|Tech Talk: Buying a Used Kart for Racing
|Article by: - by Richard Curtis, Woodbridge (Va.) Kart Club email@example.com
|There are two basic ways to buy a used racing kart. One is to start with a "roller" (rolling frame, body work, seat, sometimes a clutch) and then purchase what you need a piece at a time. Another, and this is the method I highly recommend, is to buy an entire, ready-to-race kart. There are advantages and disadvantages to each method.
Method One-Buying a "Roller"
So what happens if you choose to buy a "roller"? First, you'll need to buy the other parts that will enable you to race. Let's say you found a great, straight enduro roller, sans clutch, for $1,200. (For comparison, a brand new, bare frame will set you back around $800-$900.) To the base roller price, add the following:
Motor--$350-$800 (you should have two motors)
Exhaust--$80-$150 (header, flex, pipe and mount)
Clutch--$350 (used) to $650 (new)
Add at least $1,080 for all above stuff the $1,200 for the roller for a minimum total of $2,280.
Method Two-Buying a Race-ready Kart
The second method, which is to buy a complete "kit," is what I consider by far the most advantageous and attractive method for the beginner karter, despite its generally higher initial cost. The advantage comes from fact that you most always get a better deal, money-wise, when you buy a kit. (If the seller is getting out of karting, he or she is usually a very motivated seller, and I've seen deals for everything -- engines, extra parts, etc.) Also, with a kit, the kart is already assembled.
When buying the complete setup, look to acquire the kart, engine(s), pipes, extra headers (used ones are about $20 apiece), extra gears (used ones are about $20 apiece, new ones are $30-$50), clutch oil, clutch adjusting tools, 2-stroke engine oil (it's around $4.50 a quart at kart shops), extra brake pads, pipe mounts, axle clamps, air filters, fuel filters, spares, spares, spares. (If you don't have all this, you'll need it eventually, and $10 here and $20 there starts to add up real quickly.)
The price of buying a complete setup will vary dramatically depending on the condition of the kart and the amount of extras that are included.
Which Method is Better for You?
Only you can decide if building from a roller is a better deal than buying a complete setup. But consider these points before you decide:
Don't take lightly the time it takes to put a roller kart together. For example, if you have to mount new bodywork, it will take days and not just a few hours to finish that task. as almost any experienced karter will tell you.
Consider the time it takes to mount, for example, an exhaust system. Unless you start out in the piston port can class (where you simply bolt the muffler-with-header onto the motor), you're going to have to fabricate a method of mounting your exhaust system to the kart. What's your time worth? And the parts you'll have to buy?
Things to Look For When Buying Any Used Kart
The kart should be clean, neat, well-assembled and apparently well cared for. If it's dirty with cracked fiberglass and rust everywhere, shy away from it. If the seller doesn't care enough about it to keep it in good shape, why would you want to put your rear end in something that might fall apart at 100 mph? There are lots of karts for sale. Find a good one.
Inspect the frame closely for cracks or re-welding. A painted frame sometimes makes finding cracks more difficult than on an unpainted frame. A cracked frame that has been re-welded properly is more than likely okay, and not necessarily a reason to pass on an otherwise smart deal. Few kart frames won't have been cracked at some time or other. But look carefully for cracks around the spindles, rear axle bearing mounts, and especially around the engine mount tubes. Check seat mounts for cracking or broken welds also. Don't waste your time on a kart that has been hastily or badly repaired, or one with sloppy welding.
Check the frame for straightness by measuring the diagonals. For example, measure from the left front spindle, to the right rear axle bearing mount, then measure the other diagonal. They should be within 0.125-0.25 inches of each other. If the difference is greater than that, the frame is warped. Some warped or bent frames can be straightened, so don't pass up an otherwise good deal because of it, especially if it's not warped badly.
Roll the kart back and forth on pavement. It should roll freely and easily. Check the spindles and/or check the toe-in alignment. Spindles should look the same both left and right, and the spindle bearings should not be binding. Also, steering should be without binding.
Don't be turned off by an unpainted frame. Many karters don't paint their frames. First, unpainted frames make cracks easier to see; second, it takes longer to get a painted one from the factory; third, a painted frame is slightly heavier, and you'll find in karting that less weight is a good thing.
Some Pointers on Used Engines
There are an incredible number of variables to consider when looking for a used 2-stroke engine. The best advice is to ask around your local karting community about the seller and his/her engines. When in doubt, ask to take the motor to an independent motor builder for an appraisal. Most novices won't know enough about karting engines to make an informed decision about buying a used one, so you should definitely consult a knowledgeable engine builder when you're buying an expensive used motor. (On an inexpensive used motor, you can assume some parts are worn out.)
The Yamaha KT-100S 100cc kart motor is the most common 2-cycle in karting in the United States, and it is the type that most first-time enduro karters are likely to encounter. Here's what I'd consider when looking for a good used one.
Pistons, which start at 51.97 in a new Yamaha, are available for the Yamaha all the way to 52.75mm. Just about every time you have the engine rebuilt, a slightly larger piston will be fitted. (A rebuild includes honing the cylinder and fitting a new piston and various other small parts). Even after you've reached the largest piston size, if the rest of the engine is okay, you can simply buy a new cylinder (about $220) and start over. One knowledgeable kart shop owner and engine builder recommends not buying an engine whose piston is 52.50mm or larger, so when inspecting a used motor, be certain to ask for the current piston size. (It should be visible on the piston crown, and you can sometimes see it by taking out the spark plug and looking into the combustion chamber). Ask how many hours are on the top end and how many are on the bottom end.
Avoid cracked fins on either the head or the cylinder. Look closely at the TCI (electronic ignition module) to see if the mounting tangs are about to crack, which would mean you'd have to buy a new TCI, and they are $130). A TCI hold-down is an optional feature; if the engine you buy doesn't have one, add one yourself (they cost around $10).
The engine should come with a carburetor, and usually with the carburetor "cup" or filter (if not, add at least $7.50 for the filter and about $15 for the cup). If you buy the engine separately, you might get the 10-degree angle mount thrown in, but most often not. You'll have to buy one--another $33.
An often-overlooked, major deficiency in a used Yamaha is a worn crank, and replacing one is a major expense.
A top-end rebuild (new piston, ring, wrist pin, top-end bearing, hone and fit) costs around $125-$200. A bottom-end rebuild (disassemble the crank, fit new bearings and rod, reassemble), usually done in conjunction with a top-end rebuild, will cost around $320. Some karters do their own engine work, but most use the services of a professional engine builder.
Generally, the more you spend for an engine, the better the engine. For comparison purposes, a new, in-the-box Yamaha is around $650. Add $250-$350 for blueprinting (not always required and sometimes not even recommended until after the engine has been used). A proven, used, race-winning Yamaha can easily run $800-$1,000.
The Value of the Clutch
Beyond the engine, on an enduro, the clutch is the single most important item for generating fast track times, assuming you've got a straight kart that handles decently, and that you can actually drive competitively. Good used clutches are usually available in the $350-$450 price range.
While there are several clutch manufacturers, the most common clutches are Horstman and SMC. Both are wet, multi-plate, axle clutches. Both are good clutches that are simple to adjust and easy to maintain. The SMC is newer and generally commands a slightly higher price, both for new and used models.
As an identification guide, the body of the Horstman clutch is either dark blue or very dark maroon. The SMC is known by its shiny gold and aluminum finish. Both these manufacturers also make engine-mounted clutches for sprint karts.
In clutches, as in engines, a novice is pretty much at the mercy of the seller. But any buyer can still ask knowledgeable questions. Ask how often the oil was changed (the correct answer is at least after every race weekend, preferably after every 45-60 minutes of running time for enduros); what kind of oil was used (Horstman clutch oil, SMC clutch oil or automatic transmission fluid are all acceptable answers); and when was the clutch was last rebuilt. These clutches are usually bulletproof as long as you keep fresh oil in them at the proper level, and keep them adjusted properly.
The most common clutch maintenance, beyond changing oil, is changing the clutch springs (around $23-$30 a set). To change the clutch springs, you should take the clutch off the axle and disassemble the clutch. Replacing clutch springs is much easier than it sounds, although it can be time-consuming. After the springs, about the only item left to change is friction disks and floaters, and the bearings, and all of those generally last a long time.
If you can disassemble the clutch before buying, look for signs of excess heat, which will manifest itself in blued, almost scorched-looking floaters. Sometimes the floaters will be warped, so lay them on a flat surface to check. Inspect the bearings for any signs of heat stress. The bearings should be shiny and rotate freely without any sign of roughness; if not, they're due to be replaced. Check the pressure plate for flatness, scoring and heat stress. If you have an accurate micrometer, measure all the springs. They should be very close to the same height (within 0.003 inch). If you find signs of internal abuse, you might be able to buy the clutch for a song and merely replace all the internals: springs, floaters, friction discs and perhaps the pressure plate.
Wheels and Tires, Bearings and Brakes
Wheels should be free of cracks, obviously, but also free of hefty nicks, especially on the lips. One-piece wheels offer convenience while being more expensive initially and more expensive to replace. Two-piece wheels are somewhat of a pain to mount, and more apt to leak air, but less expensive to replace in the event of damage.
Unless the tires are new or almost new, plan on buying new tires (about $160 a set) with any used kart. The tires are good if the tread surface is soft and you can easily dig your fingernail into the rubber.
If you can feel roughness while spinning the front wheel/tire, you'll need to replace the bearings (not a big deal, nor actually expensive). Check rear bearings for roughness by spinning the axle with the belt or chain disconnected. If any roughness exists or if the axle spins slowly, you can plan on replacing the rear axle bearings (even easier than replacing front bearings, but $20 each and you'll need two; front bearings are $3.25 each and you'll need four). However, other possible causes of the rear axle spinning slowly are misaligned bearings (especially if bearing cassettes are not used), or a badly adjusted clutch.
While spinning the rear axle, also check visually for a bent rear axle. New axles start at around $55 and go much higher, depending on material and size.
Check brakes for air bubbles in the brake lines; they'll be visible when you apply the brakes. This is just a sign that you'll need to bleed the brakes. Check for ease of brake operation and whether both the fronts and rears will lock up the wheels when you apply the brakes. Check brake pads for wear (relatively easy to replace and not that expensive). Check master cylinder(s) for leaks (rebuild kits are $11 each). Check that the brake fluid is clean. Dirty, dark brake fluid is a sure sign the seller hasn't been caring for the brakes. Ask the seller what type of brake fluid he/she uses (DOT 5 is the most common in single-engine karting classes and costs around $11 a bottle). Don't mix brake fluids; always replace with the same type.
Large front disk brakes are highly desirable (and add higher value) although the small disks and small front drums are more than adequate. Some karters hold that a vented iron rear disk is an advantage, while others prefer unvented steel or iron disks for their different feel.
Other Elements to Inspect
Seats should be unbroken and firmly secured to the frame. Check the seat for comfort and fit, and if it doesn't fit, answer for yourself whether you will be able to modify or move it easily. Some seat mounts are adjustable and movable; others are welded into place. A floor pan that is not torn or dented is highly desirable, as it keeps the kart cleaner inside and adds a bit of aerodynamics. New floor pans can be made of sheet aluminum (use the old one as a template) or any type of flexible tear-resistant plastic. Whether aluminum or plastic, floor pan material is usually around $40 a sheet.
Check that fuel tanks are clean inside, with no residue from leftover fuel and oil, and that the fuel lines are flexible (they get hard with age but are cheap and easy to replace).
Check for a clean fuel filter (again, cheap and easy to replace).
Hopefully, even the roller kart will come with an engine mount. If not, you'll have to buy one; a new one can be surprisingly expensive.
Exhaust systems run the gamut from inexpensive to expensive. A piston port can exhaust is a header/exhaust in one piece, and it costs around $60 new. You simply bolt it to the engine. An open pipe class exhaust consists of header, flex, pipe and mounting system that will cost around $150-$175 new. Obviously, look for any used components to be in good order, free of rust, and well cared for. Shy away from exhausts that have large dents in them. If you're buying a pipe (as opposed to a PP Can muffler or a Sportsman can muffler), be sure to get the most recent version, or the version used by most pipe class karters at the track(s) you run. When buying used exhausts, bargain hard. Any price from free to $10-$20 is a fair price for most used pipes.
Bodywork should be straight and in good repair. It is not unusual for bodywork to have been patched (some forms of karting qualify as a contact sport!) or re-glassed. Bad bodywork shouldn't be a deal-breaker but can serve as a major negotiating point. You can always hang new bodywork for about $250 plus your own labor.
Both sprint and enduro karts must have nerf bars on the sides, or else full-length metal tanks (enduro) for protecting the driver from side impact. Karts must also have a front and a rear bumper.
Some Final Things to Consider
When buying, negotiate for all the extras you can get the seller to part with. If the seller is getting out of karting, there's a strong incentive on his/her part to get rid of it all at once. Offer to write one check for everything. You avoid the hassle of having to round up all the stuff that you're going to need, and the seller avoids the hassle of getting rid of stuff with a fairly limited market over a longer period of time.
The most crucial extras would be: a second or even third motor; a starter ($150); push stick ($35); kart stand (about $35 new); extra drivers ($20 used, lots more new); gears (around $15-$20 used, $30-$50 new, and you'll need several sets); fuel jug ($15); and extra wheels and tires (about $250 a set).
If the seller is indeed getting out of karting, ask if they kept a notebook of track setups and results. For example, I've kept a notebook that has the gearing, track conditions, air density, temperature, number of entries in the classes I raced, all lap times, and my finishing position for every track I've been to. Such information is of no use to the seller if he or she is getting out of karting, but that little notebook can be a gold mine for the novice karter. If the seller kept such a notebook, ask if they'll throw it in with the sale. Last but not least, if you're a novice karter, try to make part of the deal that the seller will accompany you to the track for your first weekend and provide technical and wrenching support. That first weekend is hectic and confusing enough for almost all novices; having someone who knows what's happening, how to tune and adjust for conditions, set up the kart, and provide a sympathetic ear for your failures (yes, there will be failures) will make karting a whole lot more enjoyable. That sort of help is worth a fortune to you. To the seller, it's a way for him/her to give something back to the sport by helping another novice get started. It also might just be what helps him or her sell the kart.
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