94Mike Posted October 25, 2011 Report Share Posted October 25, 2011 Question in title, How do powervalves work? Another question I have is, How is trinitys 400cc Cheetah kit? How would you compare it to the 421cc Cheetah? Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted October 26, 2011 Report Share Posted October 26, 2011 No personal experiance here but I have heard guys say that it is out dated. They said that you can build a bigger cc Cheetah Cub (non power valve) DM or DMX and it would have more bottom and top end than the power valved cheetah Quote Link to comment Share on other sites More sharing options...
springer Posted October 26, 2011 Report Share Posted October 26, 2011 No personal experiance here but I have heard guys say that it is out dated. They said that you can build a bigger cc Cheetah Cub (non power valve) DM or DMX and it would have more bottom and top end than the power valved cheetah so you are telling me that if you build a bigger motor, that it will have more power?? i dont buy it, i need proof. in spite of the trickery sherlock holmes speaks of above, i have a different opinion. comparing the cheetah to a dm or dmx i like comparing stockers to a cub. the power valves effectively lower the exhaust port while closed to produce more torque down low until they open. once they open, you now have an exhaust port as high, if not higher than any other drag ported cylinder (like the cub). you can change the point in the rpm's when the power valves are opened and closed to fine tune to what you like to ride. as far as the 400 compare to the 421, thats no different than any other size comparison. the 400 is actually a 392; stock stroke 68mm bore. the 421 is a +4 mil stroke, 68mm bore. I happen to own a 392 and absolutely love it. riding a pv motor is different than anything you have ever felt. i could easily trail ride the shit out of this motor and it actually has a pretty mean drag port, it just doesnt show until the pv's open. if you are considering one, dont hesitate. they are worth the time and money to get one setup properly. my advise is to find a builder that knows their way around a cheetah. by that, i mean that they know what to fix or watch out for from trinity that has given the cheeatah a bad wrap in some cases. if you use the domes trinity gives you with the "kit" i would almost promise you would have problems. mine needed a few adjustments and tweaks that trinity over looked, but it flat rips now. it really is a fun motor to ride. Quote Link to comment Share on other sites More sharing options...
springer Posted October 26, 2011 Report Share Posted October 26, 2011 A power valve changing the exhaust height or duration and timing. Not sure how the ones on the cheetah works, but I think it is pressure. wow, i guess i took forever to type that cuz your post wasnt there when i started, lol. yes, you are correct. they work off pressure. you can change the jet on the power vavle to have a bigger or smaller hole which would build pressure slower or faster which opens the valve or later or earlier. Quote Link to comment Share on other sites More sharing options...
94Mike Posted October 26, 2011 Author Report Share Posted October 26, 2011 (edited) Thanks guys, Springer would it make a good dune motor? Like a general hill shooter and duner? (more casual duning then hill shooting) Or is it more intended to be a drag motor. Another thing is, Do you have to run race gas or can it be set up for pump? Edited October 26, 2011 by 94Mike Quote Link to comment Share on other sites More sharing options...
springer Posted October 26, 2011 Report Share Posted October 26, 2011 Thanks guys, Springer would it make a good dune motor? Like a general hill shooter and duner? (more casual duning then hill shooting) Or is it more intended to be a drag motor. Another thing is, Do you have to run race gas or can it be set up for pump? personally, i think it would make a killer duner. in fact, this motor will eventually make it into a dune chassis when $$ permits. others might disagree and tell you to build a serval, but the cool thing about a cheetah is you can get the same or more more low end power and torque and still take it to race and hold your own pretty well; the only thing limiting you then is how your chassis is setup. chassis is just like a motor, the more its setup to dune, the lesser of a drag bike it will be and vise versa. as for pump gas, you can set it up for whatever you want; just need different domes. and whatever you do, dont get your domes from trinity. Quote Link to comment Share on other sites More sharing options...
94Mike Posted October 26, 2011 Author Report Share Posted October 26, 2011 personally, i think it would make a killer duner. in fact, this motor will eventually make it into a dune chassis when $$ permits. others might disagree and tell you to build a serval, but the cool thing about a cheetah is you can get the same or more more low end power and torque and still take it to race and hold your own pretty well; the only thing limiting you then is how your chassis is setup. chassis is just like a motor, the more its setup to dune, the lesser of a drag bike it will be and vise versa. as for pump gas, you can set it up for whatever you want; just need different domes. and whatever you do, dont get your domes from trinity. Thanks springer, I was going to go with a 421 serval, but now im starting to consider the 400pv. Quote Link to comment Share on other sites More sharing options...
springer Posted October 26, 2011 Report Share Posted October 26, 2011 Thanks springer, I was going to go with a 421 serval, but now im starting to consider the 400pv. you will likely get a lot of nah sayers since the serval is the new "hot" thing but i can speak from personal experience and i love my cheetah. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted October 26, 2011 Report Share Posted October 26, 2011 (edited) so you are telling me that if you build a bigger motor, that it will have more power?? i dont buy it, i need proof. in spite of the trickery sherlock holmes speaks of above, i have a different opinion. comparing the cheetah to a dm or dmx i like comparing stockers to a cub. the power valves effectively lower the exhaust port while closed to produce more torque down low until they open. once they open, you now have an exhaust port as high, if not higher than any other drag ported cylinder (like the cub). you can change the point in the rpm's when the power valves are opened and closed to fine tune to what you like to ride. as far as the 400 compare to the 421, thats no different than any other size comparison. the 400 is actually a 392; stock stroke 68mm bore. the 421 is a +4 mil stroke, 68mm bore. I happen to own a 392 and absolutely love it. riding a pv motor is different than anything you have ever felt. i could easily trail ride the shit out of this motor and it actually has a pretty mean drag port, it just doesnt show until the pv's open. Yep and you can gain torque by increaseing the stroke. Running a DM or DMX you would have more top end than the cheetah power valve motor. By the time you pay for Trinity's prices (you have to get the cheetah from trinity because they own the rights to it) you could have been well on your way to a larger motor. I cant find the posts where they talk about it because for some reason that Trinity thread was deleated after they became a site sponcer. I am just saying what was said in that thread. If you considering the cheeta you might look at your other options. Edited October 26, 2011 by jbooker82 Quote Link to comment Share on other sites More sharing options...
94Mike Posted October 26, 2011 Author Report Share Posted October 26, 2011 Yep and you can gain torque by increaseing the stroke. Running a DM or DMX you would have more top end than the cheetah power valve motor. By the time you pay for Trinity's prices (you have to get the cheetah from trinity because they own the rights to it) you could have been well on your way to a larger motor. I cant find the posts where they talk about it because for some reason that Trinity thread was deleated after they became a site sponcer. I am just saying what was said in that thread. If you considering the cheeta you might look at your other options. Im not looking for a huge motor, Also they were talking about the 485 i believe, not the 421 or 400. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted October 26, 2011 Report Share Posted October 26, 2011 Im not looking for a huge motor, Also they were talking about the 485 i believe, not the 421 or 400. Yea but they were talking by the time you get done paying trinity you could have the larger motor for the same ball park price. That is all I am saying you can get more for your money. Quote Link to comment Share on other sites More sharing options...
springer Posted October 26, 2011 Report Share Posted October 26, 2011 Yep and you can gain torque by increaseing the stroke. Running a DM or DMX you would have more top end than the cheetah power valve motor. By the time you pay for Trinity's prices (you have to get the cheetah from trinity because they own the rights to it) you could have been well on your way to a larger motor. I cant find the posts where they talk about it because for some reason that Trinity thread was deleated after they became a site sponcer. I am just saying what was said in that thread. If you considering the cheeta you might look at your other options. i was being sarcastic.. of course if you build a bigger motor you will make more power. this guy is talking about duning and you are telling him to build a DMX, Quote Link to comment Share on other sites More sharing options...
camatv Posted October 26, 2011 Report Share Posted October 26, 2011 larger motors create more tq and a lil more HP but for the massive CC increase adn additional costs of transmission, clutching, billet cases, special Huge pipes etc to me there is no comparison. compare apples to apples.. the serval is a good option but if $$$$ alows the PV motor is far supior. IF set up right. in my opinion the pv motors were to far and few to be widely understood. the setup was just flat wrong when they were released. the cylinder design is amazing in what it "fixes" from cub's, super cub's, and stock. the PV works by varying the exhaust duration. the spring can be changed and the release of gasses ( pressure ) can be tuned a lil bit. a 535 or 485 PV cheeta can be built to need one hell of a chassis to handle the broad power they produce. a pump gas cheeta wouldnt need a massive billet transmission or a 10 plate clutch to live. it wouldnt need a billet set of cases to stay together. of course a 4 mill DM wouldnt necessairly need all these items. BUT still uses a custom head, custom intake, reeds setup and needs major work to even top cases stock cases to fit. in my opinion apples to apples comparison they are an excellent choice for a dune/ drag motor they are just not the " BBD " right now. as far as being outdated? how do you figure that? to me the CUB is an outdated design. its a very necessary cylinder i believe but pure head design wise its based off of a cylinder bolt pattern of the 70's... Quote Link to comment Share on other sites More sharing options...
camatv Posted October 26, 2011 Report Share Posted October 26, 2011 http://en.wikipedia.org/wiki/Two-stroke_power_valve_system this is a great read. also IF the PV system is such a waste why did ALL the major manu's design, and use it on their motors? Quote Link to comment Share on other sites More sharing options...
94Mike Posted October 26, 2011 Author Report Share Posted October 26, 2011 Thanks Cam, So going from my motor (mods in sig) and upgrading it to a 400pv or 421 serval. Which would be the cheaper route? Quote Link to comment Share on other sites More sharing options...
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