Kart carburettors: how to choose, and what 17 UK shops charge
We compared 1116 kart carburettors listings across 17 UK shops. The typical cheapest price is £9.00, and the same part number can cost up to 38% more depending on where you buy it.
UK edition2026-11-015 min readData: PitHunt weekly scan
Key takeaways
- 17 UK shops list 1116 parts in this category; 55 part numbers are stocked by more than one shop.
- The typical cheapest price is £9.00; a tenth of parts cost £1.19 or less, a tenth £130.00 or more.
- Biggest gap for one part number: £91.70 on Iame HW-31A Mini Swift Carburetor.
- KKC Kart Components had the lowest listed price most often — 36 of the 55 part numbers stocked by several shops.
- Shops
- 17
- Listings
- 1116
- Typical cheapest
- £9.00
- Biggest gap
- £91.70
- 38% on one part
What a carburettors does
The carburettor mixes fuel into the air the engine breathes. On a kart it is also a controlled part: most classes name the exact carburettor for the engine, and what you may adjust on it is written in the regulations. Buying one is less about choice than about getting the right, legal unit and keeping it in tune.
Two families run karting. A float-bowl carburettor keeps a reservoir of fuel at a set level and meters it through jets and a tapered needle on the throttle slide; the Rotax MAX's Dell'Orto VHSB 34 and the KZ engines' VHSH 30 work this way. A diaphragm carburettor has no bowl: pressure pulses from the crankcase pump the fuel and a diaphragm meters it, which is why it works at any angle; the Tillotson HW-27A on the IAME X30 and the HW-33A on the KA100 are diaphragm units with two external adjusting needles. Four-stroke club engines mostly use a simple float carburettor fed by a separate pulse pump.
How to choose
1 · The engine and the rulebook
The carburettor is specified per engine, and in sealed classes the markings are checked.
How to judge it: Buy the unit named for the engine: Dell'Orto VHSB 34 for Rotax MAX, Tillotson HW-27A for X30, HW-33A for KA100, Dell'Orto VHSH 30 for the Vortex Rok, Walbro WB3A for the Yamaha KT100. For Rotax, the housing must carry the cast wording VHSB 34 and the stamp XS, with a cast inlet bore, and the two vent fittings must be joined by the original hose of at least 155 mm.
2 · Complete carb, or parts
A used carb with worn needle and atomiser will never jet right; a rebuild kit is cheap by comparison.
How to judge it: If the body, slide and threads are good, a gasket and diaphragm kit restores it. Comet's guidance is a rebuild at least once every 5 hours of running, and a new kit after any winter with fuel left inside.
3 · Setting it up
A carburettor arrives at a baseline, not at your track.
How to judge it: On the Rotax, the standard clip position is 3 of 5 and the air screw 2 turns out from closed, with the main jet chosen for the day's air using Rotax's app, which assumes ROZ 95 fuel. On diaphragm carbs, adjust the two needles in 1/16-turn steps: the needle nearest the engine for idle and pickup, the one furthest away for full throttle.
Compatibility. Sealed-class carburettors are part of the homologated engine: markings, floats, needle valve and jets are listed in the regulations, every jet must be correctly seated and tightened, and the competitor — not the builder — is excluded for a non-conforming part. Check the current year's regulation before buying anything that is not the genuine item.
Types, and the trade-offs
| Type | For | Against | Best for |
|---|---|---|---|
| Float-bowl (Dell'Orto VHSB 34, VHSH 30) | Precise, tuneable with jets and clip, stable fuel level. | Must sit level; a kart stored upright with fuel in the bowl lets fuel into the engine. | Rotax MAX and KZ classes, as specified. |
| Diaphragm (Tillotson HW-27A, HW-33A) | No bowl, works at any angle, two external needles. | Diaphragms and pop-off need regular checking; sensitive to pulse-hole alignment. | IAME X30, KA100 and similar two-strokes. |
| Four-stroke float carb with pulse pump | Simple and cheap. | Fixed jets, so changes happen in the pits, not on the screw. | Club four-stroke classes. |
- Main jet
- The fixed orifice that sets fuelling at full throttle; changed for weather, not driving style.
- Matters when: Every session: hot, humid or low-pressure air carries less oxygen and wants a smaller jet. Any minimum jet size in an event bulletin applies.
- Needle and clip
- The tapered needle meters part-throttle fuel; five grooves move it — groove 1 leanest, groove 5 richest.
- Matters when: Hesitation or bogging between a quarter and three-quarters throttle.
- Float height
- The fuel level in the bowl, set by the float arms. On the VHSB 34 both arms must sit inside the Rotax 277400 gauge with the carb inverted and the bowl gasket off.
- Matters when: After any rebuild, and whenever fuel runs from the overflow or the engine cuts out in long corners.
- Air screw
- Trims the first quarter of the throttle. On the VHSB 34 it is upstream, so turning it in richens, the opposite of a fuel screw.
- Matters when: Idle and pickup off the corner.
What it costs across UK shops
£1.19
a tenth cost this or less
£9.00
typical
£130.00
a tenth cost this or more
| Part | Cheapest | Range | Dearest | Gap |
|---|---|---|---|---|
| Iame HW-31A Mini Swift Carburetor cheapest at KKC Kart Components · 2 shops | £243.30 | £335.00 | £91.7038% | |
| Kart Genie Measured Rotax Carburettor Jets In Senzo Box cheapest at KKC Kart Components · 2 shops | £150.00 | £211.95 | £61.9541% | |
| OTK BWZ Brake Pump 16mm cheapest at ZipNorth · 2 shops | £289.47 | £335.95 | £46.4816% | |
| OTK BWD Brake Pump 13mm cheapest at ZipNorth · 2 shops | £245.61 | £284.95 | £39.3416% | |
| OTK Brake pump Complete cheapest at ZipNorth · 2 shops | £210.53 | £244.95 | £34.4216% | |
| Rotax Max Retrofit Kit Fuel Pump 281341 Genuine cheapest at KKC Kart Components · 2 shops | £78.33 | £110.95 | £32.6242% | |
| OTK Brake pump Complete BSM cheapest at ZipNorth · 2 shops | £168.42 | £195.95 | £27.5316% | |
| Fuel Pump / Rotax Dellorto Kit With Mount cheapest at KKC Kart Components · 3 shops | £42.92 | £60.95 | £18.0342% | |
| EM Radiator Support Kit for EM-01 (EM-05) cheapest at KKC Kart Components · 2 shops | £88.95 | £105.00 | £16.0518% | |
| Rotax Max Dellorto Carb Jet Driver & Storage Tool cheapest at ZipNorth · 3 shops | £18.00 | £33.00 | £15.0083% |
Same part number at every shop in the row. Parts listed at £10.00 or more; ranked by the gap in money, not percent.
Cheapest most often
Of the 55 part numbers stocked by more than one shop — a count of wins, not a verdict.
- KKC Kart Components36 of 55
- ZipNorth13 of 55
- LMR Kart Store4 of 55
- Next Karting1 of 55
- Precision Kart1 of 55
What this covers
This is a snapshot of kart carburettors as listed by UK kart shops on 2026-11-01. PitHunt indexed 1116 listings from 17 shops, covering 1045 distinct part numbers. Of those, 55 are stocked by more than one shop, which is where a price comparison means something: the same manufacturer part number, different tills.
Prices are the shops' own listed prices in their own currency, captured by PitHunt's weekly scan. They are not quotes, they move, and the cheapest shop for one part is not the cheapest for every part. Each one links to the shop's own page so you can check before you buy.
The price range
Taking the cheapest listing for each part number, a tenth of them cost £1.19 or less, the middle of the range sits at £9.00, and a tenth cost £130.00 or more. The spread is wide because the category mixes small hardware with complete components, so the useful comparison is always like for like — the same part number across shops.
The widest gaps for the same part
The comparison ranks part numbers by the difference between shops in money, among parts listed at £10.00 or more — a big percentage on a tiny part is arithmetic, not a saving.
The largest gap in money is on Iame HW-31A Mini Swift Carburetor: £243.30 at KKC Kart Components against £335.00 at the dearest of its two shops — £91.70, or 38%, for the same part number. The full list is in the comparison table above, ranked the same way.
A gap like that is not a judgement on either shop. Listed prices reflect stock bought at different times, different suppliers, and whether a shop is clearing a line. What it tells you is simply that for this part number, on this date, checking a second shop was worth the minute it took.
Which shops were cheapest most often
Across the 55 part numbers stocked by more than one shop, KKC Kart Components had the lowest listed price for 36 of them, followed by ZipNorth with 13. That is a count of wins, not a verdict: a shop that is cheapest on the parts you actually need matters more than one that is cheapest on average.
The honest way to use this is the boring way. Find your exact part number, look at every shop that lists it, and let the number decide. Name the part, and PitHunt lines every shop up cheapest-first.
Before you buy — the checklist
Buying used, check
- ☐Rotax: VHSB 34 cast on the body and XS stamped, cast inlet bore, vent hose present; refuse one that has been drilled or polished.
- ☐Slide closes fully with no rock; threads for the main jet and bowl screws undamaged; floats not fuel-logged.
- ☐Ask for the rebuild history; budget for a gasket and diaphragm kit regardless.
Mistakes to avoid
- ✕Buying a bigger carburettor for more power; it kills throttle response and tuning stability, and is illegal in a specified class.
- ✕Skipping rebuilds because the carb looks clean — diaphragms and seals age regardless.
- ✕Storing a kart with fuel left in the carburettor over winter, or transporting it upright with a full bowl.
- ✕Trusting a numeric jet from a forum: use the maker's app for the day and confirm with a full-throttle pull and a plug reading.
Questions
›What main jet should I run?
The one the maker's app gives for today's air, confirmed on track: pulls to the limiter on a tan plug is right; four-stroking or a black plug is rich, go one size smaller; detonation or a white plug is lean, go one size bigger now.
›Fuel pours out of the overflow after a rebuild — why?
The bowl is overfilling: floats trapped under the needle arm, fuel-logged floats, or a needle valve not seating. Check the float height with the gauge before starting it again.
›Can I adjust anything on a sealed-class carb?
Under the 2026 Rotax regulations the idle and idle-air screws and the needle clip position are free; the parts and their markings are not.
›Where do these prices come from?
From the shops' own websites, collected by PitHunt's weekly scan of UK kart retailers. Each figure is the price the shop listed on the date above, in the shop's own currency, before delivery.
›Why would the same part cost more at one shop?
Stock bought at different times, different supplier terms, and clearance decisions. None of that is visible from the price alone, which is why comparing the same part number across shops is the only fair comparison.
Sources for the buying advice
- Comet Kart Sales — kart carburetor basics: matching, tuning and maintaining
- Rotax Racing — MAX jetting app (baseline clip and air screw)
- Angri Racing — the Dell'Orto carburettor
- Global Rotax MAX Challenge Technical Regulation 2026 (PDF)
- Rotax MAX Technical Regulations 2026, UK edition v2 — JAG Rotax (PDF)
Reviewed 2026-10-28. Buying advice comes only from these sources; prices come only from PitHunt’s own scan.
How this was built
Every number on this page was computed from PitHunt’s weekly scan of kart shops’ own listed prices, in the shop’s own currency, captured on 2026-11-01. The text was then checked against that data: any figure not in it fails the article. Prices move after we scan them, and exclude delivery — always confirm on the shop’s page.