with the 22hp (670cc) Predator Engine (106lbs) - This setup will total 181-lbs.

You could also use a 23hp (627cc) Vanguard that we sell on

The 1448 and the1542 riveted jon boats are the most widely used boats for this kit.
For example, User: Backwoods reached 26-mph in a 1448 jon boat with a stock 670cc Predator engine spinning 3800 RPMs with the 9" stock prop.
We do not have many submittions for the Large Kit, but 25 mph seems to be a good ballpark average speed.

If you need more power, the next step up is the SPS Big Block Swamp Runner Kit (75lbs).
We are currently testing this kit with a handful of customers to verify everything is correct before we release it to the public.
We are designing it to fit with a 35hp to 40hp Vanguard engine (around 140lbs) totaling 215 lbs.

MakeHPModelsSpecial PTO Shaft
Briggs-Vanguard16hp (479cc)
18hp (570cc)
21hp (627cc)
23hp (627cc)
16hp: 305447-0075, 305447-3075;
18hp: 356447-0075, 356447-0079;
21hp: 385447-0075;
23hp: 386447-0020, 386447-0047, 386447-0065,
386447-3065, 386447-0079
Briggs-Vanguard16hp (479cc)
18hp (570cc)
23hp (627cc)
16hp: 305447-0087
18hp: 356447-0087
23hp: 386447-0048
Carroll Stream20hp (6cc)CS2V77
1", 1.125"
1", 1.125"
Harbor Freight Predator22hp (670cc)616141"
Home Depot: Lifan24hp (690cc)LF2V78DT1.125"
GX610 with 1" diameter "Q type" output shaft
GX620 & GX630 with 1" diameter "Q type" output shaft
Honda24hp (688cc)GX660 & GX690 with 1 1/8" diameter "Q type" shafts1.125"

*The information in this table is provided by as a courtesy service to our customers, and should only be used as a guide to help you choose a kit and match your engine with it. We could not possibly list information that would apply to all engines that are available and will fit our kits.  While every effort has been made to provide useful information, the information may change.  So, it is your responsibility to verify engine specs with the manufacturer of your engine prior to ordering.

Compatible Engines

Customers sometimes ask us for examples of engines that will fit our Large Swamp Runner™ kit.  There are simply too many engine makes and models, to list all engines that will fit.  The following is a short list of just a few of the engines that will fit our Large Kits:


1″ Output Shafts Briggs-Vanguard 16hp Models: 305447-0075, 305447-3075 Briggs-Vanguard 18hp Models: 356447-0075, 356447-0079 Briggs-Vanguard 21hp Models: 385447-0075 Briggs-Vanguard 23hp Models: 386447-0020, 386447-0047, 386447-0065, 386447-3065, 386447-0079

1 1/8″ Output Shafts: Briggs-Vanguard 16hp Model: 305447-0087 Briggs-Vanguard 18hp Model: 356447-0087 Briggs-Vanguard 23hp Model: 386447-0048


Predator 22hp Model 670cc V-twin with 1″ diameter output shaft.


1″ Output Shafts Honda 18hp Models: GX610 with 1″ diameter “Q type” output shaft. Honda 20hp Models: GX620 & GX630 with 1″ diameter “Q type” output shaft.

1-1/8″ Output Shafts: Honda 24hp Model: GX660 & GX690 with 1 1/8″ diameter “Q type” shafts.

OTHER ENGINE MODELS: Without physically seeing and measuring your engine, we cannot guarantee this kit will fit your application.  If your engine is not listed above, you will need to consult the engine manufacturer, or take some measurements of your engine to ensure it meets the following requirements;

Engine requirements

  • The engine must have a horizontal output shaft. (Vertical shaft engines will not work with this kit.)
  • The output shaft must be a straight (non-tapered & non-threaded) shaft with a keyway.  (Tapered shaft engines will not work with this kit.)

NOTE: Engines with gear reduction are not compatible with this kit.

Swamp Runner®
by SPS
Beaver Dam
Heavy-duty steel Coupler Housing is zinc plated, then powder coated for superior corrosion protection.
Cast Aluminum
Coupler Housings, Coupler Shafts, and Coupler Sleeve Joints so tough they come with a LIFETIME WARRANTY against cracking or breaking to the original owner.yesnono
Coupler shafts of Small, Medium & Large Kits ride smoothly on high quality Japanese radial bearings. yesnono
Offers longtail shafts featuring premium Bayou Bushings, a low friction proprietary bushing developed by Swamp Runner, and capable of withstanding extreme high temps without melting. Over 1000 hrs in a test tank with negligible wear. This bushing just doesn’t care what you throw at it.yesnono
Longer tiller handle designed to operate while standing up or sitting down, with position holes drilled in the handle, and locking bolts that prevent the handle from twisting in the mounting rings. yesnono
Squeeze type throttle lever that has the full throttle travel of your engine.yesnono
Stainless throttle cable that resists corrosion.yesnono
High quality sealed Japanese bearings in the gimbal mount for smooth, fluent handling of the longtail mud motor.yesnono
Gobs of shaft options to choose from: 5 different longtail shafts lengths varying from a 75" to 120" in length, Along with 4 different shaft options; Standard, Extreme Duty, Saltwater Extreme Duty, and Racing shafts.yesnono
Loads more propeller options than any other mud motor company. With more than 50 different props available including standard props, weedless props, performance props, stainless props, racing props, and even props that come with a .25" bore so you can tap it yourself!yesnono
The Weedless Skeg on Small, Medium and Large kits has a longer entry angle that repels vegetation and slides over logs easier.yesnono
First & only Thai longtail company to offer a Weed Cutter option that can be bolted directly to the weedless skeg using predrilled mounting holes.yesnono
A full time mud motor company offering knowledgeable support from over two decades of experience with Thai longtails in both Thailand and the USA.
Access to an active forum where customers enjoy learning about their longtail, and interacting with other owners and people who KNOW Thai longtails.
Access to numerous parts you can't get anywhere else.

Additional Information

Weight 45 lbs
Dimensions 23 × 19 × 7.5 in


6 reviews for Large Swamp Runner Kit (18-23hp)

  1. Rod C (verified owner)

    Just thought I’d let you know that we’re up & running with the mud motor! The kit went together very nicely. The only thing so far that’s stopped the boat is dry land. Neighbours who’ve seen a boat going where no boat has been lately are impressed!

  2. Glynn P (verified owner)

    Rig was impressive today. 3 men (520 lbs) and fishing gear. Pushed through some shallow stuff

  3. Kenny S (verified owner)

    All of our boats have your mud motor kits and WE LOVE THEM!! Just wanted to drop a comment and say thanks for making a quality product we enjoy using!

  4. Bryan G. (verified owner)

    If I could rate more than 5 stars I would! This is my second Swamp Runner kit, I have a medium kit and just bought the large. Top quality and performance!! Bullet proof design, hands down the best long tail made on the market..
    I bought a mud skipper, new design, absolute garbage!! Wouldn’t recommend Mudd Skipper brand to my worst enemy

  5. sdreese630 (verified owner)

    A little over a year ago I purchased the large kit, added a 23HP Vanguard, installed it on my 16/52 Weldbilt and it’s a solid performer. I can cruise an easy 15-18mph with a top speed around 24. Very efficient on fuel, actually surprised at the fuel consumption. I have been through solid mud, lots of vegetation and very shallow water. The only damage have been two broken props and a loose bushing. The replacement Bayou bushing is holding up well. The kit is very good quality, I have pulled up really hard on the handle to get moving (might have been stuck and panicked a little) and nothing is bending or breaking, the build quality is excellent. Also customer service is top notch, I have talked with Steve several times, before and after the purchase and he, if you can listen, has a lot of good advise. My original plan was to run my outboard from time to time, but for the places I fish and hunt a mud motor is superior to a outboard. I could go on, but I’ll just say I highly recommend this company and their products.

  6. FL_CrackerLife_1986 (verified owner)

    Went from a Medium kit to a Large kit with the 100” stainless shaft and upgraded bushings, installation with the Predator 670 was a breeze. Had a bit of a problem with the coupler bearing but called and got it figured out. (Thank you Steve) Amazing communication and customer service/support. Even on a Friday evening.

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