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.
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.
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.
Large expansion chamber type. Short or long silencer. Excellent for mod engines.
Some pistons on the compression side do not have a wear band-ring. You can order one from the rebound side and machine the piston to fit it so you have smoothness on compression (as it should be). Common SX65. Shivers have this as standard.
Note: Only use Mazzoochi Seals (a lot less drag).
Many different production types. Example: KTM Vertex is not the same piston as Vertex after-market type. Check weights!
This Italian company is spending more time and money making and testing Exhausts than others. Some of the 2 stroke systems add a lot of power. After installing a Scalvini on a SX85, the engine feels like it has had large modifications made. Exceptional results from only one item. Some pipes are hard to fit (SX65).