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Old 11-13-2013, 01:38 PM   #1
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Default Time for a motor build, Beastly edition

Building a motor takes forethought and planning, different parts can't be thrown together and expected to work 100%. First off, what are you building it for? What's your budget? How and where do you ride?

First choice is the piston, the popular choices are wiseco and JE. This is where you decide what bore and compression you would like to be at. If you're looking to go mild then a wiseco 10.25-1 is a good choice or the 85mm 10.5-1 JE. If wanting to build a performance motor then look into the 12-1 JE. If the higher compression piston is chosen then at least a half mix of race gas is recommended. The higher your compression, the more you will feel a boost in the lower rpm as the increase in cylinder pressure is what helps get the quad up and moving.

Is a port and polish in your budget? A good port will increase flow drastically and will help your motor inhale and exhale. I personally recommend using someone with experience, the proper tools and possibly even numbers to match them up.

Next is cams. Did you decide on that port and polish? If not I would look into a cam with a smaller lift as the stock head peaks at .400" of lift. Good cam choices are the hotcam stage 1 and 2 or the web .390. Maybe even the web .413 or mega .415. If you went with a port then I would look into a cam with a larger lift such as the web .413 or mega .415 again or the web .430, web .440 or the mega .450 as the higher the lift will equate to greater flow. Now to match cams with your piston. The larger cams like the web .430, .440 and mega .450 have a higher duration. The higher your duration the longer you can keep that valve way open giving big top end gains but on the downside the more compression bleed off you will have, or a lower "dynamic compression". Now the higher your compression is, the more you feel the power come in the lower rpms. If using a high compression piston, one of the larger cams with greater duration can easily be used as you're starting with a lot of "static compression" giving you sufficient "dynamic compression" even after the slight bleed off. If running one of the lower compression pistons, I would recommend one of the cams with less duration like the web .413 or mega .415. If looking for top end on one of these lower compression pistons, the web .430 or mega .450 cams are recommended as the web .440 just has too much duration with will drop your dynamic compression too low.

The difference in cams are the lower end the hc 1, hc 2 and web .390. The duration increases repectivly in them giving the hc1 the best in low end and the web the best mid to top. The mid cams, the web .413 and mega .415 are good for giving decent gains in power yet having the low rpm torque. The web .413 actually has less duration than the web .390 making a great "torque" cam, the mega will be the better of the 2 in the mid department. The web .430 is a great mid to top end cam, while the mega .450 and web .440 are the top end grinds with the web actually having the most duration. My speculation for the most efficient cam for this motor is a higher lift, shorter duration cam. If a custom grind was to be made I would do a lift somewhere at .430 with the duration somewhere between the web .413 and mega .415.


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Old 11-13-2013, 01:39 PM   #2
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Cam Terms</span>

BDC (Bottom Dead Center): Point where piston is at the lowest point of it's rotation; measured in degrees.

Base Circle: The round portion of the cam lobe where the valve lash measurement is taken; the base from where the lobe dies into.

Cam Lobe: The part of the camshaft that performs the lift of the valve.

Duration: The length of time that the valve is held off the seat by the cam. This is measured by the degrees that the crankshaft rotates. Lower duration cams produce the power in the lower RPM range. Larger duration cams operate at higher RPM, but you will lose bottom end power to gain top end power as the duration is increased.

Lobe Center: The distance measured in degrees between the centerline of the intake lobe and the centerline of the exhaust lobe in the same cylinder.

Lobe Separation Angle (LSA): The Lobe Separation Angle is the degrees that the crankshaft rotates BETWEEN the exhaust valve’s maximum lift point (Exhaust Lobe Center) and the intake valve’s maximum lift point (Intake Lobe Center). This separation generally determines where peak torque will occur within the engine's power range. Tight lobe separations cause the torque to build earlier in the RPM range of the cam. The torque will be concentrated, build quickly and peak out. Broader lobe separations allow the torque to be spread over a broader portion of the RPM range to produce better power through the upper RPM.
LSA Formula = Intake Lobe Center + Exhaust Lobe Center / 2 (the average of the 2 lobe centers).

Overlap: The point where both the intake and exhaust valves are open at the same time.
Overlap Formula = Intake Duration + Exhaust Duration /4 - LSA x 2 , or Add the intake opening to the exhaust closing.

Piston - Valve Clearance: The closest distance from the piston to the valves during the rotation of the piston through TDC, measured in thousandths.

Ramp Rate: The speed that the valve opens and closes.

TDC (Top Dead Center): Point where piston is at the highest point of it's rotation, closest to combustion chamber; measured in degrees.

Valve Float: When the speed of the engine is too great for the valve springs to control the valve, from fatigued springs, over revving the motor or a combination. The valves will stay open and/or "bounce" on their seats.

Valve Lash / Clearance: The clearance between the base circle of the camshaft and the valve bucket / rocker arm or tappet.

Valve Opening and Closing Angles: The angles (usually measured in crankshaft degrees) when the valves first leave and then return to their seats.

Valvetrain: <span style="color:#4169E1">The "train" of parts leading from the cam lobe to the valve.
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Old 11-13-2013, 01:40 PM   #3
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Anything you need to know about timing advance

The ignition system on your car has to work in perfect concert with the rest of the engine. ­The goal is to ignite the fuel at exactly the right time so that the expanding gases can do the maximum amount of work. If the ignition system fires at the wrong time, power will fall and gas consumption and emissions can increase.

When the fuel/air mixture in the cylinder burns, the temperature rises and the fuel is converted to exhaust gas. This transformation causes the pressure in the cylinder to increase dramatically and forces the piston down.

In order to get the most torque and power from the engine, the goal is to maximize the pressure in the cylinder during the power stroke. Maximizing pressure will also produce the best engine efficiency, which translates directly into better mileage. The timing of the spark is critical to success.

There is a small delay from the time of the spark to the time when the fuel/air mixture is all burning and the pressure in the cylinder reaches its maximum. If the spark occurs right when the piston reaches the top of the compression stroke, the piston will have already moved down part of the way into its power stroke before the gases in the cylinder have reached their highest pressures.

To make the best use of the fuel, the spark should occur before the piston reaches the top of the compression stroke, so by the time the piston starts down into its power stroke the pressures are high enough to start producing useful work.

Work = Force * Distance

In a cylinder:

Force = Pressure * Area of the piston
Distance = Stroke length
So when we're talking about a cylinder, work = pressure * piston area * stroke length. And because the length of the stroke and the area of the piston are fixed, the only way to maximize work is by increasing pressure.

The timing of the spark is important, and the timing can either be advanced or retarded depending on conditions.

The time that the fuel takes to burn is roughly constant. But the speed of the pistons increases as the engine speed increases. This means that the faster the engine goes, the earlier the spark has to occur. This is called spark advance: The faster the engine speed, the more advance is required.

Other goals, like minimizing emissions, take priority when maximum power is not required. For instance, by retarding the spark timing (moving the spark closer to the top of the compression stroke), maximum cylinder pressures and temperatures can be reduced. Lowering temperatures helps reduce the formation of nitrogen oxides (NOx), which are a regulated pollutant. Retarding the timing may also eliminate knocking; some cars that have knock sensors will do this automatically.
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Old 11-13-2013, 04:11 PM   #4
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Damn good info right there!!! Someones done there homework
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Old 04-25-2014, 08:32 PM   #5
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Found the spring constant of the stock valve springs, approx 334 lbf/in. Next is to compare with the "HD" springs.

Last edited by beastlywarrior228; 04-25-2014 at 08:36 PM.
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Old 08-08-2017, 04:21 AM   #6
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