There are some things that cost riders, or parents alot of money, 1. dirt passing into the engine. 2. water passing into the engine. 3. Forgetting to change the transmission oil. 4. Items coming loose.
Water and or Dirt will destr0y inside the modern 2 stroke. Past the air filter, into the CRANKCASE, cranksgaft, bearings, then into the cylinder and piston area. Airfilters, claen and reoil but also double check fitted and sealed back in place.
Over pressure washing- water in the carby? water in the transmission? water in electrical connectors? Always cover the sparkplug when washing, ( cable tie on plug connector is great too) use a air filter cover too. Dont over wash with high pressure, just enough and stop.
Dirt track bikes vibrate alot, things come loose, keep rechecking.
Chains- dry or wet ? If you clean your chain , get dirt off , then lube it, it will last longer, less friction, faster bike! WD40 first, as it will soak in , then a thicker lube on the out side works well.
Clutch adjustment- cable type or hydraulic, it must have FREEPLAY or it will get hot and burn out.
The small auto clutches KTM sx50 – you really need a Tacho to check the engagement speed, remembering if the slip speed drops, they are very hard to tune, many dads spend hours with bog,s and hesitation, only later to find its clutch speed.
Mod engines, pipes heads etc- When learning, there is no point really! Until the rider is flat out, no power increase will help anyway! More time riding is all thats needed, until there reving it flat out.
Buy in BULK- engine oil, transmission oil, brake fluid, carby cleaner, chain lube, brake cleaner, air cleaner oil and washes. Some cheap brands are available from auto shops.
Parents- riding/racing bikes starts is FUN. If you have a Champion in your family , your rider will prove to you how they are a Champion. If your rider is not ever to be a Champion, well this is still a wonderfull sport to do. Most young people who ride or race, learn skills that help them in all parts of their life, sometimes much later in life. Sometimes, working on bikes, travelling, camping , the social side is fantasic. The coaching events available , to gain skills not only in riding/racing, but other skills needed like food, exercise, education etc are fantasic. If your rider doesnt become a Champion, chances are he will meet a Champion and become friends with him, life long friends. Its a wonderfull sport and you will enjoy the ride. The kids grow FAST, i hope you enjoy the time in the sport.
The 2023 model , the first KTM 125 using fuel injection has arrived. The Efi system has been on other size engines for years and works quite well. Inside the engine has not changed very much at all. On the Dyno, compared to the older carby version 2022 , the 2023 doesnt rev as hard, so basically the midrange power has increased a small amount, but the top end power has been reduced, as well as the top end revs. A better exhaust chamber, better cylinder head and a better ignition map will give good power gains, as well as modified fueling maps. The 2024 and 2025 will only get better.
Synthetic 2 stroke engine oils are today the best oils . All lubricate very well. Some do not burn as well and leave exhaust deposits, some are very clean and have little deposits or smoke. Penrite full ester synthetic , Silkolene comp 2 are great oils for slower riders learning, as they are clean. Smaller engines with low volume crankcases now are using 60 to 1 ratio, and this works very well. Caster synthetic type oil smells great, lubricates well, but is quite dirty inside the engine, dirty,sticky exhaust deposits, not ideal for powervalve engines, and the oil can separate from the fuel in the fuel tank and carby, if not used with in 2-3 weeks. The fuel oil goes stale very quickly. Will one oil make the difference of winning or loosing a race? Using Caster, take care to regularly clean fuel and exhaust and inside engine parts, and drain and use fresh fuel and oil.
Over the years most manufacturers have made lots of improvements to Cylinder port shapes. Most cylinders can actually flow worse, if you grind /polish the area,s from under the cylinder. If you take material away, you may decrease bottom to mid power, as this effects the primary compression ratio. This can be corrected with case stuffing. Without a good small Dyno, you may not realise whats happened. The curves in the transfer ports have now a more tighter curve, increasing the slug volume speed into the cylinder, KTM have pioneered this design which works really well, and yet the ports look small! High air speed is gained. Most surface finnishes on modern cylinders cannot be changed, to gain power. Even the exhaust expansion chamber inlet is now smaller than ever, on late model pipes, keeping air speed high. However, there is still work that can be done, port windows, chrome rough edges, and the whole exhaust port can be changed that yields good power improvements over most of the rev range. Cutting through the chrome is tricky, most engine porters now using some lubrication/cooling method, so as the chrome plating is not being effected by heat and vibration. Dyno testing with many cylinder port shapes, sizes, heights etc is done to make sure the power is gained. So before you grab that file, or porting tool, call and have a chat, we can hopefully save you some time.
Some engines 85cc 125cc 150cc 250cc need to use more stronger/robust type spark plugs.
If the engine has higher internal pressures, excessive crankcase stuffing, too high compression ratios, incorrect crankshaft balance factor, Detonation, engine frequency type vibrations/pulses can harden and weaken the earth electrode and it will FALL OFF causing expensive damage. Always try to use a ECM type spark plug. Meaning NGK BR9ECM or BR9ECMIX IX is just a fine wire iridium type . The IX lasts longer if it stays clean, less energy is used to fire the spark from the coil. The std type plug BR9ECM can be better for slower riders, as it keeps firing even if dirty.
Some modern engines are already made high performance from the factory and pressures are really high and they need better spark plugs. Some 85cc and most larger 2 strokes will need these plugs. part number NGK R6918B-9 is one of the best choices. $60.00 each. Replaces BR9EIX or BR9EG or BR9EV or BR9ES etc. ( 9 ) is the heat range ,so you can buy 8,9,10 heat ranges normally. Detonation is normally the cause of sparkplug earth electrodes breaking off, high compression presures and internation high frequency vibrations.
Be careful, if the bike comes from the factory with a R6918 type plug,(like the current model Suzuki RM125) dont put a cheaper plug in as you will reduce performance and damage the engine.
In winter you always need to increase fuel supply. Approximately 5% richer.
Balance factor is different from sizes of engines. Change of the factor will change the power curve.
The new VP Roo Fueld makes combusion and mixing temperatures cooler. Good for 2 strokes! Must change jetting approx 6% richer. Best to increase compression too. Good for 4 strokes too.
Note: Race Fuel Above 100 – No point using it. Fuel testing will be done at Australian and FIM Wold Championships.
The benefits you can achieve by having components treated include:
HGS Exhaust. VHM Cylinder Head. 185-190 main jet. Ignition timing 1.1mm BTDC.