Pro Jet Sports

Product Support and Technical Information

 

Tuning Tips:

BASIC SPARK PLUG READING
Reading your spark plugs is the primary method for determining what is happening inside your engine. Acceleration, top end performance, and engine life can all be affected by an over rich or lean condition, but how can you tell what's happening? The answer is inside your cylinders, and the only way to know what's going on inside them is to sneak a peak while they're running but you gotta be quick! The easy way is to run the engine to operating temperature and get a hard run and shut the motor down right away. If this is not practical, just avoid checking the plugs after a canal or no wake zone cruise since engines tend to run rich on idle and fouling is most common in these conditions. What follows is a simple and basic explanation for analyzing the condition of your plugs to help you understand your engines state of tune and make the proper adjustments to optimize performance.
Normal Plugs
    Observed Condition: Gray to light "chocolate" brown in color
    Causation:
  • Ideal condition which indicates the engine is burning efficiently with little carbon buildup
  • It should be your goal to achieve this condition for your plugs
  • It is difficult to obtain this perfect condition so don't be frustrated by your first few attempts, this is a trial and error process
Dry Fouling
    Observed Condition: Dry, black, sooty buildup
    Causation:
  • Air/fuel mixture is too rich indicating carburetor settings are incorrect
  • Flame arrester is dirty or may have mounting problems
  • Spark plug heat range is too "cold" for operating conditions
  • Ignition system problems such as weak spark or intermittent spark
    Method of correction:
  • Adjust carb screws inward slightly one screw at a time(lean out) until condition improves-in case of multiple carbs make identical adjustments to each carb
  • Check mounting of flame arrester
  • Clean or replace flame arrester
  • Change to higher heat range plugs
  • Check ignition system, plug wires, and caps
Wet Fouling
    Observed Condition: Shiny, wet, black sooty condition
    Causation:
  • Excessive use of the choke
  • Prolonged low rpm's (idle or no wake zones)
  • Fuel to oil ratio is wrong (too much oil)
    Method of correction:
  • Check choke to insure proper operation
  • Reduce use of choke
  • Reduce amount of channel or no wake zone riding (if possible)
  • Avoid prolonged idling
  • Reduce the amount of oil used in premix (seek advice on minimum amount necessary)
  • Change the brand of oil
  • Check operation of oil injection pump
  • Convert to variable rate injection pump (PJS makes kits for this)
Deposit Fouling
    Observed Condition: Excessive deposits, ie; bumpy, chalky buildup
    Causation:
  • Poor fuel quality
  • Water in fuel
  • Oil leakage into combustion chamber
  • Oil weight is too low
  • Oil type is incorrect for injector pump
    Method of correction:
  • Drain fuel system and use fresh fuel
  • Try fuel additive to remove moisture
  • Check oil system for leakage or other problems
  • Refer to factory specifications for oil weights and type
Overheating
    Observed Condition: White, blistered or melted electrode
    Causation:
  • Spark plug heat range is too high for engine operation
  • Plug is not properly gapped
  • Plug not properly torqued into head
  • Timing advanced too far
  • Carb settings are too lean
  • Air leaking into intake tract
    Method of correction:
  • Change to lower heat range spark plug
  • Check for proper gap and adjust
  • Check plug torque for tightness
  • Check timing (refer to factory manual or professional mechanic)
  • Adjust carb mixture screws slightly and check results (in case of multiple carbs, make identical adjustments to each carb)
  • Perform a leak-down test or similar method to test for leaks in intake system

Please note that these are only general suggestions and other variables will affect tuning and performance. Trained professionals should be referred to often and especially when you aren't sure you're making the right choice. Don't be afraid to spend a few buck at a dealership, a few bucks spent there could save you hundreds later. Also, many good books are available to assist you in maintaining your ski including factory maintenance manuals and these should be part of your toolbox and maintenance routine.

 


Product Updates:


Carb Adjusting Tool
Our new Carburetor Adjusting Tool has been improved! We've widened up the tip to reduce the chance of vibrating out of the screw slot during tuning. We still use the same high quality components, brass gears, and billet construction so check it out on our tools page!
 


Helpful Hints and Suggestions:


Hint #1. Before venturing off anywhere whether it's recreation or race day, the primary rule is to always be prepared. You don't know how many bad days could have been prevented by little advance planning and preparation. We've compiled a short list of suggestions for beginners and professionals alike to help you avoid the worst case scenario...
  • Before you leave, go over your boat with a fine tooth comb looking for the obvious
  • Check all electrical connections for corrosion
  • Lubricate electrical connections with a dielectric grease or jelly
  • Check all hoses and clamps for cracks, rubbing, bubbles, or soft spots (internal blisters)
  • Check all hose clamps for tightness and for cracks
  • Check all steering bolts and fasteners
  • Check all pump and nozzle mounting bolts
  • If you can, a good test ride before a long trip is a good way to insure a successful return

Pack your toolbox carefully and include the following:
  • Screwdriver set
  • Metric open end wrench set or adjustable wrench (crescent wrench)
  • Metric allen wrench set
  • Spark plug wrench or socket
  • Spare hose clamps
  • Spare fuel and water hose (18 inch pcs.)
  • Spare gaskets and engine parts
  • Zip ties
  • Spare spark plugs
  • Extra nuts and bolts in 6, 8, and 10 mm sizes
  • Grease or grease gun
  • WD-40 (works well as a starting fluid)
  • Rags
  • Funnel
  • Ratio rite

This is only a partial list and your suggestions are welcomed. Remember, you may be saving someone else's vacation by being prepared. If you see someone if need of assistance, offer what you can. Supporting the sport also means supporting your fellow riders. If you have ideas on what may be needed please send us your suggestions.


Hint #2. After a day or weekend of riding, most folks aren't aware of the water which stays trapped inside your exhaust system and other parts of the engine. Water is circulated through the engine and exhaust system for cooling. After the ski is removed from the lake and transported, water stays trapped in passage ways and can move around inside the exhaust system. This trapped water eventually evaporates into the cylinders and engine compartment causing rust and corrosion on unprotected surfaces like your cylinders. The damage can be severe or even cause a siezure. To prevent this problem, flush the water out by starting the engine for about 1 minute, after removal from the water and during prolonged storage. Run the engine just long enough to warm the cylinders so they're warm to the touch, but not hot. "Snap" the throttle a few times to rev up the engine but don't hold it wide open. The increased rpm's and exhaust pressure will force the trapped water out of the system gradually, and the warming will help dry what is left. As you prepare to shut off the engine, rev it up one last time then pull the lanyard (or press the off button) and pull the throttle full open as the engine slows down. This will coat the cylinders with fresh fuel and oil to help lubricate the cylinders. In the event you can't start the engine to blow out the water, use a marine type "fogger" or lubricating spray to spray into the cylinders and over the engine to prevent rust from damaging these surfaces. Always leave the engine compartment at least slightly open or the seat or hood off altogether to allow trapped water to escape and the compartment to dry up completely. This process can save you the cost of a rebuilt engine so take heed!