bansheeboie Posted June 7, 2012 Report Share Posted June 7, 2012 I have a 421 cheetah pv that I haventt set up yet, I was wondering if goin to a cub wud be better than the pv setup. Thanks Quote Link to comment Share on other sites More sharing options...
RadarRacing Posted June 7, 2012 Report Share Posted June 7, 2012 They are both amazing motors compared to stock. For a drag motor the cub is often times a little better as far as HP just the wqy it is cast. If the cheetah is ported and done right it would be right with the cub. As far as riding and having lowend as well as screaming topend like for dune riding the cheetah with powervalves will win hands down. As they are cast and not ported the cub will be about 8 hp better than the 421 cheetah. Quote Link to comment Share on other sites More sharing options...
springer Posted June 7, 2012 Report Share Posted June 7, 2012 the cheetah has a lot bigger intake runners. in my opinion, there is more potential for power out of the cheetah than the cub. others may disagree, but if properly setup, i think a cheetah has many benefits to a cub if running pv's. i run a 392 cheetah myself, so maybe i am a little biased, but... just my opinion. if you already have the cheetah stuff, might as well go for it. if not, the cub has a few advantages like the ability to run a stock style head, reed cages, etc. Quote Link to comment Share on other sites More sharing options...
NickisGod Posted June 7, 2012 Report Share Posted June 7, 2012 Do some reading about the cheetahs domes. Once u correct that a cheetah w/ pv is a better option. Like ^^^ said the cheetah uses 250r reeds and they are alot larger. Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted June 7, 2012 Report Share Posted June 7, 2012 the cheetah has a lot bigger intake runners. in my opinion, there is more potential for power out of the cheetah than the cub. others may disagree, but if properly setup, i think a cheetah has many benefits to a cub if running pv's. i run a 392 cheetah myself, so maybe i am a little biased, but... just my opinion. if you already have the cheetah stuff, might as well go for it. if not, the cub has a few advantages like the ability to run a stock style head, reed cages, etc. In the smaller engine sizes (anything below the 10mil cheetah) the larger intakes actually lower your CCR (crank-case compression ratio) and can actually adversely affect the way the charge is forced into the transfers and slow everything down. (learned that from calvin from CP Industries over on planetsand) I too have a powervalve cheetah and love it. The powervalve smooths the power out very nicely and makes for a great dune setup. Mine has been ported and runs great, but I still think there is a lot of potential left in it. If done right the cheetah is a great motor. Get good domes, good pistons, correct gaskets, check all your clearances, get it ported, etc. If you want something you can just slap together and make good power go with the cub. - Jared Quote Link to comment Share on other sites More sharing options...
WINDYCITYJOHN400 Posted June 8, 2012 Report Share Posted June 8, 2012 If done right your well built P.V. Cheetah will have lower overall power than a cub. Not just peak. Some of us have spent YEARS doing a WIDE VARIETY of porting, timing. compression, dome, pipe research to figure out that the Cheetah dose NOT have a lot of hidden potential. (BigRed you have a chance as power with your 535 10 mill) But if we're talking about a 421 P.V vs a 421 cub.......The 421 P.V. motor will be hard pressed to make 4 mill stock cylinder numbers. I've owned - 400 Cheetah with block-off plates 400 Cheetah with Power Valves 472 Cheetah with Power Valves 472 Cheetah with block-off plates 492 Cheetah with block-of plates 6 different sets of domes from 3 different builders Trinity, CPI and Shearer pipes and the bike and motors have had more dyno time that a NASCAR restrictor plate motor. (I've got access to a dyno, I've got a key to the place, I pay nothing for dyno time....I'm not talking out my ass. I've burnt many a jug of fuel to learn what I know first hand. Was that short enough for you Tyler? Quote Link to comment Share on other sites More sharing options...
WINDYCITYJOHN400 Posted June 8, 2012 Report Share Posted June 8, 2012 (edited) I'm happy to be now sporting a new Redline 10 mill Cub. Now I have a new motor to thrash on the dyno for the rest of the year. Edited June 8, 2012 by WINDYCITYJOHN400 Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted June 8, 2012 Report Share Posted June 8, 2012 If done right your well built P.V. Cheetah will have lower overall power than a cub. Not just peak. Some of us have spent YEARS doing a WIDE VARIETY of porting, timing. compression, dome, pipe research to figure out that the Cheetah dose NOT have a lot of hidden potential. (BigRed you have a chance as power with your 535 10 mill) But if we're talking about a 421 P.V vs a 421 cub.......The 421 P.V. motor will be hard pressed to make 4 mill stock cylinder numbers. I've owned - 400 Cheetah with block-off plates 400 Cheetah with Power Valves 472 Cheetah with Power Valves 472 Cheetah with block-off plates 492 Cheetah with block-of plates 6 different sets of domes from 3 different builders Trinity, CPI and Shearer pipes and the bike and motors have had more dyno time that a NASCAR restrictor plate motor. (I've got access to a dyno, I've got a key to the place, I pay nothing for dyno time....I'm not talking out my ass. I've burnt many a jug of fuel to learn what I know first hand. Was that short enough for you Tyler? Out of those, which one did you like the most and which one ran the best? What was the setup on the best one you had? Just curious. Quote Link to comment Share on other sites More sharing options...
possum Posted June 8, 2012 Report Share Posted June 8, 2012 If done right your well built P.V. Cheetah will have lower overall power than a cub. Not just peak. Some of us have spent YEARS doing a WIDE VARIETY of porting, timing. compression, dome, pipe research to figure out that the Cheetah dose NOT have a lot of hidden potential. (BigRed you have a chance as power with your 535 10 mill) But if we're talking about a 421 P.V vs a 421 cub.......The 421 P.V. motor will be hard pressed to make 4 mill stock cylinder numbers. I've owned - 400 Cheetah with block-off plates 400 Cheetah with Power Valves 472 Cheetah with Power Valves 472 Cheetah with block-off plates 492 Cheetah with block-of plates 6 different sets of domes from 3 different builders Trinity, CPI and Shearer pipes and the bike and motors have had more dyno time that a NASCAR restrictor plate motor. (I've got access to a dyno, I've got a key to the place, I pay nothing for dyno time....I'm not talking out my ass. I've burnt many a jug of fuel to learn what I know first hand. Was that short enough for you Tyler? Good info wcj400 Quote Link to comment Share on other sites More sharing options...
MarineNYC Posted June 8, 2012 Report Share Posted June 8, 2012 Im liking this post. Lets hear it. Quote Link to comment Share on other sites More sharing options...
WINDYCITYJOHN400 Posted June 8, 2012 Report Share Posted June 8, 2012 Out of those, which one did you like the most and which one ran the best? What was the setup on the best one you had? Just curious. Well, I'll say that all the motor configurations ran better overall with the block-off plates installed. (I know you have had a few Twister motors, but those power valves are a little better.) But as far as the power valve theory goes....I can only Echo the statements of Tim at Titan...... "Power valves don't Boost power, they manage it by softening the hit as the motor comes on the pipe. They were developed to make it possible for a 2-stroke motorcycle to come out of the corner WITHOUT blowing off the tires." Unfortunately many believe that the power valves provide more low end torque. And to some extent that is true....if the motor has a massive exhaust port the power valve will help the motor by BLOCKING that big port till the motor is making so much power that it can move the power valve blade out of the way. But it comes at the expense of some mid and upper power. I dune mine so the P.V's were a total waste. Once I put the block-offs in, the bike came alive. But if your trying to ride woods/trails/MX you might find they help. (But I would argue that if your running a motor like that in that kind of ride style....you might have picked the wrong cylinder.) The 472 with the full porting/block-offs (on 110 race gas) made 81HP with CPI BB's and 95HP with both Shearer SB's and BB's. (I think we can all do that with a mail order 421 cub kit) Not all that impressive for a motor with the massive amount of talent that was visited on it. The 400 set-ups were JUNK! (Trinity kit. All tech help from Jaymes. ) I was loosing to a 350 bike in our group with a single carb and FMF fatty's (We have a dyno now and tested his bike and he is making 65HP.) I never got a chance to dyno the 400, but it had their domes, detonated no matter what you had for jets, ate O-rings, had Trinity pipes and was just JUNK!) The 472 P.V. motor was a basic kit and had all the same issues the 400's had. (That's why I preach about getting custom cut domes. Tim at Titan knew what to do for domes.) That motor didn't detonate any more...but still was a limp noodle as far as power. So we did the full port job on it and it was very nice. Still not as strong as you would have figured for a 472cc motor....but fun. It got even better when I pulled the power valves. We decked the bottom of cylinders when I went to 492 (moving away from the full drag porting and chasing the Serval craze) it gained low end torque and still pulled on the top end. 20 more cc's of fun! Ok, take a screen shot of this because it is a little long and is filled with my real world info based on TONS of dyno testing, opinions gathered from some of the top builders Tim Bond/Nate McCoy, as well as my own Butt dyno feedback. So I've set myself up to be called an idiot and have this entire post deleted. Sorry....I tried to keep it short. By Monday the entire thing will be gone. Quote Link to comment Share on other sites More sharing options...
rjdgriff Posted June 8, 2012 Report Share Posted June 8, 2012 Soooooo? How do you feel about your 492 vs a 421 serval? How do they compare? What are the ups and downs of both? What are the strong points? What are the weak points? Which would you recommend? And what kind of set up would you recommend for each? Quote Link to comment Share on other sites More sharing options...
papa_smurf49319 Posted June 8, 2012 Report Share Posted June 8, 2012 Good info! Really interesting read, and nice to hear some real world results! Quote Link to comment Share on other sites More sharing options...
springer Posted June 8, 2012 Report Share Posted June 8, 2012 Everyone is saying good info... Maybe good personal testimony but this guy obviously had issues he never figured out. My 392 cheetah WITH pv's runs awesome and I've never had any problems since we fixed what trinity did. So, to say the 400's are junk is incorrect. I understand you had a shitty experience, and I'm not taking up for trinity in the least, but you obviously had issues you never worked out because these motors can run good and do. I dont want to get into an argument about pv's because you wil just claim to have learned from and quote from the pro's, but the are not bad as you make then out to be. If properly tuned they will be up and out of the way so there is no way they wil hurt top end power like you say. Sucks you had all that bad experience with all your motors, but they aren't junk like you portray then to be. Quote Link to comment Share on other sites More sharing options...
DallasGDub Posted June 8, 2012 Report Share Posted June 8, 2012 My 392 cheetah WITH pv's runs awesome and I've never had any problems since we fixed what trinity did. x2, it is a runner for sure. Quote Link to comment Share on other sites More sharing options...
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