mopar1rules Posted October 31, 2013 Report Share Posted October 31, 2013 Don't know which cylinders I should go with for trail riding and playing around in fields etc. Cheetah cub 421 (68mm bore +4mil stroke), cheetah with power valves, or stock cylinders with big bore sleeves. I currently have stock cylinders that are ported for the 4mil with 4mil long rod crank, 15:1 comp, vforce2 reeds, timing +4, r2 pipes, bored stock carbs, airbox modded, and case ported. Just looking for some more hp. I guess the cheetah with power valves use cr250 reeds while the cub uses the stock reeds. Which setups have you guys used and had good luck with? Thanks. Quote Link to comment Share on other sites More sharing options...
LCW Posted October 31, 2013 Report Share Posted October 31, 2013 Serval... Quote Link to comment Share on other sites More sharing options...
Strm Trpr Posted October 31, 2013 Report Share Posted October 31, 2013 how much power do you need? If you're thinking about aftermarket nikasil cylinders, then Redline can port 421 Servals, (68mm w/+4mil) on pump gas to 80+ rwhp. http://bansheehq.com/forums/index.php?showtopic=150213&hl=redline A Redline 465cc 10mil Serval would probably be pushing ~95rwhp. Quote Link to comment Share on other sites More sharing options...
Hazzard Racing Customs Posted October 31, 2013 Report Share Posted October 31, 2013 serval for any trail bike Quote Link to comment Share on other sites More sharing options...
Coupelx Posted October 31, 2013 Report Share Posted October 31, 2013 Cheetah motherfuckers! Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted October 31, 2013 Author Report Share Posted October 31, 2013 Do the cheetahs with power valves have the same port timings as the cubs? Or do they have higher exhaust port timings, due to them having power valves? The reason im not really looking into serval cylinders, is because I thought I read on here that they dont take well to high compression and some of the higher rpm pipes?? I thought people weren't able to get them to run like ported cubs?? Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted October 31, 2013 Report Share Posted October 31, 2013 Do the cheetahs with power valves have the same port timings as the cubs? Or do they have higher exhaust port timings, due to them having power valves? The reason im not really looking into serval cylinders, is because I thought I read on here that they dont take well to high compression and some of the higher rpm pipes?? I thought people weren't able to get them to run like ported cubs??Different port lay out between cheetah and cheetah cub. The whole cub line up seems to do really well on a moderate compression. 165-175 is nice. That actually is plenty. The servals honestly don't need compression or exotic fuel to have low end grunt. That is taken care of in the port lay out. And yes the servals do seem to be ok with the bigger in frame pipes. You can always taylor it to be somewhere between a cub and serval if need be. As for your thought on not being able to get it to run like a ported cub? Well, no. It shouldn't because it's not a cub. But you can port it heavily and get it transformed in to a cub. Also in the original post you mention big bore sleeves for your current 4 mil. NO WAY! Do your self a favor and move in to an aftermarket set up. There are so many headaches and problems that all come at the cost of lots of money and reliability issues. To boot it doesn't even run much better. Stock cylinders just aren't up to the task of flowing properly to feed big bores. Sure you could weld the transfers and grind on them with the cylinder liners out and maybe triple the exhaust, but $$$$$$. 1 Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted November 1, 2013 Author Report Share Posted November 1, 2013 That's kinda what I was thinking with the stock cylinders and big bore sleeves...... nor being able to flow properly for 68mm+ bore sizes. I feel the transfer runners on the stock cylinders aren't up to the challenge. I guess I will stray from the OEM cylinder big bore idea then. I thought I remember reading somewhere that the cheetah cubs with PV's were expensive to setup right and dial in, to make power and that the non PV cubs made hp more easily??? Any truth to that? I like the idea of the power valve, so I can have low end and top end. Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted November 1, 2013 Report Share Posted November 1, 2013 Yeah, pv cylinders are more money but if done right they will have the same top end pull but still be able to lug it around. The regular cubs are consistent and simple these days and can be had cheaper then almost any other cylinder. Not to trail friendly though Quote Link to comment Share on other sites More sharing options...
WINDYCITYJOHN400 Posted November 1, 2013 Report Share Posted November 1, 2013 Do a search on the P.V. issues. I've posted plenty of info regarding why you should either go with a serval or a cub instead of the cheetah. "If done right" = spending twice as much to fix all the cheetah issues. Quote Link to comment Share on other sites More sharing options...
Coupelx Posted November 1, 2013 Report Share Posted November 1, 2013 More expensive to setup but far better for a playbike i think. As far as tuning its really no more expensive. The valves are tuned with a keihen main jet. I started drilling mine out until i liked how it felt. Downside is they require a builder familiar with a cheetah to make the most of it. I also prefer 68mm bore cheetahs to their bigger bore counterparts due to exhaust port width restrictions due to the valve. The bigger piston aggrivates this. Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted November 1, 2013 Author Report Share Posted November 1, 2013 So, you use a keihin main jet to adjust how and when the power valves open? Sounds like a shitty setup to me. I assumed they worked like the exhaust valves found on the Polaris and Ski-doo sleds. I think I will stick to the cub and give it high comp for better bottom end. Quote Link to comment Share on other sites More sharing options...
rjdgriff Posted November 1, 2013 Report Share Posted November 1, 2013 You should build a serval if you want something that will be fun and easy to ride in the trails. Redline has gotten 85-90hp on a ported 4mil serval and still has 55fpt and that is on PUMP gas. My old 421 serval was not ported but it had awesome power in the trails and when it came to drag racing it would run with the 4mil stock cylinders no problem. I would consider the serval still if I were you. Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted November 1, 2013 Author Report Share Posted November 1, 2013 Yeah I guess. The trails I ride are open and have many long straights. Which is why I didn't think it would be an issue with the cubs high exhaust timing and slight lack of low end. Quote Link to comment Share on other sites More sharing options...
Coupelx Posted November 2, 2013 Report Share Posted November 2, 2013 So, you use a keihin main jet to adjust how and when the power valves open? Sounds like a shitty setup to me. I assumed they worked like the exhaust valves found on the Polaris and Ski-doo sleds. I think I will stick to the cub and give it high comp for better bottom end. Says the guy with the retard thread. Suit yourself. 1 Quote Link to comment Share on other sites More sharing options...
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