camatv Posted August 10, 2014 Report Share Posted August 10, 2014 obviously you dont understand what the differnt port timings actually do??? the pv cheeta's seem slow because instead of a violent pipe HIT they just pull strong from a lower rpm and can be made to overrev and pull way harder than a normal 198; exahust can.. all i'm going to say.. what a joke. Quote Link to comment Share on other sites More sharing options...
jriffe23 Posted August 10, 2014 Author Report Share Posted August 10, 2014 sounds like i want to build a 421 smaller motors ftw!! Quote Link to comment Share on other sites More sharing options...
camatv Posted August 10, 2014 Report Share Posted August 10, 2014 Two seperate questions for two fellas. Mike, the first builder You took your cheetah to. Did he actually know what to do with a cheetah as in , he already had...... And why is it that Mat knew immediately what to change. Also, what did may change. Because I garuntee mat didn't just charge you to pull the PV's...... Did mat raise the exhaust or reconfigure it.... If so I gather that there isn't much room to massage the powervalves them selves. That would mean that to get the valve wide open with the new shearer exhaust port, the valve is so cut up that it's nonsense to even have it in there to do anything for the bottom end any way. (Some one please correct me if I'm wrong) Windy, on your old cheetah, what jets were in you're powervalves? And how did you verify they were opening all the way? Were they ever locked open? Just curious. I have my own thoughts and theories on why the cheetah is typically junk but I also have a few thoughts on what can make them work and I think the 485cc and 535 should definitely be doable. i will answer this.. i am convinced that most builders have no clue what the valve actually does, what makes it work, and what to do to keep it from screwing up. and even how to port for one. the valves are not that wide at least not as wide as most "builders" like to make the ports, so that infact with vavles in place will cause the valve to hang down in an too wide port ( i have seen this from multiple fucked up cheeta's i have worked on from multiple differnt shops) then this causes to much exhaust to blow past the valve causing really crazy opening to no opening at all of the valve. so they remove the pv completely install port matched blockoffs and just make the best of it. in fact the trinity 485 i started with i decided was so screwed up i couldnt use it and started with a bare casting. i use a very differnt exhaust port shape that i came up with then later noticed in a yamaha factory ported roberts cylinder from an old practice bike further validating my thoughts. most of them are also ran with the wrong oil in the mix and absolutely no valve maintenance at all. infact every valve i have seen was pluged up, jacked up, broken, blown seals etc etc etc. all from bad maintenance and the wrong oil in the fuel mix. so yea all those motors ran like shit.. infact most number you see posted are very very similar to servals with low port timings does that seem at all relavent>?? tells me the valves are stuck down hanging up halfway through their travel or just not opening the same or even similar.. of course nobody thinks about this i think. because they just say its a bad design.... Quote Link to comment Share on other sites More sharing options...
registered user Posted August 10, 2014 Report Share Posted August 10, 2014 seems like theres a variety of various PV designs. honda,yamaha,kawi,suzuki,ktm all used something alittle different. the only one im familiar with is ktm and it works pretty good. the main port is 67% of bore width which isnt far off from what you would expect to see on a nonPV port. of course you could make it even alittle wider if you wanted. getting to 70% probly wouldnt be a problem. so not all pv engines have narrow main ports. is cheetah guilitine operated by suction from the crankcase ? Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted August 10, 2014 Report Share Posted August 10, 2014 (edited) Yahtzee... I'll post this, a lot of info from Calvin Pollet. Not many people will read it but I'm sure guys like Cam might appreciate it. It lays some of people's assumptions about the cheetah design to rest. http://m.rx7club.com/showthread.php?t=727207&styleid=20 Edited August 10, 2014 by trickedcarbine Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted August 10, 2014 Report Share Posted August 10, 2014 Shit, I posted the wrong link this is 65 pages of cheetah design and a break down. Lotta TSS info to break down as well, but if you read the responses from Calvin is sorts some things out. http://www.apriliaforum.com/forums/showthread.php?246083-TSS-RS500GP-(round-3)-cylinder-problems Quote Link to comment Share on other sites More sharing options...
WINDYCITYJOHN400 Posted August 10, 2014 Report Share Posted August 10, 2014 Funny.....Calvin personally told me that the Super Cub/Serval was a superior design and that "It rendered the P.V Cheetah obsolete" His words....not mine. Carry on. 2 Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted August 10, 2014 Report Share Posted August 10, 2014 Proof? Quote Link to comment Share on other sites More sharing options...
WINDYCITYJOHN400 Posted August 10, 2014 Report Share Posted August 10, 2014 Proof? PROOF? How bout CAMATV posts a dyno run showing the amazing power of a cheetah. How bout ANY of the people who have such high hopes for a P.V. Cheetah find a dyno run out in the internet universe that backs up all that nonsense talk about potential. Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted August 10, 2014 Report Share Posted August 10, 2014 I doubt Cam wants to give you his Cheetah secrets. You have a history of taking other people's work and passing it off as your own. Quote Link to comment Share on other sites More sharing options...
WINDYCITYJOHN400 Posted August 10, 2014 Report Share Posted August 10, 2014 I doubt Cam wants to give you his Cheetah secrets. You have a history of taking other people's work and passing it off as your own. A - I don't want his secrets. I just wanna see a dyno run. REDLINE posts dyno runs without people figuring out his secrets. B- Who's work have I ever passed off as my own? Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted August 10, 2014 Report Share Posted August 10, 2014 The cheetah is exactley the same lay out as the cub, but with the larger intake and PV. Calvin states it in that thread. So how would it be a superior design? I just know the big ass intake means it takes some tricks to get the volume up to a good velocity and it has to take some thought when dealing with the fact that the auxiliary exhaust ports still trickle around the PV. Some say that's a problem, but in my mind I think it helps to keep the excessive volume of the intake at volume at lower RPM. (Please, some one say if I'm right or wrong) I'm really not wanting to debate what's better or why. I just would like to see this thread go in depth on the do's and dont's of cheetah set up. What most are over looking? What is really going on inside it? How to get it to do what every one thinks it should. Also, two neat thoughts that come from that Aprilla forum thread that Calvin started. 1. He stated that the cub and cheetah have exactley the same layout and exterior material so ports internally are the same. So the difference is the valve and intake. It was mentioned the possibility of using regular cub cyls with banshee intakes, and machining the same PV in to the cub. 2. Another unicorn cylinder idea Calvin and Stephan speak about. Setting up the internal cheetah lay out in side the DM castings. Still 250 intake though. This would mean extra material for rediculous transfer volume, excess material around the exhaust so a little bit could be done to have larger cooling capacity ( remember smaller bore then DM so the room would be there). Also the possibility of being able to make a wider PV blade to control the main exhaust port as well as the auxiliaries. To boot, this would mean new design, so no more exclusive trinity rights, lower cost, and more builders would be able to tinker with them..... Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted August 10, 2014 Report Share Posted August 10, 2014 Funny.....Calvin personally told me that the Super Cub/Serval was a superior design and that "It rendered the P.V Cheetah obsolete" His words....not mine. Carry on. I was told something similar, however he didn't state that it made a cheetah obsolete. Although what he said was close but due to politics with your friends at trinity. To paraphrase it..... Calvin said something along the lines of. "I wanted a solid all around cylinder that would do everything. So at the time trinity had the most advertised name in the business and the partnership on the cheetah was formed. Then I saw what was happening as I developed the cub cyl and knew that it was only a matter of time before I would have to make sure there was a solid rider's cyl. Eventually the demand grew so we developed the serval. It actually made enough low end that you really don't need the PV. With the cost where it is and the torque being as abundant, the cheetah is practically obsolete. If set up right, the cheetah is the hot ticket if you want it all, but cost and politics are killing sales. " This was at an off road show right after Andy posted some of the first serval runs. Quote Link to comment Share on other sites More sharing options...
Coupelx Posted August 10, 2014 Report Share Posted August 10, 2014 Dyno dyno dyno. Blah blah blah. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted August 11, 2014 Report Share Posted August 11, 2014 I only expect a few guys to chime in with insite, but here's another question. If so many peoples debates are about the peak numbers being such turd, even on cheetahs with Titan domes and clean up porting. When I see those graphs, some of them obviously make the ridiculous torque but flatline and make these 85-95 hp. So like cam is saying, "are the valves even opening?" What if those bikes were left exactley as is and had block offs installed and matched to the exhaust? I'd imagine it would be less torque for sure but it would show if the problem is within the PV it self or not right? Quote Link to comment Share on other sites More sharing options...
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