bonbon Posted January 6, 2009 Report Posted January 6, 2009 I'd just like some opinions on this. I'm either building a 421 Cheetah powervalve, or a 521. I want a potent hillclimber where I can climb most anything I want to at half throttle or just having to blurp it to make it up. Course I can still just pin it and go too. I'm leaning towards the 10 mill 73mm bore 521. I have to get the cases trenched and bored and overall will probably cost about $1000 more than the 4 mill would. Do you guys think that the increase in torque and overall power would be worth the extra grand or not? I understand more power is always good and that's what I want but I'm just afraid I'll be disappointed with the 4 mill. I'll be getting rid of a stock stroke cub that was a strong runner but had zilch for bottom end. Quote
okbeast Posted January 6, 2009 Report Posted January 6, 2009 My 421 has plenty of ooomph so far to get me up what I've thrown at it. I've only got 165lbs of compression too. I threw the t-5s on it this last weekend and I swear it was a torque monster. Otherwise anytime it would bog if it's jetted well you can just blip the throttle and it'll spin the tires and get ya goin again. Quote
bonbon Posted January 6, 2009 Author Report Posted January 6, 2009 Do you have the powervalve motor or a 421 cub? I really want one hell of a torquey beast. And I would like to shake every now and then after I ride it going holy shit what did I just do....lol. Quote
2001Stroker Posted January 6, 2009 Report Posted January 6, 2009 Here's me trying to get opinions on a couple different motors. Cheetah PV 521 is what I am going with. Lots of good answers in this thread, from some good sources. Good luck with the build. Quote
bonbon Posted January 6, 2009 Author Report Posted January 6, 2009 Here's me trying to get opinions on a couple different motors. Cheetah PV 521 is what I am going with. Lots of good answers in this thread, from some good sources. Good luck with the build. Thanks for the link. I must have missed your post over here. Lots of good info there and pretty much set me on the 521 now.......Now I just need to find my flywheel puller so I can spit the cases and ship them off to someone! Quote
FireHead Posted January 6, 2009 Report Posted January 6, 2009 I'd just like some opinions on this.I'm either building a 421 Cheetah powervalve, or a 521. I want a potent hillclimber where I can climb most anything I want to at half throttle or just having to blurp it to make it up. Course I can still just pin it and go too. I'm leaning towards the 10 mill 73mm bore 521. I have to get the cases trenched and bored and overall will probably cost about $1000 more than the 4 mill would. Do you guys think that the increase in torque and overall power would be worth the extra grand or not? I understand more power is always good and that's what I want but I'm just afraid I'll be disappointed with the 4 mill. I'll be getting rid of a stock stroke cub that was a strong runner but had zilch for bottom end. The 10mil engine will be less reliable due to the increased power outoput beating up the drivetrain. If you go with billet cases and a robust clutch/trans., then you probably won't have a problem. :geek: Quote
2001Stroker Posted January 6, 2009 Report Posted January 6, 2009 Just got done emailing back and forth with Andy at M&M ATV. The Cheetah PV motor only comes in 73mm bore. Makes it 535cc's. Quote
FireHead Posted January 7, 2009 Report Posted January 7, 2009 Just got done emailing back and forth with Andy at M&M ATV. The Cheetah PV motor only comes in 73mm bore. Makes it 535cc's. I thought you could get a 78mm Cheetah? Quote
okbeast Posted January 7, 2009 Report Posted January 7, 2009 Mine is just a cub. But believe me a 421 powervalve would be more than enough power to do what you want with it. Plus the reliability of a 4mil and availability of parts. I would do it in a heartbeat over a 10mil. Quote
2001Stroker Posted January 7, 2009 Report Posted January 7, 2009 I thought you could get a 78mm Cheetah? I'm sorry, I made that confusing. You can get them in different sizes, yes. But the one cloeset to 72 is 73mm. So, there is no 521cc, you would have to go up to a 535cc. okbeast, according to all of the builders/racers that I've spoke to, there are no more reliability issues with the 10mil than the 4mil. You just have to upgrade on transmission parts. Availability for parts is just the same as any other aftermarket Banshee cylinder. They've been making Cheetah cylinders longer than the Cubs. The cub uses stock Banshee stuff, and the Cub uses stock Honda CR intakes/reeds. The heads come with removable domes, and you can get them with either a small flange or big flange exhaust outlet. The Cheetah uses Weisco pistons, rings, wristpins, and bearings. The only thing different would be the power valves. And you can get those pretty much at any CP Industries dealer. Quote
FireHead Posted January 7, 2009 Report Posted January 7, 2009 I'm sorry, I made that confusing. You can get them in different sizes, yes. But the one cloeset to 72 is 73mm. So, there is no 521cc, you would have to go up to a 535cc. okbeast, according to all of the builders/racers that I've spoke to, there are no more reliability issues with the 10mil than the 4mil. You just have to upgrade on transmission parts. Availability for parts is just the same as any other aftermarket Banshee cylinder. They've been making Cheetah cylinders longer than the Cubs. The cub uses stock Banshee stuff, and the Cub uses stock Honda CR intakes/reeds. The heads come with removable domes, and you can get them with either a small flange or big flange exhaust outlet. The Cheetah uses Weisco pistons, rings, wristpins, and bearings. The only thing different would be the power valves. And you can get those pretty much at any CP Industries dealer. I think you mean the Cheetah used the CR reeds............ :thumbsup: Quote
J-Madd Posted January 7, 2009 Report Posted January 7, 2009 The 10mil engine will be less reliable due to the increased power outoput beating up the drivetrain. If you go with billet cases and a robust clutch/trans., then you probably won't have a problem. :geek: Dang, billet cases would be overkill on a 10 mil!! But no doubt more reliable. Quote
bonbon Posted January 7, 2009 Author Report Posted January 7, 2009 Well I'm leaning back towards the 4 mill and probably 73mm bore. I can save a bunch of money doing that and it might get kind of tight here in the next 4 months and depending on how the oilfield goes out here really tight. After I get my motor apart and stare at it for about a day I'll probably decide. I lost my damned flywheel puller so its been on hold for a few days but should get my new one today and be able to finish splitting the cases in just 20 minutes or so. Quote
FireHead Posted January 8, 2009 Report Posted January 8, 2009 Well I'm leaning back towards the 4 mill and probably 73mm bore. I can save a bunch of money doing that and it might get kind of tight here in the next 4 months and depending on how the oilfield goes out here really tight. After I get my motor apart and stare at it for about a day I'll probably decide. I lost my damned flywheel puller so its been on hold for a few days but should get my new one today and be able to finish splitting the cases in just 20 minutes or so. Cheap ass................ :biggrin: Quote
278 Posted January 8, 2009 Report Posted January 8, 2009 Man your making me jealous lol. I really want to build like a 10mil. or a 4mil cub or something along those lines, but Im right in the middle of my trail bike project and beings all I do is ride trails and MX tracks, since theres no dunes here and I dont want to do asphalt I won't find much use in it Quote
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