Thinking About a BB

[ledperformance]

The ESR cylinders are a great value. We find very significant gains with porting and our LED 350G exhaust system over what they make from ESR. The Sphinx is more expensive but will make about 4-5 hp more at the same state of tune. If you decide to go with a 76mm stroke crank (plus 4 stroke) then the Sphinx cylinder is a way better because it is available for that stroke length. A year down the road you won't even know what you did with money if you go the cheap route. If you buy the ported ESR or Sphinx, a year down the road it will still blow you mind every time you ride it!

[Pumashine]

ESR big bore cylinders are the price leaders, hands down the best bang for the buck. if you want a little more out of the same size motor than the CP cylinders are the best power IMO.

As you are looking for more power it is safe to say no matter what size you get you will always wonder what the next size up would have done for you. I started on a 250 then 310 then 330 up to 350. I had to have a 400 and went CT410... big mistake. Tried Polonda...big mistake #2. CP  Industries came out with the Puma and I got one ASAP. Without any port-work what-so-ever this stock stroke 408 Puma with an ERR 5 pipe pulled wheelies uphill in the sand  past my Polnda. I am pretty happy with the next 4 mil Puma Pete at Hybrid built me. But the $2500 it costs for a 431 verses the $1000 for a ESR330 has well been spent. Take into consideration at $1000 a cylinder I spent $6000 getting to the point where I could have started out fresh just spending the $2500. Live and learn but the main point I am trying to make is you always seem to want more power.

[The_Steve_Man]

I will be honest. My ported stock cylinder has plenty of power for me.  I was looking at a bb for more lowend grunt and of course more power.  As you know I am 3 wheeler guy and none of us are right in the head.
If I go with a bb I would sent it to led for porting and a badass pipe.
Here is where the not right in the head comes into play. KX500 in an atc frame.
There is a guy here in town that builds some of the baddest 500s around.
BB,  bolt on and go (compaired to the other option ) or 500 just for WOW. My buddy put a 500 in an 85 tecate but parts are just not there.  And I have 250r frames and parts laying around everywhere.

[The_Steve_Man]

One more question.  What is best for the most reliability?

[Pumashine]

What is best for the most reliability?

Cory, Duner on here ran 200 gallons of fuel on his first Puma without a problem. A good builder is your best bet to reliability.

[rsss396]

A cheap upgrade is the 132mm KTM rod for a little more strength and a slightly better rod ratio. But I have a friend that just received a new hot rod crank last week that has the new USA made rod on it(I believe the crank halves are still made in Taiwan) but he's said the new rods are thicker looking than the previous rods so I am not sure if the up grade is as important as it was.

in a drag setup my money is on a 431 Puma over a drag KX500, just because it has more cc's don't think it will be faster.
for a low end MX or trail setup the cc's do have the advantage and the 500 probably would work nice if the gearing works in a quad. Usually bikes transmissions have real tall first gears on them.

[The_Steve_Man]

The 500 is a crazy motor. The thing has massive power and with the power valves it pulls like a 4 stroke.
3 wheeler frames are essentially dirt bike frames so putting one in would just require cutting out the engine cradle and welding in a kx cradle.  
I have 4 frames so I might build a big bore and a 500

[udontknowme]

sounds like you need something with a PV although i dont care much for kawasaki. im not sure how well the kawasaki PV works. the only PV experience i have is with ktm and they seem to work pretty good. i would like to see a dyno graph overlay between PV/non PV pumas

[The_Steve_Man]

I think I have stray from my original topic. Thank you for all the input. I am definitely going with a bb bit not until next year.  I have a nice bottom end that I am going to use.
What got all this started was I read that a 310 is a little more than a stock cylinder so go with a 330 or bigger.  Then there are sphinx and puma.  Pv or no pv.
I understand using a good builder and everything works together as opposed to a cobbled mess that does no better than a stock motor.
I just like doing my homework so when I do it ,it is right the first time as oppsed to I should have done that. I ride trails and sand.
I will give arlen a call because I REALLY want one of his pipes.
Again thanks.  And if you have anymore suggestions keep them coming. I am sure it benifits other people in same boat as me.

[rsss396]

The problem with most all the PV motors for the trx cylinders whether they are a proX, ESR or CP Industries is they are the pressure operated style and can be confused by the pipe pressure signal. All OEM manufactures went to mechanical or electrical controled to better utilize them compared to the pressure style.
If you adjust the spring tension to tight on pressure operated PV's to keep the valve closed longer on the bottom-end it can close in the over-rev when pipe pressure starts dropping off. If you adjust the pressure lighter to give better over-rev it can open to soon on the bottom-end.

[udontknowme]

ya i dont recall any of the manufacturers using pressure control. probly for good reason. it would be much simpler by design but they normally used either mechanical or electric. now i think of it the only one to use electric that im aware of was the last generation of cr250 '02-'07. a mechanical system can almost never fail if its design is good. honda electric was pretty simple in design and should be trouble free if the servo motor doesnt go bad. one good thing about a mechanical system is they are often times adjustable. a adjustable electric unit would be possible and even a programable system which would be real cool but i think that would be to complex for a mass produced dirt machine