camatv Posted January 13, 2011 Report Share Posted January 13, 2011 build the chassis to suit the style of riding nothing over +4 for trails and +2 to +3 a-arms on the front suspension to match. hell i'd ride it in a stocker any way you look at it a serv should be a very nice rideable motor. NOT a drag engine but a top end for the rest of us. i'm hoping to do a 350 serv here before too long. i know the 421 is popular but i am curious on a 350cc. Quote Link to comment Share on other sites More sharing options...
J-Madd Posted January 13, 2011 Report Share Posted January 13, 2011 The Toomeys do not fair well on this motor. Not once in the power curve did they rise above CPI or Shearer inframes. You'd be losing all over. I can assume the pro-circuits are going to be just as miserable. Fact is, this is just too much motor for those pipes. They simply cannot support the amount of air these move. They'll choke up the motor. Theory holds that an inframe drag pipe such as the CPIs will support top end and overrev to compensate for the low exhaust port timing, while that low timing supports a better powerstroke at lower rpm. Also, the low exhaust port timing means cooler exhaust temps than a cub or hot ported stock cylinder. This keeps the pipe cool, and a cool pipe will produce more low-mid range power. This is one of the reasons alky makes more torque, is that it keeps your pipes cooler than race fuel. As for carburetors, I think 33mm carbs are a minimum also. Some builders have tested with 38mm carbs and been satisfied! I have been told on several occasions by one of my builders that the CPIs favor higher port timing than Shearers. I have also confirmed this on the dyno with one particular engine that had 200* exhaust duration. Sorry to get off subject. Just wanted to clarify that CPIs don't necessarily like low port timing (not that your implying that); but will be a better choice than lots of other pipes, as mentioned. Quote Link to comment Share on other sites More sharing options...
gotta_goatsfast Posted January 13, 2011 Report Share Posted January 13, 2011 I have been told on several occasions by one of my builders that the CPIs favor higher port timing than Shearers. I have also confirmed this on the dyno with one particular engine that had 200* exhaust duration. Sorry to get off subject. Just wanted to clarify that CPIs don't necessarily like low port timing (not that your implying that); but will be a better choice than lots of other pipes, as mentioned. No doubt the CPIs will match up better with higher port timings. Even with the CPIs and Shearers, the Serval humps over around 10-10.5K. It is interesting how they pull just as well down low as other pipes. I am curious if any pipe builder plans on designing a pipe tuned for lower port timings yet flows enough for a 421. Sort of a pipe designed to hit like a Pro-circuit but flows enough to keep up with an advanced 421... Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted January 14, 2011 Report Share Posted January 14, 2011 small carbs and mid pipes, fail miserably on the servals, and high comp and high timing also dont work well. you just built the worst serval ever, like mine LOL, the port timing numbers they have is geared more towards this setup. Stuffing big drag pipes and big carbs on them is a little goofy. I tend to agree with snop's view of setup on these. Personally I would never buy a set. I don't like CP Industries products. I will spend the extra money on twister cylinders any day. JMO. Quote Link to comment Share on other sites More sharing options...
Fastassbanshee96 Posted January 14, 2011 Report Share Posted January 14, 2011 So what do you guys think about running R2 pipes on these cylinders with 35mm air strikers on pump gas? Quote Link to comment Share on other sites More sharing options...
okbeast Posted January 14, 2011 Report Share Posted January 14, 2011 LOL, the port timing numbers they have is geared more towards this setup. Stuffing big drag pipes and big carbs on them is a little goofy. I tend to agree with snop's view of setup on these. Personally I would never buy a set. I don't like CP Industries products. I will spend the extra money on twister cylinders any day. JMO. But the dyno runs have shown that the Shearers make more usable power than the T-5's. Granted not EVERY setup has been tested, but so far the so called "drag pipes" are out performing the mid-top end pipes. Quote Link to comment Share on other sites More sharing options...
dirtydownunder Posted January 14, 2011 Report Share Posted January 14, 2011 unfortunately that view is wrong, as i had the same setup in mind but dyno testing has proved otherwise. Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted January 14, 2011 Report Share Posted January 14, 2011 But the dyno runs have shown that the Shearers make more usable power than the T-5's. Granted not EVERY setup has been tested, but so far the so called "drag pipes" are out performing the mid-top end pipes. Guess it depends on what you're doing with the bike and where you want the power to come on... Each setup will be different, and not everyone would want them to run the same. If I was going to run drag pipes and big carbs I would just get a set of cubs. That's just me though... and truth be told I would rather go with ported stock cylinders or twister cylinders over the serval or cub anyway. Quote Link to comment Share on other sites More sharing options...
SuperMex Posted January 14, 2011 Author Report Share Posted January 14, 2011 I think a set of R2's and some 33's will make that motor best at what its designed for which is low to mid Quote Link to comment Share on other sites More sharing options...
SuperMex Posted January 15, 2011 Author Report Share Posted January 15, 2011 Decision is made im getting my Serval in spring now to decide how and what I want on it any suggestions would be greatly appreciated. I ride sand Glamis mostly not a hill shooter but do from time to time I want a setup that will rip in the mid especially, which is where im mostly at in the powerband. Thanks again Quote Link to comment Share on other sites More sharing options...
supersider Posted January 16, 2011 Report Share Posted January 16, 2011 Decision is made im getting my Serval in spring now to decide how and what I want on it any suggestions would be greatly appreciated. I ride sand Glamis mostly not a hill shooter but do from time to time I want a setup that will rip in the mid especially, which is where im mostly at in the powerband. Thanks again i run 33pwks on my stock cylinder vitos superstock piston and it runs hard for what it is! with fmf pipes! i would at least run 35's. i ran 35s on my 421 stock ported cylinder and it hauled ass on the top and had great bottom end power and that was with shearer inframes small bore Quote Link to comment Share on other sites More sharing options...
rubberneck Posted January 16, 2011 Report Share Posted January 16, 2011 Mccoy made 80 Hp on a 4mil serval with stock carbs stock reed and CPIs. Im thinking you dont need real huge carbs for this set up. I think 33s and CPIs should kick ass. I just cooked down my stock cylinder 4mil so im considering going to a serval. I have CPIs and 34 mm lectrons on the bike. Quote Link to comment Share on other sites More sharing options...
SuperMex Posted January 16, 2011 Author Report Share Posted January 16, 2011 Mccoy made 80 Hp on a 4mil serval with stock carbs stock reed and CPIs. Im thinking you dont need real huge carbs for this set up. I think 33s and CPIs should kick ass. I just cooked down my stock cylinder 4mil so im considering going to a serval. I have CPIs and 34 mm lectrons on the bike. I think a lot of people over carburate and for the serval its a duners dream so why put huge carbs on it I think some 33's is a great size crab for this cylinder thats what i'm going with Quote Link to comment Share on other sites More sharing options...
camatv Posted January 16, 2011 Report Share Posted January 16, 2011 the serv may have low port timings BUT it has massive port flow it can move more air/ fuel in less degree's of rotation. and the older style of pipes are just not used to that i t was explained in detail on atvdragracers by a well know builder/ dyno proven results. after reading the explanation it is obvious why the ole trail pipe dont work well. the serv may have low port timings but its a differnt animal and is going to want a diff pipe, head combo than a stock cylinder motor. ( just like a cub) just cause it fits don't mean it works,,, what works on stockers isnt going to work ( optimal) on this cylinder. at least from what i see. now if your happy with a 65hp replacement cylinder with all your parts you have now its doable. but the easy 80hp they are capable of is right there. and they will be rideable with any set up. they are not a DRAG cylinder i see them as a nice option for replaceing heavy ported stockers that are over on bore or need sleeved. OR a good idear instead of porting stockers. IF you are going to go stroker and big bore. rember dirtbike cylinders for a LONG time have had big pipes, BIG carbs 38mm is norm on a 125cc! and they also have a huge port flow cylinder. ( and pv's) Quote Link to comment Share on other sites More sharing options...
SuperMex Posted January 16, 2011 Author Report Share Posted January 16, 2011 the serv may have low port timings BUT it has massive port flow it can move more air/ fuel in less degree's of rotation. and the older style of pipes are just not used to that i t was explained in detail on atvdragracers by a well know builder/ dyno proven results. after reading the explanation it is obvious why the ole trail pipe dont work well. the serv may have low port timings but its a differnt animal and is going to want a diff pipe, head combo than a stock cylinder motor. ( just like a cub) just cause it fits don't mean it works,,, what works on stockers isnt going to work ( optimal) on this cylinder. at least from what i see. now if your happy with a 65hp replacement cylinder with all your parts you have now its doable. but the easy 80hp they are capable of is right there. and they will be rideable with any set up. they are not a DRAG cylinder i see them as a nice option for replaceing heavy ported stockers that are over on bore or need sleeved. OR a good idear instead of porting stockers. IF you are going to go stroker and big bore. rember dirtbike cylinders for a LONG time have had big pipes, BIG carbs 38mm is norm on a 125cc! and they also have a huge port flow cylinder. ( and pv's) I agree that's why I'm running rocket R-2s just don't agree that you need huge carbs on a cylinder that's not made for dragging you will sacrifice some bottom end but hey the more people buy these and we start to see different setups then we can figure out what suits each riding style especially based up with dyno proof Quote Link to comment Share on other sites More sharing options...
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