500 CC piston kit

[Alex]

Quote: Originally Posted by TNT

We run a 495, JSR out of wichita, ks has them. We never epoxied down the port are you going to? In theory it should gain more Tq if thats what you want. We have a very torqued quad tunned for mx, around 50 hp 36 tq lots of throttle response and light weight it will tire you down if not in good shape. We held up fairly good to HON's, Suks, KTM's @ 60+ hp/38+ in Open A nats. I really think a stroker would have woke the bb up and made us more competitive but afraid of the reliability. Then again seen lots others blow bb motors too. We had a steel sleeve made, best way to go imo. CP piston.

I think I will try the epoxy work in the intake.
Does it bring more bottomend response or is it just to make more rpm?
I do not run with the mapsensor only on the trothle sensor to make it more responsive on the trothle.
Setting the injection is no problem for us because we are running a very good adjustable Cdi with Lambdacontrol.
Lets try it out in a few weeks.

[TNT]

Quote: Originally Posted by rrguy

The head has big long ports, with their angle, not sure much you can improve by just opening them up epoxy can help the velocity but also the flow by raising the floor an redirecting the port to flow through the intake valves better. So a head with better flow will be good for the 450 or 500. with fuel injection you don't have to worry about fuel atomization like on a carburetor setup, but velocity still fills the cylinder better an the right port design help prevent backflow.

[quote=Alex;19883]

Quote: Originally Posted by TNT

Does it bring more bottomend response or is it just to make more rpm?
I do not run with the mapsensor only on the trothle sensor to make it more responsive on the trothle.
Setting the injection is no problem for us because we are running a very good adjustable Cdi with Lambdacontrol.
Lets try it out in a few weeks.

I think the race teams have already proven that epoxying down the intake port gains torque on 450's, noone has on bb's I know of but in theory it should make better torque if properly done. They tried bb's back in 08 with little succees, but maybe they have evolved w/more experimenting. We did it since back in the beginning of 09, the 450 power was unknown and just as unreliable as bb. Today I think it is a known fact proven by Warnert, Motoworks, BCS, Rossier, that just as much relable power can be gained by 450 vs 500, one reason along with others being as I said the epoxy may be more effective. A stroker/bb kit is ideal opposed to just bb. Stroker is good but you have to consider reliabilitty the xtra piston ring/wear from longer storkes and additional loads on bearing's, etc. Sounds like MR Hp has tested this but more testing may be needed to say it's proven reliable.

Atomization is the combining of fuel-air molecules for effective power strokes. The faster this chemical reation occurs the faster the power is delivered w/ more torque at any rpm, but mainly when the piston is moving fast(high rev's) depending on tranny and drive train gear ratio's. Yes it's good to divert fast air directly to the intake valves at the same time produce port angles that create a low pressure area is the trick. Problem with flow benches is they don't show the delta P between the port and combustion can in a vaccum, so one has to guess at a combination of port conic shapes which in the bigger picture the interface cone between the air filter and exhaust.

So the lower the pressure at the port combined with higher velocity allows vaccum air to be pulled to the intake and combustion yes preventing backflow. With that the need for faster atomization grows, some roughen the EFI port to promote this. In a carb this all happens in a the carb body, not the fuel rail-manifold/head, so the need for a rough port and atomization post injector is reduced.

Adding a 02 sensor loop or load timmer makes the throttle more responsive, in this case as load is applied to the engine the 02 sensor senses the oxy level in the exhaust and trims the fuel map. PC 5 autotune does this, it's like getting a dyno tune while riding.

[ds450power]

stroking it shouldnt add ring/piston wear. most spec out the rod so its at the same or better angle than the stock configuration...

[soyo]

Quote: Originally Posted by ds450power

stroking it shouldnt add ring/piston wear. most spec out the rod so its at the same or better angle than the stock configuration...

im going to agree with TNT, anytime you make the piston go up/down farther you will have that much more wear.

also the more stroke you give it the more side load you will have on the piston...meaning more wear....yes you can make it to a long rod stroker for less side loads but in the end you will still have more wear than stock

[ds450power]

anytime u do performance motor work you are expected to see more wear and tear.
as for bb/stroker if done right will last a long time. i know of a few ds650's that are 800cc and were ran for 3-4 yrs no problem.

[TNT]

If you increase the stock bore and stroke porportionally and properly balance the assembly it will make more reliable power. When you move the pin away from the crank and stroke it's like gaining more leverage on a bolt, you see more torque since the engine does not have to work as hard at low rpm, this affects balance. If you add a larger bore piston this effects balance. At any point in the assemblies rotation the sum of forces must equal zero. For a rotating crankshaft, the force at the main bearings is proportional to the speed of the engine squared. Also, the further the imbalance is located from the center of gravity, the greater its effect on the part as it rotates.

So what does this actually mean in terms of the forces generated inside an engine? An imbalance of only 1/4 oz. (7 grams) located four inches out from the center of the crank on a counterweight will generate a force of about 7 lbs. at 2,000 rpm. At low rpm, you would hardly feel a thing. But at 8,000 rpm, that same force would grow to 114 lbs. with every revolution of the crank. If this same engine had one ounce (28 grams) of imbalance, the forces generated would be multiplied by a factor of four, generating 456 lbs. of unwanted gyrations at 8,000 rpm! That’s enough vibration to rattle your teeth and pound the heck out of the main bearings. It’s also wasted motion that goes into shaking the block instead of spinning the crankshaft. Consequently, imbalance hurts horsepower as well as smoothness and engine longevity.

The longer the stroke on the crankshaft, the more important balance becomes because of the distance factor. A longer stroke moves metal further from the axis of rotation and magnifies its effect on balance.

[Alex]

Tested the 500 now for more than 10 hours already.
It has an awesome torque.

[MrHorsepower]

Quote: Originally Posted by soyo

Quote: Originally Posted by ds450power

stroking it shouldnt add ring/piston wear. most spec out the rod so its at the same or better angle than the stock configuration...

im going to agree with TNT, anytime you make the piston go up/down farther you will have that much more wear.

also the more stroke you give it the more side load you will have on the piston...meaning more wear....yes you can make it to a long rod stroker for less side loads but in the end you will still have more wear than stock

The stroker goes up and down farther....well actually it only goes down farther...but anyway. Lets say the stroker motor can get the bike around the track with a quicker et while only having to turn 8000rpm. Meanwhile the stock stroke motor has to turn 9500rpm??? Just a passing thought.

Stroking the little DS 10mill is really a non issue when we are stroking the big DS's out to 100mill and turning them 10500rpm.

[Rotor515]

I need some schooling on the porting, I don't have much engine work experence but have an engineering background.
This is the way I understand it so please tell me where I am wrong:
Decreasing the the intake port will increase volocity but will add resistance to air flowing in the cylender so the total air molicules will be less than a more open port. If there is a problem getting the fuel to mix with the air, the best solution would be to increase the injector pump pressure and spray the fuel in as a very fine mist.
I know the dyno doesn't lie and if people are getting power gains by reducing the intake port then I am missing something so someone please school me on this.

[hcomras]

im not an engineer and dont really know anything about porting...but i want to take a completely uneducated shot in the dark...
i dont think there are less air molecules in an intake port that has been epoxied down, but they are denser air molecules more tightly pushed together and compacted. this actually increases air density inside the cylnider, which then requires the addition of a higher pressure injector that is capable of pumping out more fuel than the stock unit is capable of. more air+more fuel=more power.

just a thought?