Anyone know how big of a rear sprocket I can go without interfering with the stock rear skid plate?

Or, what’s the largest you’re running now on there, no issues yet?

 

The Florence Oregon Polaris dealer is getting some custom 40 tooth rear sprockets fabbed up.

Don't know if they fit or not, but I was able to slip in my 38 tooth without even taking the master link off my chain or pulling the axle. It was tight clearing the chain and rear skid plate, but it did slip on and off. Check out my pix in the Gallery to see the Red Rooster installed.....

 

Heap: That's good news. I was going after the 38, since I've heard positive things about it on this site. I will have the same setup as you, more or less. 38, WB slip, K&N, and rejetting it obviously, etc etc.

Your setup is nice, you're setting it up right... I LIKE! [img]i/expressions/face-icon-small-smile.gif[/img]

On another note, I didn't realize that K&N had a slip on the carb one, I thought they only had the one that Polaris was offering you that went in the air box. So, I bought that one.

Do you have any clue how much you lose, if any, that you make with the air box snorkel removed and the K&N vs. the K&N like the way you have it, directly on the carb?

Thanks for the help.

 

Is that a flow bench in your pocket, or are you just glad to see me?

Sorry, I'm a Boeing Engineer, not a Fuji ATV Motor Design engineer..

That long and tapered air box snorkel "didn't just happen". Only on a flow bench or using other instrumentation, you can measure and answer your "which flows more" question.

I do know, that the right and "optimal" amount of both vacuum (from intake "restrictions"), and backpressure from exhaust systems, are all taken into considerations when designing performance to a TARGET group of users.

Drag racing has different considerations that a tight woods or rock crawler trail riding. Same thing with Gearing, and many other aspects of a quads characteristics.

Polaris and Fuji have done their homework on this quad and it shines. But we all have different levels riding skills, terrain, and need for speed.

 

Heap: That's funny. [img]i/expressions/face-icon-small-smile.gif[/img]

I'll take that as, wait and see what the reports have to say on power outputs of different combos.

I'm just thinking you're going to have the least amount of inlet restriction compared to my modded airbox and K&N... I just hate seeing potential HP not being used, especially such an easy one to tap into.

Thanks to the Boeing engineers, we have a nice 747 in the sky, not a predator though, not yet anyhow....

 

03Predator - I put on my sprocket specialists 39 tooth on without any pboblems. I talked to them about sizes, they said they go to 40 before you run into problems. I can't wait to try my combo out this weekend.....if the weather will hold out.

 

vil: Wow, I didn't realize you could go that big without having a skid plate issue. I'm impressed. Let us know how it works out if the weather permits.. appreciate the info...

 

Open airboxes and wide open exhausts don't always flow "most efficiently" as you may think........I can remember seeing on a flow bench and engine dyno in College comparing results on a Chevy 350 with the dyno hooked right up to the engine crank.

By adding 2-3' of open pipe to the exhaust of the muffler, you actually added horsepower as this extra pipe length helped scavenge exhaust gases out of the muffler, instead of just having the open muffler by itself. So you'd help "pull" the exhaust gases out of the muffler, instead of how you may think its actually adding more restriction.

Same thing with intakes. A longer intake manifold path will actually build more torque (ala high-rise race manifold or something used on a truck engine) where-as a shorter more direct intake benefits higher RPMs......dual carbs on a flat 4 VW motor for example.

Heck, Alba and others even sell a "torque stuffer" for Warriors, which is a restrictor and head pipe size REDUCER! It keeps the fuel charge in the cylinder longer, and builds more torque at the slight expense of all out flow.

Sorry to go off on a tangent and steal the gearing thread, but there are many parts to the equation of trying to get "mo powa" out of an engine. No flames intended, and no I don't know "it all" but I've built a few motors in my time and know what works for me…..that's all that counts right?

 

No, Heap, the tangent was fine. I always enjoy talking engine dynamics....fun topic!

Yeah, I realize there is always a point of loss with going too big or too small. There's always a happy medium for whatever it is you're aiming for. Wish I could digress with you on this, but I'm running short on time and got to jam... but looking forward to reading more about what people find out about the combos they will be running on their predators....

Thanks for the great explanation.. makes perfect sense.

 

747 old school, 777 is badabing.


Ken