Swift 125 Unlimited Superkart


(Andre Molina) #1

NEW Project!

Kart was purchased from WA and had to be shipped to me in IL. It was expensive and it took several months, but it was totally worth it.


Exploded view:
image2 (1)


TM KV92 rotary valve (proper!) 125cc shifter. Doesn’t look stock, came with an extra cylinder. Can’t wait to open it up.

??? Looks cool, and came with the original vertical stabilizers! Has a ducted radiator intake that looks really neat. Seat is a Tillet 250 in carbon-kevlar, purchased locally and separately. Carbon fiber floor pan.

Swift (unknown vintage), it’s in solid shape and straight.

Stay tuned, kart needs a ton of work and I’ll be updating this page every step of the way.

What Are Your Racing Plans for 2018?
(James McMahon) #2

Love everything about this kart. From the rotary valve motor down to the bodywork.

That thing looks so sick. When I raced in Ireland, those Swifts and others with that body style raced on long circuit road courses and were usually were called “long circuit” Karts.

Faster than a formula ford 1.8 Zetec by about two seconds/lap if I recall correctly. Some guys ran them on the short tracks (Sprint tracks for US folk) as well and did OK.

(Andre Molina) #3

Update # 1

First thing I did was to hook up the vertical stabilizers. I can’t help it, the kart looks great with them installed!

A quick survey showed a lot of rust all over the mild steel chassis components. But further inspection revealed nothing but surface rust, and some surface rust and pitting on chrome surfaces:

This weekend I’ve finally had the time to take the kart down and work on it, despite the super cold Chicago weather. My space heaters could barely keep the garage at above freezing temps:

I’ve wrapped the rear axle and front spindles with rags soaked in EvapoRust, and let the parts sit for 48 hours.

Cleaning out the axle IN PLACE should be a first step in every kart restoration, unless your axle is too far gone or you don’t want to keep the bearing cassettes. Even if you later decide the axle needs to be replaced this step is still necessary: Banging out a rusty axle is impossible.

Although after 48 hours of soaking and about 4 hours of wire brushing, the results were fantastic:

The axle bearings are new, although installed nearly 15 years ago. Everything spins smoothly, this kart amazingly enough won’t need a rear end job.

I’m pretty happy with how it turned out. Frozen, but happy.

(Andre Molina) #4

Thoughts now are to mount the carbon/kevlar seat as low as possible. These karts were generally built with a pretty sit up stance, because that’s what the rules dictated in the UK. If I follow TAG USA superkart rules I’ll be able to mount it a lot lower, which will help me cut through the air better.

Kart came with a generic steering wheel bolted up to a quick remove hub. Which is fine, but I feel like if I go with something from the DRIVEN line it will both be smaller and more comfortable. A smaller wheel reduces the risk of my hands intruding in the airflow.

Plan is to go with DRIVEN’s quarter midget wheel. I’ve had one in the past, it’s very comfortable with thick grips and looks great with a mychron in the middle.

(James McMahon) #5

I think that wheel is gonna look pretty slick, did you make measurements. If you wanted to go extreme, you could go with the butterfly types. Not as slick looking though.

(Andre Molina) #6

Nah, having owned one before I just really like how it feels.

Another concern if I want to race with CES:


(James McMahon) #7

You aren’t entering the superkart class perse. You’re entering Unlimited, or maybe F125.
The superkart class in that context is 250cc superkarts

(Andre Molina) #8

So, essentially no rules?

(James McMahon) #9

250cc (Two stroke) limit and probably some general dimensions. But otherwise you’re good. I’m not sure on F125 though.

(Andre Molina) #10

Unlimited rule set matches up pretty nicely with WKA road racing, which is cool:


I’ll also need a road racing license. Whatever that is.

(Andre Molina) #11

Update #2:

Time to tear trough that engine.

According to the seller, the chassis used to belong to and was set up by Graham Barker. It was then sold to J. Musel in Canada (I think?) and bought by the person who ultimately sold me the package. I don’t know how much run time the kart had with Musel or Barker (some clues to that further down this post) but seller states he has only raced the kart once, in Portland in the early 2000’s. Engine has a modified liner and ignition, 4.2 mm BTC.

Coolant passages are really rusty. How when everything is made of aluminum?

Coolant surrounds the combustion chamber. The bolts securing it rust out.

Now to remove the cylinder. These guys are impossible to crank out. They take a ground down 12mm box wrench, otherwise you’ll just round out those nuts:

Combustion chamber top looks good:

Cylinder is in excellent condition, with really good port work. Even the base gasket looks like new.

Hash marks still visible. Piston has minimum wear and was ran pig rich, but check out that blowby:

Luckily, seller sold me the engine with a brand new piston package of the exact size I need. Someone was getting ready for a new top end?

Now, with an engine that sat for 15 years, you want to inspect and change the oil seals. Rubber can dry out and degrade. On the ignition side, no problem. Bust out your motoplat holder and puller, done:

Now to tackle the other end. Pull the clutch pack, taking the opportunity to inspect the condition of the clutch itself:

Oops moment:

Things look good. BUT WAIT. Turns out you need to MACHINE OUT the studs that hold the clutch basket, remove the clutch basket, then open the side case to access the oil seal under the rotary valve. That is a ridiculous amount of work for a sealed engine that is holding all it’s shit right.

Considering the gearbox still had oil and the bottom end still had castor, the executive decision after a careful risk analysis was to leave that side of the engine alone. Seal was probably kept moist, and the fact that it is enclosed helps.

In any case…

New piston will go in, with a brand new wrist bearing. New oil seal on the ignition side, then I’ll close her up and move towards installation of the motor package.

Huge thanks to Mike Giessen, my shifter go-to source, for holding my hand throughout this completely alien rebuild.

(James McMahon) #12

If tap water was used, perhaps Iron content and/or migration from the steel bolts holding the head on.

Couple of things I noticed…

  • That piston has seen some time, heat and detonation for sure. Although the top of the crown color is rich, it looks like it was detonating at some point. Also, under the crown you can see the baked-in oil.

  • The bore could use a hone for sure, not sure where you will end up on your size with that piston. Maybe even replate it.

  • Definitely replace the crank seals if you are on the fence. Mains too. Have a really good look at the bottom end bearing. At the very least, do a vacuum check on the motor when you have it together again.

  • Swap the clutch plates (inside > out… Outside > in) when you are putting it back together. You’ll likely find the outer ones are more worn than the middle plates. Swapping them will get a bit more life out of it.

Are you 100% sure that machining those pins is the only way to get the basket off? If you haven’t already, reach out to Riley Will. You might be able to get some feedback on how conservative (or not) the ignition advance might be.

I found images of an exploded view of the KV92 here and made a PDF for you: TM KV92 FC Kart Motor Exploded Parts Diagram.pdf (550.7 KB)

Incidentally… I wonder how one of these would run with a modern oval port cylinder from an ICC/KZ with port timing to match the rules for FC (Basically none :smiley: )

On the bodywork, @NSEWnoah mentioned that you’ll have to cut an opening at the top of the bodywork above your legs so you can get out when something, eh, unintended happens.

(Andre Molina) #13

“easy job”

DUDE, great suggestion. I’ll definitely do that! Noticed the inside clutch plates are a lot more worn.

Agreed. Definitely not a one-race piston. It’s been around the block.

The bore is actually in excellent condition, no scrapes and all hone marks are still in. For some reason the pictures are really compressed, or maybe I’ve downloaded the wrong ones.

The new piston I have is for this exact bore size, thus the thinking someone down the line planned for a top end rebuild before the engine was sold to me…

It does have a feet hole. Like this?

I don’t want to run without this cover, but I guess I could and install a nassau panel.

(Andre Molina) #14

@NSEWnoah How’s that even measured? Are they going to make me do an ingress and egress exercise?
The steering wheel has a quick disconnect hub which lets me get out easy.

(Noah Stark) #15

(Noah Stark) #16

Seeing that the Kart isn’t what I would consider a super Kart frame or bodywork, I would classify it more along the lines of a laydown. Even if used in unlimited etc…

Common misconception is that unlimited is truly unlimited. It is not, which I do find a bit silly. But this is a safety issue. I have been doing this for a very long time and I can tell you, I would have no desire to get into a Kart that I’m either trapped or strapped into…

Would you want to be trapped on a motorcycle? Concept is that in the event that something bad happens, you can get away from the bike… same goes with karts, or else we would have roll bars and seat belts.

(James McMahon) #17

Looks like we get to play ruleset roulette here. That looks like a WKA rule book? Andre lives near BHF so CES is what I think he’ll be running. I scoured (well speed and keyword searches) the CES rule book and didn’t find anything on foot coverings. I’ll take another look tomorrow.


As for being trapped, honestly I’ve seen people exit these kind of karts with ease in Europe :slight_smile:

Outside of the rules, it’s really down to ones comfort level. I believe these chassis and bodywork were raced as a “spec” 250twin class in the 90’s in the USA, I think that’s interesting.

For sure unlimited is anything but, it’s more of a catchall <250cc two stroke class really. A lot of things Enduro are confusing :laughing:

(Noah Stark) #18

CES references the USSK rulebook for bodywork rules in the unlimited class for 250 super karts. Unfortunately USSK collapsed as far as I know quite a few years ago and finding any of their rules that was more than a general explanation is not super easy to find. However in the rules I did find it states that legal bodywork consists on a nose, two side pods, a steering fairing, and a wing. I have driven a few of these and even though it would be very difficult to get your legs out between the nose and steering fairing, there is always an opening.

I guess it would then come down to the tech guy as to who would approve it. Seeing that I ran ALOT of pre-race safety tech for WKA National events, it would not get my sticker of approval. CES might be different and be more lenient on things.

(James McMahon) #19

Worth talking with Dave Larson about to be sure alright. Haven’t talked to him since last year :grinning:

Thanks Noah.

(Andre Molina) #20

Modern laydown enduros have no bodywork covering the leg area, but that didn’t stop Jim Ryder from breaking his back and other stuff in a flip at Daytona, after he got trapped in his kart by the traditional laydown crotch-mounted steering wheel. If the concern is getting trapped, laydowns shouldn’t exist.

But of course I wouldn’t want to be stuck in the kart. So if it comes race time the tech official tells me I need to loose the bolt on fairing and install a traditional hood fairing or in his experience I’ll get stuck, then that will be done!