gotta_goatsfast

I think its a good start. One item I would scratch off the list is the lightened flywheel. It makes your bike sound really fast in neutral, but after talking to a few builders it shows no notable increase in acceleration and takes away from the engines inertia during launch. Don't forget to set up the rest of your quad for hills. I would invest in good tires, a longer swingarm, and some budget shocks atleast!

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...

From a power aspect, forged internals won't make much of a difference. BUT, having a high quality rotating assembly provides a good reliable foundation for future "gofast" parts. You should look into sending your jugs out to a site sponsor. Call around until you find one that you feel real good about. Talk to them about what you want out of your cylinders and your riding style. Then, send your jugs off to be ported! If your cylinders are in good shape, all you'll need is a hone and some rings. Once the rings have seated and the carbs have been jetted, bricks will be shat! Option two, is to spend some coin on a CP industries Serval cub. You can keep your crank and pick up a 68X54 block, or sell your crank, purchase a +4mm stroker crank and a 68X58 serval. This will have a broad powerband that I feel is an ideal compromise for guys who ride their banshee in multiple situations (trails to racing).

Don't forget Mattoon Machine's 4 cylinder cases. What in the hell are those beasts capable of puttin out for power and torque?

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!

Your half way there! Sell the top-end and 28mm carbs on here to recoup some of the funds to build (or have built) a 421 serval.

http://farmandsandtoys.com/partdetail.asp?partid=111

If this turns into a penis-length contest, my pick is to stuff an aluminum 4 valve V8 with one... no two turbochargers.

Thack, porting WILL make the difference. Spend some time searching, you will find just about any site sponsor is capable of magic with your jugs. I choose to use Jeff from Farmandsandtoys.com (FAST) for all of my banshee needs. I've always admired James Smart (Passion Racing) and his Passion 12 port engines. Also, there are some cheap mods you can do to the transmission to help it shift easier. Anyway, once you have searched until your clicking finger bleeds and your eyes are burning and dry, post up a new topic with any additional questions that have not been answered (that way we keep this thread on track)

I too am currently building a 68x58 serval. To compliment my build, I'm assembling the engine with... HotRods 58mm crank with 115mm rods (TZ bearing and full C-clip) CPI pipes (I'll explain why later) 35mm PWK carbs-168 main, 52 pilot, CEL needle middle clip is how I have them set up for first fire Pro-Design head with 22cc domes for pump fuel Timing advanced 4 degrees Magnum clutch basket with FAST clutch and light springs DD lock out Stock trans with easy spring and modified shift shaft/shift star from FAST Getting back to my pipe selection. It seems as though the mainstream pipes such as Pro-circuits, FMFs and T5s lack the ability to support the flow of a well-designed 421. I've seen dyno charts of CPIs and Shearers pulling sooner than T5s and FMFs, whild destroying them on top. As for the rest of the bike, I've already installed +2+1 arms with PEPs triple rate shocks w/rezzies on the front. The brakes are off of a YFZ450. For the rear, I've purchased a +2 roundhouse swinger and +4 axle. For my riding style, I still depend on tight turns and hit jumps and water breaks so I need to be conservative with the length of my swingarm. The rear shock will be sent to MattSCESC so that he can tailor it to the swingarm and riding style. Now, what type of riding do you do? While this set up is going to kick ass for me, it might be all wrong for you.

Interested in the GYTR programmed CDI. Anyone have information reguarding its performance or reliability?

This is quite the rant thread! haha, never-the-less I enjoyed the frustrations.

So, you took a melted piston and put it in a good cylinder? And then you took the good piston and switched that to a blown cylinder? You cannot just hone one cylinder and use melted pistons... you need to have both jugs machined again and start over with new pistons and rings.

Contact MattSCESC. Or, you can go to socalsuspensionsystems.com and find him there. He'll give you several options all at very fair prices.

You need to run two or maybe even three boost bottles for 70hp.

Thack, I think you might be over-estimating your power a bit. With your bolt-ons, I will guess you are in the 45 to 49hp area. To get to 65hp, porting is a must. With a 54mm stroke, the porting will have to me slightly more aggressive to make that number. With a 58mm crankshaft your powerband will be broad and smooth. Also, the added stroke will enhance the bikes performance below the "pipe".

Big thanks to S-oregon for a great deal on a nice set of pipes. This thread may be deleted now.

Hey guys, I'm looking for a set of standard size CPI in-frame pipes with decent chrome. Please PM me if you have a set or know of a set that you can part with. I'm located in Albany, Wisconsin 53502. PS: I see a lot of you cpi guys wanting to switch R2s! I can help fund it! lol Anyway, thanks for looking! Jimmy

Building a 421 serval for my bike. A +6 would be too much since I need to be able to turn swiftly and be airborn quite a bit. I've been looking for a well built +2 for quite a while now. Thanks again!

Thanks for a quick and painless sale! Looking forward to the mailman.

I'll trade you some tasty drugs... oh, and I'll throw in an English Dictionary, too. You do understand that your thread is now trashed because of your behavior and child-like grammer. Hell, your reputation has been soured because of the posts you decided to share with us. Keep your stock, or cub, or cheetah banshee (not sure what engine you have in it today). I'm just wondering, does your camaro really have a stroked 632 BBC mated to a powerglide? Or is it really just a stock iron headed 350 with a hot cam and a TH350? lol

Cut down knobbies at 30psi! lol, okay, I'll quit screwing around. To the OP, the primary gears are the set of gears that drive the clutch basket from the crank. You can replace the drive gear on the crank and the driven gear behind the basket with a 2.68:1 straight cut set. If you find yourself with a huge front sprocket (like a 17 tooth) then you might want to consider this as an option. But, if you have stock gearing just play around with your sprockets. I'm curious though, why do you want to go faster? Off road it gets, umm, "exciting" when I'm pegged in 6th. Unless you have balanced tires, anything over 75mph is going to start shaking and wobbling. When we all race, its the acceleration that wins the race. And, although some wide open places I can get into 6th, I'm not there very long.

I tried to PM you but it wouldn't let me. Any chance I could get a couple shots of the swinger sent to [email protected]?

Dude, thats way slow. Not to brag, but mine will pull 70.7428374812943 no prob.

EGT probes are the sensors that measure exhaust gas tempurature within the exhaust pipe. The gauge, well that just interprets the probe so that you can read it. If you really want to monitor your exhaust gas tempurature then find a spot to mount the gauge... otherwise you should just consider plugging the holes with something very shallow or by welding them shut.. Just curious, where were the holes drilled into the pipe?