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December 2015-

Question: Why am I having so many issues with the pump gas I buy today?

The biggest reason that most ATV users are having issues with today's pump gas is the addition of ethanol. The EPA has issued mandates on gasoline to include various percentages of ethanol in an effort to lower emissions and decrease smog- This is great for autos and trucks manufactured to work with this fuel. But not the best idea for people with small engine like ATV's, motorcycles,
farm/lawn equipment etc.
Most of the gasoline now sold has some ethanol in it, but the exact amount varies by region. In general, ethanol will not exceed 10% by volume. Gasoline with 10% ethanol content by volume is known as E10, and with 15% ethanol is known as E15. E85 is 85% ethanol and 15% gasoline.

Pump fuel enriched with Ethanol, causes a number of issues :( including but not limited to the following)
The biggest issue that the ethanol blended gasoline causes is corrosion.
Ethanol blended gasoline also does not burn as consistently as race gas or pump fuel made a decade or 2 earlier, causing damage to engine parts when it misfires.
Results from the use of ethanol, can cause rust and carbon deposits inside the engine, dissolve plastic parts and more

What can be done to help off set the problems caused by Ethanol in fuel.

1. Use race gas. Though not the most economical option, using a high quality race fuel like VP Fuels or Sonoco will alleviate all the fore mentioned issues.
* See RACE FUEL- General Information TECH Document HERE on DRI website www.duncanracing.com 

2. Use a quality fuel stabilizer- The is not a cure but will substantially help

3. Drain ethanol fuel from carburetor daily. Corrosion can set in over night. Most carburetors have a drain on the float bowl.
* Refer to owner’s manual for instructions on draining the fuel.

4. Store your machine dry. Turn fuel off and run machine (at idle) until engine stops. Drain any residual fuel from carburetor, drain tank.
Draining the tank and carburetor after using Ethanol can cause some additional issues, O-rings in carburetor, petcock etc. can dry out, crack and fail prematurely.
A viable option to storing it dry is to store with a quality race fuel. The high quality of race enables it to last considerably longer than pump fuel before it goes bad.

5. Mix pump fuel with race fuel 50%-50%. This will help negate side effects from pump fuel.


L.D.

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May 2015-

Question: Do I need a lap top computer to tune my quad if I buy a Vortex ECU?


No!
A lap top computer is not required to use a VORTEX ECU (Engine Control Unit) on ATV,UTV and M/C.
Vortex has purposely designed their top of the line, state of the art ECU so that a Lap Top Computer
is NOT REQUIRED. It is plug in-install and go.

All units have 10 preprogrammed high performance spark/fuel maps preloaded in the box.
Each unit has built in fuel trim adjustment dials to fine tune the air fuel- without installing on a dyno.

Vortex has done all the work for you-all preloaded maps are pre-tuned.
Minimal fine tuning with trim dials built in to ECU all that is required.

Again installation on a dyno not required.

 

L.D.

For more details read Duncan Racing TECH Document:
Vortex ECU Installation and Tuning Tips Click Here

 

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November 2014-

Question: How best to Protect the ECU on your Fuel Injected ATV/UTV:

CHARGING The BATTERY: It is highly advisable to un-plug the ECU from the wire harness when charging the battery. This is especially recommended when using an aftermarket ECU like a Vortex.

WASHING: Most ECU’s are water resistant, NOT WATER PROOF. Avoid submerging in water. Take care when washing your machine.
For maximum reliability it is advisable to remove the ECU from the machine and clean and dry the connectors. It is safe to squirt connections with contact cleaner and lightly blow with compressed air.
*It is also recommended to use a light coat of water proof grease on the connectors

WELDING on THE CHASSIS: Always UNPLUG the ECU from the wire harness when ANY WELDING is performed on the chassis of your machine.

Programming Lead (on Vortex brand ECU): For owners of Vortex brand ECU’s it is imperative that the program wire connecter is protected. The wire lead coming out of the ECU with a pin connector must not be damaged in anyway. The plug in end must also be retained at all times.
*Damage to the wire and or connect will render the ECU programmable

L.D

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January 2014-

Question: Why am I having so many issues with the pump gas I buy today?

The biggest reason that most ATV users are having issues with today's pump gas is the addition of ethanol. The EPA has issued mandates on gasoline to include various percentages of ethanol in an effort to lower emissions and decrease smog- This is great for autos and trucks manufactured to work with this fuel. But not the best idea for people with small engine like ATV's, motorcycles, farm/lawn equipment etc.
Most of the gasoline now sold has some ethanol in it, but the exact amount varies by region. In general, ethanol will not exceed 10% by volume. Gasoline with 10% ethanol content by volume is known as E10, and with 15% ethanol is known as E15. E85 is 85% ethanol and 15% gasoline.

Pump fuel enriched with Ethanol, causes a number of issues :( including but not limited to the following)
The biggest issue that the ethanol blended gasoline causes is corrosion.
Ethanol blended gasoline also does not burn as consistently as race gas or pump fuel made a decade or 2 earlier, causing damage to engine parts when it misfires.
Results from the use of ethanol, can cause rust and carbon deposits inside the engine, dissolve plastic parts and more

What can be done to help off set the problems caused by Ethanol in fuel.

1. Use race gas. Though not the most economical option, using a high quality race fuel like VP Fuels or Sonoco will alleviate all the fore mentioned issues.
* See RACE FUEL- General Information TECH Document HERE on DRI website www.duncanracing.com 

2. Use a quality fuel stabilizer- The is not a cure but will substantially help

3. Drain ethanol fuel from carburetor daily. Corrosion can set in over night. Most carburetors have a drain on the float bowl.
* Refer to owner’s manual for instructions on draining the fuel.

4. Store your machine dry. Turn fuel off and run machine (at idle) until engine stops. Drain any residual fuel from carburetor, drain tank.
Draining the tank and carburetor after using Ethanol can cause some additional issues, O-rings in carburetor, petcock etc. can dry out, crack and fail prematurely.
A viable option to storing it dry is to store with a quality race fuel. The high quality of race enables it to last considerably longer than pump fuel before it goes bad.

5. Mix pump fuel with race fuel 50%-50%. This will help negate side effects from pump fuel.


L.D.

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December 2012-

The real scoop on 2-stroke gas/oil ratios.

One of the most common misunderstandings that we encounter at Duncan Racing regarding 2-Stroke engines that pre mix (mix oil in the gas before pouring to fuel tank) their fuel is that more oil makes machine run Richer. When in fact the opposite is true. More fuel equals a richer condition, not more oil-more oil displaces fuel resulting in machine running leaner.
When additional oil is mixed with the fuel the reduction in fuel actually leans out the air/fuel ratio.

The primary function of the oil pre-mixed with fuel is to lubricate the engines internal components; piston, bearings etc
Secondary function of the pre-mix oil is help seal the rings.

Excessive amounts of premix oil can cause engine to run improperly but those issue are not technically defined as a Rich condition.

AIR FUEL NOTES:
Example
10-1 Rich --------- Lean 14-1
*To richen up an engine more fuel is required.

OIL to FUEL RATIOS
For most 250cc to 500cc engines a PreMix ratio between 20-1 to 50-1 are most popular, ratio will vary depending on oil type and oil manufacture recommendations
DR prefers a 32-1 Ratio with Maxima 927 for most applications used in temps over 40 degrees.
Use Maxima Formula K2 for conditions below 40 degrees.

L.D.

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February 2012-

How can I tell if my clutch is slipping on my Honda TRX 450R?

There are many telling signs that your clutch is not performing properly:

Your ATV is loosing power. But engine seems to be working hard. Revving up but going no where.
• Machine is having trouble shifting
• Transmission oil smells burnt and looks Black
• Clutch lever free play adjustment has changed


An excellent test you can do is to take your ATV out to an aspalt or concrete area. Like a long driveway or road with NO TRAFFIC on it.
*Make sure conditions are SAFE.

Run your ATV through the gears. Each time you make a shift you should feel a positive sensation as additional power is delivered to the rear tires. Front wheels will try to lift and tires may chirp (slightly spin) If this is the result you feel, odds are your clutch is working properly.
If the ATV lags when changing gears and there is little or no additional power sensation when changing gears, odds are clutch is slipping.

Generally when a clutch is “slipping” it because the fiber plates and steel plates are not adequately gripping. Fiber plates can get hard and wear. Steel plates can get hot and warp while getting a smooth finish, which can increase slippage.

It is always advisable to replace clutch fiber plates, steel plates and clutch springs as a complete unit.
When servicing your clutch it is always recommended to closely inspect all clutch related components; inner hub, pressure plate, outer clutch basket, pushrod, clutch ball, spacing washers, clutch arm etc.
Failure or wear on any of these items can cause clutch malfunction impeding engine performance.
It is encouraged to consult OEM Service Manual and or a Professional trained mechanic with any questions.

Transmission oil is essential to prolonged clutch life and proper clutch performance.

DRI recommends the following Maxima Oils:

2-Stroke: Maxima MTL Endurance 85W

4-Stroke: Maxima Premium 4 10W40

For more information check out the Maxima website

www.maximausa.com

 

L.D.

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September 2011-

I always get a little confused with how air temperature and elevation effect the jetting on my ATV. Can you give me a few pointers?

TUNING TIPS-VARIOUS WEATHER CONDITIONS

The engines fuel requirements are in a large part determined by the amount of air getting into the engine. More air requires more fuel, less air requires less fuel.

-Temperature; Cold weather conditions require the richest carburetor jet settings. This is because cold air condenses allowing more air into the engine than warm conditions where air expands allowing less air into the engine.

-Humidity; Conditions of high humidity cause your engine to run richer and make less power than moderate to dry conditions. The moisture in the air, displaces oxygen causing the engine run richer in humid conditions. Moisture in the air allows less air into the engine, requiring less fuel.

-Rain: Is humidity at the next level. During rainy conditions your engine will require leaner jetting because the rain displaces the air. *Always note the ambient temperature. Sometimes cold temperatures during rain sessions can off set oxygen displacement.

-Elevation: Knowing the elevation is critical in fine-tuning an engine for maximum performance. Base line elevation should always be sea level. As engines are used at altitude above sea level for example 2000 ft, 4000 ft. etc. adjustments must be made to compensate for the loss in compression. (Atmospheric pressure decrease as altitude increases causing less air to be compressed into the cylinder)
The proper initial adjustment for high altitude use, is to alter the cylinder head volume and or piston compression (consult your engine tuner for specific instructions) to try to off set the loss of air to compress. After this adjustment is made the engine must have the jetting checked and possibly adjusted. If the engine is not modified for the new altitude, then the carburetion will most definitely need to be adjusted. As a basic rule of thumb the higher the altitude, the leaner the jetting

L.D.

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July 2011-

My clutch plates from my Honda TRX 450 measure good according to the tolerances listed in the manual, but the clutch feels like it slips when I ride my machine. What do you think the problem could be?

There are a number of factors that can be causing you clutch to slip.
Following I will try to hit the most common sources;

FREE PLAY: It is imperative that the proper amount of free play is kept in the clutch cable (generally adjusted at clutch perch) generally 1/8"-1/4" is necessary (check service/owners manual for your exact model specifications). Running with improper free play adjustment can and will cause clutch slippage and clutch plate damage.

FIBER PLATES: Plates must be checked and measured to ensure they are still with in tolerance.
*Note on occasion fiber plates may measure with-in correct tolerance but have hardened due to extreme heat. If plates are hard and glazed they should be replaced.

STEEL PLATES: Plates must be checked and measured to ensure they are still with in spec. Plates should also be checked on a surface plate for flatness. Warped plates will not operate properly. Plates should also be inspected for discoloration. If turning blue,brown from heat they should be replaced.

SPRINGS: Springs should be measured according to specs in oem service manual. If there is any doubt to their condition, springs should be replaced.

NOTE: As a general practice. DR replaces fiber plates, steel plates and springs all at one time as a complete set.

Other Potential Components to be Inspected

CLUTCH BASKET: Inspect basket for grooves in the ears on the basket. Excessive grooving from wear caused by fiber plates will impede clutch operation and may cause basket failure.
It is also recommended to check for movement of drive gear on bottom of clutch basket.

INNER HUB: This component is splined onto the main shaft and sits inside clutch basket. Check for wear from splines on steel plates. Check for wear on clutch plate surface.
If any sign of wear replace. Worn inner hub will adversely effect clutch function.

PRESSURE PLATE: This component sits inside clutch basket on top of clutch plate stack. Check for wear on clutch plate surface. If any sign of wear replace.

CLUTCH ARM: Check clutch arm for any wear. Specifically inspect area where pushrod touches clutch arm. If there are any signs of wear-replace.

CLUTCH PUSH ROD ASSY: Check both ends of push rod. If any sign of wear replacement should be considered. Pushrod wear will affect clutch operation and feel at clutch perch.

CLUTCH CABLE: Make sure cable operates freely at both ends. Inner cable must be lubed properly and slide freely back and forth.

We have only covered the high points of the ATV clutch operation. If there is any reservations to repair or service knowledge, a profession mechanic should be consulted. It is unwise to attempt to work on the RH cover, clutch assembly etc. without the assistance of the OEM Service Manual.

L.D.

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June 2011-

What is Pressure Testing a 2-Stroke engine?

Pressure testing a 2-stroke engine is a test done to 2-stroke engines to check for air leaks.
The test is performed after the engine is assembled, but before exhaust pipe and carburetor are installed.
To perform the test the exhaust side of cylinder is blocked off, spark plug is installed and air through a one-way valve with a gauge in the system is pumped inside the 2-stroke portion of the engine. 6lbs. of air is pumped into the engine. The engine must hold 6lbs of pressure for 6 minutes without leaking. If any air leaks are found coming from the engine they must be corrected and engine retested.

The primary advantage to performing this test is to ensure that the engine does not have any air leaks which will cause engine failure.

PRESSURE TESTING FACTS

• Performing a Pressure Test on a freshly assembled 2-stroke engine should be mandatory step in the repair process.
• All ATV/MC shops should be capable of performing a basic Pressure Test. Cost for test should be under $100
• Spraying a soapy water based solution around potential leak areas on the engine is an excellent way to locate and specifically identify leaks.
• Air leaks can be found in multiple locations: For example-base gasket, head gasket, reed gasket, main seals, center case gasket.
• Just because a gaskets main seal etc is new, doesn’t mean it cannot leak.
• Just because sealer was used on the gasket doesn’t mean it cannot leak.
• Air leaks can cause air fuel mixture to run lean causing engine to seize and in severe cases burn a hole in the piston.
• Richening up the jetting will not effectively correct the air fuel ratio of an engine with an air leak.
• When an engine fails for an unexplained reason. It is a wise to perform a pressure test before the engine is disassembled.

L.D.

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May 2011-

My Raptor 700 has been sitting since last season (over 6 months). I cannot get it to start. It was running fine when I last rode it, what could be wrong?

For starters you need to get the battery charged. The best way to charge a battery that has been sitting for an extended period is to use a trickle charger (most are 2 amps) and leave it on for 24-48 hours. Check all connections are corrosion free.

* In the future it is recommended to use a battery tender. The devices are very economical, easy to use and save a lot of inconvience.

Secondly you need to change the fuel. Fuel starts to go bad in as short as 30 days. When a bike has been sitting for that long the tank should be removed and completely flushed out. On fuel injected machines be careful not to damage the fuel pump inside the tank. Fuel Injected models like the Raptor 700 also have a filter inside that should be checked and cleaned.

It is also recommended to remove the throttle body and clean in solvent designed to wash small engine parts. (It is un advisable to clean with kerosene, gas etc). A new plug, fresh air filter, fluid level check are also in order.

If your machine fails to start after the above mentioned maintenance. It will probable be necessary to remove injector and clean (in severe cases injector may require replacement). If starting issue persists a trip to your mechanic is probably next on the agenda.

Good Luck

L.D.


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April 2011-

My Yamaha Banshee got sand in the motor. What damage will getting sand inside the engine cause?

Basically getting sand inside the engine of your 2-stroke Banshee greatly accelerates the wear and tear on the engine. Depending on how much debris and how long it has been getting into your engine will determine to what extent damage is done. The following components are generally affected most when a 2-stroke is sanded

A. Piston wear. When foreign debris passes through the engine, foreign debris gets caught between the pistons and cylinder walls. Since the pistons are made from aluminum and the cylinder liners (sleeves) are generally steel the pistons wear first. A quick example: average piston clearance is .0025”. (Less than half thickness of fingernail-how long would it take to sand a few thousands away from a piston? Image engine turning 10’000 RPM’s. If piston/cylinders are run for extended periods of time damage and unnecessary wear will happen to cylinders also.

B. Ring wear. When debris gets between rings and cylinders, ring efficiency is affected almost immediately. If rings are used for prolonged amount of time, they can and will break. Causing severe damage to cylinders, pistons, head, crankshaft, main bearings.

C. Crankshaft and Main Bearings: Foreign debris run through a 2-stroke causes the crankshaft, lower and upper rod bearings, and main bearing to wear out considerable faster. Causing the parts to fail prematurely.
Example: A crank assembly may have 50 hours on it. The customer is riding at desert and air cleaner falls off and rider is unaware and rider that way for approximately 1 hour. The engine sucks a substantial amount of dirt/sand. All that debris runs through crank bearings. Crank assembly now is worn like it has 100 hours on it.

L.D.

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March 2011-

Why do some hi-performance camshafts bolt right in and others require user to change additional valve train parts?


There tends to be growing trend of 2 types of hi-performance camshafts sold to users in the Sport ATV world.

Option A. Is a bolt in cam and requires no modifications to valve train other than setting correct valve lash. The manufactures of these types of cams use a foot print (lift/duration) very similar to the stock camshaft thus allowing cam type A to work with stock valve springs, guides, piston etc. Since these cams are very similar to stock, power gain is minimal.

Option B These types of cams are true hi-performance models. Lift and duration has been changed substantially to offer maximum power gain. But when camshafts are redesigned with greater lift and increased duration many of the valve train parts must be changed to work with the true hi-performance camshaft. These are camshaft used by true performance enthusiast and professional engine builders.

Following is a brief summary of additional valve train components and how they are effected by installing a hi-performance camshaft.

VALVE SPRINGS: Stiffer higher quality springs are required to keep valves from floating (lifter not following cam lobe). Failure to use correct springs will result in severe engine damage. Broken valves etc.
GUIDES: Shorter valve guides are required on many models. When camshaft lift is increased (so valve will open farther) the valve spring retainer can and will come down and hit the valve guide seal and or guide. Again this is a serious no-no and will damage a valve train severely if engine is ran this way.
PISTON: In many cases when a camshaft is installed in an engine that has more valve lift the the valves will hit the stock piston. To correct this problem either the piston must be modified (valve pockets machined to increase clearance) or a modified piston designed to work with high lift camshaft be installed. * It is not advisable to modify/machine a stock oem cast piston. Cast pistons will be weakened when machined on.
ROCKER ARMS: In some cases the pad on the rocker arm must be modified to work with the higher lift camshaft being installed.

L.D.


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February 2011-

I have a ’06 TRX 450ER with a DR Stage 1 kit (Fat Boy 4 Exhaust- Pro Flow Kit-DR jet kit). I ride mainly in the sand.
What paddles are best?

There is no clear cut answer for your question.
Following I will outline some factors that will help determine which choice to make.
First you must determine what type of riding Sand Duning, Hill Racing, and Drag Racing.
Each type of riding requires a different tire design.

Consider the following when choosing your tires;
How wet is the sand? The more moisture in the sand the less aggressive the tire needs to be (wet sand fewer paddles)
If your tire is too aggressive, the tires will rob power and slow your machine down.
On the flip side, the dryer the sand the more aggressive the paddle needs to be (dry sand more paddles)

Tire size: Larger tires (21”-22”) get better forward traction, but are heavier and require more HP to turn them. Taller tires offer a smoother ride, but do not corner the best. Shorter tires (19”-20”) spin faster, offer a rougher ride, corner and slide better than taller tires.

Dune Tire: Should be 1 piece generally and 8 paddle design. I-piece tires will slide better in the dunes, stay on bead better when jumping, and resist flats better. A good 1 piece dune tire is not as fast as drag tires but offer superior durability and better handling.

Flat Drag Tire: The most important thing to consider for flat sand drag racing is to choose a tire that stays on top of the sand and throws a flatter roost. Generally 7 or 8 paddle on a shaved carcass. You do not want a tire that digs down and throws a taller roost. Unless you have 800 HP. A tire that digs is slower than a tire that floats.
* Analogy is very similar to how a speed boat gets up on plane. It is fastest when contact with water is minimal.

Hill Racing: Tire choice is very similar to Flat Drag tire but tire weight is critical. Care should be taken to use lightest tire possible.  

To truly maximize performance, testing must be done. Riding styles, motors, sand conditions all play a factor in how the tire works.
Various tire styles, air pressure settings, gearing must be tested to optimize the best combination.

To summarize there is not exact answer on what tires works best.
For those who don’t want to test, following guideline will get you in the ballpark;
Dune Riding: 1 piece molded 20: 8-paddle tire
Drag/Hill Racing: shaved 8 paddle 20” hauler tire.

L.D.

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December 2010-

My Honda TRX 250R has kind of a loud rattle coming from the top end of the engine.
What do you think the noise is?

Without disassembling and inspecting the engines internal components it is impossible to be 100% accurate when diagnosing the origination of the engine noise’s.

But with that said it is more than likely caused by excessive piston to cylinder wall clearance and the noise you are hearing is commonly termed as “piston slap”.

In a 2 stroke engine, there is a specific clearance between the widest point on the piston (towards the bottom of piston on the “skirt”) and the inner bore surface of the cylinder (example: for most 250cc engines the piston to cylinder clearance is set at .0025”). Many things can cause excessive piston clearance; normal wear, the ingestion of foreign material (dirt,sand,silt,mud,etc.), metal transferring from lower end.etc.

Once the noise has become apparent or excessive hours have been calculated it is HIGHLY RECOMMENDED to address the problem before the engine breaks. Preventative maintenance will almost always save you in the long run.
Call a DRI Tech for more information.

The following are some tips regarding 2-stroke top end maintenance:
·Under normal riding conditions for a recreational engine the top end should be rebuilt and piston/cylinder tolerances should be checked every 30 -50 hours. For race engines this curve should be accelerated to 5-10 hours depending on racing application.

·A basic 2-Stroke “Top End Rebuild” consists of the following; top end removal, parts wash and inspection, piston-cylinder inspection and measurement-followed by: cylinder hone or bore, ring replacement or if piston is worn below specification piston replacement, reed pedal inspection, gaskets/o-rings replacement, power valve clean and service (when applicable), top end bearing, (top end washers replacement Suzuki LT 250/500 only), Pressure Test.

·Pressure Testing a 2-Stroke is a priceless tool to help combat air leaks that can cause jetting issues and piston seizures. DRI recommends Pressure Testing all 2-Stroke engines after assemble and any engine that has any issues before disassembly.
See DRI TECH CENTER for complete instructions.

·Piston to cylinder and other engine tolerances should always be measured with the proper equipment (micrometer, dial bore gauges, etc) by a trained technician.

L.D.

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November 2010-

What is a 4 Stroke leak down test?

I like to compare a leak down test performed on a 4-stroke engine to blood pressure test you take ate the doctors office. Neither test will tell you everything you need to know. But they are a quick, economical way to get a basic idea of the condition of the health of your machine and body.
By pressurizing the combustion chamber of the engine, with the piston at TDC (top dead center), a 4-stroke leak down test’s the condition of the engines; piston rings, intake and exhaust valve seal and head gasket.

The leak down test will give you a quick heads up and let you know if engine has a problem and will help point you in the right direction. Leak down tests are great for helping diagnose bent valves, worn rings, blown head gaskets and a number of other potential problems. We perform leak down tests on both race and recreational engines on a very consistent basis.

Click here to check the DRI website in the TECH CENTER/Tech Documents-4-Stroke/4-Stroke Leak Down Test

L.D.

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October 2010-
Why is the oil filter so important when changing the oil on your 4-stroke ATV?

Changing the oil regularly on you ATV is vital to the reliability of your engine. Failing to replace the oil filter with a new oil filter when performing an oil change leaves the job incomplete. The filter should be changed every time engine oil is changed. The old filter should be inspected closely with a flashlight for any sign of debris. When an internal part(s) of the engine begins to fail (example: rod bearing coming apart, broken gear, piston failing, etc) the vast majority of the time foreign debris will be caught in the filter. With consistent oil filter inspection engine failure can be caught in the early stages and serious engine damage can be contained to a minimum.

Following are some oil changing tips;
·Warm engine up for 5-10 minutes before dumping the oil (be careful not to burn yourself).
·Always dump oil into a clean pan. Inspect oil in drain pan after draining.
·Drain engine oil and transmission oil into separate drain pans (on applicable on engines like Honda TRX 450 that separate engine oil and transmission oil.)
·Always dispose of your used oil properly.
·Record oil changes. Date and hour meter reading work great.
·On race and modified engines save used oil filters in plastic bag with date and hour reading recorded.
·Refer to OEM service manual or owner’s manual for correct procedure for checking oil level and exact engine oil capacity.
·Torque your drain plug(s) to factory specs-refer to your OEM service manual.
·Change your aluminum crush washer every time you change the oil to prevent stripping the threads in the engine case or oil tank.

For 2-stroke engines, generally there is no oil filter because the oil only lubricates the transmission and clutch via splash. (Most 2-stroke engines have no oil pump.) It is very important to change oil when warm and to dump into a clean drain pan. Inspect closely, you can even run a magnet through the used oil to see if any debris is picked up.

L.D.

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August 2010-
I have a Suzuki LTR 450 fuel injected ATV. I want to do some performance modifications to it (pipe, air cleaner kit, cams etc.) but I am worried about it running too lean. What can I do to ensure my bike runs properly and is reliable with these mods?

The stock oem ecu system is an open system that does not adjust the air/fuel ratio when intake and exhaust air flow is increased. To correct the air/fuel ratio it is necessary do one of the following modifications;

1. Install an EFI controller- basically an EFI controller, like a Vortex Interceptor, taps into the fuel injector drive circuit from the standard ECU whilst monitoring the Throttle Position Sensor (TPS) then remaps the injector pulses thus the fuel flow to better match the increased air flow created by the addition of air box and pipe modifications. This is done over all throttle positions and RPM. The pre-programmed fuel map is developed by Vortex Performance and is intended to work with aftermarket pipe and silencer combinations. In addition they have included three rotary switches which represent 0-33%, 34-66% and 67-100% Throttle Openings. Each switch allows the user to richen or lean the pre programmed fuel map.

2. Install a Vortex ECU- The Vortex ECU is like a Vortecx X10 CDI and EFI Interceptor rolled into one module. The ECU controls not only Spark timing and Voltage output but also Fuel Metering and other engine management functions. The result is more power, better power, easier starting and ultimately faster lap times. This unit comes pre-programmed with 10 Performance Fuel & Spark timing maps as well as having 3 additional switches for user trimming (adjusting) of Fuel in Lo, Mid and Hi throttle openings. The ECU plugs directly into the bikes standard wiring harness and interfaces with all the standard engine sensors such as ECT (Engine Coolant Temperature), IAT (Intake Air Temperature), MAP (Manifold Absolute Pressure), TPS (Throttle Position Sensor), CPS (Crank Position Sensor) to adjust fuel and spark timing for optimum power delivery in all weather, altitude and load mx bikes. All of the development work is done for you! All that is left is for you to do is chose a setting that best suits your riding style or track conditions and ride!

In summary-Option 1 will get the job done-Option 2 offers the latest technology for your machine to maximize rideability and performance.

L.D.

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April 2010-
How often and why do I need to repack my Fat Boy 4 exhaust system?

A properly packed Fat Boy 4 exhaust system will make maximum horsepower and keep db levels to a minimum. A Fat Boy 4 run with “Blown Out” packing can cause your engine to lose up to 10% of its HP and allow db levels to climb 10+points. Not Good.

Try to follow the follow guidelines in regards to repacking your Fat   Boy 4.
-When used in average riding conditions it is recommended to repack your Fat Boy 4 exhaust system every 20-30 hours.
- When used in extreme riding conditions repacking may be required in 10 hours.

Repacking your Fat Boy 4 exhaust is a rather painless operation.
The basic process goes as follows:
-Remove (4) button head Allen head screws securing Fat Boy 4 end cap.
-Remove end cap (DRI used special end cap removal tool), slide out old packing pillow, slide out core, clean and inspect inside off muffler, clean and inspect core (replace core if necessary), slide core into new packing pillow, install pillow/core into muffler (make sure core slides into slot machined in front end cap), reinstall rear end cap.
-Reinstall (4) button head allen screw (replace if damaged).

Additional Repack Tips:

-Use ONLY Genuine Fat Boy 4 packing material
- DO Not Repack your Fat Boy 4 with packing other than genuine FB4 packing pillows. Performance of muffler will be affected, damage can occur.

*Packing/Cores and related items are not covered under DRI Fat Boy 4 warranty
*Damage incurred to Fat Boy 4 mufflers and cores from lack of proper muffler maintenance
*(Failure to keep properly repacked) is NOT covered under DRI Fat Boy 4 warranty

 

 
L.D.

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December 2009-
My Yamaha YFZ 450 is really hard to start, it does not want to idle and back fires and pops. I don’t know what is wrong? The last time I rode it in the summer it ran great.

More than likely what has happened is old gas has dried out in your carburetor because it has been sitting so long and clogged the pilot jet. This is a common problem in ATV’s that sit for extended periods of time.
To correct this problem you will need to remove the carburetor, completely disassemble it, wash all parts, clean and blow through all jets, confirm they all 100% clear of any obstruction then reassemble and reinstall carburetor. It is also highly recommended to flush out you fuel tank and change to fresh fuel.
To prevent this in the future you should drain the gas out of your machine anytime it is going to sit for more than a 45-60 day period.
If machine is stored or sits for a 60 day plus period of time with fuel in it, it is necessary to remove and replace carburetor and clean and change fuel in tank.

NOTE: This issue is common among ALL model ATV’s. The above mentioned procedure should be followed for all ATV’s that sit for prolonged periods of time.
Depending on your mechanical skills and facility to work on your machine, it may be necessary to have a trained professional clean your carburetor and change the fuel.

*Operating your ATV with partially clogged jets in your carburetor can and will cause harm to your engine

L.D

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August 2009-
Why do I have to adjust the valves on my Honda TRX 450 so frequently? The most common reason that the valve lash clearance changes on your Honda TRX 450 is because the valves are wearing. During operation the valves open and close once for every RPM (approximately 400,000+ times per hour)

The valve face must seal against the valve seat (in the cylinder head) on each cycle, for proper engine function. Over time the face of the valve will begin to cup (this allows valve to travel higher up into the head decreasing the clearance between lifter and camshaft)

* All camshafts have a recommended clearance between cam lobe and lifter/rocker arm. This clearance is set by camshaft manufacture and is required for correct valve train function. (this clearance is also referred to as valve lash)

Under normal conditions engines with stock valve trains should check their valves every 20 hours. Engines with high performance valve trains should check valves every 10-15 hours.
Under optimal conditions valve wear will be minimal. But many factors can accelerate this wear: ingesting dirt and mud into intake, over revving engine, valve spring fatigue, high lift camshafts used with stock spring. 

Some but not all side effects caused from incorrect valve lash setting are; hard starting, excessive top end noise, decreased engine power. 

Valve checks and adjustments must be done by a trained professional. Failure to maintain your valve train properly will result in severe and expensive engine damage.
L.D.

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