a long rod will not have the same effect as a stroker. u could increase the rod length 10 feet, and the stroke would still be the same. its hard to explain online, but if u increase the rod length 5mm, then when the piston is at BDC (bottom dead center) it will be 5mm higher than it would be stock, and when it is at TDC (top dead center), it will be 5mm higher than stock. therefore the stroke is the same. when you increase the stroke you are lowering the BDC, and raising the TDC. the offset between the main journal and the rod journal on the crankshaft is increased. a longer rod may decrease the maximum angle that the rod uses, so you won't have to have as much work done on your cases for clearance, but you would risk your piston hitting your head and/or valves, which would keep your motor from running at all.

a guy in my autoservice class put longer rods in his motor after getting a "stroker" crank. he didn't buy a thicker head gasket to adjust for clearance issues with the head. when he brought his motor in, one of the valves had put a hole in the piston, and was stuck, and the head had been cracked and pushed away from the cylinder. he also bent the rod, and spun the bearings. the cylinder was designed for the stroker crank, but the +2mm rods pushed the pistons above the top of the cylinder.

 

shav, were u talking about 2-strokes when you mentioned getting the longer rod, instead of a stroker kit? if you were, then i don't know if everything i said applies (i know the valve thing doesn't). i was talking about 4-strokes. jus wanted to clarify so i dont' look like a total jacka$$

 

I have the 4mm stroker with a 87mm piston.439.9cc It is going to 88mm. 450.1cc There was no case mods done at all. It fit right in. Powroll stroked the crank and installed their shortened rod. The price was right around $800. That is the cost of my guy splitting the cases, sending the crank and rod to Powroll, them doing their thing, mailing it back here and then my guy putting it back in.

 

Q]

I have the 4mm stroker with a 87mm piston.439.9cc It is going to 88mm. 450.1cc There was no case mods done at all. It fit right in. Powroll stroked the crank and installed their shortened rod. The price was right around $800. That is the cost of my guy splitting the cases, sending the crank and rod to Powroll, them doing their thing, mailing it back here and then my guy putting it back in.[/quote]



how quick is your bike compared to a regular 416 with similar mods, minus the crank? i am debating on this but others say do a -1 on the crank and go with a larger bore. i really dont' know what works best. i think i want one of those pancake style piston for saving weight. maybe that is a waste, i don't know. i am wanting something for drag racing. i have my 426 set up right now that it runs with stock yfz's dragging. a piped one will take me though. i have my lightened flywheel here now but i haven't installed it yet.

 

A longer rod will still have a similar effect on the engine. Because the rod is now longer, it creates a larger crankcase which can draw in a bigger intake charge for the next stroke. Your not changing the CC's of the engine because the rod length is still staying the same, as you said. However your piston is still travelling further away from the crank (which also raises BDC) which causes the crankcase to vacuumzie for a longer period of time, which is what results in the larger charge. This is basically the same effect that a stroker crank can give you with half the cost.
Torgue is equal to force over distance, which is why using a longer wrench helps to get off stuborn bolts. Your piston is still applying the same force on the rod, only this time its longer, which results in greater torque being transfred to the rear wheels.
Also, the longer rod will decrease rod angle which results in less wear on your cylinder and a smaller "out of round" condition usually caused by shorter rods. So not only are you gaining power but your giving your engine extended life, which is always good.
When building a long rod or stroker set up you need to raise the cylinder to keep the piston(s) from hitting the head. This is usually done by creating a spacer plate to set the deck height to the right position and the right compression.

TractorPacker, Not every engine needs to be trenched. Like I said, it depends on how radical the application. Adding the shorter rod is the worst thing you could have done for that engine. Not only are you deasing torque but you are putting a tremendious amount of extra stress on the cylinder walls, which will cause them to come out of round very quickly. Usually anyone who strokes there crank also adds a longer rod to counter act the effect..
I have yet to figure out why Powroll is doing that, it's just asking for trouble. Like I said before the best way is to use a spacer plate but the only conclusion I can come to is by using the shorter rod it saves them time and money by not creating a spacer plate, which is just a cheap way out in my opinion. I would rip that motor apart and put longer rods, probably +5 in and get a spacer plate made. You will have more power as well as longer engine life

Jmo
Shav0

 

ok shav, i get it. i thought u meant to just put a long rod in to increase displacement. i didn't know that just a longer rod with a spacer plate would increase torque. another mod to add to my to-do list. i assume that you could have somebody make a spacer plate out of aluminum at a machine shop, but what about the rod? do you know of anybody that makes rods for the 450r? that definately seems like a cheap and easy way to get more power.

 

You can ususally find a rod that will fit, but thats longer. For example I am using a banshee rod in my blaster because its 5mm longer so it works out well. If not you could probably find some aftermarket companies that will have somthing. The spacer plate must be set exactly to the right height. Remember your cylinder height controls your compression levels, so to high could result in detnotation, and too low could decrease peformance. Some shops will actually make a spacer for you when they install the rod so that they can set the height to the exact position.

 

how quick is your bike compared to a regular 416 with similar mods, minus the crank? i am debating on this but others say do a -1 on the crank and go with a larger bore. i really dont' know what works best. i think i want one of those pancake style piston for saving weight. maybe that is a waste, i don't know. i am wanting something for drag racing. i have my 426 set up right now that it runs with stock yfz's dragging. a piped one will take me though. i have my lightened flywheel here now but i haven't installed it yet.[/quote]

I have never ridden a standard 416, nor raced against one. In a drag race I don't do well, because of the slower revs. I can pull alonger gear than others, so that helps with speed. If you want to build a quick 400ex, don't stroke it. If you want to ruin grips because you have more torque than you can imagine, stroke it.

There are stroker kits coming out now for the 450r. I will never spend the money to stroke the R.

 

Most people are to scared to go with a 92mm piston. Either from the magical 450 mark, cost, or whatever other reason. Thats the way to go though if you just wanter to be all out fast.