Thumpstar 125cc Dirt Bike
The all-new Thumpstar range is making big waves in the pit bike world, pushing the boundaries for what a pit bike should be (small), the 2021 range all come with 17/14 wheels and a seat height of 88cm, The Thumpstar is for the pit bike rider who wants the feel of a bigger bike.
Specification subject to change.
- Engine: Lifan 125, oil-cooled
- Carb: 22mm Carb
- Gearbox: N1234 all up gearbox
- Frame: Exclusive race engineered 3 beam with cradle and perimeter mounting of the engine
- Forks: New 790mm upside-down forks
- Shock: New 325mm 1000lbs rear shock
- Wheels: 17/14″ wheels with MX Innova pattern tyres
- Brakes: TWIN pot front and single pot rear hydraulic brakes
- Chain/sprockets: KMC 428 pitch chain 41 tooth rear sprocket 15t front sprocket wrap around chain sliders
- Bars: Pro taper style fat bar
- Grips: Soft black bar grips
- Seat: Gripper seat
- Levers: Fold back Levers
- Kick Start: MX kick start
- Seat height: 88cm seat height
- Weight limit: 15 stone
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Stomp Build | Warranty
You have chosen wisely, the Pit Bike / Kayo Quad Bike you have bought in order that you will enjoy your machine to the full.
Your bike has been supplied in a crate. This is NOT the same as buying a bike fully PDI’d (Pre Delivery Inspection) bike from a dealer. It is entirely your responsibility to ensure a qualified motorcycle mechanic puts your bike together correctly. Failure to do so will invalidate the warranty supplied with your bike.
In order to qualify for this warranty you must fill in the supplied Proof Of Purchase, PDI & Warranty & post it to the supplied address. in your user manual
GUIDE FOR STOMP BIKE ASSEMBLY
This document is supplied only as a guide to a professional and may not be exhaustive. Each machine may require individual attention & therefore ONLY qualified persons should only carry out the following:
- Remove Bike & all accessories from crate & inspect to ensure all necessary parts have been supplied correctly
- Mount shock (where applicable)
- Tighten lower fork bolt, reached from underside of forks.
- Mount front wheel & ensure free rotation – check for potential bearing &/or brake drag Ensure all frame bolts are tight (use thread lock compound where necessary) – use locking wheel nut (supplied)
- Check spokes and tighten if necessary
- Loosen triple clamps around fork legs & set desired fork height. Use copper grease on triple clamp bolts to prevent damage to the alloy threads & then firmly tighten
- Fit handlebars and clutch cable to clutch lever
- Pump front brake lever until firm (bleed if necessary). Check front braking system for potential leaks or damage by pulling brake lever very hard several times. Visually inspect all joints for leaks & remedy where necessary. Spin wheel to ensure calliper is releasing from disk
- Fit rear brake pedal where necessary & repeat procedure described for front brake
- Check fluid levels, top up with DOT4 where necessary
- Fit front mudguard using thread locking compound where required
- Fit foot pegs
- Loosen rear wheel & adjust chain tension. Find tightest point in chain by spinning rear wheel, there should 15mm up & 15mm down at the longest section of chain with rider sat on bike. Ensure chain runs true & is on top of chain roller. Ensure chain does not foul on rear chain guide (use shims/washer to space if necessary)
- Working from front to rear, ensure all nuts & bolts are tight. Where no nyloc nuts or spring washers are present, ensure thread-locking compound has been used. If none has been used during factory assembly, remove nut or bolt, apply locking compound & re-tighten. Pay particular attention to the following critical safety areas: Wheel nuts, brake calliper bolts (thread lock), Top & rear engine bolts (frame must be hard tight against the engine, use thread lock), chain tensioners, rear shock bolts, triple clamp bolts (yokes), Handlebars, brake/ clutch/throttle, swing-arm, front & rear sprocket
- Check all engine hardware is tight, (including but not exclusive): flywheel, inlet manifold, exhaust bolts,
- Remove Transit Oil and Replace with a quality Motorcycle 10w40 such as Putoline DX4 semi synthetic 10w 40 4-stroke engine oil
Adjust tappets. Set engine to TDC (ONLY rotate engine anticlockwise) & check cam timing alignment (cam sprocket/cylinder head – adjust is necessary), remove tappet covers & adjust tappet clearances : inlet ~0.15mm - exhaust ~0.20mm
- Fully ensure nothing is touching the exhaust system. On oil cooled models, ensure the oil cooler pipes do not touch the exhaust manifold
- that the heat protection springs are located on the correct part of the pipe in order that should they touch the exhaust the heat will not damage them.
- Ensure all cables pipes & wiring are away from moving components such as the wheels, use cable ties where necessary Carb –SS140 – set needle height on second notch from bottom for UK conditions. 110/125/150 engines normally do not need adjustment
- Fuel bike & check for fuel leaks
Check oil level with bike in upright position using dipstick. Top up with 10W 40 semi synthetic oil, if necessary
- Adjust tension for both clutch & throttle cables
- Ensure wheel spokes are tight & wheels run true
- Start engine & warm up (using choke if necessary). Set idle speed so engine ticks over comfortably without stalling or racing
(bearing in mind that the pads will need to bed in prior to optimum performance)
1 HOUR SERVICE
- Drain oil & replace with Putoline DX4 semi synthetic 10w 40 4-stroke engine oil
- Check all nuts & bolts & tighten where necessary (use PDI data as reference)
- Check flywheel nut
- Check wheel spokes (especially rear wheel drive side) & tighten where necessary
- Re-Adjust throttle cable & clutch cable if required
- Re-tension chain
- Check wheel bearings for any sign of wear of free-play
- Check brake calliper operation & brake pad wear
- Check spark plug gap ~0.6mm-0.7mm
- Check tyre pressures
RIDING TIPS FOR LONG ENGINE LIFE - IMPORTANT
- Do not over rev your engine as you may cause damage to valves. This is particularly applicable where an inner rotor kit is used. Under load the engine is capable of revving into major valve bounce that can cause permanent damage to your engine. If you feel the power dropping every 10 hours use.
- Do not stamp through the gears – always use the clutch.
- If you miss a gear do NOT stamp into gear from high engine revs.
- Do not drop your clutch heavily, or slip it unnecessarily.
- Do not allow your air filter to fill with fuel – this can occur by incorrect float height setting – see above, or the bike falling onto its side.
- If the engine back-fires while the air filter is filled with fuel, it may ignite – check air filter regularly while riding.
STOMP PROBLEM SOLVING
- Exhaust Glows Red (fast tick over) – Carburetion too lean, richen mixture via raising needle
- Engine misfires at mid to high engine speed, open throttle – Mixture too rich, drop needle
- Engine Pops & bangs on over-run – mixture too rich, drop needle
- Engine kicks back hard whilst starting – Ignition too advanced, or mixture too lean
- Weak Spark – Pick-up coils too far from rotor (where inner rotor kit fitted) or bad earth
- No spark – Either poor earth or faulty Rotor Coils/CDI/Coil/Lead/Cap/Plug – use moving coil multimeter to diagnose
- Fuel leaks from overflow – Floats set incorrectly or blocked by debris or sticking
- Engine runs fine, but then starts to misfire – faulty rotor coils/CDI/Coil/Plug
- Rattles from engine – Tappets set incorrectly
- Engine will not tick over when warm – tappets set incorrectly
- Engine will not return to idle & races – sticking throttle cable
STOMP CORRECT JETTING
Take out the spark plug and check the electrode; the colour should be golden brown. If it is white, the engine is running too lean (not enough fuel). If it is black (sooty colour) it is too rich (too much fuel). If it is white & black, the engine is VERY lean & causing misfire, which you should be able to detect whilst riding. As your jets are close to what they should be for the UK, minor alterations can be made by
To add more fuel, raise the needle one notch. This is achieved by removing the carb from the engine, removing the throttle slide, removing the needle & adjusting the position of the circlip. Conversely, if you need to reduce the amount of fuel, drop the needle one notch. Re-assemble the carb & continue testing, remembering to check the colour of your spark plug.
Once you have achieved the correct full load fuelling, you can set the idle mixture screw. The 140 & 150 engines like to run very rich at idle, this way you get a clean progression from idle jet to main jet. To achieve a richer mixture, turn the air screw (next to filter) clockwise. Idle speed may need to be adjusted at same time to keep engine running.
- It is advisable to fully service and lubricate the bike prior to leaving the bike unused/unattended for any length of time.
- It is advisable to fully drain the tank and carb of fuel prior to leaving the bike unused/unattended for any length of time.